Papermaking sewage treatment agent and application thereof

Abstract

The invention provides a papermaking sewage treatment agent. The papermaking sewage treatment agent 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) carrying out iron-aluminum hydrotalcite modification on the charcoal pretreated in the step (1); (3) adding graphene oxide and the iron-aluminum hydrotalcite modified charcoal obtained in the step (2) into the treating fluid, soaking, washing, filtering and drying; 4) uniformly mixing the graphene oxide / hydrotalcite modified charcoal obtained in the step 3) and polyacrylamide, and performing heat treatment; in the step (3), a treatment agent is an aqueous solution containing C16ESOCOONa with the concentration of 3-4.5 g / L and FeCl3 with the concentration of 0.5-2 g / L. The removal rate of COD and BOD in the papermaking wastewater is high.

Description

Technical Field

[0001] The invention patent relates to the field of wastewater technology, and in particular to a papermaking wastewater treatment agent and its application. Background Art

[0002] The papermaking industry is seriously polluted, with a large amount of wastewater discharged and many types of pollutants. Hundreds of organic pollutants have been detected in papermaking wastewater. In the prior art, polyaluminum chloride is used to flocculate and precipitate wastewater, but the treatment effect is still unsatisfactory. There are also methods of adding bacterial flora for treatment, but the process is difficult to control and difficult to achieve industrialization.

[0003] Biochar can be prepared by high-temperature pyrolysis of a variety of biomass materials such as shells, straw, wood, sludge and various feces. The raw materials are easy to obtain and 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 applications, its adsorption effect still does not meet the requirements.

[0004] In view of this, it is necessary to provide a papermaking wastewater treatment agent that has good treatment effect on pollutants in papermaking wastewater. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art to a certain extent. Thus, in a first aspect of the present invention, the present invention provides a papermaking wastewater treatment agent, comprising 85-95 parts by weight of a composite modified biochar adsorbent, 3-8 parts by weight of polyaluminium 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): Pre-treat the 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) to the treatment liquid, soaking, washing, filtering and drying to obtain graphene oxide / hydrotalcite modified biochar;

[0010] 4): The graphene oxide / hydrotalcite modified biochar and polyacrylamide obtained in step 3) are mixed and heat treated to obtain the composite modified biochar adsorbent;

[0011] In the step 3), the treatment solution is an aqueous solution including 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 above 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. Under the system environment of the treatment liquid, the intermediate layer formed by hydrotalcite and graphene forms a more complex maze structure, and the complex ion environment forms a one-way drainage, making it easier for pollutants to enter the inner layer, but more difficult to go from the inner layer to the outer layer. After the pollutants in the sewage are adsorbed into the inner layer, it is not easy to escape, thereby binding the pollutants, thereby achieving a good effect of removing pollutants from the sewage.

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

[0014] Preferably, in step 2) of the method for preparing the composite modified biochar adsorbent, the biochar pretreated in step 1) is modified with iron-aluminum hydrotalcite, which comprises the following steps: preparing a mixture containing Al 3+ and Fe 2+ The aqueous solution is added with the pretreated biochar obtained in step 1) to obtain a mixed solution A, and an aqueous solution containing NaOH and Na2CO3 is prepared to obtain a mixed solution B. The mixed solution A and the mixed solution B are added into a container at the same time, stirred while reacting, so that the pH value of the reaction solution is maintained at 10, aged, filtered, washed, and dried to obtain a hydrotalcite-modified biochar.

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

[0016] Preferably, in step 4) of the method for preparing the composite modified biochar adsorbent, the mass ratio of 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 method for preparing the composite modified biochar adsorbent, the heat treatment temperature is 190-210° C., and the heat treatment time is 1.5-2.5 h.

[0018] Preferably, the method for preparing the composite modified biochar adsorbent further comprises: after step 3) and before step 4), uniformly mixing bentonite with the graphene oxide / hydrotalcite modified biochar prepared by the preparation method of step 3), and subjecting it to hydrothermal treatment.

[0019] Through the above technical solution, bentonite may form a buffer layer, making it easier for pollutants to enter the middle layer from the polyacrylamide layer. In addition, bentonite can increase the compatibility between the middle layer and the polyacrylamide layer, making the contact closer and more stable, thereby improving the adsorption effect.

