Coking wastewater membrane concentrated solution treating agent and preparation method thereof

Abstract

The invention belongs to the field of coking wastewater concentrated solution treatment, and discloses a coking wastewater membrane concentrated solution treatment agent and a preparation method thereof. The treating agent comprises the following raw materials in parts by weight: 5-15 parts of ethylenediamine tetraacetic acid, 10-30 parts of sodium persulfate, 20-50 parts of modified cellulose and 10-25 parts of lime, wherein the modified cellulose is a composite material obtained by reacting cellulose with sulfonated waxberry tannin according to a mass ratio of 1: (2-3). The modified cellulose obtained by compounding the cellulose and the sulfonated waxberry tannin is used in the treatment agent, so that the adsorption performance and the complexing capacity of the treatment agent in wastewater treatment can be remarkably improved, and the removal capacity on organic matters is enhanced. According to the treatment agent disclosed by the invention, through the synergistic effect of various components, high-concentration organic matters, high salinity and high chromaticity in the coking wastewater membrane concentrated solution can be efficiently removed at the same time.

Description

Technical Field

[0001] The invention relates to the field of coking wastewater concentrated liquid treatment, and in particular to a coking wastewater membrane concentrated liquid treating agent and a preparation method thereof. Background Art

[0002] Coking wastewater membrane concentrate is a high-concentration pollutant solution produced after coking wastewater is concentrated by membrane treatment technology. Its characteristics and treatment difficulty far exceed those of ordinary coking wastewater. This concentrate has extremely high organic matter content, salt concentration and chromaticity, which is a major environmental challenge faced by the coking industry. The characteristics of coking wastewater membrane concentrate are mainly manifested in the following aspects: First, the organic matter content is extremely high, and the chemical oxygen demand can reach tens of thousands or even hundreds of thousands of mg / L, which is much higher than ordinary coking wastewater. These organic substances mainly include phenols, polycyclic aromatic hydrocarbons, heterocyclic compounds and other difficult-to-degrade substances. They are not only highly toxic, but also extremely difficult to remove by conventional biological treatment methods. Secondly, the salt concentration is abnormally high, reaching tens of thousands of mg / L, mainly including inorganic salts such as chlorides, sulfates, and sodium salts. High salt content not only increases the difficulty of treatment, but also causes corrosion to subsequent treatment equipment, affecting the treatment effect. Third, the chromaticity is extremely high, often dark brown or black, which not only affects the beauty of the water body, but also hinders the transmission of light and affects the aquatic ecosystem. In addition, the coking wastewater membrane concentrate also contains a large amount of toxic substances such as ammonia nitrogen, sulfide, cyanide, and various heavy metal ions such as iron, manganese, copper, zinc, etc. The complex combination of these pollutants makes the coking wastewater membrane concentrate an extremely difficult industrial wastewater to treat.

[0003] At present, there are many technical difficulties in treating the membrane concentrate of coking wastewater. Traditional biological treatment methods are difficult to work due to the presence of high concentrations of toxic substances in the concentrate, and it is difficult for microorganisms to survive and reproduce in such a harsh environment. Although physical and chemical treatment methods such as flocculation precipitation and activated carbon adsorption can remove some pollutants, the effect is limited and is often accompanied by high operating costs and the problem of large amounts of sludge. Advanced oxidation technologies such as ozone oxidation and Fenton oxidation have good removal effects on organic matter, but when treating such high-concentration wastewater, the consumption of oxidants is huge and the economy is difficult to guarantee. Although membrane treatment technologies such as nanofiltration and reverse osmosis can effectively remove salt, membrane pollution is very likely to occur when facing high-concentration organic matter, resulting in a sharp decline in membrane life and a surge in maintenance costs. Although evaporation and crystallization technology can achieve "zero emissions", it consumes huge energy and the solid waste generated is difficult to treat. In addition, a single treatment technology is often difficult to simultaneously deal with multiple pollution characteristics such as high COD, high salinity, and high chroma, and multiple technologies need to be used in combination, which increases the complexity of the process and the difficulty of operation.

[0004] In order to solve these problems, researchers have begun to try to use various treatment agents to improve the treatment effect of membrane concentrate in recent years. Summary of the invention

[0005] In order to solve the problems in the background technology, the present invention provides a coking wastewater membrane concentrate treating agent and a preparation method thereof, so as to solve the problem of removing high-concentration organic matter, high ammonia nitrogen and high salt in the coking wastewater membrane concentrate.

