A flocculant for papermaking wastewater and a preparation method and application thereof

Abstract

The application provides a papermaking wastewater flocculant, a preparation method and application thereof, and is prepared from polyaluminum chloride, aluminum sulfate, anionic polyacrylamide and biomass charcoal. In the application, the polyaluminum chloride, the aluminum sulfate, the anionic polyacrylamide and the biomass charcoal are mixed and heated, and then ammonium persulfate is added to react to form long polymer chains, so that the polymer adsorption bridging performance of the flocculant is enhanced. Since the application is used for treating papermaking wastewater, the papermaking wastewater contains pollutants such as fibers, inorganic salts and pigments, and most of the pollutants are high molecular compounds, the structure of which is difficult to break, and the biodegradability is low. Traditional adsorbents are difficult to dissolve in the papermaking wastewater, so that the adsorption performance is obviously reduced. The papermaking wastewater flocculant prepared by the application has good water solubility in the papermaking wastewater, can be quickly dispersed in the papermaking wastewater, and can adsorb the pollutants in the papermaking wastewater.

Description

TECHNICAL FIELD

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

[0002] With the improvement of people's living standards, the quality requirements for paper are also increasing, and the use of dyes in the paper industry has gradually become popular, providing the color difference required by people, but with the popularity of dyes, the wastewater generated has become a major source of water pollution. At present, there are tens of thousands of dyes, which not only have specific colors, but also have complex structures.

[0003] Most of the dyes used in the paper industry are high molecular combinations, which are difficult to break down and have low biodegradability. Most of them have potential toxicity, and their fate in the environment depends on many unknown factors. In addition, dye production has the characteristics of many varieties, small batch size, and rapid updating, making it difficult to find an effective treatment method for dye wastewater. Based on the above difficulties, there is no effective treatment method at home and abroad,

[0004] The commonly used method is to reduce the cleaning frequency of the dye system, which makes it difficult to ensure the cleanliness of the system, and in severe cases, it affects the quality of the paper. The dye water washed out is treated together with the wastewater system, and the mixing ratio is difficult to control and often causes the color of the paint wastewater to be severely exceeded, causing environmental accidents.

[0005] Preparation of a flocculant for papermaking wastewater is crucial to the cleanliness of the dye system and the quality of the paper, and can reduce the risk of temporary dye leakage and the pressure on water treatment, and avoid environmental accidents. SUMMARY

[0006] In view of this, the present application provides a preparation method of a flocculant for papermaking wastewater to solve the above problems.

[0007] The technical scheme of the present application is as follows:

[0008] A flocculant for papermaking wastewater, by weight, the raw materials include polyaluminum chloride 1.5-2.5 parts, aluminum sulfate 1.7-2.3 parts, anionic polyacrylamide 0.6-0.8 parts and biomass charcoal 1-1.3 parts.

[0009] Further, the biomass charcoal is prepared from coconut waste, and the coconut waste includes coconut tree leaves, coconut tree trunks and coconut shells.

[0010] Further, the preparation method of the biomass charcoal includes the following steps:

[0011] (1) crushing the coconut waste to obtain coconut waste powder, mixing the coconut waste powder, phenolic resin and sodium silicate solution, carbonizing to obtain coconut carbide;

[0012] (2) soaking the coconut carbide in zinc chloride solution to obtain activated coconut carbide;

[0013] (3) drying the activated coconut carbide under inert atmosphere at 500-600 DEG C, acid washing, water washing to neutral, drying to obtain the finished product.

[0014] Further, in step (1), the mass ratio of the coconut waste powder, phenolic resin and sodium silicate solution is 2:0.1-0.18:4-5, and the carbonization is carried out at 750-850 DEG C for 40-60 min.

[0015] Further, in step (2), the mass concentration of the zinc chloride solution is 20-30%, the mass ratio of the zinc chloride solution and the coconut carbide is 10-15:1, and the soaking time is 20-30 min.

[0016] Further, in step (3), the activated coconut carbide is heated to 300 DEG C at 10-15 DEG C / min under nitrogen atmosphere, heated to 500-600 DEG C at 5-8 DEG C / min, and kept for 120-150 min.

[0017] Further, the mass concentration of the sodium silicate solution is 7-10%.

