Papermaking wastewater treatment agent and application thereof

Abstract

The application provides a papermaking wastewater treatment agent, which comprises 85-95 parts by weight of a composite modified biochar adsorbent, 3-8 parts by weight of polyaluminum chloride, 2-6.5 parts by weight of silicon dioxide and 0.5-2 parts by weight of sodium acetate; the preparation method of the composite modified biochar adsorbent comprises the following steps: 1) pretreating biochar; 2) modifying the biochar pretreated in step 1) with iron-aluminum hydrotalcite; 3) adding graphene oxide and the biochar modified with iron-aluminum hydrotalcite obtained in step 2) into a treatment liquid, soaking, washing, filtering and drying; 4) uniformly mixing the graphene oxide / hydrotalcite modified biochar obtained in step 3) with polyacrylamide and heat treating; in step 3), the treatment agent is an aqueous solution comprising C 16 ESOCONa with a concentration of 3-4.5 g / L and FeCl3 with a concentration of 0.5-2 g / L. The removal rate of COD and BOD in papermaking wastewater is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wastewater, in particular to a papermaking wastewater treatment agent and application thereof. BACKGROUND

[0002] The papermaking industry is seriously polluted, with large amount of wastewater discharge and various pollutants. There are hundreds of organic pollutants in the papermaking wastewater detected at present. In the prior art, polyaluminum chloride is used to make the wastewater flocculate and precipitate, but the treatment effect is still not ideal. Bacterial flora is added for treatment, but the process is not easy to control and industrialization is difficult to achieve.

[0003] Biochar can be prepared by high-temperature pyrolysis of various biomass materials such as shell, straw, wood, sludge and various feces, and the raw materials are easy to obtain. The preparation method of biochar is relatively simple, so the cost is low. Biochar has a large specific surface area, which makes it have a certain adsorption capacity. However, in practical application, its adsorption effect still cannot meet the requirements.

[0004] Therefore, it is necessary to provide a papermaking wastewater treatment agent with good treatment effect on pollutants in papermaking wastewater. SUMMARY

[0005] The present application aims to at least solve one of the technical problems existing in the prior art, and thus in the first aspect of the present application, the present application provides a papermaking wastewater treatment agent, comprising 85-95 parts by weight of a composite modified biochar adsorbent, 3-8 parts by weight of polyaluminum chloride, 2-6.5 parts by weight of silicon dioxide, and 0.5-2 parts by weight of sodium acetate.

[0006] The preparation method of the composite modified biochar adsorbent comprises the following steps:

[0007] 1) : pretreating biochar;

[0008] 2) : modifying the biochar pretreated in step 1) with iron-aluminum hydrotalcite;

[0009] 3) : adding graphene oxide and the biochar modified with iron-aluminum hydrotalcite obtained in step 2) into a treatment liquid, soaking, washing, filtering and drying to obtain graphene oxide / hydrotalcite modified biochar;

[0010] 4) : mixing the graphene oxide / hydrotalcite modified biochar obtained in step 3) with polyacrylamide, and heat treating to obtain the composite modified biochar adsorbent;

[0011] In step 3), the treatment liquid is an aqueous solution comprising 4-(methylsulfinyl)-2-(palmitoyloxy) butyric acid sodium salt with a concentration of 3-4.5 g / L and FeCl3 with a concentration of 0.5-2 g / L.

[0012] Through the technical scheme, the composite modified biochar adsorbent has a pretreated biochar layer, an intermediate layer composed of hydrotalcite and graphene, and a polyacrylamide layer partially coated on the intermediate layer. In the system environment of the treatment liquid, the intermediate layer is composed of hydrotalcite and graphene to form a more complex labyrinth structure, and a complex ion environment forms a one-way guide, so that the pollutants are more easily entered into the inner layer and are more difficult to escape from the inner layer to the outer layer. After the pollutants in the sewage are adsorbed to the inner layer, the pollutants are difficult to escape, so that the pollutants are bound, and a good effect of removing the pollutants in the sewage is achieved.

[0013] Preferably, the concentration ratio of 4-(methylsulfinyl)-2-(palmitoyloxy) butyric acid sodium salt and FeCl3 in the treatment liquid is 1.5-9:1, preferably 4:1.

