CN110818047A - Preparation method of polysilicate ferro-manganese graphene flocculant - Google Patents

Abstract

The invention discloses a preparation method of polysilicon ferromanganese graphene flocculant, comprising the following steps: (1) mixing silica fume and concentrated sulfuric acid, and aging to obtain polysilicic acid; (2) adding graphite powder to polysilicic acid (3) mixing sodium peroxodisulfate and potassium permanganate to obtain a mixed oxidizing agent, adding the mixed oxidizing agent to graphite polysilicic acid and mixing uniformly, ultrasonically treating, Ageing to obtain graphene oxide manganese silicate; (4) mixing humic acid, iron powder and graphene oxide manganese silicate, ageing, adjusting pH to acidity, continuing ageing, drying, grinding, That is, the polysilicon ferromanganese graphene flocculant is obtained. The polysilicon ferromanganese graphene flocculant polysilicon manganese graphene flocculant can simultaneously capture multiple pollutants, the flocculant recovery efficiency is high, and the flocculant is suitable for a wide pH range; the preparation process is simple, the preparation condition requirements are low, and the preparation process It is easy to realize, and the required raw materials come from a wide range of sources.

Description

A kind of preparation method of polysilicon ferromanganese graphene flocculant

technical field

The invention relates to a preparation method of an inorganic flocculant, in particular to a preparation method of a polysilicon ferromanganese graphene flocculant for treating landfill leachate.

Background technique

Due to natural precipitation and anaerobic decomposition of microorganisms, domestic garbage is likely to form a kind of domestic garbage leachate containing complex pollutants, high concentration of pollutants and toxic in the overburden during the landfill process. Domestic landfill leachate has the characteristics of complex water quality, many types of heavy metals, high ammonia nitrogen content, and large fluctuations in water quantity and water quality. Domestic garbage leachate contains a large amount of toxic and harmful substances. If not disposed of properly, it will cause serious damage to the ecological environment and seriously affect the health of local residents.

The disposal methods of domestic waste leachate mainly include physical and chemical treatment, biological treatment, and advanced oxidation. At present, the flocculation-precipitation method has been widely used in industrial wastewater treatment because of its simple operation and remarkable disposal effect. However, due to the variety and complexity of harmful substances in domestic waste leachate, the treatment difficulty is very high, and it is difficult to use traditional polysilicon-based flocculants to treat leachate to meet the discharge standards. Specifically, the current application of polysilicon-based flocculants to treat domestic waste leachate mainly has problems such as poor flocculant capturing multiple pollutants at the same time, low flocculant recovery efficiency due to easy hydrolysis of flocculants, and narrow pH range for flocculants.

SUMMARY OF THE INVENTION

Purpose of the invention: In view of the above problems, the present invention proposes a preparation method of a polysilicon ferromanganese graphene flocculant for treating landfill leachate. The prepared polysilicon ferromanganese graphene flocculant can simultaneously capture a variety of pollutants, flocculate The recovery efficiency of the agent is high, and the pH range of the flocculant is wide.

Technical scheme: the preparation method of a polysilicon ferromanganese graphene flocculant according to the present invention comprises the following steps:

(1) mixing silica fume and concentrated sulfuric acid, and aging to obtain polysilicic acid;

(2) adding graphite powder to polysilicic acid, mixing, and aging to obtain graphite polysilicic acid;

(3) mixing sodium peroxodisulfate and potassium permanganate to obtain a mixed oxidant, adding the mixed oxidant to graphite polysilicic acid and mixing, ultrasonically treating, and aging to obtain graphene oxide polymanganese silicate;

(4) Mix humic acid, iron powder and graphene oxide polymanganese silicate, age, adjust pH to acidity, continue ageing, dry and grind to obtain polysilicon manganese ferromanganese graphene flocculant.

Wherein, in the step (2), the mass ratio of graphite powder to polysilicic acid is 5-30:100, more preferably 5-25:100.

In the step (3), the mass ratio of sodium peroxodisulfate to potassium permanganate is 10-25:100, more preferably 10-20:100.

In the step (4), the mass ratio of humic acid, iron powder and graphene oxide polysilicate manganese is 10-50:10-25:100, more preferably 10-40:10-20:100.

