CN116329261B - Method for treating hexavalent chromium pollution building rubbish - Google Patents
Method for treating hexavalent chromium pollution building rubbish Download PDFInfo
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- CN116329261B CN116329261B CN202310299453.8A CN202310299453A CN116329261B CN 116329261 B CN116329261 B CN 116329261B CN 202310299453 A CN202310299453 A CN 202310299453A CN 116329261 B CN116329261 B CN 116329261B
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- hexavalent chromium
- solid
- soaking
- liquid mixture
- foaming agent
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- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 title claims abstract description 88
- 238000000034 method Methods 0.000 title claims abstract description 54
- 239000010813 municipal solid waste Substances 0.000 title description 6
- 239000007788 liquid Substances 0.000 claims abstract description 79
- 239000002699 waste material Substances 0.000 claims abstract description 70
- 239000000203 mixture Substances 0.000 claims abstract description 66
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 56
- 238000010276 construction Methods 0.000 claims abstract description 53
- 238000002791 soaking Methods 0.000 claims abstract description 41
- 239000004088 foaming agent Substances 0.000 claims abstract description 34
- 238000002604 ultrasonography Methods 0.000 claims abstract description 33
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 21
- 238000002156 mixing Methods 0.000 claims abstract description 21
- 235000003891 ferrous sulphate Nutrition 0.000 claims description 25
- 239000011790 ferrous sulphate Substances 0.000 claims description 25
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 claims description 21
- 229910000359 iron(II) sulfate Inorganic materials 0.000 claims description 21
- 239000000463 material Substances 0.000 claims description 21
- 239000007790 solid phase Substances 0.000 claims description 17
- 239000003945 anionic surfactant Substances 0.000 claims description 15
- DBMJMQXJHONAFJ-UHFFFAOYSA-M Sodium laurylsulphate Chemical group [Na+].CCCCCCCCCCCCOS([O-])(=O)=O DBMJMQXJHONAFJ-UHFFFAOYSA-M 0.000 claims description 14
- 238000009210 therapy by ultrasound Methods 0.000 claims description 12
- 238000000926 separation method Methods 0.000 claims description 10
- GVGUFUZHNYFZLC-UHFFFAOYSA-N dodecyl benzenesulfonate;sodium Chemical compound [Na].CCCCCCCCCCCCOS(=O)(=O)C1=CC=CC=C1 GVGUFUZHNYFZLC-UHFFFAOYSA-N 0.000 claims description 9
- 229940080264 sodium dodecylbenzenesulfonate Drugs 0.000 claims description 9
- AKHNMLFCWUSKQB-UHFFFAOYSA-L sodium thiosulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=S AKHNMLFCWUSKQB-UHFFFAOYSA-L 0.000 claims description 3
- 235000019345 sodium thiosulphate Nutrition 0.000 claims description 3
- BDHFUVZGWQCTTF-UHFFFAOYSA-M sulfonate Chemical compound [O-]S(=O)=O BDHFUVZGWQCTTF-UHFFFAOYSA-M 0.000 claims description 3
- DPLVEEXVKBWGHE-UHFFFAOYSA-N potassium sulfide Chemical compound [S-2].[K+].[K+] DPLVEEXVKBWGHE-UHFFFAOYSA-N 0.000 claims description 2
- 229910052979 sodium sulfide Inorganic materials 0.000 claims description 2
- GRVFOGOEDUUMBP-UHFFFAOYSA-N sodium sulfide (anhydrous) Chemical compound [Na+].[Na+].[S-2] GRVFOGOEDUUMBP-UHFFFAOYSA-N 0.000 claims description 2
- 125000001273 sulfonato group Chemical group [O-]S(*)(=O)=O 0.000 claims 1
- 230000000694 effects Effects 0.000 abstract description 15
- 230000002035 prolonged effect Effects 0.000 abstract description 5
- 239000003814 drug Substances 0.000 abstract description 3
- 238000009270 solid waste treatment Methods 0.000 abstract description 2
- 230000000052 comparative effect Effects 0.000 description 21
- 238000002386 leaching Methods 0.000 description 18
- 239000000243 solution Substances 0.000 description 15
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 14
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 14
- 238000001914 filtration Methods 0.000 description 14
- 239000007864 aqueous solution Substances 0.000 description 13
- 229940083575 sodium dodecyl sulfate Drugs 0.000 description 13
- 235000019333 sodium laurylsulphate Nutrition 0.000 description 13
- 235000014113 dietary fatty acids Nutrition 0.000 description 7
- 239000000194 fatty acid Substances 0.000 description 7
- 229930195729 fatty acid Natural products 0.000 description 7
- 150000002191 fatty alcohols Chemical class 0.000 description 6
- 238000000527 sonication Methods 0.000 description 6
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 5
- 125000004432 carbon atom Chemical group C* 0.000 description 5
- -1 fatty acid salt Chemical class 0.000 description 5
- 150000004665 fatty acids Chemical class 0.000 description 5
- 239000007791 liquid phase Substances 0.000 description 5
- 229910017604 nitric acid Inorganic materials 0.000 description 5
- 229940051841 polyoxyethylene ether Drugs 0.000 description 5
- 229920000056 polyoxyethylene ether Polymers 0.000 description 5
- 150000003467 sulfuric acid derivatives Chemical class 0.000 description 5
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 4
- 229910019142 PO4 Inorganic materials 0.000 description 4
- 239000010452 phosphate Substances 0.000 description 4
- 239000013043 chemical agent Substances 0.000 description 3
- 239000003795 chemical substances by application Substances 0.000 description 3
- 229910052804 chromium Inorganic materials 0.000 description 3
- 239000011651 chromium Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 239000002910 solid waste Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- ACIAHEMYLLBZOI-ZZXKWVIFSA-N Unsaturated alcohol Chemical compound CC\C(CO)=C/C ACIAHEMYLLBZOI-ZZXKWVIFSA-N 0.000 description 2
- 125000000217 alkyl group Chemical group 0.000 description 2
- JBIROUFYLSSYDX-UHFFFAOYSA-M benzododecinium chloride Chemical compound [Cl-].CCCCCCCCCCCC[N+](C)(C)CC1=CC=CC=C1 JBIROUFYLSSYDX-UHFFFAOYSA-M 0.000 description 2
- 239000003093 cationic surfactant Substances 0.000 description 2
- 239000004568 cement Substances 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 150000001844 chromium Chemical class 0.000 description 2
- 239000000356 contaminant Substances 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- ZODDGFAZWTZOSI-UHFFFAOYSA-N nitric acid;sulfuric acid Chemical compound O[N+]([O-])=O.OS(O)(=O)=O ZODDGFAZWTZOSI-UHFFFAOYSA-N 0.000 description 2
