A coking wastewater membrane concentrate treatment agent and its preparation method

Abstract

This invention belongs to the field of coking wastewater concentrate treatment, and discloses a coking wastewater membrane concentrate treatment agent and its preparation method. The treatment agent comprises the following raw materials in parts by weight: 5-15 parts ethylenediaminetetraacetic acid, 10-30 parts sodium persulfate, 20-50 parts modified cellulose, and 10-25 parts lime; wherein the modified cellulose is a composite material obtained by reacting cellulose with sulfonated myricetin at a mass ratio of 1:(2-3). The treatment agent of this invention uses modified cellulose obtained by combining cellulose and sulfonated myricetin, which can significantly improve its adsorption performance and complexing ability in wastewater treatment, and enhance its ability to remove organic matter. Through the synergistic effect of multiple components, the treatment agent of this invention can simultaneously and efficiently remove high concentrations of organic matter, high salinity, and high color from coking wastewater membrane concentrate.

Description

Technical Field

[0001] This invention relates to the field of coking wastewater concentrate treatment, specifically to a coking wastewater membrane concentrate treatment agent and its preparation method. Background Technology

[0002] Coking wastewater membrane concentrate is a high-concentration pollutant solution produced after coking wastewater has been concentrated using membrane treatment technology. Its characteristics and treatment challenges far exceed those of ordinary coking wastewater. This concentrate has extremely high organic matter content, salt concentration, and color, posing a significant environmental challenge to the coking industry. The characteristics of coking wastewater membrane concentrate are mainly reflected in the following aspects: First, the organic matter content is extremely high, with chemical oxygen demand reaching tens of thousands or even hundreds of thousands of mg / L, far exceeding that of ordinary coking wastewater. These organic substances mainly include phenols, polycyclic aromatic hydrocarbons, heterocyclic compounds, and other recalcitrant substances, which are not only highly toxic but also extremely difficult to remove using conventional biological treatment methods. Second, 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 salinity not only increases the difficulty of treatment but also corrodes subsequent treatment equipment, affecting treatment efficiency. Third, the color is extremely high, often appearing dark brown or black, which not only affects the aesthetics of the water body but also obstructs light transmission, impacting the aquatic ecosystem. In addition, coking wastewater membrane concentrate contains large amounts of toxic substances such as ammonia nitrogen, sulfides, and cyanides, as well as various heavy metal ions such as iron, manganese, copper, and zinc. This complex combination of pollutants makes coking wastewater membrane concentrate an extremely difficult type of industrial wastewater to treat.

[0003] Currently, treating membrane concentrate from coking wastewater faces numerous technical challenges. Traditional biological treatment methods are ineffective due to the presence of high concentrations of toxic substances in the concentrate, as microorganisms struggle to survive and reproduce in such a harsh environment. Physicochemical treatment methods, such as flocculation sedimentation and activated carbon adsorption, can remove some pollutants, but their effectiveness is limited and often comes with high operating costs and the generation of large amounts of sludge. Advanced oxidation technologies, such as ozone oxidation and Fenton oxidation, are effective at removing organic matter, but when treating such high-concentration wastewater, the consumption of oxidants is enormous, making economic viability difficult to guarantee. Membrane treatment technologies, such as nanofiltration and reverse osmosis, can effectively remove salts, but are prone to membrane fouling when faced with high concentrations of organic matter, leading to a sharp decline in membrane life and a surge in maintenance costs. Evaporation crystallization technology can achieve "zero emissions," but it consumes a huge amount of energy and generates solid waste that is difficult to treat. Furthermore, single treatment technologies often cannot simultaneously address multiple pollution characteristics such as high COD, high salinity, and high color, requiring the combined use of multiple technologies, which further increases the complexity of the process and the difficulty of operation.

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

[0005] To address the problems in the background art, this invention provides a coking wastewater membrane concentrate treatment agent and its preparation method, thereby solving the problem of removing high concentrations of organic matter, high ammonia nitrogen, and high salinity from coking wastewater membrane concentrate.

[0006] To achieve the above objectives, the first technical solution adopted by the present invention is as follows:

[0007] A coking wastewater membrane concentrate treatment 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.