In the step (1), the solid-to-liquid ratio of silica fume and concentrated sulfuric acid is 1:1 to 2 (mg:mL), the aging time is 3 to 6 hours, and the mass fraction of concentrated sulfuric acid is 70% to 90%. In step (2), the aging time is 3-6h.

In the step (3), the mass ratio of the mixed oxidant to the graphite polysilicic acid is 10-30:100, the ultrasonic treatment power is 600-2400W, the treatment temperature is 60-90°C, the ultrasonic time is 2-4h, and the aging is 3 hours. ~6h.

In the step (4), the aging is carried out for 6-12 hours, and the pH is adjusted to 3-5 with 5-10 mol/L sodium hydroxide solution, and then the aging is continued for 6-12 hours.

In the strong acid environment, the silicate in the silica fume is dissolved, hydrolyzed and polymerized to generate polysilicic acid. After the graphite powder is mixed into the polysilicic acid, the graphite powder can be uniformly distributed in the polysilicic acid through the electrostatic adsorption on the surface of the polysilicic acid to obtain the graphite polysilicic acid. Mixing the mixed oxidant with graphitic polysilicic acid, potassium permanganate can directly oxidize graphite and convert it into graphene to obtain graphene oxide manganese silicate. Under heating conditions, sodium peroxodisulfate can decompose sulfate radicals. Peroxodisulfate enhances the oxidation process of graphite by increasing the oxidation potential and promotes the formation of graphene. At the same time, sulfate radicals can convert low-valence manganese into high-valence manganese through oxidation, so that the process of potassium permanganate graphite oxidation can be maintained. Ultrasound can make the generated graphene evenly dispersed in the polysilicic acid. At the same time, when the ultrasonic wave acts on water, a large number of holes can be generated, and the implosion of the holes can generate a strong shear force on the graphite, thereby promoting the exfoliation and delamination of the graphite. The effective exfoliation of graphite can make potassium permanganate more effectively interspersed between the graphite layers and strengthen the oxidation process of graphite. Mixing humic acid and iron powder into graphene oxide manganese silicate, part of humic acid can directly convert graphene oxide into graphene. Unreacted humic acid can be effectively loaded on the surface of graphene flocculants. Iron powder can absorb hydrogen ions and convert them into ferrous ions. Ferrous ions can react with graphene oxide to form graphene and ferric ions. At the same time, ferrous ions can also react with high-valent manganese ions to promote the price reduction of manganese ions to form ferromanganese nodules. The ferric ions can interact with the polysilicic acid distributed with graphene and combine with manganese of different valences, thereby inducing the formation of the three-dimensional spatial structure of the flocculant. Adding sodium hydroxide solution to pH adjustment during the mixing process of humic acid, iron powder, graphene oxide and manganese silicate can also induce the formation of iron-manganese layered hydroxide in the flocculant, which is beneficial to improve the flocculant's ability to prevent pollutants. The capture and adsorption effect of the flocculant is beneficial to increase the amount of pollutants adsorbed by the flocculant. Graphene is evenly distributed in the structure of the flocculant, which can effectively weaken the replacement effect of hydrogen ions on the cations in the polysilicon structure by absorbing hydrogen ions, and the iron manganese nodules can effectively block hydrogen ions from entering the flocculant migration, all of which are beneficial to reduce the hydrolysis loss rate of the flocculant of the present invention and improve the pH applicable range of the flocculant.

Beneficial effects: compared with the prior art, the significant advantages of the present invention are: (1) the present invention combines the polysilicon ferromanganese flocculant and the graphene preparation process into one, and effectively combines the graphene and polysilicon ferromanganese into one. Combined together to generate flocculants with high stability and high adsorption performance, and capture multiple pollutants at the same time, it can achieve up to 97% COD, 98% ammonia nitrogen, 99% total phosphorus, 98% zinc, 98% copper in landfill leachate , 99% lead and 99% chromium removal; (2) The hydrolysis loss of the flocculant is small, and the recovery of 99% of the flocculant can be achieved; (3) It is not limited by the pH of the landfill leachate, and the flocculant is suitable for pH 1～13 (4) The preparation process of the present invention is simple, the preparation condition requirements are low, the preparation process is easy to realize, and the required raw material sources are wide.

Description of drawings

Fig. 1 is the flow chart of the present invention

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and embodiments.