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

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

[0022] Preferably, the pyrolysis treatment is carried out at 575-585°C for 2.5-3.5 hours; the acid treatment is carried out in a 5-7wt% aqueous sulfuric acid solution with stirring for 17-19 hours; and the alkali treatment is carried out in a 6-8wt% aqueous sodium hydroxide solution with stirring for 21-23 hours.

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

[0024] The beneficial effects of the present invention are:

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

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

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

[0028] The present invention will be further described below in conjunction with specific examples, but the following examples are only used to illustrate the present invention and should not be considered to limit the scope of the present invention. In the following examples, if specific conditions are not specified, they are carried out according to normal conditions or conditions recommended by the manufacturer. The methods used are conventional methods known in the art unless otherwise specified, and the consumables and reagents used are commercially available unless otherwise specified. Unless otherwise specified, the professional and scientific terms used herein have the same meaning as those familiar to those skilled in the art. In addition, any method or material similar or equivalent to the recorded content may also be applied to the present invention.

[0029] Graphene oxide was purchased from Hangzhou Gaoxin Technology Co., Ltd., product model GX-pGO-2. Bentonite was purchased from Zhejiang Yuhong New Materials Co., Ltd., product model YH-GH-10. Polyacrylamide was purchased from Anhui Tianrun Chemical Industry Co., Ltd. Non-ionic polyacrylamide, product model N100. Polyaluminium chloride was purchased from Guangdong Zhongke Water Purification Materials Co., Ltd. Industrial grade polyaluminium chloride.

[0030] Example 1

[0031] A papermaking wastewater treatment agent is obtained by mixing 90 parts by weight of a composite modified biochar adsorbent, 5 parts by weight of polyaluminium 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: Grind corn stalks, put them into a coking furnace, heat them to 580°C, treat them for 3 hours, soak them in a 6wt% aqueous sulfuric acid solution and stir them for 18 hours, wash them with water until they are neutral, dry them, soak them in a 7wt% aqueous sodium hydroxide solution and stir them for 22 hours, wash them with water until they are neutral, and dry them to obtain pretreated biochar.

[0034] 2) Modifying the pretreated biochar obtained in step 1): adding 2.41 g of AlCl3·6H2O and 3.98 g of FeCl2·4H2O to 600 mL of deionized water, and then adding 20 g of the pretreated biochar obtained in step 1) to the solution, mixing evenly to obtain a mixed solution A, and then taking 16.0 g of NaOH and 13.25 g of Na2CO3 and adding them to 500 mL of water to obtain a mixed solution B; dripping the mixed solution A and the mixed solution B into a container at the same time, stirring while reacting, keeping the reaction temperature at 60°C, and adjusting the dropping speed to keep the pH of the reaction solution at 10, continuing the reaction for 30 minutes after the addition is completed, aging at 80°C for 24 hours, filtering, washing with water, and then drying at 80°C for 36 hours to obtain a biochar modified with hydrotalcite.

[0035] 3) Preparation of graphene oxide / hydrotalcite modified biochar: 4 g / L of 4-(methylsulfinyl)-2-(palmitoyloxy)butyric acid sodium salt (C 16 ESOCOONa), 1g / L FeCl3 aqueous solution to obtain a treatment solution, add graphene oxide and the hydrotalcite-modified biochar obtained in step 2) to 2L of the treatment solution, control the mass volume ratio of graphene oxide to the treatment solution to be 4g / L, soak for 1h, wash with deionized water, filter, and dry to obtain graphene oxide / hydrotalcite-modified biochar.

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

[0037] 4-(Methylsulfinyl)-2-(palmitoyloxy)butyric acid sodium salt (C 16 The synthesis of ESOCOONa) is based on the preparation method of Example 1 and Example 4 in Chinese patent CN108026489B, which is as follows:

[0038] Step 1: Synthesis of 4-(methylthio)-2-(palmitoyloxy)butanoic acid. To a solution of 2-hydroxy-4-(methylthio)butanoic acid (10.08 g, 67.1 mmol) in dichloromethane (DCM; 200 mL) at 0°C was added 4-dimethylaminopyridine (DMAP; cat.; 0.5 mmol), triethylamine (Et3N; 18.7 mL, 134 mmol), followed by palmitoyl chloride (10.2 mL, 33.6 mmol). The reaction was warmed to room temperature with stirring overnight, 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 with 0%-25% ethyl acetate (EA) / heptane and 1% acetic acid (AcOH) additive.