[0008] The modified cellulose is a composite material obtained by reacting cellulose with sulfonated bayberry tannin at a mass ratio of 1:(2~3).

[0009] Preferably, the modified fiber is prepared by:

[0010] Sulfonated bayberry tannin was obtained by reacting bayberry tannin with sodium bisulfite and concentrated sulfuric acid at 55-65℃ for 3-5 hours, adjusting the pH of the reaction solution to 6.5-7.5, dialyzing, and freeze-drying.

[0011] The alkalized cellulose suspension was mixed with the sulfonated bayberry tannin solution and reacted at pH 4.5-5.0 and 60℃ for 4 hours. The reaction product was separated by centrifugation, washed, dried and purified.

[0012] Preferably, the mass ratio of sodium bisulfite, concentrated sulfuric acid, and myricetin is (0.5~2):(0.5~2):1.

[0013] Preferably, the preparation method of the alkalized cellulose suspension is as follows: the microcrystalline cellulose is alkalized, stirred at room temperature for 2 hours under pH 12-13 conditions, filtered, washed with deionized water until neutral, and the alkalized cellulose is suspended in deionized water.

[0014] Preferably, the alkaline reagent for alkalization is sodium hydroxide.

[0015] Preferably, the purification method is as follows: the dried product is ground into powder, extracted with ethanol as solvent for 20-28 hours to remove unreacted tannins, filtered, and vacuum dried at 55-65°C for 10-14 hours.

[0016] Preferably, it further comprises 15-35 parts of modified polyaluminum chloride, wherein the modified polyaluminum chloride is obtained by reacting modified polyaluminum chloride with ferric chloride and maleic anhydride, and has carboxyl groups on its surface. The mass ratio of polyaluminum chloride, ferric chloride and maleic anhydride is (3-6):(0.5-2):1.

[0017] Preferably, the modified polyaluminum chloride is prepared by reacting polyaluminum chloride solution with ferric chloride solution at pH 3.5-4.0 and 80℃-85℃ for 2-2.5h; lowering the temperature of the reaction solution to 70℃-75℃, adding maleic anhydride, and reacting at pH 4.0-4.5 for 3.5h; adding a precipitant to precipitate, collecting the precipitate by filtration, washing, and drying.

[0018] Preferably, the precipitant is ethanol.

[0019] The second technical solution adopted in this invention is:

[0020] A method for preparing a coking wastewater membrane concentrate treatment agent, comprising:

[0021] Sodium persulfate, ethylenediaminetetraacetic acid solution, and modified cellulose were thoroughly mixed at pH 6.8-7.2, then dried, ground, and sieved.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The treatment agent of this invention uses modified cellulose obtained by combining cellulose and sulfonated bayberry tannin, which can significantly improve its adsorption performance and complexing ability in wastewater treatment, and enhance its ability to remove organic matter. Through the synergistic effect of multiple components, the treatment agent of this invention can simultaneously and efficiently remove high concentrations of organic matter, high salinity, and high color from coking wastewater membrane concentrate.

[0024] 2. The treatment agent of this invention uses modified natural materials and low-residue chemicals, reducing secondary pollution. The treatment process is more environmentally friendly, meets stringent environmental protection requirements, and reduces potential impacts on the ecosystem.

[0025] 3. The components of this treatment agent exhibit synergistic effects, reducing dosage and cost. It has strong applicability and can be widely applied to various coking plants without significant adjustments, thus improving practical value and economic benefits. Detailed Implementation

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] The first embodiment of the present invention provides a coking wastewater membrane concentrate treatment 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;

[0028] The modified cellulose is a composite material obtained by reacting cellulose with sulfonated bayberry tannin at a mass ratio of 1:(2~3).

[0029] It should be noted that modified cellulose is an adsorbent material chemically compounded from cellulose and sulfonated bayberry tannin. Cellulose provides numerous adsorption sites, while the introduction of sulfonic acid groups in the sulfonated bayberry tannin increases the material's hydrophilicity and ion exchange capacity. The polyphenolic structure of bayberry tannin provides excellent adsorption performance. This deep compounding process results in a composite material with more uniform adsorption performance and stronger pollutant capture capacity, effectively removing colored substances, aromatic compounds, and other organic pollutants from wastewater. Simultaneously, the polyphenolic structure of bayberry tannin also possesses a certain chelating ability, which can further adsorb and immobilize heavy metal ions.