It should be noted that the landfill leachate of the present invention is obtained from a sanitary landfill of domestic waste in Lianyungang City. The mass concentration of COD in the landfill leachate is 1345mg/L, the concentration of ammonia nitrogen is 821mg/L, the total phosphorus is 242mg/L, and the heavy metal pollutants are 56mg/L zinc ion (Zn ²⁺ ), 21mg/L copper ion (Cu ²⁺ ), 12mg/L lead ion (Pb ²⁺ ), 26mg/L cadmium ion (Cd ²⁺ ).

Example 1

Influence of the mass ratio of graphite powder and polysilicic acid on the effect of preparing flocculants for landfill leachate treatment

Preparation of polysilicon ferromanganese graphene flocculant: as shown in Figure 1, weigh silica fume and concentrated sulfuric acid according to a solid-liquid ratio of 1:1 (mg:mL), mix, stir evenly, and age for 3 hours to obtain polysilicon Acid, in which the mass fraction of concentrated sulfuric acid is 70%; according to the mass ratio of graphite powder and polysilicic acid 2.5:100, 3.5:100, 4.5:100, 5:100, 15:100, 25:100, 26:100, 28 : 100, 30:100, respectively, weigh graphite powder and polysilicic acid, mix, stir evenly, and age for 3 hours to obtain graphite polysilicic acid; weighed according to the mass ratio of sodium peroxodisulfate and potassium permanganate 10:100 Sodium disulfate and potassium permanganate, mix and stir evenly to obtain a mixed oxidant; weigh the mixed oxidant and graphite polysilicic acid according to the mass ratio of the mixed oxidant and graphite polysilicic acid at 10:100, mix, stir evenly, and apply ultrasonic waves for 2 hours , the temperature in the ultrasonic process is set to 60 ° C, followed by aging for 3 hours to obtain graphene oxide polysilicate manganese silicate, wherein the ultrasonic action power is 600W; : 10:100 Weigh humic acid, iron powder, graphene oxide polysilicate manganese, mix, stir until the iron powder is completely dissolved, age for 6 hours, add 5mol/L sodium hydroxide solution to adjust the pH to 3, and then Aged for 6 hours, dried and ground to obtain polysilicon ferromanganese graphene flocculant.

Landfill leachate treatment: adjust the pH of the landfill leachate to 1 with 5mol/L sulfuric acid, weigh the flocculant according to the solid-liquid ratio of 20:1 (g:L), add it to the landfill leachate, stir for 30 minutes, and place it in a centrifuge In the process, centrifuge at 5000 rpm for 5 minutes to separate the solid and liquid, take the supernatant for the detection of pollutants in the landfill leachate, and dry and weigh the solid part.

Detection of COD concentration and calculation of COD removal rate: The concentration of chemical oxygen demand (COD) in landfill leachate is determined according to the national standard "Dichromate Method for Determination of Chemical Oxygen Demand in Water Quality" (GB 11914-1989); COD removal rate Calculated according to formula (1), where R _COD is the COD removal rate, and c ₀ and c _t are the COD concentrations (mg/L) of the landfill leachate before and after treatment, respectively.

Ammonia nitrogen concentration detection and ammonia nitrogen removal rate calculation: the concentration of ammonia nitrogen in landfill leachate is determined according to "Determination of ammonia nitrogen in water quality by salicylic acid spectrophotometry"(HJ536-2009); ammonia nitrogen removal rate is calculated according to formula (2), where R _N is the ammonia nitrogen removal rate, _{cN0 is the initial concentration of ammonia nitrogen in the landfill leachate before treatment (mg/L), and cNt is} the remaining concentration of ammonia nitrogen in the landfill leachate after treatment (mg/L).

Total phosphorus concentration detection and total phosphorus removal rate calculation: the total phosphorus concentration in landfill leachate is determined according to "Determination of total phosphorus in water quality"(GB1893-89); total phosphorus removal rate is calculated according to formula (3), where R _p is the total phosphorus removal rate, c _p0 is the initial concentration of total phosphorus in the landfill leachate before treatment (mg/L), and c _pt is the remaining concentration of total phosphorus in the landfill leachate after treatment (mg/L).

Heavy metal ion concentration detection and removal rate calculation: The four heavy metal ion concentrations of zinc, copper, lead and cadmium in landfill leachate were determined according to "Determination of 32 Elements in Water Quality by Inductively Coupled Plasma Emission Spectrometry" (HJ 776-2015). The removal rate of heavy metal M ions (M: Zn, Cu, Pb, Cd) is calculated according to formula (4), where R _M is the removal rate of heavy metal ions, and c _M0 is the initial concentration of heavy metal M ions in the landfill leachate before treatment (mg/ L), c _Mt is the heavy metal M ion concentration (mg/L) in the treated landfill leachate.