- 239000002736 nonionic surfactant Substances 0.000 description 2
- 230000000149 penetrating effect Effects 0.000 description 2
- 239000012466 permeate Substances 0.000 description 2
- 238000005375 photometry Methods 0.000 description 2
- 239000002574 poison Substances 0.000 description 2
- 231100000614 poison Toxicity 0.000 description 2
- RYYKJJJTJZKILX-UHFFFAOYSA-M sodium octadecanoate Chemical compound [Na+].CCCCCCCCCCCCCCCCCC([O-])=O RYYKJJJTJZKILX-UHFFFAOYSA-M 0.000 description 2
- DAJSVUQLFFJUSX-UHFFFAOYSA-M sodium;dodecane-1-sulfonate Chemical compound [Na+].CCCCCCCCCCCCS([O-])(=O)=O DAJSVUQLFFJUSX-UHFFFAOYSA-M 0.000 description 2
- 150000003871 sulfonates Chemical class 0.000 description 2
- 239000001117 sulphuric acid Substances 0.000 description 2
- 235000011149 sulphuric acid Nutrition 0.000 description 2
- 231100000419 toxicity Toxicity 0.000 description 2
- 230000001988 toxicity Effects 0.000 description 2
- 238000004383 yellowing Methods 0.000 description 2
- 239000004711 α-olefin Substances 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 1
- 206010020751 Hypersensitivity Diseases 0.000 description 1
- 206010027336 Menstruation delayed Diseases 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 125000005037 alkyl phenyl group Chemical group 0.000 description 1
- 229940045714 alkyl sulfonate alkylating agent Drugs 0.000 description 1
- 150000008052 alkyl sulfonates Chemical class 0.000 description 1
- 208000026935 allergic disease Diseases 0.000 description 1
- 230000007815 allergy Effects 0.000 description 1
- 238000003321 atomic absorption spectrophotometry Methods 0.000 description 1
- 238000002419 base digestion Methods 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 239000011449 brick Substances 0.000 description 1
- 239000004566 building material Substances 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 230000000711 cancerogenic effect Effects 0.000 description 1
- 231100000315 carcinogenic Toxicity 0.000 description 1
- 238000009713 electroplating Methods 0.000 description 1
- SFNALCNOMXIBKG-UHFFFAOYSA-N ethylene glycol monododecyl ether Chemical compound CCCCCCCCCCCCOCCO SFNALCNOMXIBKG-UHFFFAOYSA-N 0.000 description 1
- 238000011010 flushing procedure Methods 0.000 description 1
- 230000009395 genetic defect Effects 0.000 description 1
- 239000003673 groundwater Substances 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 230000002045 lasting effect Effects 0.000 description 1
- 231100001231 less toxic Toxicity 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 150000003013 phosphoric acid derivatives Chemical class 0.000 description 1
- 238000005554 pickling Methods 0.000 description 1
- 229920001021 polysulfide Polymers 0.000 description 1
- 239000005077 polysulfide Substances 0.000 description 1
- 150000008117 polysulfides Polymers 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- XAEFZNCEHLXOMS-UHFFFAOYSA-M potassium benzoate Chemical compound [K+].[O-]C(=O)C1=CC=CC=C1 XAEFZNCEHLXOMS-UHFFFAOYSA-M 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000007873 sieving Methods 0.000 description 1
- 159000000000 sodium salts Chemical class 0.000 description 1
- XDFGPVSVSMWVQE-UHFFFAOYSA-M sodium;dodecanoic acid;hydrogen sulfate Chemical compound [Na+].OS([O-])(=O)=O.CCCCCCCCCCCC(O)=O XDFGPVSVSMWVQE-UHFFFAOYSA-M 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 239000002352 surface water Substances 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
- 238000004065 wastewater treatment Methods 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09B—DISPOSAL OF SOLID WASTE NOT OTHERWISE PROVIDED FOR
- B09B3/00—Destroying solid waste or transforming solid waste into something useful or harmless
- B09B3/80—Destroying solid waste or transforming solid waste into something useful or harmless involving an extraction step
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/58—Construction or demolition [C&D] waste
Landscapes
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
The invention relates to the field of solid waste treatment, and discloses a method for treating hexavalent chromium-polluted construction waste. The method comprises the following steps: (1) Mixing hexavalent chromium-contaminated construction waste with a foaming agent and optionally water to obtain a first solid-liquid mixture, performing first ultrasound, and then removing the foaming agent; (2) Mixing the hexavalent chromium-polluted building waste treated in the step (1) with a reducing agent and optional water to obtain a second solid-liquid mixture, and soaking; wherein at least part of the time of soaking is performed under a second ultrasound. By adopting the method, a better hexavalent chromium removal effect can be obtained, the dosage of the medicament does not need to be increased or the soaking time is prolonged, and the treatment efficiency is higher.
Description
Technical Field
The invention relates to the field of solid waste treatment, in particular to a method for treating hexavalent chromium-polluted construction waste.
Background
Hexavalent chromium pollution mainly comes from industries such as chromium salt, electroplating and the like, and the leak hexavalent chromium usually migrates along with groundwater and surface water, so that the site pollution of production enterprises is caused. Hexavalent chromium is a yellow substance, has strong oxidizing property, is a swallow poison/inhalant extreme poison, can cause allergy when being contacted with skin, is more likely to cause genetic defects, can be carcinogenic when being inhaled, and has lasting danger to the environment. In hexavalent chromium pollution site treatment, not only is the polluted soil required to be treated, but also the polluted building garbage generated by dismantling equipment and construction buildings is required to be emphasized. Because hexavalent chromium has strong water solubility, hexavalent chromium can climb upwards along the wall surface of a building under the capillary action of rainwater, flushing water and the like, and can permeate into the building material through pores under the long-term soaking action, so that the surface and the inside of the wall body are yellow due to year-by-year enrichment. Hexavalent chromium in the construction waste is released to the environment under specific conditions, so that the hexavalent chromium pollutes the construction waste with high hazard.