[0030] The mechanisms of action of the remaining components in this treatment agent are as follows:

[0031] Ethylenediaminetetraacetic acid (EDTA): This is a chelating agent that can form stable complexes with various metal ions, especially heavy metal ions, thus reducing their toxicity. Its chelating effect also softens water, creating favorable conditions for subsequent treatment.

[0032] Sodium persulfate: As an oxidant, sodium persulfate can generate sulfate free radicals. These free radicals have strong oxidizing properties and can degrade organic pollutants in wastewater, especially some recalcitrant aromatic compounds and heterocyclic compounds. Through oxidation, large organic molecules are broken down into smaller molecules, significantly reducing the chemical oxygen demand (COD) of the wastewater. Simultaneously, this process also destroys chromophores that produce color, effectively reducing the color of the wastewater.

[0033] Lime: Used to adjust the pH of wastewater, it can quickly raise the pH value and create an alkaline environment. In this environment, many metal ions will form hydroxide precipitates, thus being removed. It can also react with bicarbonate ions in wastewater to form calcium carbonate precipitates, effectively removing carbonate hardness from the water. In addition, the addition of lime can promote the hydrolysis and precipitation of certain organic matter, further reducing COD.

[0034] This invention achieves highly efficient treatment of coking wastewater membrane concentrate through the synergistic interaction of the above components. Specifically, the oxidation effect of sodium persulfate converts large organic molecules into smaller molecules that are more easily adsorbed, improving the treatment efficiency of modified cellulose and modified polyaluminum chloride. The complexing effect of ethylenediaminetetraacetic acid prevents metal ions from interfering with flocculation, optimizing the flocculation effect and enhancing the oxidation effect of sodium persulfate. Lime not only adjusts the pH but also forms a powerful flocculation system with modified polyaluminum chloride, significantly improving the pollutant removal rate.

[0035] Through this series of complex physicochemical processes, the treatment agent effectively reduces the organic matter content, salt concentration, and color of coking wastewater membrane concentrate. High concentrations of organic matter are removed through oxidative decomposition and adsorption flocculation; high salt content is reduced through chemical precipitation and ion exchange; and high color is mainly eliminated through oxidative bleaching and flocculation adsorption. In summary, this treatment agent achieves comprehensive treatment of coking wastewater membrane concentrate through multiple mechanisms including complexation, oxidation, adsorption, precipitation, and flocculation.

[0036] In some preferred embodiments, the modified fiber is prepared by:

[0037] Sulfonated bayberry tannin was obtained by reacting bayberry tannin with sodium bisulfite and concentrated sulfuric acid at 55-65℃ for 3-5 hours, adjusting the pH of the reaction solution to 6.5-7.5, dialyzing, and freeze-drying.

[0038] The alkalized cellulose suspension was mixed with the sulfonated bayberry tannin solution and reacted at pH 4.5-5.0 and 60℃ for 4 hours. The reaction product was separated by centrifugation, washed, dried and purified.

[0039] Among them, alkalized cellulose suspension is a commonly used treatment method in this field. Specifically, the microcrystalline cellulose is alkalized by stirring at room temperature for 2 hours under pH 12-13 conditions, filtered, washed with deionized water until neutral, and then the alkalized cellulose is suspended in deionized water.

[0040] The alkaline reagent used in the alkalization process is a commonly used alkaline reagent in this field, such as sodium hydroxide, with a mass concentration of 5%-20%.

[0041] It should be noted that the method for preparing sulfonated bayberry tannin is a commonly used sulfonation treatment method in this field. Those skilled in the art can select appropriate raw material dosages and process parameters according to the object being treated. For example, the mass ratio of sodium bisulfite, concentrated sulfuric acid, and bayberry tannin is (0.5~2):(0.5~2):1.