Calculation of flocculant recovery rate: The flocculant recovery efficiency is calculated according to formula (5), where R _Si-C is the flocculant recovery efficiency, m is the drying mass (g) of the solid separated after the landfill leachate treatment, and V is the pH adjustment After the landfill leachate volume (L), c _Si-C0 is the flocculant dosage (g/L).

The test results of the removal rate of COD, ammonia nitrogen, total phosphorus and heavy metal ions in landfill leachate and the recovery rate of flocculant are shown in Table 1.

Table 1 Influence of the mass ratio of graphite powder and polysilicic acid on the effect of preparing flocculants to treat landfill leachate

As can be seen from Table 1, when the mass ratio of graphite powder and polysilicic acid is less than 5:100 (as in Table 1, the mass ratio of graphite powder and polysilicic acid = 4.5:100, 3.5:100, 2.5:100 and Table 1 The lower value not listed in ), the graphite mixed into the polysilicic acid is less, the graphene generated and compounded in the polysilicon flocculant is successively less, and the amount of humic acid loaded through the graphene surface is also reduced, which ultimately As a result, the removal rates of COD, ammonia nitrogen, and total phosphorus in the landfill leachate were all lower than 84%, the removal rate of heavy metal ions was lower than 80%, and the recovery rate of flocculants was lower than 81%. , heavy metal ion removal rate and flocculant recovery rate decreased significantly with the decrease of the mass ratio of graphite powder and polysilicic acid. When the mass ratio of graphite powder and polysilicic acid is equal to 5-25:100 (as shown in Table 1, the mass ratio of graphite powder and polysilicic acid = 5:100, 15:100, 25:100), dispersed in polysilicic acid There is more graphite, and more graphene is generated and compounded in the polysilicon flocculant. At the same time, the amount of humic acid loaded on the surface of graphene is sufficient, and the removal rates of COD, ammonia nitrogen, total phosphorus and heavy metal ions in the final landfill leachate are all More than 92%, the recovery rate of flocculant is more than 94%. When the mass ratio of graphite powder and polysilicic acid is greater than 25:100 (as in Table 1, the mass ratio of graphite powder and polysilicic acid = 26:100, 28:100, 30:100 and higher values not listed in Table 1 ), the COD, ammonia nitrogen, total phosphorus, heavy metal ion removal rate and flocculant recovery rate in the landfill leachate did not change significantly with the further increase of the mass ratio of graphite powder and polysilicic acid. Therefore, in general, combined with benefits and costs, when the mass ratio of graphite powder and polysilicic acid is equal to 5-25:100, it is most beneficial to improve the removal of COD, ammonia nitrogen, total phosphorus and heavy metal ions in landfill leachate by the prepared flocculant. And improve the recovery rate of flocculant.

Example 2

Influence of mass ratio of sodium peroxodisulfate and potassium permanganate on the effect of preparing flocculants for landfill leachate treatment

Preparation of polysilicon ferromanganese graphene flocculant: Weigh silica fume and concentrated sulfuric acid according to the solid-liquid ratio of 1:1.5 (mg:mL), mix, stir evenly, and age for 4.5 hours to obtain polysilicic acid, in which the concentrated sulfuric acid is The mass fraction is 80%; according to the mass ratio of graphite powder and polysilicic acid 25:100, weigh graphite powder and polysilicic acid, mix, stir evenly, and age for 4.5 hours to obtain graphite polysilicic acid; The mass ratio of potassium manganate is 5:100, 7:100, 9:100, 10:100, 15:100, 20:100, 21:100, 23:100, 25:100, respectively, and weigh sodium peroxodisulfate and permanganate Potassium acid, mix and stir evenly to obtain a mixed oxidant; weigh the mixed oxidant and graphite polysilicic acid according to the mass ratio of the mixed oxidant and graphite polysilicic acid at 20:100, mix, stir evenly, ultrasonically act for 3 hours, and set the temperature during the ultrasonic wave. be 75 ° C, then aged for 4.5 hours to obtain graphene oxide polysilicate manganese silicate, wherein the ultrasonic action power is 1500W; weighed according to the mass ratio of humic acid, iron powder and graphene oxide manganese silicate polysilicate 25:15:100 Humic acid, iron powder, graphene oxide polymanganese silicate, mix, stir until the iron powder is completely dissolved, age for 9 hours, add 7.5mol/L sodium hydroxide solution to adjust the pH to 4, and age for another 9 hours , drying and grinding to obtain polysilicon ferromanganese graphene flocculant.