How to make hexavalent chromium harmless is the key of the absorption and disposal of hexavalent chromium pollution building rubbish. In the existing hexavalent chromium harmless technology, pickling is one of the common methods, and mainly uses clear water or a chemical agent (such as acid, alkali, ferrous sulfate and calcium polysulfide) solution to soak the construction waste. Hexavalent chromium on the surface of the construction waste is easy to remove, but hexavalent chromium which permeates into the construction waste is difficult to remove, so that repair is difficult to reach the standard. In addition, the undetached hexavalent chromium in the construction waste slowly seeps out, and a yellowing phenomenon occurs (namely, the repaired solid hexavalent chromium pollution medium has hexavalent chromium on the surface after being stored for a period of time, and the hexavalent chromium is yellow). In order to remove hexavalent chromium to reach the standard, the dosage of a reducing agent is generally required to be increased, the soaking time is prolonged, the dosage of the agent is increased, the treatment efficiency is reduced, and a good removing effect on the construction waste with higher hexavalent chromium content is still difficult to obtain.
Therefore, there is a need to develop a treatment method which is suitable for the treatment of hexavalent chromium-contaminated construction waste, and which is less in the amount of chemicals, higher in efficiency and better in the removal effect.
Disclosure of Invention
The invention aims to overcome the problems in the prior art and provide a method for treating hexavalent chromium-polluted construction waste, by adopting the method, a better hexavalent chromium removal effect can be obtained, the dosage of a medicament does not need to be increased or the soaking time does not need to be prolonged, and the treatment efficiency is higher.
In order to achieve the above object, the present invention provides a method for treating hexavalent chromium-contaminated construction waste, comprising:
(1) Mixing hexavalent chromium-contaminated construction waste with a foaming agent and optionally water to obtain a first solid-liquid mixture, performing first ultrasound, and then removing the foaming agent;
(2) Mixing the hexavalent chromium-polluted building waste treated in the step (1) with a reducing agent and optional water to obtain a second solid-liquid mixture, and soaking;
wherein at least part of the time of soaking is performed under a second ultrasound.
Through the technical scheme, a better hexavalent chromium removing effect can be obtained, and the dosage of the medicament does not need to be increased or the soaking time does not need to be prolonged. The method provided by the invention can be used for fully removing hexavalent chromium on the surface of the construction waste, and can obtain a good removal effect on hexavalent chromium permeated into the construction waste. The method can lead the construction waste polluted by hexavalent chromium to reach the repair requirement in a shorter time, or obviously improve the hexavalent chromium removal effect in the same time.
Detailed Description
The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.
The invention provides a method for treating hexavalent chromium-polluted construction waste, which comprises the following steps:
(1) Mixing hexavalent chromium-contaminated construction waste with a foaming agent and optionally water to obtain a first solid-liquid mixture, performing first ultrasound, and then removing the foaming agent;
(2) Mixing the hexavalent chromium-polluted building waste treated in the step (1) with a reducing agent and optional water to obtain a second solid-liquid mixture, and soaking;
wherein at least part of the time of soaking is performed under a second ultrasound.
For the treatment of hexavalent chromium polluted construction waste, the traditional technology adopts a mode of directly soaking the construction waste by clean water or chemical agents, however, hexavalent chromium permeated into the construction waste is difficult to remove, so that the removal effect is generally improved by adopting a mode of increasing the dosage of the agents or prolonging the soaking time. However, such a treatment method is not only large in dosage of the chemical agent, high in cost, but also long in time, low in efficiency, and unsatisfactory in removal effect. However, the inventor of the present invention found in the research that if the above method provided by the present invention is adopted, the pretreatment of step (1) is performed on hexavalent chromium-contaminated construction waste, and then the reducing agent reduction method is adopted, so that chromium on the surface and in the interior of the construction waste can be sufficiently removed, and no special increase of the dosage of the agent or the prolonged soaking time is required, the cost is lower, and the efficiency is higher. In addition, hexavalent chromium permeated into the construction waste is sufficiently removed, and the phenomenon of 'yellowing' of the construction waste in the later stage after the construction waste is treated in the traditional mode is avoided. The step-by-step treatment mode can also separate the foaming agent and ferrous sulfate for reuse, saves the treatment cost and reduces the difficulty of subsequent wastewater treatment.
Wherein, the construction waste can be in the form of cement blocks, building blocks or bricks, etc.
According to the present invention, in order to further enhance the removal effect of hexavalent chromium, it is preferable that the hexavalent chromium-contaminated construction waste has a block diameter of 3cm or less. The construction waste with the target block diameter can be obtained through sieving, for example, materials which can pass through a sieve with a sieve mesh size of 3cm are taken, and the block diameter of the materials is less than or equal to 3cm. More preferably, the hexavalent chromium pollutes the building rubbish, and the block diameter is less than or equal to 2cm (for example, the material which can pass through a sieve with the mesh size of 2cm can be taken). Generally, the hexavalent chromium-contaminated construction waste obtained from the contaminated site has a larger mass diameter than the above-mentioned range, and the hexavalent chromium-contaminated construction waste may be crushed into the above-mentioned range.