[0014] Preferably, in step 2) of the preparation method of the composite modified biochar adsorbent, the iron-aluminum hydrotalcite modification of the pretreated biochar obtained in step 1) comprises the following steps: preparing an aqueous solution containing Al 3+ and Fe 2+ , adding the pretreated biochar obtained in step 1) to obtain a mixed solution A, preparing an aqueous solution containing NaOH and Na2CO3 to obtain a mixed solution B, simultaneously adding the mixed solution A and the mixed solution B into a container, stirring while reacting, keeping the pH of the reaction liquid at 10, aging, filtering, washing, and drying to obtain the hydrotalcite modified biochar.

[0015] Preferably, in step 2) of the preparation method of the composite modified biochar adsorbent, the amount of substance of Al 3+ , the mass of the pretreated biochar in step 2), and the mass of the graphene oxide in step 3) are in a ratio of 0.01 mol:20 g:(8-10) g.

[0016] Preferably, in step 4) of the preparation method of the composite modified biochar adsorbent, the mass ratio of the polyacrylamide to the graphene oxide / hydrotalcite modified biochar obtained in step 3) is (0.5-0.8):9.

[0017] Preferably, in step 4) of the preparation method of the composite modified biochar adsorbent, the heat treatment temperature is 190-210℃, and the heat treatment time is 1.5-2.5h.

[0018] Preferably, the preparation method of the composite modified biochar adsorbent further comprises: before step 4), mixing bentonite with the graphene oxide / hydrotalcite modified biochar prepared in step 3) and hydrothermally treating.

[0019] By the above technical scheme, the bentonite can constitute a buffer layer, so that the pollutants can more easily enter the intermediate layer from the polyacrylamide layer, and the bentonite can increase the compatibility of the intermediate layer and the polyacrylamide layer, so that the contact is more close and stable, and the adsorption effect is improved.

[0020] Preferably, the mass ratio of the bentonite, the polyacrylamide used in step 4) and the graphene oxide / hydrotalcite modified biochar prepared by the preparation method of step 3) is 0.09:(0.5-0.8):9.

[0021] Preferably, in step 1) of the preparation method of the composite modified biochar adsorbent, the pretreatment comprises pyrolysis treatment, acid treatment and alkali treatment.

[0022] Preferably, the pyrolysis treatment is treated at 575-585℃ for 2.5-3.5h; the acid treatment is stirred in a sulfuric acid aqueous solution with a concentration of 5-7wt% for 17-19h; and the alkali treatment is stirred in a sodium hydroxide aqueous solution with a concentration of 6-8wt% for 21-23h.

[0023] In the second aspect of the present application, the present application provides an application of the papermaking wastewater treatment agent in the first aspect of the present application in reducing COD and / or BOD in wastewater.

[0024] The present application has the following beneficial effects:

[0025] 1. The present application provides a papermaking wastewater treatment agent, which comprises a composite modified biochar adsorbent, and has good treatment effect on COD and BOD in papermaking wastewater. After treatment, the removal rates of COD and BOD in papermaking wastewater are more than 80% and more than 75% respectively, and even both reach more than 90%.

[0026] 2. The papermaking wastewater treatment agent provided by the present application can transport pollutants to the core of the papermaking wastewater treatment agent, and has high treatment efficiency and low dosage.

[0027] 3. The papermaking wastewater treatment agent provided by the present application uses biochar as the main raw material, and has low cost. DETAILED DESCRIPTION

[0028] The present application is further described below in combination with specific examples, but the following examples are only used to illustrate the present application, and should not be regarded as limiting the scope of the present application. In the following examples, the specific conditions are not specified, and the conventional conditions or the conditions recommended by the manufacturers are used, and the methods used are the conventional methods known in the art, and the consumables and reagents used are commercially available unless otherwise specified. Unless otherwise specified, the professional and scientific terms used in this paper have the same meaning as those familiar to those skilled in the art. In addition, any method or material similar or equivalent to the described content can also be applied to the present application.

[0029] The graphene oxide was purchased from Hangzhou Gao'ene Technology Co., Ltd., product type GX-pGO-2. The bentonite was purchased from Zhejiang Yuhong New Material Co., Ltd., product type YH-GH-10. The polyacrylamide was purchased from Anhui Tianlun Chemical Industry Co., Ltd., product type N100. The polyaluminum chloride was purchased from Guangdong Zhongke Water Purification Material Co., Ltd.

