CN104628073B - A kind of preparation method of the Nanoscale Iron processed for waste water - Google Patents

Abstract

The invention discloses the preparation method of a kind of Nanoscale Iron processed for waste water, first aqueous anaerobic digestion dewatered sludge pulverized, grind, be placed in deionized water, heating in water bath is also repeated 3 times, all filtrates being mixed, regulation pH value is 8.5, obtains organic solution；Adding dilute sulfuric acid by the Capacity Ratio of 0.1～0.5:1 again, regulating pH value after heating in water bath is 9, obtains the organic solution of reduction；Again by the acidleach filtrate obtaining iron salt in steel pickling waste liquor mud；Finally the organic solution of reduction is mixed by the Capacity Ratio of 1.3～15:1 with the acidleach filtrate of iron salt, sucking filtration after stirring, washing, precipitation is proceeded to vacuum-pumping container, obtains Nanoscale Iron.Present invention dyestuff and removal of various heavy in water, the clearance of heavy metal is 86～92%, and the clearance of COD is 85%, and in waste water, the clearance of colourity is 97.65%.

Description

A kind of preparation method of nano-iron for wastewater treatment

technical field

The present invention relates to wastewater treatment and urban and industrial sludge treatment, in particular to a method for preparing nano-iron for wastewater treatment by using sewage anaerobic digestion sludge and iron and steel pickling wastewater sludge, the nano-iron can simultaneously remove Dyes and various heavy metals.

Background technique

Municipal sludge is solid waste generated during the treatment of urban domestic sewage and industrial wastewater, and is a regular product of urban sewage treatment plants. Municipal sludge has a high water content and contains parasite eggs and pathogenic microorganisms. If it is not properly treated and discharged randomly, it will cause serious secondary pollution to the environment.

The conventional treatment and disposal methods of municipal sewage sludge mainly include: sludge composting, sludge digestion, sludge landfill, sludge incineration and sludge reclamation.

In the construction of sewage treatment plants in developed countries such as Europe and the United States, the investment in urban sludge treatment and disposal accounts for 50-70% of the total investment, while my country only has 20-50%. With the acceleration of my country's urbanization process and the increasing emphasis on environmental protection, the number of urban sewage treatment plants has increased rapidly, resulting in a sharp increase in the output of sewage sludge. According to estimates, the amount of sludge (dry weight) discharged by urban sewage treatment plants in my country is about 1.3 million tons per year, and the annual growth rate is greater than 10%. Especially in several cities and regions with a high level of urbanization in my country, sewage The problem of sludge outlet has become very prominent.

A large amount of pickling wastewater is generated by pickling steel in steel and steel product factories. In order to protect the environment, save and rationally utilize resources, scholars at home and abroad have conducted some research on the treatment of pickling wastewater, mainly using direct roasting, acid separation and oxidation neutralization methods to recover iron resources in pickling wastewater.

At present, some iron and steel enterprises still adopt traditional treatment methods, that is, generally use lime, calcium carbide slag or calcium hydroxide to neutralize them, and generate a large amount of sludge at the same time, and the reprocessing of the generated sludge is difficult and takes up a lot of land, and cause secondary pollution and waste of resources. With the improvement of my country's steel output and quality, the amount of pickling wastewater has increased rapidly, and the problem of the outlet of pickling wastewater sludge has become very prominent.

Chemically synthesized nano-iron has a small particle size and a large specific surface area, which can absorb pollutants and reduce them. It has been widely used in the in-situ remediation of groundwater and soil pollution. Its remediation performance is superior, but due to the large specific surface area of nano-iron, It is very easy to agglomerate, and the zero-valent iron that plays a reducing role is easily oxidized in the environment, which affects the stability of its repair pollution. In addition, the chemical synthesis of nano-iron requires a large amount of chemical reagents, and the cost is very high. Therefore, the development of low-cost nano-iron with anti-agglomeration and anti-oxidation has become a new direction for the development of nano-iron materials.