[0039] Step 2: Synthesis of 4-(methylsulfinyl)-2-(palmitoyloxy)butyric acid. At 0°C, hydrogen peroxide (30%, 4.57 mL, 44.8 mmol) was added to a solution of 4-(methylthio)-2-(palmitoyloxy)butyric acid (5.8 g, 14.9 mmol) in methanol (30 mL). The reaction was warmed to room temperature and stirred for 5.5 hours. The reaction was diluted with 200 mL DCM, washed with water (1 x 100 mL), and the formed 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. Purification by silica gel column chromatography with 2%-10% MeOH / DCM containing 1% AcOH additive gave 4-(methylsulfinyl)-2-(palmitoyloxy)butyric acid.

[0040] Step 3: Dowex MAC-3 resin (proton form) was swollen and neutralized with excess NaOH / water solution and then assembled into an exchange column. After equilibrating the resin with 2 column volumes of 30% by volume water / ethanol, 1 column volume of 0.1 g / mL of a 30% by volume water / ethanol solution of 4-(methylsulfinyl)-2-(palmitoyloxy)butyric acid obtained in step 2 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% by volume water / ethanol, and the eluent was collected. After passing through the exchange column, the pH of the 1% by weight solution / suspension of the solid increased from 4 to 8. The solvent was then evaporated in vacuo under moderate heating (40° C.) to obtain 4-(methylsulfinyl)-2-(palmitoyloxy)butyric acid sodium salt (C 16 ESOCOONa).

[0041] Example 2

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

[0043] Example 3

[0044] The difference between Example 3 and Example 1 is that in the preparation method of the composite modified biochar adsorbent, the treatment liquid in step 3) contains 3g / L C 16 ESOCOONa, 2g / L FeCl3 aqueous solution.

[0045] Example 4

[0046] The difference between Example 4 and Example 1 is that in the preparation method of the composite modified biochar adsorbent, the treatment liquid in step 3) contains 4.5 g / L C 16 ESOCOONa, 0.5g / L FeCl3 aqueous solution.

[0047] Example 5

[0048] The difference between Example 5 and Example 1 is that in the preparation method of the composite modified biochar adsorbent, step 2) is different. In Example 5, step 2) is: add 2.41g of AlCl3·6H2O and 3.98g of FeCl2·4H2O to 600mL of deionized water, mix evenly to obtain a mixed solution A, and then take 16.0g of NaOH and 13.25g of Na2CO3 and add them to 500mL of water to obtain a mixed solution B; drip the mixed solution A and the mixed solution B into the container at the same time, stir while reacting, keep the reaction temperature at 60°C, and adjust the dropping speed to keep the pH of the reaction solution at 10. After the dropwise addition is completed, continue the reaction for 30min, age at 80°C for 24 hours, filter, wash with water, and then dry at 80°C for 36 hours to obtain hydrotalcite; mix the obtained hydrotalcite with 20g of the pretreated biochar obtained in step 1), and heat treat at 200°C for 2h to obtain hydrotalcite-modified biochar.

[0049] Example 6

[0050] The difference between Example 6 and Example 1 is that in the method for preparing 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] The difference between Example 7 and Example 1 is that in the preparation method of the composite modified biochar adsorbent, after step 3) and before step 4), it also includes weighing bentonite, controlling the mass ratio of bentonite, polyacrylamide used in step 4) and graphene oxide / hydrotalcite modified biochar prepared by the preparation method of step 3) to be 0.09:0.5:9, after step 3) and before step 4), adding bentonite and graphene oxide / hydrotalcite modified biochar prepared by the preparation method of step 3) to 400g of water, mixing evenly, reacting in a reactor at 80°C for 2h, washing, filtering, and drying, and then performing the operation of step 4).