[0030] Example 1

[0031] A papermaking wastewater treatment agent, which is obtained by mixing 90 parts by weight of a composite modified biochar adsorbent, 5 parts by weight of polyaluminum chloride, 3 parts by weight of silicon dioxide, and 2 parts by weight of sodium acetate.

[0032] The preparation method of the composite modified biochar adsorbent comprises the following steps:

[0033] 1) Pretreatment of biochar: corn straw was ground and crushed, and then placed in a coking furnace and heated to 580℃ for 3h. The pretreated biochar was soaked in a 6wt% sulfuric acid aqueous solution for 18h, washed with water until neutral, dried, soaked in a 7wt% sodium hydroxide aqueous solution for 22h, washed with water until neutral, and dried to obtain pretreated biochar.

[0034] 2) Modification of the pretreated biochar obtained in step 1): 2.41g of AlCl3·6H2O and 3.98g of FeCl2·4H2O were added to 600mL of deionized water, and then 20g of the pretreated biochar obtained in step 1) was added to the solution and mixed uniformly to obtain a mixed solution A. Separately, 16.0g of NaOH and 13.25g of Na2CO3 were added to 500mL of water to obtain a mixed solution B. The mixed solution A and the mixed solution B were simultaneously dropped into a container, and the reaction was stirred while maintaining the reaction temperature at 60℃. The pH of the reaction solution was maintained at 10 by adjusting the dropping speed. After the dropping was completed, the reaction was continued for 30min. The mixture was aged at 80℃ for 24h, filtered, washed with water, and then dried at 80℃ for 36h to obtain a hydrotalcite modified biochar.

[0035] 3) Preparation of graphene oxide / hydrotalcite modified biochar: an aqueous solution containing 4g / L of 4-(methylsulfinyl)-2-(palmitoyloxy)butyric acid sodium salt (C 16 ESOCOONa) and 1g / L of FeCl3 was prepared to obtain a treatment solution. Graphene oxide and the hydrotalcite modified biochar obtained in step 2) were added to 2L of the treatment solution. The mass / volume ratio of the graphene oxide to the treatment solution was controlled at 4g / L. The mixture was soaked for 1h, washed with deionized water, filtered, and dried to obtain graphene oxide / hydrotalcite modified biochar.

[0036] 4) Preparation of composite adsorbent: Take 10g of polyacrylamide and the graphene oxide / hydrotalcite modified biochar obtained by the preparation method in step 3). Control the mass ratio of polyacrylamide and graphene oxide / hydrotalcite modified biochar obtained in step 3) to be 0.5:9, mix well, heat treat, control the heat treatment temperature to be 200℃, and the heat treatment time to be 2h to obtain composite modified biochar adsorbent.

[0037] Sodium 4-(methylsulfinyl)-2-(palmitoyloxy)butyrate (C 16 The synthesis of ESOCOONa was performed according to the preparation methods in Examples 1 and 4 of Chinese Patent CN108026489B, as detailed below:

[0038] Step 1: Synthesis of 4-(methylthio)-2-(palmitoyloxy)butyric acid. At 0 °C, 4-dimethylaminopyridine (DMAP; cat.; 0.5 mmol) and triethylamine (Et3N; 18.7 mL, 134 mmol) were added dropwise to a solution of 2-hydroxy-4-(methylthio)butyric acid (10.08 g, 67.1 mmol) in dichloromethane (DCM; 200 mL), followed by the addition of palmitoyl chloride (10.2 mL, 33.6 mmol). The reaction mixture was heated to room temperature overnight with stirring, concentrated, and redissolved in heptane (300 mL). The organic layer was washed with 1N HCl (3 x 100 mL), water (2 x 100 mL), and brine (1 x 100 mL), then dried over magnesium sulfate, filtered, and evaporated to give a white solid. The white solid was purified by silica gel column chromatography using 0%-25% ethyl acetate (EA) / heptane and 1% acetic acid (AcOH) as additives.