Landfill leachate treatment: adjust the pH of the landfill leachate to 7 with 5mol/L sulfuric acid and 5mol/L sodium hydroxide, weigh the flocculant according to the solid-liquid ratio of 20:1 (g:L), add it to the landfill leachate, and stir. 30 minutes, placed in a centrifuge, centrifuged at 5000 rpm for 5 minutes, solid-liquid separation, the supernatant was taken for the detection of pollutants in landfill leachate, and the solid part was dried and weighed.

COD concentration detection and calculation of COD removal rate, ammonia nitrogen concentration detection and ammonia nitrogen removal rate calculation, total phosphorus concentration detection and total phosphorus removal rate calculation, heavy metal ion concentration detection and removal rate calculation, and flocculant recovery rate calculation are all the same as in Example 1, The test results are shown in Table 2.

Table 2 Influence of the mass ratio of sodium peroxodisulfate and potassium permanganate on the effect of preparing flocculants to treat landfill leachate

As can be seen from Table 2, when the mass ratio of sodium peroxodisulfate and potassium permanganate is less than 10:100 (as in Table 2, the mass ratio of sodium peroxodisulfate and potassium permanganate=9:100, 7:100, 5 : 100 and lower values not listed in Table 2), there is less sodium peroxodisulfate in the mixed oxidant, less sulfate radicals are generated, the graphite oxidation process is weakened, and more low-valent manganese is generated, leading to landfill seepage The removal rates of COD, ammonia nitrogen, and total phosphorus in the filtrate were all less than 85%, the removal rate of heavy metal ions was less than 87%, and the recovery rate of flocculants was less than 90%. The COD, ammonia nitrogen, total phosphorus and heavy metal ions in the landfill leachate The removal rate and flocculant recovery rate decreased significantly with the decrease of the mass ratio of sodium peroxodisulfate and potassium permanganate. When the mass ratio of sodium peroxodisulfate and potassium permanganate is equal to 10-20:100 (as shown in Table 2, the mass ratio of sodium peroxodisulfate and potassium permanganate = 10:100, 15:100, 20:100) mixed There are many sodium persulfate in the oxidant. Under heating, sodium persulfate can decompose a large number of sulfate radicals. Sulfate radicals can strengthen the oxidation process of graphite by increasing the oxidation potential and promote the formation of graphene. Oxidation converts low-valence manganese into high-valence manganese, which can maintain the process of potassium permanganate oxidation of graphite, and the removal rates of COD, ammonia nitrogen, total phosphorus and heavy metal ions in the final landfill leachate are all greater than 94%, and the recovery rate of flocculant greater than 97%. When the mass ratio of sodium peroxodisulfate and potassium permanganate is greater than 20:100 (as in Table 3, the mass ratio of sodium peroxodisulfate and potassium permanganate=21:100, 23:100, 25:100 and in Table 2 Higher values not listed), COD, ammonia nitrogen, total phosphorus, heavy metal ion removal rate and flocculant recovery rate in landfill leachate did not change significantly with the further increase of the mass ratio of sodium peroxodisulfate and potassium permanganate. Therefore, in general, combined with benefits and costs, when the mass ratio of sodium peroxodisulfate and potassium permanganate is equal to 10-20:100, it is most beneficial to improve the removal of COD, ammonia nitrogen and total phosphorus in landfill leachate by the prepared flocculant. , heavy metal ions and improve the recovery rate of flocculant.