[0053] Example 8

[0054] The difference between Example 8 and Example 7 is that in the preparation method of the composite modified biochar adsorbent, after step 3) and before step 4), no hydrothermal treatment is included, 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 by the preparation method of step 3) to be 0.09:0.5:9, after step 3) and before step 4), the bentonite and the graphene oxide / hydrotalcite modified biochar prepared by the preparation method of step 3) are evenly mixed, and then the operation of step 4) is performed.

[0055] Example 9

[0056] The difference between Example 9 and Example 7 is that in the preparation method of the composite modified biochar adsorbent, bentonite is added in step 4), and step 4) is: take polyacrylamide, bentonite, graphene oxide / hydrotalcite modified biochar obtained by the preparation method of step 3), and bentonite, control the mass ratio of bentonite, polyacrylamide and graphene oxide / hydrotalcite modified biochar prepared by the preparation method of step 3) to be 0.09:0.5:9, mix, heat treat, control the heat treatment temperature to be 200°C, and the heat treatment time to be 2h. A composite modified biochar adsorbent is obtained.

[0057] Example 10

[0058] The difference between Example 10 and Example 1 is that the components of the papermaking wastewater treatment agent are different in the number of parts. Example 11 consists of 85 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.

[0059] Embodiment 11

[0060] The difference between Example 11 and Example 1 is that the components of the papermaking wastewater treatment agent are different in the number of parts. Example 12 consists of 95 parts by weight of a 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] The difference between Comparative Example 1 and Example 1 is that in the preparation method of the composite modified biochar adsorbent, step 2) is different. Step 2) of Comparative Example 1 is: modifying the pretreated biochar obtained in step 1): adding 2.41g of AlCl3·6H2O and 6.09g of MgCl2·6H2O to 600mL of deionized water, and then adding 20g of the pretreated biochar obtained in step 1) to the solution, mixing evenly to obtain a mixed solution A, and then taking 16.0g of NaOH and 13.25g of Na2CO3 and adding them to 500mL of water to obtain a mixed solution B; the mixed solution A and the mixed solution B are dripped into a container at the same time, stirring while reacting, keeping the reaction temperature at 60°C, and adjusting the dripping speed to keep the pH of the reaction solution at 10, and continuing the reaction for 30min after the dripping is completed, aging at 80°C for 24 hours, filtering, washing with water, and then drying at 80°C for 36 hours to obtain hydrotalcite-modified biochar.

[0063] Comparative Example 2

[0064] The difference between Comparative Example 2 and Example 1 is that in the method for preparing the composite modified biochar adsorbent, step 2) and step 3) are swapped. Specifically:

[0065] 1) Pretreatment of biochar: Grind corn stalks, put them into a coking furnace, heat them to 580°C, treat them for 3 hours, soak them in a 6wt% aqueous sulfuric acid solution and stir them for 18 hours, wash them with water until they are neutral, dry them, soak them in a 7wt% aqueous sodium hydroxide solution and stir them for 22 hours, wash them with water until they are neutral, and dry them to obtain pretreated biochar.

[0066] 2) Modify the pretreated biochar obtained in step 1): prepare a biochar containing 4 g / LC 16 ESOCOONa and 1g / LFeCl3 aqueous solution are prepared to obtain a treatment solution, graphene oxide and 20g of the pretreated biochar obtained in step 1) are added to 2L of the treatment solution, the mass volume ratio of graphene oxide to the treatment solution is controlled to be 4g / L, and the mixture is soaked for 1h, washed with deionized water, filtered, and dried to obtain modified biochar.

[0067] 3) Preparation of graphene oxide / hydrotalcite modified biochar: 2.41 g of AlCl3·6H2O and 3.98 g of FeCl2·4H2O were added to 600 mL of deionized water, and the modified biochar obtained in step 2) was added to the solution, mixed evenly, and a mixed solution A was obtained. 16.0 g of NaOH and 13.25 g of Na2CO3 were added to 500 mL of water to obtain a mixed solution B; the mixed solution A and the mixed solution B were dripped into a container at the same time, stirred while reacting, the reaction temperature was maintained at 60°C, and the pH of the reaction solution was maintained at 10 by adjusting the dripping speed. After the dripping was completed, the reaction was continued for 30 minutes, aged at 80°C for 24 hours, filtered, washed with water, and then dried at 80°C for 36 hours to obtain graphene oxide / hydrotalcite modified biochar.