[0018] Further, the preparation method of the papermaking wastewater flocculant comprises the following steps: adding polyaluminum chloride, aluminum sulfate, anionic polyacrylamide and biomass carbon into water, passing nitrogen, increasing the temperature to 70-80 DEG C, keeping for 20-30 min, adding ammonium persulfate and reacting for 15-20 min, stopping passing nitrogen, stirring for 3-4 h, cooling to room temperature after stirring, adding acetone to precipitate the solid, drying the solid, and obtaining the finished product.

[0019] Further, the addition amount of the ammonium persulfate is 15-20 mmol / L.

[0020] Compared with the prior art, the beneficial effects of the present application are:

[0021] The application uses polyaluminum chloride, aluminum sulfate, anionic polyacrylamide and biomass charcoal to prepare a papermaking wastewater flocculant, and the polyaluminum chloride, aluminum sulfate, anionic polyacrylamide and biomass charcoal are mixed and heated, and ammonium persulfate is added to react to form a long chain of macromolecules, thereby enhancing the macromolecular adsorption bridging performance of the flocculant. Since the application is used to treat papermaking wastewater, the papermaking wastewater contains pollutants such as fibers, inorganic salts and pigments, and most of them are high molecular compounds, which are difficult to break and have low biodegradability. Traditional adsorbents are difficult to dissolve in papermaking wastewater, which significantly reduces the adsorption performance. The papermaking wastewater flocculant prepared by the application has good water solubility in papermaking wastewater, can quickly disperse in papermaking wastewater, and can adsorb pollutants in papermaking wastewater.

[0022] The preparation method of the biomass charcoal prepared by the application is to mix coconut waste powder, phenolic resin and sodium silicate solution and then carbonize, and the carbonization is treated at a high temperature of 750-850 in the application, and the addition of phenolic resin and sodium silicate solution can promote the sintering of the coconut waste powder. According to the types of pollutants in papermaking wastewater, the pore structure of the biomass charcoal is mainly microporous and macroporous, the micropores can provide more adsorption sites, and the macropores can reduce the diffusion barrier in the adsorption process. In the application, the coconut carbonates are soaked in zinc chloride solution, and the pore structure of the biomass carbon is generated by controlling the heating rate. BRIEF DESCRIPTION OF DRAWINGS

[0023] Fig. 1 Wastewater treated in Example 1

[0024] Fig. 2 Wastewater treated in Comparative Example 1

[0025] Fig. 3 Wastewater treated in Comparative Example 2 DETAILED DESCRIPTION

[0026] In order to better understand the technical content of the application, the following specific examples are provided to further illustrate the application.

[0027] The experimental methods used in the embodiments of the application are conventional methods unless otherwise specified.

[0028] The materials, reagents and the like used in the embodiments of the application can be obtained from commercial channels unless otherwise specified.

[0029] The molecular weight of the anionic polyacrylamide in the application is about 12 million.

[0030] Example 1

[0031] The preparation method of the biomass charcoal includes the following steps:

[0032] (1) Coconut waste is crushed to obtain coconut waste powder, and the coconut waste powder, phenolic resin and 8.5wt% sodium silicate solution are mixed according to a mass ratio of 2:0.14:4.5, and then the mixture is kept at 800℃ for 50min to obtain coconut carbide;

[0033] (2) The coconut carbide and 25wt% zinc chloride solution are mixed according to a mass ratio of 1:13, and then the mixture is soaked for 25min to obtain activated coconut carbide;

[0034] (3) The activated coconut carbide is heated to 300℃ at a rate of 13℃ / min under a nitrogen atmosphere, and then heated to 550℃ at a rate of 7℃ / min, and kept at 550℃ for 140min. The dried coconut carbide is subjected to acid washing and water washing until neutral, and then dried to obtain a finished product.

[0035] The preparation method of the papermaking wastewater flocculant is as follows:

[0036] (1) 2 parts of polyaluminum chloride, 2 parts of aluminum sulfate, 0.7 parts of anionic polyacrylamide and 1.15 parts of biomass charcoal are weighed according to weight parts.

[0037] (2) The polyaluminum chloride, aluminum sulfate, anionic polyacrylamide and biomass charcoal are added to water, nitrogen is introduced, the temperature is raised to 75℃, and the mixture is kept at 75℃ for 25min. 18mmol / L ammonium persulfate is added and reacted for 20min. Nitrogen is stopped, and the mixture is stirred for 3.5h. After stirring, the mixture is cooled to room temperature, and acetone is added to precipitate the solid. The solid is dried to obtain a finished product.