[0039] Step 2: Synthesis of 4-(methylsulfinyl)-2-(palmitoyloxy)butyric acid. Hydrogen peroxide (30%, 4.57 mL, 44.8 mmol) was added to a methanol (30 mL) solution of 4-(methylthio)-2-(palmitoyloxy)butyric acid (5.8 g, 14.9 mmol) at 0 °C. The reaction mixture was heated to room temperature and stirred for 5.5 hours. The reaction mixture was diluted with 200 mL of DCM, washed with water (1 x 100 mL), and the resulting emulsion was separated overnight. The organic layer was washed with 10% sodium bisulfite (1 x 100 mL), dried over magnesium sulfate, filtered, and evaporated to give a white solid. The solid was purified by silica gel column chromatography with 2%–10% MeOH / DCM containing 1% AcOH additive to give 4-(methylsulfinyl)-2-(palmitoyloxy)butyric acid.

[0040] Step 3: Dowex MAC-3 resin (proton form) was swelled and neutralized with an excess of NaOH / aqueous solution and then assembled into an exchange column. After equilibrating the resin with 2 column volumes of 30% water / ethanol, 1 column volume of a 0.1 g / mL solution of 4-(methylsulfinyl)-2-(palmitoyloxy)butanoic acid from Step 2 in 30% water / ethanol was loaded into the exchange column and incubated in the exchange column for 10 minutes. Subsequently, the resin was rinsed with 2 column volumes of 30% water / ethanol and the eluate was collected. After passing through the exchange column, the pH of a 1 wt% solution / suspension of the solid increased from 4 to 8. The solvent was then evaporated under vacuum with moderate heating (40 °C) to give 4-(methylsulfinyl)-2-(palmitoyloxy)butanoic acid sodium salt (C 16 ESOCOONa).

[0041] Example 2

[0042] Example 2 differs from Example 1 in that in the preparation method of the composite modified biochar adsorbent, in step 3), the mass-volume ratio of graphene oxide to the treatment solution is controlled to be 5 g / L, that is, the ratio of the amount of substance of AlCl3·6H2O in step 2), the mass of the pretreated biochar in step 2) to the mass of graphene oxide in step 3) is 0.01 mol:20 g:10 g.

[0043] Example 3

[0044] Example 3 differs from Example 1 in that in the preparation method of the composite modified biochar adsorbent, in step 3), the treatment solution is an aqueous solution containing 3 g / L of C 16 ESOCOONa, 2 g / L of FeCl3.

[0045] Example 4

[0046] Example 4 differs from Example 1 in that in the preparation method of the composite modified biochar adsorbent, in step 3), the treatment solution is an aqueous solution containing 4.5 g / L of C 16 ESOCOONa, 0.5 g / L of FeCl3.

[0047] Example 5

[0048] Example 5 differs from Example 1 in that the preparation method of the composite modified biochar adsorbent, in step 2), in Example 5, step 2) is: 2.41 g of AlCl3-6H2O and 3.98 g of FeCl2-4H2O are added to 600 mL of deionized water, mixed uniformly to obtain a mixed solution A, and then 16.0 g of NaOH and 13.25 g of Na2CO3 are added to 500 mL of water to obtain a mixed solution B; the mixed solution A and the mixed solution B are simultaneously dropped into a container, stirred while reacting, the reaction temperature is maintained at 60°C, and the pH of the reaction solution is maintained at 10 by adjusting the dropping speed, after the dropping is completed, the reaction is continued for 30 min, and the aging is carried out at 80°C for 24 hours, filtered, washed with water, and then dried at 80°C for 36 hours to obtain a hydrotalcite; the obtained hydrotalcite is mixed uniformly with 20 g of the pretreated biochar obtained in step 1), and the hydrotalcite modified biochar is obtained by heat treatment at 200°C for 2 h.

[0049] Example 6

[0050] Example 6 differs from Example 1 in that the preparation method of the composite modified biochar adsorbent, in step 4), the mass ratio of polyacrylamide and the graphene oxide / hydrotalcite modified biochar obtained in step 3) is controlled to be 0.8:9.

[0051] Example 7

[0052] Example 7 differs from Example 1 in that the preparation method of the composite modified biochar adsorbent, after step 3) and before step 4), further includes: weighing bentonite, controlling the mass ratio of bentonite, polyacrylamide used in step 4), and graphene oxide / hydrotalcite modified biochar prepared in step 3) to be 0.09:0.5:9, and before step 4), the bentonite and the graphene oxide / hydrotalcite modified biochar prepared in step 3) are added to 400 g of water, mixed uniformly, reacted in a reaction kettle at 80°C for 2 h, washed, filtered, dried, and then the operation of step 4) is performed.