[0042] The purification method described is a commonly used purification technique in the art, involving washing or extraction combined with drying. Specific parameters can be selected by those skilled in the art based on the actual purification target. For example, the dried product can be ground into powder, extracted with ethanol as a solvent for 20-28 hours to remove unreacted tannins, filtered, and vacuum dried at 55-65°C for 10-14 hours.

[0043] 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, which is obtained by reacting polyaluminum chloride with ferric chloride and maleic anhydride. The modified polyaluminum chloride has carboxyl groups on its surface, and the mass ratio of polyaluminum chloride, ferric chloride and maleic anhydride is (3 to 6): (0.5 to 2): 1.

[0044] Polyaluminum chloride (PAC) is modified with ferric chloride to enhance its flocculation capacity and pH adaptability. Subsequent reaction with maleic anhydride introduces carboxyl groups, improving its adsorption capacity for organic matter. This carefully designed structure allows the modified PAC to form positively charged colloids in wastewater, efficiently coagulating suspended solids, colloids, and dissolved organic matter through mechanisms such as charge neutralization, adsorption bridging, and entrapment. The resulting large flocs promote rapid sedimentation and separation of pollutants. Furthermore, due to the introduction of carboxyl groups, the modified PAC also possesses a certain chelating ability, which can further remove some heavy metal ions.

[0045] In the process of working synergistically with other components, the flocculation effect of modified polyaluminum chloride causes oxidized organic matter and modified cellulose adsorbed with pollutants to settle together, achieving the synergistic removal of multiple pollutants. The adsorption effect of modified cellulose can provide more nucleation sites for modified polyaluminum chloride, promoting floc formation.

[0046] In some preferred embodiments, the modified polyaluminum chloride is prepared by reacting a polyaluminum 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 to precipitate, collecting the precipitate by filtration, washing, and drying.

[0047] The second embodiment of the present invention provides a method for preparing a coking wastewater membrane concentrate treatment agent, comprising:

[0048] Mix all raw materials thoroughly at pH 6.8-7.2, then dry, grind, and sieve.

[0049] There are no special restrictions on the order of mixing the raw materials; those skilled in the art can make adaptive adjustments based on the raw materials. The final particle size after sieving can also be adapted to the conditions of the wastewater to be treated.

[0050] The following detailed description of the coking wastewater membrane concentrate treatment agent and its effects is provided through several specific examples.

[0051] The experimental equipment and formulations used in the embodiments described below are as follows:

[0052] Electronic balance (Sartorius, Germany), electric heating blower constant temperature dryer (Shanghai Fuma Experimental Equipment), stainless steel reaction vessel (Shanghai Laibei), electric heating constant temperature water bath (Jiangsu Kedao), rotary evaporator (Shanghai Daluo Scientific Instruments), pulverizer (Shandong Tianfang Machinery), magnetic stirrer (Shanghai Meiyingpu), Soxhelt extractor (Qingdao Juchuang); chemical reagents were purchased from Sigma-Aldrich.

[0053] Example 1

[0054] The coking wastewater membrane concentrate treatment agent is composed of the following raw materials in parts by weight: 12 parts ethylenediaminetetraacetic acid, 23 parts sodium persulfate, 38 parts modified cellulose, 21 parts lime, and 28 parts modified polyaluminum chloride.

[0055] The modified cellulose contains cellulose and sulfonated bayberry tannin in a mass ratio of 1:2.2, and the preparation method is as follows:

[0056] S11. Mix bayberry tannin, sodium bisulfite and concentrated sulfuric acid in a mass ratio of 1:1:1, stir and react in an ice bath for 30 min, raise the reaction temperature to 60℃, and continue stirring and reacting for 4 h.

[0057] S12. After the reaction is complete, add ice water to adjust the pH of the reaction solution to 7.0, dialyze multiple times, and freeze-dry the dialyzed solution to obtain sulfonated bayberry tannin;

[0058] S13. Add 10% sodium hydroxide solution to microcrystalline cellulose, stir at room temperature for 2 hours, filter, wash with deionized water until neutral, and suspend the alkalized cellulose in deionized water;

[0059] S14. Mix the sulfonated bayberry tannin solution and the alkalized cellulose suspension evenly, adjust the pH to 4.5~5.0, and react at 60℃ for 4h;

[0060] S15. After the reaction is complete, the product is separated by centrifugation, washed, and then vacuum dried at 60°C for 12 hours.