According to the invention, preferably, the hexavalent chromium pollution building waste has a mass content of hexavalent chromium of 20-1000mg/kg. More preferably, the hexavalent chromium is present in the hexavalent chromium-contaminated construction waste in a mass content of 40-500mg/kg (for example, 40mg/kg, 42mg/kg, 45mg/kg, 50mg/kg, 100mg/kg, 200mg/kg, 250mg/kg, 270mg/kg, 300mg/kg, 400mg/kg, 450mg/kg, 500mg/kg, and any two or more values thereof may form a range and a range of values). The scheme of the invention is particularly suitable for treating the hexavalent chromium-polluted building waste, and can obtain better effect on the hexavalent chromium-polluted building waste meeting the range. Hexavalent chromium the leaching concentration of hexavalent chromium contaminating the construction waste may be 2-100mg/L (e.g., may be 2mg/L, 3mg/L, 4mg/L, 10mg/L, 20mg/L, 25mg/L, 30mg/L, 40mg/L, 50mg/L, 60mg/L, 70mg/L, 80mg/L, 90mg/L, 100mg/L, and any two of the above values may form a range and a range of values). The determination of leaching concentration can be carried out by leaching hexavalent chromium according to the method in sulfuric acid nitric acid method (HJT-299-2007) of solid waste leaching toxicity leaching method, and then determining the concentration of hexavalent chromium in the leaching solution by adopting the method in flow injection-diphenylcarbodihydrazide photometry (HJ 908-2017) of determination of hexavalent chromium in water quality.
According to the present invention, preferably, the foaming agent is selected from one of an anionic surfactant, a cationic surfactant, or a nonionic surfactant. Wherein the cationic surfactant can be dodecyl dimethyl benzyl ammonium chloride. The nonionic surfactant can be specifically fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether and fatty acid polyoxyethylene ether, and the structural unit from the fatty alcohol, the alkyl or the fatty acid can have 9-24 carbon atoms.
According to a particularly preferred embodiment of the invention, the foaming agent is selected from anionic surfactants. The inventors of the present invention have further found that the anionic surfactant is better able to match the first ultrasound, and thus the subsequent steps, to obtain a better hexavalent chromium removal effect.
According to the present invention, preferably, the anionic surfactant is selected from at least one of a fatty acid salt type anionic surfactant, a sulfate salt type anionic surfactant, a phosphate salt type anionic surfactant, and a sulfonate type anionic surfactant. Wherein the fatty acid salt type anionic surfactant has 9 to 24 carbon atoms in the structural unit derived from a fatty acid, and may be a corresponding sodium salt or potassium salt, for example, sodium stearate. The sulfate salt type anionic surfactant generally includes a fatty alcohol sulfate salt, a fatty alcohol polyoxyethylene ether sulfate salt, a sulfate salt of a fatty acid derivative, a sulfate salt of an unsaturated alcohol, and the like, wherein the number of carbon atoms of the structural unit derived from a fatty alcohol, or a fatty acid derivative, or an unsaturated alcohol may be 9 to 24 each independently, and for example, sodium laurate sulfate may be used. The phosphate type anionic surfactant generally includes fatty alcohol phosphate and fatty alcohol polyoxyethylene ether phosphate, and the number of carbon atoms of the structural unit derived from the fatty alcohol may be 9 to 24, and may be, for example, zinc laureth phosphate. The sulfonate type anionic surfactants generally include alkylbenzenesulfonates, alkylsulfonates, alpha-olefin sulfonates, alkylnaphthalene sulfonates, etc., and the number of carbon atoms of the structural units derived from the above-mentioned alkylphenyl, alkyl, alpha-olefin, alkylnaphthalene may be 9 to 24.
According to a particularly preferred embodiment of the invention, the foaming agent is a sulfonate-type anionic surfactant selected from sodium dodecyl sulfate and/or sodium dodecyl benzene sulfonate. Can be a mixture of sodium dodecyl sulfonate and sodium dodecyl benzene sulfonate, which can be mixed in any proportion, for example, the mass ratio of the sodium dodecyl sulfonate to the sodium dodecyl benzene sulfonate can be 1:0.1-10.
According to the present invention, it is preferable that the mass concentration of the foaming agent in the liquid in the first solid-liquid mixture is 2 to 6wt% (for example, may be 2wt%, 3wt%, 4wt%, 5wt%, 6 wt%). The inventors of the present invention have further found that, within the above-mentioned range, the foaming agent can better cooperate with ultrasound, thereby better cooperate with the subsequent steps, and more sufficiently remove hexavalent chromium, particularly hexavalent chromium penetrating into the interior of the construction waste. More preferably, the mass concentration of the foaming agent in the liquid in the first solid-liquid mixture is 3-5wt%.
According to the invention, in the step (1), preferably, the mass and the usage ratio of hexavalent chromium to the construction waste to the foaming agent are 1: (0.01-0.09), more preferably 1: (0.03-0.05). So that the foaming agent can be better matched with ultrasound, and the subsequent steps can be better matched, and hexavalent chromium, in particular hexavalent chromium permeated into the construction waste, can be more fully removed.
The amount of water in the first solid-liquid mixture can be determined according to the mass concentration of the foaming agent and the mass usage ratio of hexavalent chromium to the building waste and the foaming agent. It will be appreciated that the foaming agent may be used in solid form or may be formulated as an aqueous solution and used in aqueous solution, and if it is used in aqueous solution of the foaming agent and the water content in the aqueous solution is sufficient to meet the water content in the first solid-liquid mixture, in step (1), it is only necessary to mix hexavalent chromium-contaminated construction waste with the aqueous solution of the foaming agent and not to add water.
According to the present invention, preferably, in the step (1), the means for removing the foaming agent comprises: and (3) carrying out solid-liquid separation on the material after the first ultrasonic treatment, mixing the obtained solid phase and water (the mass and the dosage ratio of the solid phase to the water can be 1 (0.7-2)), carrying out third ultrasonic treatment, and carrying out solid-liquid separation on the material after the third ultrasonic treatment again. The solid-liquid separation may be performed by filtration. The conditions of the third ultrasound are not particularly limited, and for example, the frequency may be 20 to 40kHz (for example, may be a range and a value within a range formed of any two of 20kHz, 23kHz, 25kHz, 30kHz, 35kHz, 40kHz and above), the power may be 0.1 to 0.5W/g of the mixture (for example, may be a range and a value within a range formed of any two of 0.1W/g of the mixture, 0.15W/g of the mixture, 0.2W/g of the mixture, 0.25W/g of the mixture, 0.3W/g of the mixture, 0.4W/g of the mixture, 0.5W/g of the mixture and any two of the above) and the time may be 3 to 10min (for example, may be 3min, 4min, 5min, 6min, 7min, 8min, 9min, 10min and a range and a value within a range and within a range formed of any two of the above). Therefore, the foaming agent can be more fully separated and removed, the foaming agent can be reused, the wastewater production amount can be reduced, and the treatment difficulty is reduced.