[0053] Example 8

[0054] Example 8 differs from Example 7 in that the preparation method of the composite modified biochar adsorbent, after step 3) and before step 4), does not include hydrothermal treatment, that is, after step 3) and before step 4), it includes: weighing bentonite, controlling the mass ratio of bentonite, polyacrylamide used in step 4), and graphene oxide / hydrotalcite modified biochar prepared in step 3) to be 0.09:0.5:9, and before step 4), the bentonite and the graphene oxide / hydrotalcite modified biochar prepared in step 3) are mixed uniformly, and then the operation of step 4) is performed.

[0055] Example 9

[0056] Example 9 differs from Example 7 in that the bentonite is added in step 4) in the preparation method of the composite modified biochar adsorbent, and step 4) is: taking polyacrylamide, bentonite, the graphene oxide / hydrotalcite modified biochar prepared in step 3) of the preparation method, bentonite, controlling the mass ratio of bentonite, polyacrylamide and the graphene oxide / hydrotalcite modified biochar prepared in step 3) of the preparation method to be 0.09:0.5:9, mixing uniformly, heat treatment, and controlling the heat treatment temperature to be 200℃ and the heat treatment time to be 2h. The composite modified biochar adsorbent is obtained.

[0057] Example 10

[0058] Example 10 differs from Example 1 in that the proportions of the components of the papermaking wastewater treatment agent are different, and Example 11 is composed of 85 parts by weight of the composite modified biochar adsorbent, 5 parts by weight of polyaluminum chloride, 3 parts by weight of silicon dioxide, and 2 parts by weight of sodium acetate.

[0059] Example 11

[0060] Example 11 differs from Example 1 in that the proportions of the components of the papermaking wastewater treatment agent are different, and Example 12 is composed of 95 parts by weight of the composite modified biochar adsorbent, 3 parts by weight of polyaluminum chloride, 2 parts by weight of silicon dioxide, and 1 part by weight of sodium acetate.

[0061] Comparative Example 1

[0062] Comparative Example 1 differs from Example 1 in that step 2) is different in the preparation method of the composite modified biochar adsorbent, and step 2) of Comparative Example 1 is: modifying the pretreated biochar obtained in step 1) as follows: 2.41g of AlCl3·6H2O and 6.09g of MgCl2·6H2O are added to 600mL of deionized water, and then 20g of the pretreated biochar obtained in step 1) is added to the solution, mixed uniformly to obtain a mixed solution A, and then 16.0g of NaOH and 13.25g of Na2CO3 are added to 500mL of water to obtain a mixed solution B; mixed solution A and mixed solution B are simultaneously dropped into a container, and the reaction is stirred, the reaction temperature is maintained at 60℃, and the pH of the reaction solution is maintained at 10 by adjusting the dropping speed, after the dropping is completed, the reaction is continued for 30min, and the aging is carried out at 80℃ for 24 hours, then filtered, washed with water, and then dried at 80℃ for 36 hours to obtain the hydrotalcite modified biochar.

[0063] Comparative Example 2

[0064] The difference between Comparative Example 2 and Example 1 is that the positions of steps 2) and 3) are exchanged in the preparation method of the composite modified biochar adsorbent. Specifically:

[0065] 1) Pretreatment of biochar: corn straw was taken, ground and crushed, and placed in a coking furnace, heated to 580℃, treated for 3h, soaked in a 6wt% sulfuric acid aqueous solution and stirred for 18h, washed with water until neutral, dried, soaked in a 7wt% sodium hydroxide aqueous solution and stirred for 22h, washed with water until neutral, and dried to obtain pretreated biochar.

[0066] 2) Modification of the pretreated biochar obtained in step 1): an aqueous solution containing 4g / L C 16 ESOCOONa, 1g / L FeCl3 was prepared to obtain a treatment solution, 20g of the pretreated biochar obtained in step 1) and graphene oxide were added to 2L of the treatment solution, the mass / volume ratio of graphene oxide to the treatment solution was controlled to be 4g / L, soaked for 1h, washed with deionized water, filtered, and dried to obtain modified biochar.