[0068] 4) Preparation of composite adsorbent: Take polyacrylamide and the graphene oxide / hydrotalcite modified biochar obtained by the preparation method of step 3), control the mass ratio of polyacrylamide to the graphene oxide / hydrotalcite modified biochar obtained in step 3) to 0.5:9, mix well, and heat treat, control the heat treatment temperature to 200°C, and the heat treatment time to 2h to obtain a composite modified biochar adsorbent.

[0069] Comparative Example 3

[0070] The difference between Comparative Example 3 and Example 1 is that in the preparation method of the composite modified biochar adsorbent, graphene oxide is not added in step 3). That is, step 3) and step 4) become:

[0071] 3) Configuration containing 4g / LC 16ESOCOONa and 1g / LFeCl3 aqueous solution are prepared to obtain a treated solution, and the hydrotalcite-modified biochar obtained in step 2) is added to 2L of the treated solution, and the mixture is soaked for 1h. The mixture is washed with deionized water, filtered, and dried to obtain a secondary modified biochar.

[0072] 4) Preparation of composite adsorbent: Take polyacrylamide and the secondary modified biochar obtained by the preparation method of step 3), control the mass ratio of polyacrylamide to the secondary modified biochar obtained by step 3) to 0.5:9, mix well, and heat treat, control the heat treatment temperature to 200°C, and the heat treatment time to 2h to obtain a composite modified biochar adsorbent.

[0073] Comparative Example 4

[0074] The difference between Comparative Example 4 and Example 1 is 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: Grind corn stalks, put them into a coking furnace, heat them to 580°C, treat them for 3 hours, soak them in a 6wt% aqueous sulfuric acid solution and stir them for 18 hours, wash them with water until they are neutral, dry them, soak them in a 7wt% aqueous sodium hydroxide solution and stir them for 22 hours, wash them with water until they are neutral, and dry them to obtain pretreated biochar.

[0076] 2) Preparation of graphene oxide modified biochar: 4 g / L of 4-(methylsulfinyl)-2-(palmitoyloxy)butyric acid sodium salt (C 16 ESOCOONa), 1g / L FeCl3 aqueous solution to obtain a treatment solution, add graphene oxide and 20g of the pretreated biochar obtained in step 1) to 2L of the treatment solution, control the mass volume ratio of graphene oxide to the treatment solution to be 4g / L, soak for 1h, wash with deionized water, filter and dry to obtain graphene oxide / hydrotalcite modified biochar.

[0077] 3) Preparation of composite adsorbent: Take polyacrylamide and graphene oxide / hydrotalcite modified biochar obtained by the preparation method in step 2), control the mass ratio of polyacrylamide and graphene oxide / hydrotalcite modified biochar obtained in step 2) to 0.5:9, mix well, heat treat, control the heat treatment temperature to 200°C, and the heat treatment time to 2h to obtain a composite modified biochar adsorbent.

[0078] Comparative Example 5

[0079] The difference between Comparative Example 5 and Example 1 is that in the preparation method of the composite modified biochar adsorbent, the treatment liquid in step 3) contains 5 g / L of C 16 Aqueous solution of ESOCOONa.

[0080] Comparative Example 6

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

[0082] Comparative Example 7

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

[0084] Comparative Example 8

[0085] The difference between Comparative Example 8 and Example 1 is that in the preparation method of the composite modified biochar adsorbent, step 4) does not include a heat treatment process. That is, step 4) is to take 10g of polyacrylamide and the graphene oxide / hydrotalcite modified biochar obtained by the preparation method of step 3), control the mass ratio of polyacrylamide to the graphene oxide / hydrotalcite modified biochar obtained in step 3) to be 0.5:9, mix them evenly, and obtain the composite modified biochar adsorbent.

[0086] 0.01 g of each adsorbent prepared in the embodiment and the comparative example was added into 1 L of a papermaking wastewater sample for treatment. Before treatment, the COD value was 654 mg / L and the BOD value was 236 mg / L. After treatment, the results are shown in Table 1 below.

[0087] Table 1

[0088]

[0089]

[0090] Comparison of Comparative Example 1 with Example 1 in combination with Table 1 shows 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 COD and BOD in papermaking wastewater by the treatment agent is significantly reduced.