According to the invention, preferably, before performing step (2), the method further comprises: mixing the hexavalent chromium-contaminated construction waste treated in the step (1) with water, and adjusting the pH of the mixture to 4 to 5 (for example, the pH may be 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5 and any two values thereof may be formed in a range and a value within a range), and then performing solid-liquid separation. The mass and consumption ratio of hexavalent chromium-polluted building rubbish and water treated in the step (1) can be 1: (0.7-2). The inventors of the present invention have further found that by performing this step prior to treatment with the reducing agent, it is possible to avoid that when the reducing agent reduces hexavalent chromium to trivalent chromium, the trivalent chromium forms hydroxide precipitates, thereby blocking the channels in the construction waste and hindering the subsequent reduction, and by adopting this step hexavalent chromium can be removed more sufficiently. Generally, after hexavalent chromium is mixed with construction waste and water, the liquid portion becomes alkaline, and sulfuric acid, hydrochloric acid or nitric acid may be used to adjust the pH to the above range.
According to the invention, in the step (2), preferably, the mass and the dosage ratio of the hexavalent chromium-polluted building waste treated in the step (1) to the reducing agent are 1: (0.01-0.1), more preferably 1: (0.015-0.04). It will be appreciated that the use of a reducing agent allows the reduction of the more toxic hexavalent chromium to the less toxic trivalent chromium.
According to the present invention, preferably, the reducing agent is selected from at least one of ferrous sulfate, sodium thiosulfate, sodium sulfide and potassium sulfide.
Wherein in step (2), mixing is just completed, and the mass concentration of the reducing agent in the liquid of the resulting second solid-liquid mixture may be 1 to 10wt% (for example, may be 1wt%, 2wt%, 2.2wt%, 2.5wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt% and values within a range and range formed by any two of the above), particularly 2 to 4wt%.
The water content in the second solid-liquid mixture can be determined according to the mass concentration of the reducing agent and the mass dosage ratio of hexavalent chromium to the building waste and the reducing agent. The reducing agent may be used in the form of a solid powder thereof, or may be formulated into an aqueous solution and used in the form of an aqueous solution. If the reducing agent is used in the form of an aqueous solution thereof and the water content in the aqueous solution can meet the water content in the second solid-liquid mixture, in the step (2), the hexavalent chromium-polluted building waste treated in the step (1) is only mixed with the reducing agent, and water is not required to be added.
According to the present invention, preferably, in the step (2), the soaking time is 20 to 72 hours, more preferably 25 to 40 hours (for example, 25 hours, 26 hours, 28 hours, 30 hours, 32 hours, 34 hours, 36 hours, 38 hours, 40 hours, and any two values thereof form a range and a value within a range).
According to the present invention, it is preferable that the soaking is performed under a condition of pH.ltoreq.5 (more preferably pH 4.5 to 5). During the soaking process, the pH of the liquid is monitored, if the pH deviates (the pH value of the liquid tends to be larger in general), and sulfuric acid, hydrochloric acid or nitric acid can be used for adjusting the pH to the range. It will be appreciated that ferrous sulphate is generally currently being prepared, and that sulphuric acid is typically added to inhibit the hydrolysis of ferrous iron when preparing the ferrous sulphate solution, and in order to not unduly deviate from the above pH range for the initial state of the second solid-liquid mixture, sulphuric acid is added to bring the pH of the ferrous sulphate solution within the above range when preparing the ferrous sulphate solution.
The soaking period may be performed under the second ultrasonic wave only for a part of the time (the part of the time may be in any period of soaking, for example, the ultrasonic wave may be intermittently turned on in the early or late period of soaking, or during the soaking), or the ultrasonic wave may be turned on throughout the soaking. Preferably, however, the soaking mode is as follows: and (3) soaking the second solid-liquid mixture under the second ultrasonic, then turning off the second ultrasonic, and finally soaking. The inventor of the present invention found in the study that if the above-mentioned manner is used for soaking, not only can the cost be saved, but also a better hexavalent chromium removal effect can be obtained.
According to the present invention, in order to be able to further ensure that a better hexavalent chromium removal effect is obtained in a shorter time, it is preferable that the conditions of the first ultrasound include: the frequency is 15-30kHz (e.g., may be 15kHz, 17kHz, 19kHz, 20kHz, 21kHz, 22kHz, 23kHz, 24kHz, 25kHz, 27kHz, 29kHz, 30kHz, and any two values above) and the power is 0.1-0.3W/g of the first solid-liquid mixture for 15-150 minutes (e.g., may be 15 minutes, 20 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes, 65 minutes, 70 minutes, 75 minutes, 80 minutes, 85 minutes, 90 minutes, 100 minutes, 120 minutes, 140 minutes, 150 minutes, and any two values above).
According to the present invention, preferably, the conditions of the second ultrasound include: the frequency is 15-30kHz (e.g., may be 15kHz, 17kHz, 19kHz, 20kHz, 21kHz, 22kHz, 23kHz, 24kHz, 25kHz, 27kHz, 29kHz, 30kHz, and any two values above) and the power is 0.1-0.3W/g of the second solid-liquid mixture for 15-150 minutes (e.g., may be 15 minutes, 20 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes, 65 minutes, 70 minutes, 75 minutes, 80 minutes, 85 minutes, 90 minutes, 100 minutes, 120 minutes, 140 minutes, 150 minutes, and any two values above).
More preferably, the conditions of the first ultrasound include: the frequency is 20-25kHz, the power is 0.15-0.25W/g of the first solid-liquid mixture, and the time is 30-45min.
More preferably, the conditions of the second ultrasound include: the frequency is 20-25kHz, the power is 0.15-0.25W/g of the second solid-liquid mixture, and the time is 45-90min.