Because anaerobic digestion in municipal sludge also contains rich organic matter such as protein and oligosaccharides, the concentration of organic matter is generally 60-70%. of iron salts. Therefore, the protein, oligosaccharides and other organic matter in anaerobic digestion sludge are converted into reducing sugars to reduce iron salts in iron and steel pickling wastewater sludge, and nano-iron containing zero-valent iron can be prepared. The iron can be combined with the nano-iron due to the hydroxyl group on the reducing sugar, so that the nano-iron particles repel each other and are not easy to agglomerate, and can reduce the probability of the reaction between the nano-iron and the oxygen in the environment, which has a good shielding effect and improves Anti-agglomeration and anti-oxidation of iron nanoparticles. Moreover, using solid waste sewage sludge and iron and steel pickling wastewater sludge as raw materials can reduce the manufacturing cost of nano-iron, and use it to simultaneously remove dyes and various heavy metals in wastewater, so as to achieve the purpose of treating waste with waste.

Contents of the invention

The purpose of the present invention is to address the shortcomings of the existing nano-iron, which is easy to aggregate, poor oxidation resistance and high manufacturing cost. The present invention extracts the organic matter in the anaerobic digestion sludge for the first time, and uses it as a reducing agent to reduce the iron and steel pickling wastewater from the iron and steel pickling wastewater. The iron salt extracted from the mud is used to prepare nano-iron to achieve the removal of dyes and various heavy metals in wastewater.

The present invention is achieved through the following technical solutions.

A preparation method for nano-iron for wastewater treatment, comprising the steps of:

① Extraction of organic matter in anaerobic digestion sludge

The anaerobic digested dry sludge with a water content of 40% is crushed and ground into particles with a particle size of 1mm, placed in deionized water, the mass ratio of dry sludge to deionized water is 1:25, and then heated at 60-100°C Heat in a water bath for 3-6 hours, filter, and keep the filtrate;

Repeat the above-mentioned water bath heating for the filtered residue twice, mix all the filtrates, add 3mol/L sodium hydroxide solution, adjust the pH value to 8.5, obtain an organic solution, cool it in a vacuum desiccator, and set aside;

② Reduction of extracted organic matter

Add 2mol/L dilute sulfuric acid to the organic matter solution extracted in step ①, the volume ratio of the organic matter solution to 2mol/L dilute sulfuric acid is 0.1-0.5:1, heat in a water bath at 50°C for 30min-2h, and then use 3mol/L dilute sulfuric acid L of sodium hydroxide solution to adjust the pH value to 9 to obtain a reduced organic solution, which is stored in a vacuum refrigerator at 4°C;

③ Extraction of iron salts in iron and steel pickling wastewater sludge

Iron and steel pickling wastewater sludge was dried at 105°C for 12 hours to obtain dried iron and steel pickling wastewater sludge, which was ground and passed through a 100-mesh sieve; then the dried and sieved iron and steel pickling wastewater sludge was immersed in a concentration of In 3mol/L hydrochloric acid, the mass ratio of dried iron and steel pickling wastewater sludge to hydrochloric acid is 0.5-5:1, immerse at room temperature for 60min, filter and separate, and obtain the acid leaching filtrate of iron salt;

④Preparation of nano-iron

In a closed container, mix the organic matter solution reduced in step ② with the acid leaching filtrate of iron salt in step ③, the volume ratio of the organic matter solution and the acid leaching filtrate of iron salt is 1.3-15:1, stir for 15 minutes, and obtain a black precipitate. The nano-iron was suction-filtered, and the precipitate was quickly washed three times with 90% ethanol, and the precipitate was transferred into a vacuum container to obtain the nano-iron.

The temperature of the water bath in the step ① is 80° C., and the water bath is heated for 4 hours.

The volume ratio of the organic matter solution in the step ② to 2mol/L dilute sulfuric acid is 0.2:1, and the water bath is heated for 1 hour.

In the step ③, the mass ratio of the dried iron and steel pickling wastewater sludge to 3mol/L hydrochloric acid is 2.5:1.