[0038] Example 2

[0039] The preparation method of the biomass charcoal comprises the following steps:

[0040] (1) Coconut waste is crushed to obtain coconut waste powder, and the coconut waste powder, phenolic resin and 7wt% sodium silicate solution are mixed according to a mass ratio of 2:0.1:4, and then the mixture is kept at 750℃ for 40min to obtain coconut carbide;

[0041] (2) The coconut carbide and 20wt% zinc chloride solution are mixed according to a mass ratio of 1:10, and then the mixture is soaked for 20min to obtain activated coconut carbide;

[0042] (3) The activated coconut carbide is heated to 300℃ at a rate of 10℃ / min under a nitrogen atmosphere, and then heated to 500℃ at a rate of 5℃ / min, and kept at 500℃ for 120min. The dried coconut carbide is subjected to acid washing and water washing until neutral, and then dried to obtain a finished product.

[0043] The preparation method of the papermaking wastewater flocculant is as follows:

[0044] (1) 1.5 parts of polyaluminum chloride, 1.7 parts of aluminum sulfate, 0.6 parts of anionic polyacrylamide and 1 part of biomass charcoal by weight were weighed.

[0045] (2) The polyaluminum chloride, aluminum sulfate, anionic polyacrylamide and biomass charcoal were added to water, nitrogen was introduced, the temperature was raised to 70℃, and the solution was kept at this temperature for 20 min. 15 mmol / L of ammonium persulfate was added and reacted for 15 min. Nitrogen was stopped, and the solution was stirred for 3 h. After the stirring was completed, the solution was cooled to room temperature, and acetone was added to precipitate the solid. The solid was dried to obtain the finished product.

[0046] Example 3

[0047] The preparation method of the biomass charcoal comprises the following steps:

[0048] (1) The coconut waste was crushed to obtain coconut waste powder. The coconut waste powder, phenolic resin and 10 wt% sodium silicate solution were mixed according to a mass ratio of 2:0.18:5, and a coconut carbide was prepared by keeping the mixture at 850℃ for 60 min.

[0049] (2) The coconut carbide and 20-30 wt% zinc chloride solution were mixed according to a mass ratio of 1:15, and the activated coconut carbide was prepared by soaking for 30 min.

[0050] (3) The activated coconut carbide was heated to 300℃ at a rate of 15℃ / min under a nitrogen atmosphere, and then heated to 600℃ at a rate of 8℃ / min, and kept at this temperature for 150 min. The dried coconut carbide was washed with acid and water until neutral, and then dried to obtain the finished product.

[0051] The preparation method of the papermaking wastewater flocculant is:

[0052] (1) 2.5 parts of polyaluminum chloride, 2.3 parts of aluminum sulfate, 0.8 parts of anionic polyacrylamide and 1.3 parts of biomass charcoal by weight were weighed.

[0053] (2) The polyaluminum chloride, aluminum sulfate, anionic polyacrylamide and biomass charcoal were added to water, nitrogen was introduced, the temperature was raised to 80℃, and the solution was kept at this temperature for 30 min. 20 mmol / L of ammonium persulfate was added and reacted for 20 min. Nitrogen was stopped, and the solution was stirred for 4 h. After the stirring was completed, the solution was cooled to room temperature, and acetone was added to precipitate the solid. The solid was dried to obtain the finished product.

[0054] Comparative Example 1

[0055] On the basis of Example 1, the preparation method of the biomass charcoal was adjusted, specifically:

[0056] The preparation method of the biomass charcoal comprises the following steps:

[0057] (1) Coconut waste is crushed to obtain coconut waste powder, and the coconut waste powder is kept at 800 DEG C for 50 min to obtain coconut carbide;

[0058] (2) The coconut carbide and 25wt% zinc chloride solution are mixed according to a mass ratio of 1:13, soaked for 25 min, and activated coconut carbide is obtained;

[0059] (3) The activated coconut carbide is heated to 300 DEG C at a rate of 13 DEG C / min under a nitrogen atmosphere, heated to 550 DEG C at a rate of 7 DEG C / min, kept for 140 min, and then dried. The dried coconut carbide is washed with acid and water until neutral, dried, and finished product is obtained.

[0060] The preparation method of the papermaking wastewater flocculant is as follows:

[0061] (1) 2 parts of polyaluminum chloride, 2 parts of aluminum sulfate, 0.7 parts of anionic polyacrylamide and 1.15 parts of biomass charcoal are weighed according to weight parts.