The soaking after the second ultrasound is turned off may be performed for 24-60 hours (for example, 24 hours, 26 hours, 28 hours, 30 hours, 35 hours, 40 hours, 45 hours, 50 hours, 55 hours, 60 hours, and any two values thereof may form a range and a value within a range).
According to the invention, preferably, the method further comprises: and (3) carrying out solid-liquid separation on the material treated in the step (2). The solid-liquid separation mode can be filtration.
The inventors of the present invention have also found in the study that, when hexavalent chromium-contaminated construction waste is treated by the method provided by the present invention, water used, for example, water used when preparing an aqueous foaming agent solution or an aqueous reducing agent solution, water used when removing the foaming agent, and water used when mixing and adjusting pH of hexavalent chromium-contaminated construction waste treated in the step (1) before the step (2), are preferably both water which is freshly boiled and cooled to normal temperature. The inventors of the present invention have unexpectedly found that with the water thus treated, it is possible to further ensure sufficient removal of hexavalent chromium from hexavalent chromium-contaminated construction waste.
The present invention will be described in detail by examples.
In the following examples, hexavalent chromium-contaminated construction waste samples A, B, C and D were obtained from retired chromium salt production sites in Jinan, shandong province, and were cement blocks, which were yellow on the surface and light yellow inside after knocked out.
The construction waste is polluted by hexavalent chromium which is not treated and is treated by the method provided by the invention: determining the content of hexavalent chromium by adopting a solid waste hexavalent chromium determination alkali digestion flame atomic absorption spectrophotometry (HJ 687-2014); hexavalent chromium is leached according to the method in sulfuric acid nitric acid method (HJT 299-2007) of solid waste leaching toxicity leaching method, and the concentration of hexavalent chromium in the leaching solution is detected according to the method in flowing injection-diphenylcarbodihydrazide photometry (HJ 908-2017) of determination of water quality hexavalent chromium, so that the leaching concentration of hexavalent chromium is obtained.
According to measurement, in the sample A, the hexavalent chromium content is 42mg/kg, and the leaching concentration of the hexavalent chromium is 3.9mg/L;
in the sample B, the hexavalent chromium content is 458mg/kg, and the leaching concentration of hexavalent chromium is 43.6mg/L;
in the sample C, the hexavalent chromium content is 969mg/kg, and the leaching concentration of the hexavalent chromium is 89.3mg/L;
in sample D, the hexavalent chromium content was 272mg/kg, and the hexavalent chromium leaching concentration was 25.6mg/L.
Sulfuric acid, nitric acid and hydrochloric acid, all purchased from the metallocene chemical reagent plant in the Tianjin city;
ferrous sulfate, analytically pure, purchased from national pharmaceutical community chemical reagent limited;
sodium dodecyl sulfate, analytically pure, purchased from cantonese biotechnology limited;
sodium dodecylbenzenesulfonate, analytically pure, purchased from the company of the chemical industry, division of the tin-free city.
In the following examples and comparative examples, unless otherwise specified, water was used ， Is water which is freshly boiled and just cooled to normal temperature.
In the following examples and comparative examples, the reducing agent solution used was also prepared using water which was freshly boiled and cooled to normal temperature, and was adjusted to pH 4.5-5 with sulfuric acid.
Example 1
(1) Sample a was crushed to a size that allowed to pass through a sieve having a mesh size of 0.8cm (i.e., crushed to a mass diameter of 0.8cm or less), and the crushed sample a was mixed with an aqueous solution of sodium dodecyl sulfate so that the mass concentration of sodium dodecyl sulfate was 4wt% in the liquid of the obtained first solid-liquid mixture, and the mass usage ratio of sample a to sodium dodecyl sulfate was 1:0.04. subjecting the first solid-liquid mixture to a first ultrasound, the conditions of the first ultrasound comprising: the frequency was 20kHz, the power was 0.2W/g of the first solid-liquid mixture, and the time was 30 minutes.
After the end of the first sonication, the material was filtered to remove the liquid, then water was added to the solid phase (mass ratio of solid phase to water 1:1) to give a mixture, and a third sonication (frequency 20kHz, power 0.2W/g mixture, time 4 min) was performed. And filtering the material after the third ultrasonic treatment.
The solid phase obtained after filtration was mixed with water (mass ratio of solid phase to water: 1:1) and adjusted to pH 5 with hydrochloric acid. The liquid was then removed by filtration.
(2) Mixing the sample A treated in the step (1) with a ferrous sulfate solution, so that the mass and the dosage ratio of the sample A treated in the step (1) to the ferrous sulfate is 1:0.02, and the mass concentration of ferrous sulfate in the liquid of the resulting second solid-liquid mixture was 2wt%.
After the mixing is completed, starting ultrasonic waves, and soaking the second solid-liquid mixture under the second ultrasonic waves, wherein the conditions of the second ultrasonic waves comprise: the frequency was 20kHz, the power was 0.2W/g of the second solid-liquid mixture, and the time was 60 minutes. The ultrasound was then turned off and soaked for an additional 24 hours. During the soaking, the pH was monitored and controlled within the range of 4.5-5 (with slight deviations in the period, hydrochloric acid was used to adjust back to the above range).
After the soaking, the materials are filtered to remove the liquid phase.
Example 2
(1) Sample B was crushed to a size capable of passing through a sieve having a mesh size of 1.2cm (crushing to a mass diameter of 1.2cm or less was considered), and the crushed sample B was mixed with an aqueous solution of sodium dodecylbenzenesulfonate so that the mass concentration of sodium dodecylbenzenesulfonate in the liquid of the obtained first solid-liquid mixture was 3wt%, and the mass usage ratio of sample B to sodium dodecylbenzenesulfonate was 1:0.03. subjecting the first solid-liquid mixture to a first ultrasound, the conditions of the first ultrasound comprising: the frequency was 25kHz, the power was 0.25W/g of the first solid-liquid mixture, and the time was 45 minutes.