[0067] 3) Preparation of graphene oxide / hydrotalcite modified biochar: 2.41g of AlCl3·6H2O and 3.98g of FeCl2·4H2O were added to 600mL of deionized water, and the modified biochar obtained in step 2) was added to the solution, mixed uniformly to obtain a mixed solution A, and 16.0g of NaOH and 13.25g of Na2CO3 were added to 500mL of water to obtain a mixed solution B; mixed solution A and mixed solution B were simultaneously dropped into a container, stirred during the reaction, the reaction temperature was maintained at 60℃, and the pH of the reaction solution was maintained at 10 by adjusting the dropping speed, after the dropping was completed, the reaction was continued for 30min, aged at 80℃ for 24h, filtered, washed with water, and then dried at 80℃ for 36h to obtain graphene oxide / hydrotalcite modified biochar.

[0068] 4) Preparation of composite adsorbent: polyacrylamide and graphene oxide / hydrotalcite modified biochar prepared by the preparation method of step 3) were taken, the mass ratio of polyacrylamide to graphene oxide / hydrotalcite modified biochar obtained in step 3) was controlled to be 0.5:9, mixed uniformly, heat treated, and the heat treatment temperature was controlled to be 200℃ and the heat treatment time was 2h to obtain a composite modified biochar adsorbent.

[0069] Comparative Example 3

[0070] The difference between Comparative Example 3 and Example 1 is that no graphene oxide is added in step 3) in the preparation method of the composite modified biochar adsorbent. That is, steps 3) and 4) are changed to:

[0071] 3) An aqueous solution containing 4g / L C 16ESOCOONa, 1 g / L FeCl3 aqueous solution to obtain a treatment solution, 20 g of the pre-treated biochar obtained in step 1) was added into 2 L of the treatment solution, the mass / volume ratio of graphene oxide to the treatment solution was controlled to be 4 g / L, and soaking was performed for 1 h, deionized water was used for washing, filtration was performed, and drying was performed to obtain graphene oxide / hydrotalcite modified biochar.

[0072] 4) Preparation of the composite adsorbent: polyacrylamide and the secondary modified biochar obtained in step 3) were taken, the mass ratio of polyacrylamide to the secondary modified biochar obtained in step 3) was controlled to be 0.5:9, uniform mixing was performed, heat treatment was performed, the heat treatment temperature was controlled to be 200 ℃, and the heat treatment time was controlled to be 2 h to obtain the composite modified biochar adsorbent.

[0073] Comparative Example 4

[0074] Comparative Example 4 is different from Example 1 in that the preparation method of the composite modified biochar adsorbent does not include step 2). That is, the preparation method of the composite modified biochar adsorbent includes the following steps:

[0075] 1) Pretreatment of biochar: corn straw was taken, grinding and crushing were performed, the corn straw was placed in a coking furnace, the temperature was raised to 580 ℃, and treatment was performed for 3 h, the corn straw was soaked in a 6 wt% sulfuric acid aqueous solution for stirring treatment for 18 h, water washing was performed until neutral, drying was performed, the corn straw was soaked in a 7 wt% sodium hydroxide aqueous solution for stirring treatment for 22 h, water washing was performed until neutral, drying was performed, and the pretreated biochar was obtained.

[0076] 2) Preparation of graphene oxide modified biochar: an aqueous solution containing 4 g / L of 4-(methylsulfinyl)-2-(palmitoyloxy)butyric acid sodium salt (C 16 ESOCOONa), 1 g / L of FeCl3 to obtain a treatment solution, 20 g of the pre-treated biochar obtained in step 1) was added into 2 L of the treatment solution, the mass / volume ratio of graphene oxide to the treatment solution was controlled to be 4 g / L, and soaking was performed for 1 h, deionized water was used for washing, filtration was performed, and drying was performed to obtain graphene oxide / hydrotalcite modified biochar.

[0077] 3) Preparation of the composite adsorbent: polyacrylamide and the graphene oxide / hydrotalcite modified biochar obtained in step 2) were taken, the mass ratio of polyacrylamide to the graphene oxide / hydrotalcite modified biochar obtained in step 2) was controlled to be 0.5:9, uniform mixing was performed, heat treatment was performed, the heat treatment temperature was controlled to be 200 ℃, and the heat treatment time was controlled to be 2 h to obtain the composite modified biochar adsorbent.