[0062] (2) The polyaluminum chloride, aluminum sulfate, anionic polyacrylamide and biomass charcoal are added to water, nitrogen is introduced, the temperature is raised to 75 DEG C, and kept for 25 min. 18 mmol / L ammonium persulfate is added and reacted for 20 min. Nitrogen is stopped, stirred for 3.5 h, cooled to room temperature, and then acetone is added to precipitate the solid. The solid is dried to obtain the finished product.

[0063] Comparative Example 2

[0064] On the basis of Example 1, the preparation method of biomass charcoal is adjusted, which is as follows:

[0065] The preparation method of biomass charcoal comprises the following steps:

[0066] (1) Coconut waste is crushed to obtain coconut waste powder, and the coconut waste powder, phenolic resin and 8.5wt% sodium silicate solution are mixed according to a mass ratio of 2:0.14:4.5, and kept at 800 DEG C for 50 min to obtain coconut carbide;

[0067] (2) The coconut carbide and 85wt% phosphoric acid solution are mixed according to a mass ratio of 1:5, soaked for 5h, and activated coconut carbide is obtained;

[0068] (3) The activated coconut carbide is heated to 300 DEG C at a rate of 13 DEG C / min under a nitrogen atmosphere, heated to 550 DEG C at a rate of 7 DEG C / min, kept for 140 min, and then dried. The dried coconut carbide is washed with water until neutral, dried, and finished product is obtained.

[0069] The preparation method of the papermaking wastewater flocculant is as follows:

[0070] (1) Take 2 parts of polyaluminum chloride, 2 parts of aluminum sulfate, 0.7 parts of anionic polyacrylamide and 1.15 parts of biomass charcoal by weight.

[0071] (2) Add polyaluminum chloride, aluminum sulfate, anionic polyacrylamide and biomass charcoal into water, pass in nitrogen, raise the temperature to 75℃, keep warm for 25 min, add 18 mmol / L of ammonium persulfate and react for 20 min, stop passing in nitrogen, stir for 3.5 h, cool to room temperature after stirring is completed, add acetone to make the solution precipitate solids, dry the solids to obtain the finished product.

[0072] Comparative Example 3

[0073] On the basis of Example 1, the preparation method of biomass charcoal is adjusted, specifically:

[0074] The preparation method of biomass charcoal includes the following steps:

[0075] (1) Crush the coconut waste to obtain coconut waste powder, mix the coconut waste powder, phenolic resin and 8.5wt% sodium silicate solution according to the mass ratio of 2:0.14:4.5, heat at 800℃ for 50 min to obtain coconut carbide;

[0076] (2) Mix the coconut carbide and 25wt% zinc chloride solution according to the mass ratio of 1:13, soak for 25 min to obtain activated coconut carbide;

[0077] (3) Heat the activated coconut carbide to 550℃ under nitrogen atmosphere, keep warm for 140 min, dry the coconut carbide after washing with acid and water until neutral, dry to obtain the finished product.

[0078] The preparation method of the papermaking wastewater flocculant is:

[0079] (1) Take 2 parts of polyaluminum chloride, 2 parts of aluminum sulfate, 0.7 parts of anionic polyacrylamide and 1.15 parts of biomass charcoal by weight.

[0080] (2) Add polyaluminum chloride, aluminum sulfate, anionic polyacrylamide and biomass charcoal into water, pass in nitrogen, raise the temperature to 75℃, keep warm for 25 min, add 18 mmol / L of ammonium persulfate and react for 20 min, stop passing in nitrogen, stir for 3.5 h, cool to room temperature after stirring is completed, add acetone to make the solution precipitate solids, dry the solids to obtain the finished product.

[0081] Test Example 1

[0082] The flocculants prepared by examples 1-3 and comparative examples 1-3 were tested, and the test water sample was taken from Hainan Jinhai pulp paper Co., Ltd. The papermaking wastewater and tap water were mixed according to the mass ratio of 1:1, the flocculant was added in an amount of 5 kg / ton, the pH value of the wastewater after adding the flocculant was reduced to below 5.0, the pH of the wastewater was adjusted to 7.0 with 20% sodium hydroxide solution, and the stirring was continued for about three minutes, then the wastewater was placed for 90 min for observation.