Example 3

Effect of mass ratio of humic acid, iron powder and graphene oxide polymanganese silicate on the effect of preparing flocculants for landfill leachate treatment

Preparation of polysilicon ferromanganese graphene flocculant: Weigh silica fume and concentrated sulfuric acid according to the solid-liquid ratio of 1:2 (mg:mL), mix, stir evenly, and age for 6 hours to obtain polysilicic acid, in which the concentrated sulfuric acid is The mass fraction is 90%; according to the mass ratio of graphite powder and polysilicic acid 25:100, weigh graphite powder and polysilicic acid, mix, stir evenly, and age for 6 hours to obtain graphite polysilicic acid; according to sodium peroxodisulfate and high The mass ratio of potassium manganate is 20:100, and sodium peroxodisulfate and potassium permanganate are weighed, mixed and stirred evenly to obtain a mixed oxidant; according to the mass ratio of mixed oxidant and graphite polysilicic acid 30:100, the mixed oxidant and graphite polysilicon are weighed Acid, mix, stir evenly, ultrasonically act for 4 hours, the temperature during ultrasonication is set to 90 ° C, and then age for 6 hours to obtain graphene oxide polymanganese silicate, wherein the ultrasonic action power is 2400W; according to humic acid, iron powder and graphene oxide polymanganese silicate mass ratio 5:10:100, 7:10:100, 9:10:100, 10:5:100, 10:7:100, 10:9:100, 10:10: 100, 25:10:100, 40:10:100, 10:15:100, 25:15:100, 40:15:100, 10:20:100, 25:20:100, 40:20:100, 42:20:100, 45:20:100, 50:20:100, 40:21:100, 40:23:100, 40:25:100 Weigh humic acid, iron powder, graphene oxide polysilicic acid Manganese, mix, stir until the iron powder is completely dissolved, age for 12 hours, add 10mol/L sodium hydroxide solution to adjust the pH to 5, age for another 12 hours, dry and grind to obtain polysilicon ferrosilicon manganese graphene flocculant.

Landfill leachate treatment: adjust the pH of the landfill leachate to 13 with 5mol/L sodium hydroxide, weigh the flocculant according to the solid-to-liquid ratio of 20:1 (g:L), add it to the landfill leachate, stir for 30 minutes, and place it in the landfill leachate. In a centrifuge, centrifuge at 5000 rpm for 5 minutes to separate the solid and liquid, take the supernatant for the detection of pollutants in the landfill leachate, and dry and weigh the solid part.

COD concentration detection and calculation of COD removal rate, ammonia nitrogen concentration detection and ammonia nitrogen removal rate calculation, total phosphorus concentration detection and total phosphorus removal rate calculation, heavy metal ion concentration detection and removal rate calculation, and flocculant recovery rate calculation are all the same as in Example 1, The test results are shown in Table 3.

Table 3 Influence of mass ratio of humic acid, iron powder and graphene oxide polymanganese silicate on the effect of preparing flocculants to treat landfill leachate

As can be seen from Table 3, when the mass ratio of humic acid, iron powder and graphene oxide polymanganese silicate is less than 10:10:100 (as in Table 3, humic acid, iron powder and graphene oxide polymanganese silicate Mass ratio = 10:9:100, 10:7:100, 10:5:100, 9:10:100, 7:10:100, 5:10:100 and lower values not listed in Table 3) , the humic acid and iron powder mixed into the graphene oxide polysilicate manganese are less, the reduction efficiency of graphene is low, the humic acid loaded on the surface of the graphene flocculant is less, and the amount of ferric ions generated is less. The three-dimensional structure of flocculants is not fully developed, resulting in the removal rates of COD, ammonia nitrogen, total phosphorus and heavy metal ions in the landfill leachate being lower than 87%, and the recovery rate of flocculants being lower than 93%. The removal rate of total phosphorus and heavy metal ions and the recovery rate of flocculant decreased significantly with the decrease of the mass ratio of humic acid, iron powder and graphene oxide polymanganese silicate. When the mass ratio of humic acid, iron powder and graphene oxide polymanganese silicate is equal to 10～40:10～20:100 (as shown in Table 3, the mass ratio of humic acid, iron powder and graphene oxide polymanganese silicate= 10:10:100, 25:10:100, 40:10:100, 10:15:100, 25:15:100, 40:15:100, 10:20:100, 25:20:100, 40: 20:100), mix humic acid and iron powder into graphene oxide polysilicate manganese, part of humic acid can directly convert graphene oxide into graphene, and unreacted humic acid can be effectively loaded on graphene. flocculant surface. Iron powder can absorb hydrogen ions and convert them into ferrous ions. Ferrous ions can react with graphene oxide to generate graphene and ferric ions. At the same time, ferrous ions can also react with high-valent manganese ions to promote the price reduction of manganese ions. Iron ions can interact with polysilicic acid distributed in graphene and combine with manganese of different valences, thereby inducing the formation of three-dimensional spatial structure of flocculants, and finally, the removal rate of COD, ammonia nitrogen, total phosphorus and heavy metal ions in the final landfill leachate All are greater than 94%, and the recovery rate of flocculant is greater than 98%. When the mass ratio of humic acid, iron powder and graphene oxide polymanganese silicate is greater than 40:20:100 (as in Table 3, the mass ratio of humic acid, iron powder and graphene oxide polymanganese silicate=42:20: 100, 45:20:100, 50:20:100, 40:21:100, 40:23:100, 40:25:100 and higher values not listed in Table 3), COD, The removal rate of ammonia nitrogen, total phosphorus, heavy metal ions and flocculant recovery rate did not change significantly with the further increase of the mass ratio of humic acid, iron powder and graphene oxide polymanganese silicate. Therefore, in general, combining benefits and costs, when the mass ratio of humic acid, iron powder and graphene oxide polymanganese silicate is equal to 10-40:10-20:100, it is most beneficial to improve the prepared flocculant to remove landfill seepage. COD, ammonia nitrogen, total phosphorus, heavy metal ions in the filtrate and improve the recovery rate of flocculant.