[0091] By comparing Comparative Example 2 with Example 1 in combination with Table 1, it can be seen that 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 with hydrotalcite and then modified with graphene oxide to first modified with graphene oxide and then modified with hydrotalcite, the removal rate of COD and BOD in papermaking wastewater by the treatment agent is significantly reduced.

[0092] Comparison of Comparative Example 3 with Example 1 in combination with Table 1 shows that in the preparation method of the composite modified biochar adsorbent, when graphene oxide is not added in step 3), the removal rate of COD and BOD in papermaking wastewater by the treatment agent is significantly reduced.

[0093] Comparison of Comparative Example 4 with Example 1 in combination with Table 1 shows that, in the preparation method of the composite modified biochar adsorbent, when hydrotalcite modification is not included, the removal rate of COD and BOD in papermaking wastewater by the treatment agent is significantly reduced.

[0094] Comparison of Comparative Examples 5 and 6 with Example 1 in combination with Table 1 shows that when the treatment solution contains only C 16 When ESOCOONa or FeCl3 is added, the removal rate of COD and BOD in papermaking wastewater by the treatment agent decreases significantly.

[0095] Comparison of Comparative Example 7 with Example 1 in combination with Table 1 shows that when the C 16 ESOCOONa was replaced by 4-(methylthio)-2-(dodecanoyloxy)butyric acid sodium salt (C 12 When ESCOONa) was increased, the removal rate of COD and BOD in papermaking wastewater by the treatment agent decreased significantly.

[0096] Comparison of Comparative Example 8 with Example 1 in combination with Table 1 shows that when step 4) does not include a heat treatment process, the removal rate of COD and BOD in the papermaking wastewater by the treatment agent is significantly reduced.

[0097] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention, which shall all be included in the scope of protection of the present invention.

Claims

1. A papermaking wastewater treatment agent, characterized in that: It comprises 85-95 parts by weight of a composite modified biochar adsorbent, 3-8 parts by weight of polyaluminium 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): Pre-treat the 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) to the treatment liquid, soaking, washing, filtering and drying to obtain graphene oxide / hydrotalcite modified biochar; 4): The graphene oxide / hydrotalcite modified biochar and polyacrylamide obtained in step 3) are mixed and heat treated to obtain the composite modified biochar adsorbent; In the step 3), the treatment solution is an aqueous solution including 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.

2. The papermaking wastewater treatment agent according to claim 1, characterized in that: In step 2) of the method for preparing the composite modified biochar adsorbent, the biochar pretreated in step 1) is modified with iron-aluminum hydrotalcite, which comprises the following steps: preparing a composite modified biochar adsorbent containing Al 3+ and Fe 2+ The aqueous solution is added with the pretreated biochar obtained in step 1) to obtain a mixed solution A, and an aqueous solution containing NaOH and Na2CO3 is prepared to obtain a mixed solution B. The mixed solution A and the mixed solution B are added into a container at the same time, stirred while reacting, so that the pH value of the reaction solution is maintained at 10, aged, filtered, washed, and dried to obtain a 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 the substance, the mass of the biochar pretreated in step 2) and the mass of the 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 method for preparing the composite modified biochar adsorbent, the mass ratio of polyacrylamide to 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 method for preparing the composite modified biochar adsorbent, the heat treatment temperature is 190-210° C., and the heat treatment time is 1.5-2.5 h.

6. The papermaking wastewater treatment agent according to claim 1, characterized in that: The method for preparing the composite modified biochar adsorbent further comprises: after step 3) and before step 4), uniformly mixing bentonite with the graphene oxide / hydrotalcite modified biochar prepared by the preparation method of step 3), and subjecting the mixture to hydrothermal treatment.

7. The papermaking wastewater treatment agent according to claim 6, characterized in that: The mass ratio of bentonite, the polyacrylamide used in step 4) and the graphene oxide / hydrotalcite modified biochar prepared by the preparation method in step 3) is 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 method for preparing 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° C. for 2.5-3.5 hours; the acid treatment is carried out in a 5-7wt% aqueous sulfuric acid solution with stirring for 17-19 hours; and the alkali treatment is carried out in a 6-8wt% aqueous sodium hydroxide solution with stirring for 21-23 hours.

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

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