After the end of the first sonication, the material was filtered to remove the liquid, then water was added to the solid phase (mass ratio of solid phase to water 1:1.5) to give a mixture, and a third sonication (frequency 25kHz, power 0.25W/g mixture, time 3 min) was performed. And filtering the material after the third ultrasonic treatment.
The solid phase obtained after filtration was mixed with water (mass ratio of solid phase to water: 1:1.6) and adjusted to pH 4.8 with sulfuric acid. The liquid was then removed by filtration.
(2) Mixing the sample B treated in the step (1) with a ferrous sulfate solution, so that the mass and the dosage ratio of the sample B treated in the step (1) to the ferrous sulfate is 1:0.04, and the mass concentration of ferrous sulfate in the liquid of the obtained second solid-liquid mixture was 4wt%.
Turning on the second ultrasound, the conditions including: the frequency was 25kHz, the power was 0.25W/g of the second solid-liquid mixture, and the time was 90 minutes. The ultrasound was then turned off and soaked for a further 36 hours. During the soaking, the pH was monitored and controlled within the range of 4.5-5 (with slight deviations in the period, the above range was adjusted back with sulfuric acid).
After the end, the material was filtered to remove the liquid phase.
Example 3
(1) Sample A was crushed to pass through a sieve having a mesh size of 0.6cm (crushing to a mass diameter of 0.6cm or less was considered), and an aqueous solution of the crushed sample A and a foaming agent (containing sodium dodecylsulfate and sodium dodecylbenzenesulfonate in a mass ratio of 1:1) were mixed so that the mass concentration of the foaming agent in the liquid of the obtained first solid-liquid mixture was 5% by weight, and the mass usage ratio of sample A and the foaming agent was 1:0.05. subjecting the first solid-liquid mixture to a first ultrasound, the conditions of the first ultrasound comprising: the frequency was 23kHz, the power was 0.15W/g of the first solid-liquid mixture, and the time was 40 minutes.
After the end of the first sonication, the material was filtered to remove the liquid, then water was added to the solid phase (mass ratio of solid phase to water 1:0.8) to give a mixture, and a third sonication (frequency 23kHz, power 0.15W/g mixture, time 6 min) was performed. And filtering the material after the third ultrasonic treatment.
The solid phase obtained after filtration was mixed with water (mass ratio of solid phase to water: 1:0.8) and adjusted to pH 4.6 with nitric acid. The liquid was then removed by filtration.
(2) Mixing the sample A treated in the step (1) with a ferrous sulfate solution, so that the mass and the dosage ratio of the sample A treated in the step (1) to the ferrous sulfate is 1:0.015, and the resulting second solid-liquid mixture has a mass concentration of ferrous sulfate of 2.5wt%.
Turning on the second ultrasound, the conditions including: the frequency was 23kHz, the power was 0.15W/g of the second solid-liquid mixture, and the time was 45 minutes. Then the ultrasound was turned off and soaked for another 30 hours. During the soaking, the pH was monitored and controlled within the range of 4.5-5 (with slight deviations in the period, nitric acid was used to adjust back to the above range).
After the end, the material was filtered to remove the liquid phase.
Example 4
The procedure of example 1 was followed except that sample A was replaced with sample D.
Example 5
The process was followed in accordance with example 2, except that the first and second ultrasound were each at a frequency of 30kHz.
Example 6
The treatment was carried out in accordance with the method of example 1, except that sample A was crushed to pass through a sieve having a mesh size of 2.7cm but not 2.2cm (i.e., 2.2cm < material particle size. Ltoreq.2.7 cm).
Example 7
The procedure of example 1 was followed except that sample A was replaced with sample C.
Example 8
The procedure of example 1 was followed except that sodium dodecyl sulfate was replaced with sodium stearate.
Example 9
The procedure of example 1 was followed except that sodium dodecyl sulfate was replaced with dodecyldimethylbenzyl ammonium chloride.
Example 10
The procedure is as in example 1, except that in step (1), the mass concentration of sodium dodecyl sulfate is 1% by weight, and the mass ratio of sample A to sodium dodecyl sulfate is 1:0.01.
example 11
The process was performed as in example 1, except that in step (2), ultrasound was turned on all the way through the soaking.
Example 12
The treatment was performed in the same manner as in example 1, except that the water used in any of the steps (1) to (2) was not boiled.
Example 13
The procedure of example 1 was followed except that ferrous sulfate was replaced with sodium thiosulfate.
Comparative example 1
Sample A was crushed to pass through a sieve having a mesh size of 0.8cm and then mixed with water (mass ratio of solid phase to water 1:1) and adjusted to pH 5 with hydrochloric acid. The liquid was then removed by filtration.
And then treated in the manner of step (2) in example 1.
Comparative example 2
The treatment was performed in the same manner as in comparative example 1, except that the sample a and the ferrous sulfate solution were mixed such that the mass usage ratio of the sample a and the ferrous sulfate after the treatment in step (1) was 1:0.08, and the mass concentration of ferrous sulfate in the liquid of the resulting second solid-liquid mixture was 8wt%.
Comparative example 3
The treatment was carried out in the same manner as in comparative example 1 except that the second ultrasonic treatment was carried out for 60 minutes, and the ultrasonic treatment was turned off and then the second ultrasonic treatment was carried out for 72 hours.
Comparative example 4
Sample A was crushed to pass through a sieve having a mesh size of 0.8cm and then mixed with water (mass ratio of solid phase to water 1:1) and adjusted to pH 5 with hydrochloric acid. The liquid was then removed by filtration.
Then mixing the sample A with an aqueous solution of sodium dodecyl sulfate and a ferrous sulfate solution so that the mass concentration of the sodium dodecyl sulfate in the mixture is 4wt%, wherein the mass dosage ratio of the sample A to the sodium dodecyl sulfate is 1:0.04, the mass usage ratio of the sample A to the ferrous sulfate is 1:0.02, the mass concentration of ferrous sulfate in the liquid of the mixture was 2wt%.
After the completion of the mixing, the material was treated in the manner of "after the completion of the mixing in step (2) of example 1, after the completion of the soaking by opening ultrasonic … …, and the liquid phase was removed by filtration".
Comparative example 5
The process was followed in example 1, except that the first ultrasound was turned off.