Example 4

Preparation of polysilicon ferromanganese graphene flocculant: Weigh silica fume and concentrated sulfuric acid according to the solid-liquid ratio of 1:2 (mg:mL), mix, stir evenly, and age for 6 hours to obtain polysilicic acid, wherein the mass of concentrated sulfuric acid is obtained. The fraction is 90%; according to the mass ratio of graphite powder and polysilicic acid 25:100, weigh graphite powder and polysilicic acid, mix, stir evenly, and age for 6 hours to obtain graphite polysilicic acid; according to sodium peroxodisulfate and high manganese Weigh sodium peroxodisulfate and potassium permanganate in a mass ratio of potassium acid 20:100, mix and stir evenly to obtain a mixed oxidant; weigh the mixed oxidant and graphite polysilicic acid according to the mass ratio of mixed oxidant and graphite polysilicic acid 30:100 , mixed, stirred evenly, ultrasonically acted for 4 hours, the temperature during the ultrasonic wave was set to 90 ° C, and then aged for 6 hours to obtain graphene oxide polymanganese silicate, in which the ultrasonic action power was 2400W; according to humic acid, iron powder and The mass ratio of graphene oxide polymanganese silicate is 25:15:100, weigh humic acid, iron powder, and graphene oxide polymanganese silicate, mix, stir until the iron powder is completely dissolved, age for 12 hours, and add 10mol/L The sodium hydroxide solution was adjusted to pH 5, then aged for 12 hours, dried, and ground to obtain a polysilicon-ferromanganese graphene flocculant.

Comparative Example 1

Preparation of polysilicon flocculant: Weigh silica fume and concentrated sulfuric acid according to the solid-liquid ratio of 1:2 (mg:mL), mix, stir evenly, and age for 6 hours to obtain polysilicic acid, wherein the mass fraction of concentrated sulfuric acid is 90 %; According to the mass ratio of humic acid, iron powder and polysilicic acid 25:15:100, weigh humic acid, iron powder, polysilicic acid, mix, stir until the iron powder is completely dissolved, age for 12 hours, add 10mol /L sodium hydroxide solution to adjust the pH to 5, then age for 12 hours, dry and grind to obtain polysilicon flocculant.

Comparative Example 2

Preparation of polysilicon ferromanganese flocculant: Weigh silica fume and concentrated sulfuric acid according to the solid-liquid ratio of 1:2 (mg:mL), mix, stir evenly, and age for 6 hours to obtain polysilicic acid, wherein the mass fraction of concentrated sulfuric acid is: 90%; according to the mass ratio of potassium permanganate and polysilicic acid 30:100, weigh potassium permanganate and polysilicic acid, mix, stir evenly, ultrasonically act for 4 hours, set the temperature to 90°C during ultrasonication, and then age In 6 hours, polysilicate manganese was obtained, wherein the ultrasonic power was 2400W; humic acid, iron powder and manganese polysilicate were weighed according to the mass ratio of humic acid, iron powder and manganese polysilicate at 25:15:100, and mixed. , stir until the iron powder is completely dissolved, age for 12 hours, add 10mol/L sodium hydroxide solution to adjust the pH to 5, age for another 12 hours, dry and grind to obtain polysilicon manganese flocculant.