[0006] To achieve the above object, the first technical solution adopted by the present invention is: A coking wastewater membrane concentrate treating agent comprises the following raw materials in parts by weight: 5-15 parts of ethylenediaminetetraacetic acid, 10-30 parts of sodium persulfate, 20-50 parts of modified cellulose, and 10-25 parts of lime; The modified cellulose is a composite material obtained by reacting cellulose with sulfonated bayberry tannin in a mass ratio of 1:(2-3).

[0007] Preferably, the preparation method of the modified fiber is: The sulfonation reaction of bayberry tannin with sodium bisulfite and concentrated sulfuric acid at 55-65°C for 3-5h was carried out, the pH of the reaction solution was adjusted to 6.5-7.5, dialyzed, and freeze-dried to obtain sulfonated bayberry tannin; The alkalized cellulose suspension is mixed with the sulfonated bayberry tannin solution, reacted at pH 4.5-5.0 and 60°C for 4 hours, and the reaction product is separated by centrifugation, washed, dried and purified.

[0008] Preferably, the mass ratio of sodium bisulfite, concentrated sulfuric acid and bayberry tannin is (0.5~2):(0.5~2):1.

[0009] Preferably, the preparation method of the alkalized cellulose suspension is: alkalizing microcrystalline cellulose, stirring at room temperature for 2 hours under the condition of pH 12-13, filtering, washing with deionized water until neutral, and suspending the alkalized cellulose in deionized water.

[0010] Preferably, the alkaline agent for alkalization treatment is sodium hydroxide.

[0011] Preferably, the purification method is: grinding the dried product into powder, extracting with ethanol as solvent for 20 to 28 hours, removing unreacted tannins, filtering, and vacuum drying at 55 to 65° C. for 10 to 14 hours.

[0012] Preferably, it also contains 15 to 35 parts of modified polyaluminium chloride, wherein the modified polyaluminium chloride is obtained by modifying polyaluminium chloride and ferric chloride and then reacting with maleic anhydride, and has carboxyl groups on the surface, and the mass ratio of polyaluminium chloride, ferric chloride and maleic anhydride is (3 to 6): (0.5 to 2): 1.

[0013] Preferably, the preparation method of the modified polyaluminium chloride is: reacting a polyaluminium chloride solution with a ferric chloride solution at pH 3.5-4.0 and 80°C-85°C for 2-2.5 hours; lowering the temperature of the reaction solution to 70°C-75°C, adding maleic anhydride, and reacting at pH 4.0-4.5 for 3.5 hours; adding a precipitant for precipitation, collecting the precipitate by suction, washing, and drying.

[0014] Preferably, the precipitant is ethanol.

[0015] The second technical solution adopted by the present invention is: A method for preparing a coking wastewater membrane concentrate treating agent comprises: Sodium persulfate, ethylenediaminetetraacetic acid solution and modified cellulose are fully mixed at pH 6.8-7.2, dried, ground and sieved.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The treatment agent of the present invention uses modified cellulose obtained by compounding cellulose and sulfonated bayberry tannin, which can significantly improve its adsorption performance and complexing ability in wastewater treatment and enhance the removal ability of organic matter. The treatment agent of the present invention can simultaneously and efficiently remove high-concentration organic matter, high salt content and high chroma in the coking wastewater membrane concentrate through the synergistic effect of multiple components.

[0017] 2. The treatment agent of the present invention adopts modified natural materials and chemicals with low residual risk to reduce secondary pollution. The treatment process is more green and environmentally friendly, meets strict environmental protection requirements, and reduces the potential impact on the ecosystem.

[0018] 3. The components of the treatment agent of the present invention are synergistically effective, reducing the dosage and cost. It has strong applicability and can be widely used in different coking enterprises without major adjustments, thus improving the practical value and economic benefits. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] The first embodiment of the present invention provides a coking wastewater membrane concentrate treating agent, comprising the following raw materials in parts by weight: 5-15 parts of ethylenediaminetetraacetic acid, 10-30 parts of sodium persulfate, 20-50 parts of modified cellulose, and 10-25 parts of lime; The modified cellulose is a composite material obtained by reacting cellulose with sulfonated bayberry tannin in a mass ratio of 1:(2-3).