Comparative example 6
The procedure was followed as in example 1, except that the second ultrasound was turned off.
Comparative example 7
Sample a was crushed to pass through a sieve having a mesh size of 0.8cm and then mixed with water so that the mass of the obtained first solid-liquid mixture was the same as that of the first solid-liquid mixture in example 1, and then treated in the manner of "after the first ultrasonic … … soaking of the first solid-liquid mixture was completed, the material was filtered to remove the liquid phase" in example 1.
Comparative example 8
Sample B was taken and treated as in example one of CN 107745001B.
Test case
Hexavalent chromium content and hexavalent chromium leaching concentration were measured for hexavalent chromium-contaminated construction waste treated in the above examples and comparative examples, and the results are shown in table 1.
TABLE 1
| Examples numbering | Hexavalent chromium content (mg/kg) | Hexavalent chromium leaching concentration (mg/L) |
| Example 1 | ND | ND |
| Example 2 | ND | ND |
| Example 3 | ND | ND |
| Example 4 | ND | ND |
| Example 5 | ND | 0.04 |
| Example 6 | ND | 0.06 |
| Example 7 | ND | 0.08 |
| Example 8 | ND | 0.02 |
| Example 9 | ND | 0.04 |
| Example 10 | 2.4 | 0.22 |
| Example 11 | ND | ND |
| Example 12 | ND | 0.04 |
| Example 13 | ND | ND |
| Comparative example 1 | 12.7 | 1.08 |
| Comparative example 2 | 10.9 | 0.96 |
| Comparative example 3 | 11.3 | 1.02 |
| Comparative example 4 | 5.6 | 0.47 |
| Comparative example 5 | 8.9 | 0.72 |
| Comparative example 6 | 4.3 | 0.32 |
| Comparative example 7 | 9.2 | 0.81 |
| Comparative example 8 | 72.2 | 6.38 |
Wherein ND, namely NOT DETECTED, represents undetected, represents below the detection limit of 2mg/kg for hexavalent chromium content, and represents below the detection limit of 0.004mg/L for hexavalent chromium leaching concentration. From the results of the above table, it can be seen that the examples, particularly examples 1-4 and 11, 13, are better able to remove hexavalent chromium from the contaminants, particularly hexavalent chromium penetrating into the interior of the contaminants. Wherein, for examples 6 and 7, the inventors of the present invention also found that under the condition that other conditions were not changed, the power of the first ultrasonic wave and the second ultrasonic wave were increased to 0.32-0.5W/g (W/g of the first solid-liquid mixture or W/g of the second solid-liquid mixture), the time of the first ultrasonic wave and the second ultrasonic wave were increased to 60-120min, and the hexavalent chromium content and the leaching concentration of hexavalent chromium in the treated hexavalent chromium building waste were both ND results. As the results show, the hexavalent chromium in the hexavalent chromium building waste can be better removed by adopting the method provided by the invention. In particular to construction waste with hexavalent chromium content of 40-500mg/kg or block diameter less than or equal to 2cm, the method can obtain better treatment effect under the condition of lower cost (lower ultrasonic power and shorter time).
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.
Claims (8)
1. A method for treating hexavalent chromium-contaminated construction waste, the method comprising:
(1) Mixing hexavalent chromium-contaminated construction waste with a foaming agent and optionally water to obtain a first solid-liquid mixture, performing first ultrasound, and then removing the foaming agent;
wherein the foaming agent is a sulfonate type anionic surfactant, and the sulfonate type anionic surfactant is selected from sodium dodecyl sulfate and/or sodium dodecyl benzene sulfonate;
the mass concentration of the foaming agent in the liquid in the first solid-liquid mixture is 3-5wt%; the mass and the dosage ratio of hexavalent chromium pollution building waste to foaming agent are 1: (0.01-0.09);
the conditions of the first ultrasound include: the frequency is 20-25kHz, the power is 0.15-0.25W/g of the first solid-liquid mixture, and the time is 30-45min;
(2) Mixing the hexavalent chromium-polluted building waste treated in the step (1) with a reducing agent and optional water to obtain a second solid-liquid mixture, and soaking;
the conditions of the second ultrasound include: the frequency is 20-25kHz, the power is 0.15-0.25W/g of the second solid-liquid mixture, and the time is 45-90min;
the soaking mode is as follows: and (3) soaking the second solid-liquid mixture under the second ultrasonic, then turning off the second ultrasonic, and finally soaking.
2. The method of claim 1 wherein in step (1) the hexavalent chromium-contaminated construction waste has a bulk diameter of 3cm or less;
and/or the mass content of hexavalent chromium in the hexavalent chromium-polluted building waste is 20-1000mg/kg.
3. The method according to claim 1 or 2, wherein in the step (1), the hexavalent chromium-contaminated construction waste has a bulk diameter of 2cm or less;
and/or the mass content of hexavalent chromium in the hexavalent chromium-polluted building waste is 40-500mg/kg.
4. The method of claim 2, wherein in step (1), the means for removing the foaming agent comprises: and carrying out solid-liquid separation on the material after the first ultrasonic treatment, mixing the obtained solid phase with water, carrying out third ultrasonic treatment, and carrying out solid-liquid separation on the material after the third ultrasonic treatment again.
5. The method of claim 1 or 4, wherein prior to step (2), the method further comprises: and (3) mixing the hexavalent chromium-polluted building waste treated in the step (1) with water, adjusting the pH value of the mixture to be 4-5, and then carrying out solid-liquid separation.
6. The method according to claim 1 or 2, wherein in the step (2), the mass usage ratio of the hexavalent chromium-polluted building waste treated in the step (1) to the reducing agent is 1: (0.01-0.1);
and/or the reducing agent is selected from at least one of ferrous sulfate, sodium thiosulfate, sodium sulfide and potassium sulfide.
7. The method according to claim 1 or 2, wherein in step (2), the soaking time is 20-72 hours;
and/or the soaking is performed under the condition that the pH value is less than or equal to 5.
8. The method of claim 1, wherein the method further comprises: and (3) carrying out solid-liquid separation on the material treated in the step (2).
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