[0061] S16. Grind the dried product into powder, extract with ethanol as solvent for 24 hours to remove unreacted tannins, filter, and vacuum dry at 60°C for 12 hours to obtain purified modified cellulose.

[0062] The preparation method of modified polyaluminum chloride (polyaluminum chloride: ferric chloride: maleic anhydride in a mass ratio of 4:2:1) includes:

[0063] S21. Slowly add ferric chloride solution dropwise to polyaluminum chloride solution over 30 min, maintaining the pH of the reaction solution at 3.5-4.0. After the addition is complete, raise the temperature to 85℃ and continue the reaction for 2 h, maintaining the pH at 3.5-4.0.

[0064] S22. Reduce the reaction temperature to 70℃, add maleic anhydride, and react at pH 4.0~4.5 and 75℃ for 3.5h;

[0065] S23. After the reaction is complete, cool the solution to room temperature and add anhydrous ethanol to precipitate the solution.

[0066] S24. Filter the above reaction solution, collect the precipitate, wash the precipitate, dry the precipitate under vacuum at 60℃ for 12h, and grind the dried product into fine powder.

[0067] The preparation method of the coking wastewater membrane concentrate treatment agent is as follows: mix all raw materials thoroughly at pH 6.8~7.2, dry, grind and sieve.

[0068] Example 2

[0069] The coking wastewater membrane concentrate treatment agent is composed of the following raw materials in parts by weight: 5 parts ethylenediaminetetraacetic acid, 10 parts sodium persulfate, 20 parts modified cellulose, 10 parts lime, and 15 parts modified polyaluminum chloride (the mass ratio of polyaluminum chloride: ferric chloride: maleic anhydride is 3:0.5:1). The preparation methods of modified cellulose and modified polyaluminum chloride are as described in Example 1, where the mass ratio of cellulose to sulfonated bayberry tannin in the modified cellulose is 1:2.

[0070] Example 3

[0071] The coking wastewater membrane concentrate treatment agent is composed of the following raw materials in parts by weight: 15 parts ethylenediaminetetraacetic acid, 30 parts sodium persulfate, 50 parts modified cellulose, 25 parts lime, and 35 parts modified polyaluminum chloride (the mass ratio of polyaluminum chloride: ferric chloride: maleic anhydride is 6:2:1).

[0072] The preparation methods of modified cellulose and modified polyaluminum chloride are as described in Example 1. The mass ratio of cellulose to sulfonated bayberry tannin in the modified cellulose is 1:3.

[0073] Example 4

[0074] The coking wastewater membrane concentrate treatment agent is composed of the following raw materials in parts by weight: 10 parts ethylenediaminetetraacetic acid, 20 parts sodium persulfate, 35 parts modified cellulose, 17 parts lime, and 25 parts modified polyaluminum chloride (the mass ratio of polyaluminum chloride: ferric chloride: maleic anhydride is 4.5:1.25:1). The preparation methods of modified cellulose and modified polyaluminum chloride are as described in Example 1, where the mass ratio of cellulose to sulfonated myricetin in the modified cellulose is 1:2.5.

[0075] Example 5

[0076] The coking wastewater membrane concentrate treatment agent is composed of the following raw materials in parts by weight: 8 parts ethylenediaminetetraacetic acid, 12 parts sodium persulfate, 26 parts modified cellulose, 16 parts lime, and 26 parts modified polyaluminum chloride (the mass ratio of polyaluminum chloride: ferric chloride: maleic anhydride is 5:1.8:1). The preparation methods of the modified cellulose and modified polyaluminum chloride are as described in Example 1, where the mass ratio of cellulose to sulfonated myricetin in the modified cellulose is 1:2.8.

[0077] Example 6

[0078] The coking wastewater membrane concentrate treatment agent is composed of the following raw materials in parts by weight: 12 parts ethylenediaminetetraacetic acid, 23 parts sodium persulfate, 38 parts modified cellulose, and 21 parts lime.

[0079] The preparation method of modified cellulose is described in Example 1.