[0021] It should be noted that modified cellulose is an adsorption material formed by chemically compounding cellulose and sulfonated bayberry tannins, in which cellulose provides a large number of adsorption sites, the introduction of sulfonic acid groups in sulfonated bayberry tannins increases the hydrophilicity and ion exchange capacity of the material, and the polyphenol structure of bayberry tannins provides excellent adsorption performance. This deep compounding process makes the resulting composite material have more uniform adsorption performance and stronger pollutant capture ability, and can effectively remove organic pollutants such as colored substances and aromatic compounds in wastewater. At the same time, the polyphenol structure of bayberry tannins also has a certain chelating ability, which can further adsorb and fix heavy metal ions.

[0022] The mechanism of action of the remaining components in the treatment agent is as follows: Ethylenediaminetetraacetic acid: It is a chelating agent that can form stable complexes with a variety of metal ions, especially heavy metal ions to form stable soluble complexes. This process reduces the toxicity of heavy metal ions. Its complexing action can also soften water quality, creating favorable conditions for subsequent treatment.

[0023] Sodium persulfate: As an oxidant, sodium persulfate can produce sulfate radicals, which are highly oxidizing and can degrade organic pollutants in wastewater, especially some aromatic compounds and heterocyclic compounds that are difficult to degrade. Through oxidation, large molecular organic matter is broken down into small molecular substances, significantly reducing the chemical oxygen demand of wastewater. At the same time, this process can also destroy the chromophore that produces color, effectively reducing the color of wastewater.

[0024] Lime: It is used to adjust the pH value of wastewater. It can quickly increase the pH value of wastewater and create an alkaline environment. In this environment, many metal ions will form hydroxide precipitation and be removed. It can also react with bicarbonate in wastewater to form calcium carbonate precipitation, effectively removing carbonate hardness in water. In addition, the addition of lime can promote the hydrolysis and precipitation of certain organic matter, further reducing COD.

[0025] The embodiments of the present invention achieve efficient treatment of coking wastewater membrane concentrate by the synergy of the above components. Specifically, the oxidation of sodium persulfate converts macromolecular organic matter into small molecules that are more easily adsorbed, thereby improving the treatment efficiency of modified cellulose and modified polyaluminium chloride. The complexation of ethylenediaminetetraacetic acid prevents metal ions from interfering with flocculation, optimizes the flocculation effect, and can also enhance the oxidation effect of sodium persulfate. Lime not only adjusts the pH, but also forms a strong flocculation system with modified polyaluminium chloride, greatly improving the removal rate of pollutants.

[0026] Through this series of complex physical and chemical processes, the treatment agent can effectively reduce the organic matter content, salt concentration and chromaticity in the membrane concentrate of coking wastewater. High-concentration organic matter is removed through oxidation decomposition and adsorption flocculation; high salt is reduced through chemical precipitation and ion exchange; high chromaticity is mainly eliminated through oxidation bleaching and flocculation adsorption. In summary, this treatment agent achieves comprehensive treatment of coking wastewater membrane concentrate through multiple mechanisms such as complexation, oxidation, adsorption, precipitation, and flocculation.

[0027] In some preferred embodiments, the preparation method of the modified fiber is: The sulfonation reaction of bayberry tannin with sodium bisulfite and concentrated sulfuric acid at 55-65°C for 3-5h was carried out, the pH of the reaction solution was adjusted to 6.5-7.5, dialyzed, and freeze-dried to obtain sulfonated bayberry tannin; The alkalized cellulose suspension is mixed with the sulfonated bayberry tannin solution, reacted at pH 4.5-5.0 and 60°C for 4 hours, and the reaction product is separated by centrifugation, washed, dried and purified.

[0028] Among them, alkalizing the cellulose suspension is a commonly used treatment method in the art, specifically: alkalizing the microcrystalline cellulose, stirring at room temperature for 2 hours under the condition of pH 12-13, filtering, washing with deionized water to neutrality, and suspending the alkalized cellulose in deionized water.

[0029] The alkaline agent used in the alkalization process is a commonly used alkaline agent for alkalization treatment in the art, for example, sodium hydroxide, and the mass concentration is usually 5%-20%.

[0030] It should be noted that the preparation method of sulfonated bayberry tannin is a commonly used sulfonation treatment method in the art, and those skilled in the art can select appropriate raw material dosage and process parameters according to the treatment object. For example, the mass ratio of sodium bisulfite, concentrated sulfuric acid, and bayberry tannin is (0.5~2): (0.5~2): 1.