The organic matter solution reduced in step ② is mixed with the acid leaching filtrate in step ③, and the volume ratio of the organic matter solution and the acid leaching filtrate of iron salt is 5:1.

Beneficial effects of the present invention: the anaerobic digestion sludge of sewage and iron and steel pickling wastewater sludge are used for the first time to prepare nano-iron, which is used to remove dyes and various heavy metals in water. The removal rate of heavy metal in waste water of the invention reaches 86-92%, the removal rate of COD is 85%, and the removal rate of chroma in waste water is 97.65%.

detailed description

The present invention will be further described below in conjunction with specific examples.

The sewage sludge used as the raw material of the present invention comes from a sewage treatment plant.

Example 1

① Extraction of organic matter in anaerobic digestion sludge

The anaerobic digested dry sludge with a moisture content of 40% was pulverized and ground into particles with a particle size of 1mm, placed in deionized water, the mass ratio of dry sludge to deionized water was 1:25, and then placed in a water bath at 60°C Heating for 6h, filtering, and retaining the filtrate;

Repeat the above-mentioned water bath heating for the filtered residue twice, mix all the filtrates, add 3mol/L sodium hydroxide solution, adjust the pH value to 8.5, obtain an organic solution, cool it in a vacuum desiccator, and set aside;

② Reduction of extracted organic matter

Add 2 mol/L dilute sulfuric acid to the organic matter solution extracted in step ①, the volume ratio of the organic matter solution to 2 mol/L dilute sulfuric acid is 0.1:1, heat in a water bath at 50°C for 2 hours, and then oxidize with 3 mol/L hydrogen The sodium solution adjusted the pH value to 9 to obtain a reduced organic matter solution, which was stored in a vacuum refrigerator at 4°C;

③ Extraction of iron salts in iron and steel pickling wastewater sludge

Iron and steel pickling wastewater sludge was dried at 105°C for 12 hours to obtain dried iron and steel pickling wastewater sludge, which was ground and passed through a 100-mesh sieve; then the dried and sieved iron and steel pickling wastewater sludge was immersed in a concentration of In 3mol/L hydrochloric acid, the mass ratio of dried iron and steel pickling wastewater sludge to hydrochloric acid is 0.5:1, immerse at room temperature for 60min, filter and separate, and obtain the acid leaching filtrate of iron salt;

④Preparation of nano-iron

In a closed container, mix the organic matter solution reduced in step ② with the acid leaching filtrate of iron salt in step ③. The volume ratio of the organic matter solution and the acid leaching filtrate of iron salt is 1.3:1, and stir for 15 minutes to obtain a black precipitate that is nano-iron , filtered with suction, washed the precipitate three times quickly with 90% ethanol, and transferred the precipitate into a vacuum container to obtain iron nanoparticles.

The detection of dyestuff and heavy metal removal effect in the waste water of embodiment 1:

Prepare methylene blue concentration (20mg/L) and several heavy metals Cu ²⁺ (concentration is 15mg/L), Zn ²⁺ (concentration is 40mg/L), Pb ²⁺ (concentration is 40mg/L) and Cd ²⁺ (Concentration is 40mg/L) simulated mixed waste water, adjust its pH value to be neutral, add 0.5g nano-iron each wherein, shake 1h at room temperature, filter, measure the concentration of heavy metal ion in waste water with atomic absorption spectrometer, adopt The COD of wastewater was determined by potassium dichromate method, and the chromaticity in wastewater was tested with a colorimeter.

Where α ₀ — heavy metal concentration mg/L, COD value and chromaticity in wastewater before removal

α _i — heavy metal concentration mg/L mg/L, COD value and chromaticity in wastewater after removal

The calculated removal effects of heavy metals and methylene blue in wastewater are shown in Table 1. (The removal effect of methylene blue in the table is expressed by the removal rate of COD and chroma)

Table 1

heavy metal Zn(II) Cu(II) Pb(II) Cr(VI) COD Chroma Removal rate/% 71.26 75.23 81.62 85.76 76.83 75.29