[0080] Example 7

[0081] The coking wastewater membrane concentrate treatment agent is composed of the following raw materials in parts by weight: 5 parts ethylenediaminetetraacetic acid, 10 parts sodium persulfate, 20 parts modified cellulose, and 10 parts lime.

[0082] The preparation method of modified cellulose is described in Example 1.

[0083] Example 8

[0084] The coking wastewater membrane concentrate treatment agent is composed of the following raw materials in parts by weight: 15 parts ethylenediaminetetraacetic acid, 30 parts sodium persulfate, 50 parts modified cellulose, and 25 parts lime.

[0085] The preparation method of modified cellulose is described in Example 1.

[0086] Example 9

[0087] The coking wastewater membrane concentrate treatment agent is composed of the following raw materials in parts by weight: 10 parts ethylenediaminetetraacetic acid, 20 parts sodium persulfate, 35 parts modified cellulose, and 17 parts lime.

[0088] The preparation method of modified cellulose is described in Example 1.

[0089] Example 10

[0090] The coking wastewater membrane concentrate treatment agent is composed of the following raw materials in parts by weight: 8 parts ethylenediaminetetraacetic acid, 12 parts sodium persulfate, 26 parts modified cellulose, and 16 parts lime.

[0091] The preparation method of modified cellulose is described in Example 1.

[0092] Comparative Example 1

[0093] The treatment agent differs from that in Example 1 only in that the modified cellulose and modified polyaluminum chloride are omitted from the composition, which is: 12 parts of ethylenediaminetetraacetic acid, 23 parts of sodium persulfate, and 21 parts of lime.

[0094] Comparative Example 2

[0095] The treatment agent differs from that in Example 1 only in that the components EDTA and modified polyaluminum chloride are omitted, and the composition is: 23 parts sodium persulfate, 38 parts modified cellulose, and 21 parts lime.

[0096] Comparative Example 3

[0097] The treatment agent differs from that in Example 1 only in that the components of sodium persulfate and modified polyaluminum chloride are omitted, and the composition is: 12 parts of ethylenediaminetetraacetic acid, 38 parts of modified cellulose, and 21 parts of lime.

[0098] Comparative Example 4

[0099] The treatment agent differs from that in Example 1 only in that the use of lime and modified polyaluminum chloride has been eliminated. The composition is: 12 parts ethylenediaminetetraacetic acid, 23 parts sodium persulfate, and 38 parts modified cellulose.

[0100] Comparative Example 5

[0101] The treatment agent differs from that in Example 6 only in that the modified cellulose is replaced with an equal amount of unmodified cellulose, i.e., the composition is: 12 parts ethylenediaminetetraacetic acid, 23 parts sodium persulfate, 38 parts unmodified cellulose, and 21 parts lime.

[0102] Comparative Example 6

[0103] The treatment agent differs from that in Example 1 only in that the modified polyaluminum chloride is replaced with an equal amount of unmodified polyaluminum chloride, i.e., the composition is: 12 parts ethylenediaminetetraacetic acid, 23 parts sodium persulfate, 38 parts modified cellulose, 21 parts lime, and 28 parts unmodified polyaluminum chloride.

[0104] Test case

[0105] The treatment agents prepared in the above examples and comparative examples were used to treat coking wastewater membrane concentrate, and their treatment effects were tested. The coking wastewater membrane concentrate used had a COD of 8500 mg / L, a color of 350 degrees, a Pb concentration of 25 mg / L, a Cr concentration of 20 mg / L, a Cd concentration of 15 mg / L, and a total dissolved solids (TDS) concentration of 1200 mg / L.

[0106] Take 5g of the coking wastewater membrane concentrate treatment agent from each embodiment and comparative example, and add it to 500mL of coking wastewater membrane concentrate. Shake at a constant temperature until adsorption equilibrium is reached, then centrifuge. Use the supernatant and untreated coking wastewater membrane concentrate as test samples. Determine the concentrations of organic pollutants, color, heavy metals, and total dissolved solids in both the treated and untreated coking wastewater membrane concentrates, and calculate the removal rate. The detection methods for each indicator are as follows, and the results are shown in Table 1.