[0031] The purification method is a commonly used purification method in the art, washing or extraction combined with drying, and specific parameters can be selected by those skilled in the art according to the actual purification object. For example, the dried product can be ground into powder, extracted with ethanol as solvent for 20 to 28 hours, unreacted tannins can be removed, filtered, and vacuum dried at 55 to 65°C for 10 to 14 hours.

[0032] In some preferred embodiments, in order to further improve the removal effect of pollutants, the above-mentioned treatment agent may also contain 15 to 35 parts of modified polyaluminum chloride, wherein the modified polyaluminum chloride is obtained by modifying polyaluminum chloride and ferric chloride and then reacting with maleic anhydride, and has a carboxyl group on the surface. The mass ratio of polyaluminum chloride, ferric chloride and maleic anhydride is (3 to 6): (0.5 to 2): 1.

[0033] Polyaluminium chloride is modified with ferric chloride to enhance its flocculation ability and pH adaptability. The subsequent reaction with maleic anhydride introduces carboxyl groups, which improves its adsorption capacity for organic matter. This carefully designed structure allows the modified polyaluminium chloride to form positively charged colloids in wastewater, and through mechanisms such as electrical neutralization, adsorption bridging and net capture, it can efficiently condense suspended matter, colloids and soluble organic matter in wastewater. The large flocs formed promote the rapid precipitation and separation of pollutants. At the same time, due to the introduction of carboxyl groups, the modified polyaluminium chloride also has a certain chelating ability, which can further remove some heavy metal ions.

[0034] In the process of cooperating with other components, the flocculation effect of modified polyaluminium chloride settles the oxidized organic matter and the modified cellulose adsorbed with pollutants together, realizing the synergistic removal of multiple pollutants. The adsorption effect of modified cellulose can provide more nucleation sites for modified polyaluminium chloride and promote floc formation.

[0035] In some preferred embodiments, the preparation method of the modified polyaluminium chloride is as follows: reacting a polyaluminium chloride solution with a ferric chloride solution at pH 3.5-4.0 and 80°C-85°C for 2-2.5 hours; lowering the temperature of the reaction solution to 70°C-75°C, adding maleic anhydride, and reacting at pH 4.0-4.5 for 3.5 hours; adding a precipitant for precipitation, collecting the precipitate by suction, washing, and drying.

[0036] The second embodiment of the present invention provides a method for preparing a coking wastewater membrane concentrate treating agent, comprising: The raw materials were thoroughly mixed at pH 6.8-7.2, dried, ground and sieved.

[0037] There is no need to specifically limit the order of mixing the raw materials, and the technical personnel in this field can make adaptive adjustments according to the component raw materials; the final sieved particle size can also be adaptively adjusted according to the wastewater to be treated.

[0038] The following is a detailed description of the coking wastewater membrane concentrate treatment agent and its effects through a number of specific examples.

[0039] The test equipment and preparations of the examples described below are as follows: Electronic balance (Sartorius, Germany), electric blast constant temperature dryer (Shanghai Fomar Experimental Equipment), stainless steel reactor (Shanghai Laibei), electric constant temperature water bath (Jiangsu Kedao), rotary evaporator (Shanghai Darlow Scientific Instruments), pulverizer (Shandong Tianfang Machinery), magnetic stirrer (Shanghai Meiyingpu), Soxhelt extractor (Qingdao Juchuang); chemicals and reagents were purchased from Sigma-Aldrich.

[0040] Example 1 The coking wastewater membrane concentrate treating agent is composed of the following raw materials in parts by weight: 12 parts of ethylenediaminetetraacetic acid, 23 parts of sodium persulfate, 38 parts of modified cellulose, 21 parts of lime and 28 parts of modified polyaluminium chloride.

[0041] The mass ratio of cellulose to sulfonated bayberry tannin in the modified cellulose is 1:2.2, and the preparation method is: S11. Mix bayberry tannin, sodium bisulfite and concentrated sulfuric acid in a mass ratio of 1:1:1, stir in an ice bath for 30 min, raise the reaction temperature to 60 ° C, and continue stirring for 4 h; S12. After the reaction, ice water was added to adjust the pH of the reaction solution to 7.0, dialyzed several times, and the dialyzed solution was freeze-dried to obtain sulfonated bayberry tannin; S13. Add 10% sodium hydroxide solution to microcrystalline cellulose, stir at room temperature for 2 h, filter, wash with deionized water until neutral, and suspend the alkalized cellulose in deionized water; S14. The sulfonated bayberry tannin solution and the alkalized cellulose suspension were mixed evenly, the pH was adjusted to 4.5-5.0, and the mixture was reacted at 60°C for 4 hours; S15. After the reaction is completed, the product is separated by centrifugation, washed and then dried in vacuum at 60°C for 12h; S16. The dried product was ground into powder, extracted with ethanol as solvent for 24 h, unreacted tannins were removed, filtered, and vacuum dried at 60° C. for 12 h to obtain purified modified cellulose.