Comparative Example 3

Acrylamide flocculant (PAM): commercially available.

The flocculants prepared in Example 4 and Comparative Examples 1 to 3 were used for the treatment of landfill leachate, and the treatment process was the same as that in Example 2. COD concentration detection and calculation of COD removal rate, ammonia nitrogen concentration detection and ammonia nitrogen removal rate calculation, total phosphorus concentration detection and total phosphorus removal rate calculation, heavy metal ion concentration detection and removal rate calculation, and flocculant recovery rate calculation are all the same as in Example 1, The test results are shown in Table 4.

Table 4 Comparison of the effects of flocculants prepared in Example 4 and Comparative Examples 1 to 3 in treating landfill leachate

It can be seen from Table 4 that, compared with the commonly used acrylamide flocculant (PAM) on the market, the polysilicon ferromanganese graphene flocculant prepared by the present invention has better effect on landfill leachate treatment. Due to the synergy between the raw materials used, the polysilicon ferromanganese graphene flocculant of the present invention has higher removal rates and recovery rates for COD, ammonia nitrogen, total phosphorus and heavy metal ions than polysilicon flocculants and polysilicon. The sum of the effects of iron and manganese flocculants.

Claims (10)

1. a preparation method of polysilicon ferromanganese graphene flocculant, is characterized in that, comprises the following steps: (1) mixing silica fume and concentrated sulfuric acid, and aging to obtain polysilicic acid; (2) adding graphite powder to polysilicic acid, mixing, and aging to obtain graphite polysilicic acid; (3) mixing sodium peroxodisulfate and potassium permanganate to obtain a mixed oxidant, adding the mixed oxidant to graphite polysilicic acid and mixing, ultrasonically treating, and aging to obtain graphene oxide polymanganese silicate; (4) Mix humic acid, iron powder and graphene oxide polymanganese silicate, age, adjust pH to acidity, continue ageing, dry and grind to obtain polysilicon manganese ferromanganese graphene flocculant. 2. The preparation method of polysilicon ferromanganese graphene flocculant according to claim 1, characterized in that, in the step (2), the mass ratio of graphite powder to polysilicic acid is 5～30:100. 3. the preparation method of polysilicon iron manganese graphene flocculant according to claim 2, is characterized in that, described step (2), in described step (2), the mass ratio of graphite powder and polysilicic acid is 5 ~25:100. 4. the preparation method of polysilicon ferromanganese graphene flocculant according to claim 1, is characterized in that, in described step (3), the mass ratio of sodium peroxodisulfate and potassium permanganate is 10～25:100 . 5. the preparation method of polysilicon ferromanganese graphene flocculant according to claim 4, is characterized in that, in described step (3), the mass ratio of sodium peroxodisulfate and potassium permanganate is 10～20:100 . 6. the preparation method of polysilicon ferromanganese graphene flocculant according to claim 1, is characterized in that, in described step (4), the mass ratio of humic acid, iron powder and graphene oxide polymanganese silicate is 10 ～50:10～25:100. 7. the preparation method of polysilicon ferromanganese graphene flocculant according to claim 6, is characterized in that, in described step (4), the mass ratio of humic acid, iron powder and graphene oxide polymanganese silicate is 10 ～40:10～20:100. 8. the preparation method of polysilicon ferromanganese graphene flocculant according to claim 1, is characterized in that, in described step (1), the solid-liquid ratio of silica fume and vitriol oil is 1: 1～2, aging The time is 3-6h, the mass fraction of concentrated sulfuric acid is 70%-90%, and the aging time in the step (2) is 3-6h. 9. the preparation method of polysilicon iron manganese graphene flocculant according to claim 1, is characterized in that, in described step (3), the mass ratio of mixed oxidant to graphite polysilicic acid is 10～30:100, ultrasonic wave The processing power is 600-2400W, the processing temperature is 60-90°C, the ultrasonic time is 2-4h, and the aging is 3-6h. 10. The preparation method of polysilicon ferromanganese graphene flocculant according to claim 1, is characterized in that, in described step (4), ageing 6～12h first, use the sodium hydroxide solution of 5～10mol/L Adjust the pH to 3～5, and continue to age for 6～12h.

Images