[0107] 1. COD removal rate

[0108] Determination of COD concentration: Take 10.0 ml of the water sample to be tested into an Erlenmeyer flask, add mercuric sulfate solution, 5.00 ml of potassium dichromate standard solution, and a few anti-boiling glass beads in sequence, and shake well. The mercuric sulfate solution is added at a mass ratio of m[HgSO4]:m[Cl]>20:1, with a maximum addition volume of 2 ml. Slowly add 15 ml of silver sulfate-sulfuric acid solution from the top of the condenser. Heat the mixed water sample under reflux for 2 hours. After cooling, add ferroin indicator and titrate with ferrous ammonium sulfate standard solution until the solution color changes to reddish-brown. Calculate the COD value based on the volume of ferrous ammonium sulfate standard solution consumed in the titration. The COD removal rate is calculated 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%.

[0109] 2. Color removal rate

[0110] A series of platinum-cobalt standard solutions were prepared using a spectrophotometer to establish a standard curve. Samples were filtered using a 0.45 μm filter membrane. The water sample was placed in a 3 cm cuvette, and the absorbance was measured at 339 nm. The actual colorimetric value was calculated based on the standard curve and dilution factor. The colorimetric removal rate was calculated using the following formula: Colorimetric removal rate (%) = (Colorimetric value of untreated coking wastewater membrane concentrate - Colorimetric value of coking wastewater membrane concentrate treated with the treatment agent) / Colorimetric value of untreated coking wastewater membrane concentrate × 100%.

[0111] 3. Heavy metal removal rate

[0112] Determination of heavy metal concentration (lead, chromium, cadmium): Prepare a series of multi-element standard solutions (national standard samples) with known concentrations to establish 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 make up to 25 ml, and filter through a 0.45 μm membrane to complete the pretreatment. Inject the pretreated sample solution into an ICP-OES instrument, and determine the heavy metal concentration in the sample through instrument analysis. The formula for calculating the heavy metal removal rate is: Heavy metal removal rate (%) = (Heavy metal concentration of untreated coking wastewater membrane concentrate - Heavy metal concentration of coking wastewater membrane concentrate after treatment) / Heavy metal concentration of untreated coking wastewater membrane concentrate × 100%.

[0113] 4. Total dissolved solids (TDS) removal rate

[0114] Place the cleaned evaporating dish in an oven and dry at 105℃±2℃ for 1 hour. Then, place it in a desiccator to cool and weigh it. Repeat the drying and weighing process until a constant weight is achieved. Take 100 mL of the water sample to be tested, filtered through a 0.45 μm membrane, and place it in the pre-weighed evaporating dish. First, evaporate it to a small volume on a hot plate, then evaporate it to dryness in a water bath. Place the evaporating dish in an oven and dry at 105℃±2℃ for 1 hour. Remove the evaporating dish and place it in a desiccator to cool and weigh it. Repeat the drying and weighing process until a constant weight is achieved. The TDS removal rate is calculated as follows: TDS removal rate (%) = (TDS of untreated coking wastewater membrane concentrate - TDS of coking wastewater membrane concentrate treated with the treatment agent) / TDS of untreated coking wastewater membrane concentrate × 100%.

[0115] Table 1. Results of pollutant removal from coking wastewater membrane concentrate in examples and comparative cases.

[0116] .

[0117] Table 1 shows the results of removing pollutants from the membrane concentrate of coking wastewater in the example groups and comparative examples. Overall, there are significant differences between Examples 1-10 and Comparative Examples 1-6 in the removal efficiency of various pollutants.

[0118] Among the example groups, Example 1 performed the best, with high removal rates for all indicators: COD removal rate of 90.5%, heavy metal (Pb, Cr, Cd) removal rates all above 90%, color removal rate of 89.8%, and TDS removal rate of 87.6%. This indicates that the formulation used in Example 1 (12 parts ethylenediaminetetraacetic acid, 23 parts sodium persulfate, 38 parts modified cellulose, 21 parts lime, and 28 parts modified polyaluminum chloride) has the best synergistic treatment effect.