[0078] Comparative Example 5

[0079] Comparative Example 5 is different from Example 1 in that, in the preparation method of the composite modified biochar adsorbent, the treatment solution in step 3) is an aqueous solution containing 5 g / L of C 16 ESOCOONa.

[0080] Comparative Example 6

[0081] Comparative Example 6 differs from Example 1 in that the preparation method of the composite modified biochar adsorbent, in step 3), the treatment solution is an aqueous solution containing 5 g / L of FeCl3.

[0082] Comparative Example 7

[0083] Comparative Example 7 differs from Example 1 in that the preparation method of the composite modified biochar adsorbent, in step 3), the treatment solution, C 16 ESOCOONa is replaced with an equal amount of 4-(methylthio)-2-(dodecanoyloxy) butyric acid sodium salt (C 12 ESCOONa). The preparation method of 4-(methylthio)-2-(dodecanoyloxy) butyric acid sodium salt (C 12 ESCOONa) is the same as that of C 16 ESCOONa in Example 1. The only difference is that palmitoyl chloride in step 2 is replaced with an equal molar amount of lauroyl chloride.

[0084] Comparative Example 8

[0085] Comparative Example 8 differs from Example 1 in that the preparation method of the composite modified biochar adsorbent, step 4) does not include a heat treatment process. That is, step 4) is that 10 g of polyacrylamide is taken, and the graphene oxide / hydrotalcite modified biochar obtained by the preparation method of step 3), the mass ratio of polyacrylamide and the graphene oxide / hydrotalcite modified biochar obtained by step 3) is controlled to be 0.5:9, and the mixture is uniformly mixed to obtain a composite modified biochar adsorbent.

[0086] 0.01 g of the adsorbent obtained by the preparation of the examples and comparative examples is added to 1 L of a certain papermaking wastewater sample for treatment. Before treatment, the COD value is 654 mg / L, and the BOD value is 236 mg / L. After treatment, the results are shown in Table 1.

[0087] Table 1

[0088]

[0089]

[0090] Comparative Example 1 and Example 1 combined with Table 1, it can be seen that in the preparation method of the composite modified biochar adsorbent, when the hydrotalcite of the modified biochar is changed from iron-aluminum hydrotalcite to magnesium-aluminum hydrotalcite, the removal rate of the treatment agent for COD and BOD in papermaking wastewater is significantly reduced.

[0091] As can be seen from the comparison of Comparative Example 2 and Example 1 in combination with Table 1, in the preparation method of the composite modified biochar adsorbent, when the preparation of the graphene oxide / hydrotalcite modified biochar is changed from first modified by hydrotalcite and then modified by graphene oxide to first modified by graphene oxide and then modified by hydrotalcite, the removal rates of the treatment agent for COD and BOD in the papermaking wastewater are significantly reduced.

[0092] As can be seen from the comparison of Comparative Example 3 and Example 1 in combination with Table 1, in the preparation method of the composite modified biochar adsorbent, when no graphene oxide is added in step 3), the removal rates of the treatment agent for COD and BOD in the papermaking wastewater are significantly reduced.

[0093] As can be seen from the comparison of Comparative Example 4 and Example 1 in combination with Table 1, in the preparation method of the composite modified biochar adsorbent, when the modification by hydrotalcite is not included, the removal rates of the treatment agent for COD and BOD in the papermaking wastewater are significantly reduced.

[0094] As can be seen from the comparison of Comparative Examples 5 and 6 and Example 1 in combination with Table 1, when the treatment liquid only contains C 16 ESOCOONa or FeCl3, the removal rates of the treatment agent for COD and BOD in the papermaking wastewater are significantly reduced.

[0095] As can be seen from the comparison of Comparative Example 7 and Example 1 in combination with Table 1, when C 16 ESOCOONa in the treatment liquid is replaced by 4-(methylthio)-2-(dodecanoyloxy) butyric acid sodium salt (C 12 ESCOONa), the removal rates of the treatment agent for COD and BOD in the papermaking wastewater are significantly reduced.