[0042] The preparation method of modified polyaluminium chloride (the mass ratio of polyaluminium chloride: ferric chloride: maleic anhydride is 4:2:1) comprises: S21. Slowly add the ferric chloride solution to the polyaluminium chloride solution within 30 minutes, and keep the pH of the reaction solution at 3.5-4.0. After the addition is completed, raise the temperature to 85°C, continue the reaction for 2 hours, and keep the pH at 3.5-4.0; S22. The reaction temperature was lowered to 70°C, maleic anhydride was added, and the reaction was carried out at pH 4.0-4.5 and 75°C for 3.5h; S23. After the reaction is completed, the solution is cooled to room temperature and anhydrous ethanol is added for precipitation; S24. The above reaction solution is filtered, the precipitate is collected, the precipitate is washed, the precipitate is vacuum dried at 60° C. for 12 h, and the dried product is ground into fine powder.

[0043] The preparation method of the coking wastewater membrane concentrate treating agent is as follows: fully and evenly mix the raw materials at pH 6.8-7.2, dry, grind and sieve.

[0044] Example 2 The coking wastewater membrane concentrate treatment agent is composed of the following raw materials in parts by weight: 5 parts of ethylenediaminetetraacetic acid, 10 parts of sodium persulfate, 20 parts of modified cellulose, 10 parts of lime, and 15 parts of modified polyaluminum chloride (the mass ratio of polyaluminum chloride: ferric chloride: maleic anhydride is 3:0.5:1). The preparation method of modified cellulose and modified polyaluminum chloride is as shown in Example 1, and the mass ratio of cellulose to sulfonated bayberry tannin in the modified cellulose is 1:2.

[0045] Example 3 The coking wastewater membrane concentrate treating agent is composed of the following raw materials in parts by weight: 15 parts of ethylenediaminetetraacetic acid, 30 parts of sodium persulfate, 50 parts of modified cellulose, 25 parts of lime, and 35 parts of modified polyaluminum chloride (the mass ratio of polyaluminum chloride: ferric chloride: maleic anhydride is 6:2:1).

[0046] The preparation method of modified cellulose and modified polyaluminium chloride is as shown in Example 1. The mass ratio of cellulose to sulfonated bayberry tannin in the modified cellulose is 1:3.

[0047] Example 4 The coking wastewater membrane concentrate treatment agent is composed of the following raw materials in parts by weight: 10 parts of ethylenediaminetetraacetic acid, 20 parts of sodium persulfate, 35 parts of modified cellulose, 17 parts of lime, and 25 parts of modified polyaluminum chloride (the mass ratio of polyaluminum chloride: ferric chloride: maleic anhydride is 4.5:1.25:1). The preparation method of modified cellulose and modified polyaluminum chloride is as shown in Example 1, and the mass ratio of cellulose to sulfonated bayberry tannin in the modified cellulose is 1:2.5.

[0048] Example 5 The coking wastewater membrane concentrate treatment agent is composed of the following raw materials in parts by weight: 8 parts of ethylenediaminetetraacetic acid, 12 parts of sodium persulfate, 26 parts of modified cellulose, 16 parts of lime, and 26 parts of modified polyaluminum chloride (the mass ratio of polyaluminum chloride: ferric chloride: maleic anhydride is 5:1.8:1). The preparation method of modified cellulose and modified polyaluminum chloride is as shown in Example 1, and the mass ratio of cellulose to sulfonated bayberry tannin in the modified cellulose is 1:2.8.

[0049] Example 6 The coking wastewater membrane concentrate treating agent is composed of the following raw materials in parts by weight: 12 parts of ethylenediaminetetraacetic acid, 23 parts of sodium persulfate, 38 parts of modified cellulose and 21 parts of lime.

[0050] The preparation method of modified cellulose is shown in Example 1.