[0119] From Example 1 to Example 10, the treatment effect gradually decreased with the adjustment of the proportions of each group. Among them, the removal rates of various indicators in Examples 2-5 remained at a good level of over 80%, while the treatment effects of Examples 6-10 were relatively poor, but still generally better than the comparative examples. This indicates that the combined use of modified cellulose and modified polyaluminum chloride plays an important role in improving the treatment effect.

[0120] The results of the comparative experiments further validated this point. Comparative Examples 1-4 lacked certain key components, resulting in generally unsatisfactory treatment effects, particularly a significant reduction in the removal rates of COD and TDS. Comparative Example 5 used unmodified cellulose, and Comparative Example 6 used unmodified polyaluminum chloride. Although the removal rates were improved, they were still lower than the optimal results of the example groups. This fully demonstrates the importance of modified cellulose and modified polyaluminum chloride in improving treatment effectiveness.

[0121] In terms of various pollutant indicators, the removal efficiency of heavy metals (Pb, Cr, Cd) is generally better than that of other indicators. This is related to the chelating effect of ethylenediaminetetraacetic acid and the functional groups on the surface of modified cellulose and modified polyaluminum chloride.

[0122] In summary, the experimental data demonstrate that the synergistic effect of the complete formulation and the modification of materials are key factors in improving the treatment effect of coking wastewater membrane concentrate. Among these, the formulation and proportions in Example 1 are the most reasonable, achieving the optimal comprehensive treatment effect. This provides a feasible technical solution for the treatment of coking wastewater membrane concentrate.

[0123] Finally, it should be noted that although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A coking wastewater membrane concentrate treatment agent, characterized in that, The raw materials include the following 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 at a mass ratio of 1:(2~3); The reaction conditions are as follows: alkalized cellulose and sulfonated bayberry tannin are reacted at pH 4.5-5.0 and 60°C.

2. The treatment agent as described in claim 1, characterized in that, The preparation method of sulfonated bayberry tannin is as follows: Sulfonated bayberry tannin was obtained by reacting bayberry tannin with sodium bisulfite and concentrated sulfuric acid at 55-65℃ for 3-5 hours, adjusting the pH of the reaction solution to 6.5-7.5, dialyzing, and freeze-drying. After reacting alkalized cellulose with sulfonated bayberry tannin at pH 4.5-5.0 and 60℃, the process also includes: centrifuging to separate the reaction products, washing, drying, and purifying them.

3. The treatment agent as described in 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 as described in claim 2, characterized in that, The preparation method of alkalized cellulose suspension is as follows: alkalize microcrystalline cellulose, stir at room temperature for 2 hours under pH 12-13 conditions, filter, wash with deionized water until neutral, and suspend the alkalized cellulose in deionized water.

5. The treatment agent as described in claim 4, characterized in that, The alkaline reagent used for alkalization is sodium hydroxide.

6. The treatment agent as described in claim 2, characterized in that, The purification method is as follows: the dried product is ground into powder, extracted with ethanol as solvent for 20-28 hours to remove unreacted tannins, filtered, and vacuum dried at 55-65°C for 10-14 hours.

7. The treatment agent according to any one of claims 1-6, characterized in that, It also contains 15-35 parts of modified polyaluminum chloride, which is obtained by modifying polyaluminum chloride with ferric chloride and then reacting it with maleic anhydride. The surface has carboxyl groups, and the mass ratio of polyaluminum chloride, ferric chloride and maleic anhydride is (3-6):(0.5-2):

1.

8. The treatment agent as described in claim 7, characterized in that, The modified polyaluminum chloride is prepared by reacting polyaluminum chloride solution with ferric chloride solution at pH 3.5-4.0 and 80℃-85℃ for 2-2.5h; lowering the temperature of the reaction solution to 70℃-75℃, adding maleic anhydride, and reacting at pH 4.0-4.5 for 3.5h; adding a precipitant to precipitate, collecting the precipitate by filtration, washing, and drying.

9. The treatment agent as described in claim 8, characterized in that, The precipitant is ethanol.

10. The method for preparing the coking wastewater membrane concentrate treatment agent according to any one of claims 1-9, characterized in that, Include: Mix all raw materials thoroughly at pH 6.8-7.2, then dry, grind, and sieve.