[0096] As can be seen from the comparison of Comparative Example 8 and Example 1 in combination with Table 1, when the heat treatment process is not included in step 4), the removal rates of the treatment agent for COD and BOD in the papermaking wastewater are significantly reduced.

[0097] Although the embodiments of the present application have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present application, and those of ordinary skill in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present application, which should be included in the protection scope of the present application.

Claims

1. A papermaking wastewater treatment agent, characterized in that, It includes 85-95 parts by weight of composite modified biochar adsorbent, 3-8 parts by weight of polyaluminum chloride, 2-6.5 parts by weight of silica, and 0.5-2 parts by weight of sodium acetate; The preparation method of the composite modified biochar adsorbent includes the following steps: 1): Pretreatment of biochar; 2): Modify the pretreated biochar from step 1) with iron-aluminum hydrotalcite; 3): Add graphene oxide and the iron-aluminum hydrotalcite modified biochar obtained in step 2) to the treatment solution, soak, wash, filter, and dry to obtain graphene oxide / hydrotalcite modified biochar. 4): Mix the graphene oxide / hydrotalcite modified biochar obtained in step 3) with polyacrylamide, and heat treat to obtain the composite modified biochar adsorbent. In step 3), the treatment solution is an aqueous solution comprising sodium 4-(methylsulfinyl)-2-(palmitoyloxy)butyrate at a concentration of 3-4.5 g / L and FeCl3 at a concentration of 0.5-2 g / L.

2. The papermaking wastewater treatment agent according to claim 1, characterized in that, In step 2) of the preparation method of the composite modified biochar adsorbent, the modification of the pretreated biochar in step 1) with iron-aluminum hydrotalcite includes the following steps: preparing a mixture containing Al 3+ and Fe 2+ Add the pretreated biochar obtained in step 1) to the aqueous solution to obtain mixture A. Prepare an aqueous solution containing NaOH and Na2CO3 to obtain mixture B. Add mixture A and mixture B to the container at the same time, stir while reacting, keep the pH of the reaction solution at 10, age, filter, wash, and dry to obtain hydrotalcite modified biochar.

3. The papermaking wastewater treatment agent according to claim 2, characterized in that, In step 2) of the preparation method of the composite modified biochar adsorbent, Al 3+ The ratio of the amount of substance, the mass of the pretreated biochar in step 2) to the mass of graphene oxide in step 3) is 0.01 mol: 20 g: (8-10) g.

4. The papermaking wastewater treatment agent according to claim 1, characterized in that, In step 4) of the preparation method of the composite modified biochar adsorbent, the mass ratio of polyacrylamide and the graphene oxide / hydrotalcite modified biochar obtained in step 3) is (0.5-0.8):

9.

5. The papermaking wastewater treatment agent according to claim 1, characterized in that, In step 4) of the preparation method of the composite modified biochar adsorbent, the heat treatment temperature is 190-210℃ and the heat treatment time is 1.5-2.5h.

6. The papermaking wastewater treatment agent according to claim 1, characterized in that, The preparation method of the composite modified biochar adsorbent further includes: after step 3) and before step 4), mixing bentonite with the graphene oxide / hydrotalcite modified biochar obtained in step 3) evenly and then performing hydrothermal treatment.

7. The papermaking wastewater treatment agent according to claim 6, characterized in that, The mass ratio of bentonite, polyacrylamide used in step 4), and graphene oxide / hydrotalcite modified biochar obtained in step 3) was controlled to be 0.09:(0.5-0.8):

9.

8. The papermaking wastewater treatment agent according to claim 1, characterized in that, In step 1) of the preparation method of the composite modified biochar adsorbent, the pretreatment includes pyrolysis treatment, acid treatment, and alkali treatment.

9. The papermaking wastewater treatment agent according to claim 8, characterized in that, The pyrolysis treatment is carried out at 575-585℃ for 2.5-3.5 hours; the acid treatment is carried out in a 5-7 wt% sulfuric acid aqueous solution with stirring for 17-19 hours; and the alkali treatment is carried out in a 6-8 wt% sodium hydroxide aqueous solution with stirring for 21-23 hours.

10. The use of the papermaking wastewater treatment agent according to any one of claims 1-9 in reducing COD and / or BOD in wastewater.

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