Example 2

① Extraction of organic matter in anaerobic digestion sludge

The anaerobic digested dry sludge with a moisture content of 40% was crushed and ground into particles with a particle size of 1mm, placed in deionized water, the mass ratio of dry sludge to deionized water was 1:25, and then placed in a water bath at 80°C Heating for 4h, filtering, and retaining the filtrate;

Repeat the above-mentioned water bath heating for the filtered residue twice, mix all the filtrates, add 3mol/L sodium hydroxide solution, adjust the pH value to 8.5, obtain an organic solution, cool it in a vacuum desiccator, and set aside;

② Reduction of extracted organic matter

Add 2 mol/L dilute sulfuric acid to the organic matter solution extracted in step ①, the volume ratio of the organic matter solution to 2 mol/L dilute sulfuric acid is 0.2:1, heat in a water bath at 50°C for 1 hour, and then oxidize with 3 mol/L hydrogen The sodium solution adjusted the pH value to 9 to obtain a reduced organic matter solution, which was stored in a vacuum refrigerator at 4°C;

③ Extraction of iron salts in iron and steel pickling wastewater sludge

Iron and steel pickling wastewater sludge was dried at 105°C for 12 hours to obtain dried iron and steel pickling wastewater sludge, which was ground and passed through a 100-mesh sieve; then the dried and sieved iron and steel pickling wastewater sludge was immersed in a concentration of In the hydrochloric acid of 3mol/L, the mass ratio of the dried iron and steel pickling wastewater sludge to hydrochloric acid is 2.5:1, immerse at normal temperature for 60min, filter and separate, and obtain the acid leaching filtrate of iron salt;

④Preparation of nano-iron

In a closed container, mix the organic matter solution reduced in step ② with the acid leaching filtrate of iron salt in step ③. The volume ratio of the organic matter solution and the acid leaching filtrate of iron salt is 5:1, and stir for 15 minutes to obtain a black precipitate that is nano-iron , filtered with suction, washed the precipitate three times quickly with 90% ethanol, and transferred the precipitate into a vacuum container to obtain iron nanoparticles.

The detection procedure of heavy metal and methylene blue removal effect in the wastewater of embodiment 2 is the same as that of embodiment 1, and the removal effect of heavy metal and methylene blue in wastewater calculated by the detection result is shown in Table 2.

Table 2

heavy metal Zn(II) Cu(II) Pb(II) Cr(VI) COD Chroma Removal rate/% 90.37 86.21 91.26 92.18 85.28 97.65

Example 3

① Extraction of organic matter in anaerobic digestion sludge

The anaerobic digested dry sludge with a moisture content of 40% was crushed and ground into particles with a particle size of 1mm, placed in deionized water, the mass ratio of dry sludge to deionized water was 1:25, and then placed in a water bath at 100°C Heat for 3h, filter, and keep the filtrate;

Repeat the above-mentioned water bath heating for the filtered residue twice, mix all the filtrates, add 3mol/L sodium hydroxide solution, adjust the pH value to 8.5, obtain an organic solution, cool it in a vacuum desiccator, and set aside;

② Reduction of extracted organic matter

Add 2 mol/L dilute sulfuric acid to the organic matter solution extracted in step ①, the volume ratio of the organic matter solution to 2 mol/L dilute sulfuric acid is 0.5:1, heat in a water bath at 50°C for 2 hours, and then oxidize with 3 mol/L hydrogen The sodium solution adjusted the pH value to 9 to obtain a reduced organic matter solution, which was stored in a vacuum refrigerator at 4°C;

③ Extraction of iron salts in iron and steel pickling wastewater sludge

Iron and steel pickling wastewater sludge was dried at 105°C for 12 hours to obtain dried iron and steel pickling wastewater sludge, which was ground and passed through a 100-mesh sieve; then the dried and sieved iron and steel pickling wastewater sludge was immersed in a concentration of In the hydrochloric acid of 3mol/L, the mass ratio of the dried iron and steel pickling wastewater sludge to hydrochloric acid is 5:1, immerse at normal temperature for 60min, filter and separate to obtain the acid leaching filtrate of iron salt;

④Preparation of nano-iron

In a closed container, mix the organic matter solution reduced in step ② with the acid leaching filtrate of iron salt in step ③. The volume ratio of the organic matter solution and the acid leaching filtrate of iron salt is 15:1, and stir for 15 minutes to obtain a black precipitate that is nano-iron , filtered with suction, washed the precipitate three times quickly with 90% ethanol, and transferred the precipitate into a vacuum container to obtain iron nanoparticles.