[0051] Example 7 The coking wastewater membrane concentrate treating agent is composed of the following raw materials in parts by weight: 5 parts of ethylenediaminetetraacetic acid, 10 parts of sodium persulfate, 20 parts of modified cellulose and 10 parts of lime.

[0052] The preparation method of modified cellulose is shown in Example 1.

[0053] Example 8 The coking wastewater membrane concentrate treating agent is composed of the following raw materials in parts by weight: 15 parts of ethylenediaminetetraacetic acid, 30 parts of sodium persulfate, 50 parts of modified cellulose and 25 parts of lime.

[0054] The preparation method of modified cellulose is shown in Example 1.

[0055] Example 9 The coking wastewater membrane concentrate treating agent is composed of the following raw materials in parts by weight: 10 parts of ethylenediaminetetraacetic acid, 20 parts of sodium persulfate, 35 parts of modified cellulose and 17 parts of lime.

[0056] The preparation method of modified cellulose is shown in Example 1.

[0057] Example 10 The coking wastewater membrane concentrate treating agent is composed of the following raw materials in parts by weight: 8 parts of ethylenediaminetetraacetic acid, 12 parts of sodium persulfate, 26 parts of modified cellulose and 16 parts of lime.

[0058] The preparation method of modified cellulose is shown in Example 1.

[0059] Comparative Example 1 The treatment agent is different from that in Example 1 only in that the modified cellulose and modified polyaluminium chloride are omitted from the composition, that is, the composition is: 12 parts of ethylenediaminetetraacetic acid, 23 parts of sodium persulfate, and 21 parts of lime.

[0060] Comparative Example 2 The treatment agent is different from that in Example 1 only in that ethylenediaminetetraacetic acid and modified polyaluminium chloride are omitted from the composition, that is, the composition is: 23 parts of sodium persulfate, 38 parts of modified cellulose and 21 parts of lime.

[0061] Comparative Example 3 The treatment agent is different from that in Example 1 only in that sodium persulfate and modified polyaluminium chloride are omitted from the composition, namely, the composition is: 12 parts of ethylenediaminetetraacetic acid, 38 parts of modified cellulose and 21 parts of lime.

[0062] Comparative Example 4 The treatment agent is different from that in Example 1 only in that lime and modified polyaluminium chloride are omitted from the composition, namely, the composition is: 12 parts of ethylenediaminetetraacetic acid, 23 parts of sodium persulfate, and 38 parts of modified cellulose.

[0063] Comparative Example 5 The treatment agent is different from that in Example 6 only in that the modified cellulose is replaced by an equal amount of unmodified cellulose, that is, the composition is: 12 parts of ethylenediaminetetraacetic acid, 23 parts of sodium persulfate, 38 parts of unmodified cellulose, and 21 parts of lime.

[0064] Comparative Example 6 The treatment agent, compared with Example 1, is different only in that the modified polyaluminium chloride is replaced by an equal amount of unmodified polyaluminium chloride, that is, the composition is: 12 parts of ethylenediaminetetraacetic acid, 23 parts of sodium persulfate, 38 parts of modified cellulose, 21 parts of lime, and 28 parts of unmodified polyaluminium chloride.

[0065] Test example The treatment agent prepared in the above examples and comparative examples was used to treat the coking wastewater membrane concentrate to detect its treatment effect. The coking wastewater membrane concentrate used had a COD of 8500 mg / L, a chromaticity of 350 degrees, a Pb of 25 mg / L, a Cr of 20 mg / L, a Cd of 15 mg / L, and a total dissolved solids (TDS) of 1200 mg / L.

[0066] Take 5g of the coking wastewater membrane concentrate treatment agent of each embodiment and comparative example, add it to 500mL of coking wastewater membrane concentrate, shake it at constant temperature until adsorption equilibrium is reached, centrifuge it, take the supernatant and the untreated coking wastewater membrane concentrate as the water samples to be tested, and measure the concentration of organic pollutants, chromaticity, heavy metals and total dissolved solids in the coking wastewater membrane concentrate treated with the treatment agent and the untreated coking wastewater membrane concentrate, and calculate the removal rate. The detection method of each index is as follows, and the detection results are shown in Table 1.

[0067] 1. COD removal rate Determination of COD concentration: Take 10.0ml of the water sample to be tested in a conical flask, add mercuric sulfate solution, 5.00ml of potassium dichromate standard solution and several explosion-proof glass beads in turn, and shake well. Mercuric sulfate solution is added at a mass ratio of m[HgSO4]:m[C1]>20:1, and the maximum addition amount is 2ml. Slowly add 15ml of silver sulfate-sulfuric acid solution from the upper end of the condenser. Heat the mixed water sample under reflux for 2 hours. After cooling, add the ferrous acid indicator and titrate with ammonium ferrous sulfate standard solution until the color of the solution changes to reddish brown. Calculate the COD value based on the volume of ammonium ferrous sulfate standard solution consumed in the titration. The COD removal rate calculation formula is as follows: COD removal rate (%) = (COD of untreated coking wastewater membrane concentrate - COD of coking wastewater membrane concentrate treated with treatment agent) / COD of untreated coking wastewater membrane concentrate × 100%.

[0068] 2. Chroma removal rate A spectrophotometer was used to prepare a series of platinum-cobalt standard solutions for establishing a standard curve. The samples were filtered using a 0.45 μm filter membrane. The water sample to be tested was placed in a 3 cm cuvette. The absorbance was measured at a wavelength of 339 nm. The actual chromaticity value was calculated based on the standard curve and the dilution multiple. The chromaticity removal rate was calculated as follows: Chromaticity removal rate (%) = (chromaticity value of untreated coking wastewater membrane concentrate - chromaticity value of coking wastewater membrane concentrate treated with a treatment agent) / chromaticity value of untreated coking wastewater membrane concentrate × 100%.

[0069] 3. Heavy metal removal rate Determination of heavy metal concentration (lead, chromium, cadmium): Prepare a series of multi-element standard solutions (national standard samples) of known concentrations for establishing a standard curve. Take 5 ml of the water sample to be tested, add 5 ml of hydrogen peroxide and 5 ml of nitric acid, digest to <5 ml, then adjust the volume to 25 ml, and filter with a 0.45 μm membrane to complete the pretreatment. Inject the pretreated sample solution into the ICP-OES instrument, and determine the heavy metal concentration in the sample by instrumental analysis. The heavy metal removal rate calculation formula is: Heavy metal removal rate (%) = (untreated coking wastewater membrane concentrate heavy metal concentration - coking wastewater membrane concentrate heavy metal concentration after treatment agent) / untreated coking wastewater membrane concentrate heavy metal concentration × 100%.

[0070] 4. Total dissolved solids (TDS) removal rate Place the cleaned evaporating dish in an oven, bake it at 105℃±2℃ for 1h, then place it in a dryer, cool it, weigh it, and repeat the drying and weighing of the evaporating dish until it reaches a constant weight. Pipette 100mL of the water sample to be tested that has been filtered through a 0.45μm filter membrane into an evaporating dish of constant weight, first evaporate it to a small volume on a hot plate, and then evaporate it in a water bath. Place the evaporating dish in an oven, bake it at 105℃±2℃ for 1h, take out the evaporating dish, place it in a dryer, cool it, and weigh it. Repeat the drying and weighing until it reaches a constant weight. The formula for calculating the TDS removal rate is: TDS removal rate (%) = (TDS of untreated coking wastewater membrane concentrate - TDS of coking wastewater membrane concentrate treated with treatment agent) / TDS of untreated coking wastewater membrane concentrate × 100%.

[0071] Table 1: Removal of pollutants from coking wastewater membrane concentrate in Examples and Comparative Examples .

[0072] The removal of pollutants from the coking wastewater membrane concentrate by the embodiment group and the comparative example is shown in Table 1. Overall, there are significant differences in the removal effects of various pollutants between the embodiments 1-10 and the comparative examples 1-6.

[0073] In the example group, Example 1 performed the best, and the removal rates of various indicators reached a high level: COD removal rate was 90.5%, heavy metal (Pb, Cr, Cd) removal rates were all above 90%, chroma removal rate was 89.8%, and TDS removal rate was 87.6%. This shows that the formula used in Example 1 (12 parts of ethylenediaminetetraacetic acid, 23 parts of sodium persulfate, 38 parts of modified cellulose, 21 parts of lime, and 28 parts of modified polyaluminium chloride) has the best synergistic treatment effect.

[0074] From Example 1 to Example 10, as the proportion of each group was adjusted, the treatment effect showed a gradually decreasing trend. Among them, the removal rates of various indicators of Examples 2-5 were still maintained at a good level of more than 80%, while the treatment effects of Examples 6-10 were relatively poor, but still generally better than the comparative example. This shows that the combined use of modified cellulose and modified polyaluminium chloride plays an important role in improving the treatment effect.