The detection steps of heavy metals and methylene blue removal effect in the wastewater of Example 2 are the same as in Example 1, and the removal effects of heavy metals and methylene blue in the wastewater calculated by the detection results are shown in Table 3.

table 3

heavy metal Zn(II) Cu(II) Pb(II) Cr(VI) COD Chroma Removal rate/% 83.67 75.43 87.92 89.56 82.14 93.46

Claims (5)

1. the preparation method of Nanoscale Iron processed for waste water, has following steps:

1. Organic substance in anaerobically digested sludge is extracted

The anaerobic digestion dewatered sludge that moisture content is 40% is pulverized, is ground to the granule of particle diameter 1mm, is placed in deionized water, dry Mud is 1:25 with the mass ratio of deionized water, heating in water bath 3～6h at 60～100 DEG C, filters, and retains filtrate；

Residue after filter is repeated above-mentioned heating in water bath 2 times, all filtrates are mixed, add the sodium hydroxide solution of 3mol/L, adjust Joint pH value is 8.5, obtains organic solution, cools down in vacuum desiccator, standby；

2. reduce extract Organic substance

Will step 1. in the organic solution that extracts adds the dilute sulfuric acid of 2mol/L, the dilute sulfuric acid of organic solution and 2mol/L Capacity Ratio be 0.1～0.5:1, heating in water bath 30min～2h at 50 DEG C, then regulate pH with the sodium hydroxide solution of 3mol/L Value is 9, obtains the organic solution of reduction, is placed in 4 DEG C of preservations in Vacuum refrigerator；

3. the iron salt in steel pickling waste liquor mud is extracted

Steel pickling waste liquor mud is dried 12h in 105 DEG C, obtains the steel pickling waste liquor mud of mummification, grind, cross 100 mesh Sieve；Again by mummification, sieve after steel pickling waste liquor mud immerse concentration be 3mol/L hydrochloric acid in, the pickling iron and steel of mummification give up Sewage sludge is 0.5～5:1 with the mass ratio of hydrochloric acid, normal temperature dipping 60min, filters and separates, obtains the acidleach filtrate of iron salt；

4. Nanoscale Iron is prepared

The organic solution of step 2. middle reduction is mixed by hermetic container with the acidleach filtrate of step 3. middle iron salt, Organic substance Solution is 1.3～15:1 with the Capacity Ratio of the acidleach filtrate of iron salt, stirs 15min, obtains black precipitate and be Nanoscale Iron, take out Filter, then wash rapidly precipitation 3 times with 90% ethanol, proceed to precipitation, in vacuum-pumping container, obtain Nanoscale Iron.

The preparation method of a kind of Nanoscale Iron processed for waste water the most according to claim 1, it is characterised in that described step Rapid bath temperature 1. is 80 DEG C, heating in water bath 4h.

The preparation method of a kind of Nanoscale Iron processed for waste water the most according to claim 1, it is characterised in that described step Rapid organic solution 2. is 0.2:1 with the Capacity Ratio of the dilute sulfuric acid of 2mol/L, heating in water bath 1h.

The preparation method of a kind of Nanoscale Iron processed for waste water the most according to claim 1, it is characterised in that described step The rapid 3. steel pickling waste liquor mud of mummification is 2.5:1 with the mass ratio of 3mol/L hydrochloric acid.

The preparation method of a kind of Nanoscale Iron processed for waste water the most according to claim 1, it is characterised in that described general The organic solution of step 2. middle reduction mixes with the acidleach filtrate of step 3. middle iron salt, the acidleach filter of organic solution and iron salt The Capacity Ratio of liquid is 5:1.