[0075] The experimental results of the comparative examples further verified this point. Comparative Examples 1-4 lacked certain key components, resulting in generally unsatisfactory treatment effects, especially significantly reduced removal rates of COD and TDS. Comparative Example 5 used unmodified cellulose and Comparative Example 6 used unmodified polyaluminium chloride. Although the removal rates were improved, they were still lower than the optimal effect of the embodiment group, which fully demonstrated the importance of modified cellulose and modified polyaluminium chloride in improving treatment effects.

[0076] From the perspective of various pollutant indicators, the removal effect of heavy metals (Pb, Cr, Cd) is generally better than other indicators, which is related to the chelating effect of EDTA and the functional groups on the surfaces of modified cellulose and modified polyaluminium chloride.

[0077] In summary, the experimental data show that the synergistic effect of the complete formula and the modified treatment of the materials are the key factors to improve the treatment effect of the coking wastewater membrane concentrate. Among them, the formula composition and ratio of Example 1 are the most reasonable, and can achieve the best comprehensive treatment effect. This provides a feasible technical solution for the treatment of coking wastewater membrane concentrate.

[0078] Finally, it should be noted that: Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A coking wastewater membrane concentrate treating agent, characterized in that: The method comprises the following raw materials in parts by weight: 5-15 parts of ethylenediaminetetraacetic acid, 10-30 parts of sodium persulfate, 20-50 parts of modified cellulose, and 10-25 parts of lime; The modified cellulose is a composite material obtained by reacting cellulose with sulfonated bayberry tannin in a mass ratio of 1:(2-3).

2. The treatment agent according to claim 1, characterized in that The preparation method of the modified fiber is: The sulfonation reaction of bayberry tannin with sodium bisulfite and concentrated sulfuric acid at 55-65°C for 3-5h was carried out, the pH of the reaction solution was adjusted to 6.5-7.5, dialyzed, and freeze-dried to obtain sulfonated bayberry tannin; The alkalized cellulose suspension is mixed with the sulfonated bayberry tannin solution, reacted at pH 4.5-5.0 and 60°C for 4 hours, and the reaction product is separated by centrifugation, washed, dried and purified.

3. The treatment agent according to claim 2, characterized in that The mass ratio of sodium bisulfite, concentrated sulfuric acid and bayberry tannin is (0.5~2):(0.5~2):

1.

4. The treatment agent according to claim 2, characterized in that The preparation method of the alkalized cellulose suspension is as follows: alkalizing microcrystalline cellulose, stirring at room temperature for 2 hours under the condition of pH 12-13, filtering, washing with deionized water to neutrality, and suspending the alkalized cellulose in deionized water.

5. The treatment agent according to claim 4, characterized in that The alkaline agent for alkalization treatment is sodium hydroxide.

6. The treatment agent according to claim 2, characterized in that The purification method is as follows: grinding the dried product into powder, extracting with ethanol as solvent for 20-28 hours, removing unreacted tannin, filtering, and vacuum drying at 55-65° C. for 10-14 hours.

7. The treating agent according to any one of claims 1 to 6, characterized in that: The invention also comprises 15 to 35 parts of modified polyaluminium chloride, wherein the modified polyaluminium chloride is obtained by modifying polyaluminium chloride and ferric chloride and then reacting with maleic anhydride, and has a carboxyl group on the surface. The mass ratio of polyaluminium chloride, ferric chloride and maleic anhydride is (3 to 6): (0.5 to 2):

1.

8. The treatment agent according to claim 7, characterized in that The preparation method of the modified polyaluminium chloride comprises: reacting a polyaluminium chloride solution with a ferric chloride solution at pH 3.5-4.0 and 80-85°C for 2-2.5 hours; lowering the temperature of the reaction solution to 70-75°C, adding maleic anhydride, and reacting at pH 4.0-4.5 for 3.5 hours; adding a precipitant for precipitation, collecting the precipitate by suction filtration, washing, and drying.

9. The treatment agent according to claim 8, characterized in that The precipitant is ethanol.

10. The method for preparing a coking wastewater membrane concentrate treating agent according to any one of claims 1 to 9, characterized in that: Include: The raw materials were thoroughly mixed at pH 6.8-7.2, dried, ground and sieved.