[0083] Table 1 experimental results of treating papermaking wastewater with the flocculants prepared by examples 1-3 and comparative examples 1-2

[0084]

[0085]

[0086] See Figs. 1 to 3 , Fig. 1 the wastewater treated by example 1, Fig. 2 the wastewater treated by comparative example 1, Fig. 3 the wastewater treated by comparative example 2. According to the analysis in table 1, the flocculant prepared by the present application has high surface charge density and strong adsorption bridging ability. The biomass carbon in the present application is prepared by a specific method, which improves the pore size distribution and connectivity of the biomass carbon. The present application treats papermaking wastewater, which contains pollutants such as fibers, inorganic salts and pigments. The main pollutants are high molecular compounds, which are difficult to break down and have low biodegradability. The adsorption effect of traditional adsorbents is poor. The biomass carbon prepared by the present application mainly contains micropores and macropores. Micropores can provide more adsorption sites, and macropores can reduce the diffusion barrier in the adsorption process. In the present application, polyaluminum chloride, aluminum sulfate, anionic polyacrylamide and biomass carbon are mixed. Polyaluminum chloride, aluminum sulfate, anionic polyacrylamide and biomass carbon have the effects of electric neutralization, adsorption bridging and precipitation net trapping, which can quickly improve the flocculation ability of the composite flocculant.

[0087] In comparative example 1, the preparation method of biomass carbon was changed. In the present application, coconut waste powder, phenolic resin and sodium silicate solution were mixed and reacted at high temperature. After heating, phenolic resin and sodium silicate can generate sintering agents such as silicon oxide and silicon carbide, and hard components. The specific surface area of biomass carbon can be increased under high temperature conditions, and the pore wall strength of biomass carbon can be improved by combining components such as silicon oxide and silicon carbide. The adsorption effect of the flocculant is further improved.

[0088] The preparation method of the biomass charcoal is changed in the comparative example 2, the phosphoric acid solution is used for activating, the number of oxygen-containing groups, hydroxyl groups, carboxylic acid groups and the like on the surface of the biomass charcoal is reduced, and the adsorption effect of the adsorbent is reduced. In the application, the coconut carbonization is soaked in the zinc chloride solution, the electrostatic effect and the hydrogen bond effect of the biomass charcoal are increased, and the adsorption capacity of the high molecular waste in the papermaking wastewater is improved.

[0089] In the comparative example 3, the temperature is not controlled by using the gradient temperature rising program, in the application, the closed hole ablation is promoted to form the through hole, the number of the large holes is increased, with the increase of the temperature, the temperature rising rate is reduced, the carbon atom is beneficial to volatilize in the form of the gas, and the micropore is formed.

[0090] The above only describes the preferred embodiments of the application and is not used to limit the application, and any modification, equivalent replacement, improvement and the like made within the spirit and principle of the application should be included in the protection scope of the application.

Claims

1. A flocculant for papermaking wastewater, characterized in that, By weight, the raw material consists of 1.5-2.5 parts polyaluminum chloride, 1.7-2.3 parts aluminum sulfate, 0.6-0.8 parts anionic polyacrylamide, and 1-1.3 parts biochar. The biochar is made from coconut waste, which includes coconut leaves, coconut trunks, and coconut shells. The method for preparing the biochar includes the following steps: (1) Coconut waste is crushed to obtain coconut waste powder. Coconut waste powder, phenolic resin and sodium silicate solution are mixed in a mass ratio of 2:0.1-0.18:4-5 and carbonized at 750-850℃ for 40-60 minutes to obtain coconut carbon. (2) Coconut carbide was soaked in zinc chloride solution to obtain activated coconut carbide; (3) The activated coconut carbide is dried at 500-600℃ under an inert atmosphere.

2. The flocculant for papermaking wastewater as described in claim 1, characterized in that, In the preparation method of biochar, in step (2), the mass concentration of the zinc chloride solution is 20-30%, the mass ratio of zinc chloride solution to coconut carbon is 10-15:1, and the soaking time is 20-30 min.

3. The flocculant for papermaking wastewater as described in claim 1, characterized in that, In the preparation method of biochar, in step (3), the activated coconut carbon is heated to 300℃ at 10-15℃ / min under a nitrogen atmosphere, then heated to 500-600℃ at 5-8℃ / min, and kept at that temperature for 120-150min.

4. The flocculant for papermaking wastewater as described in claim 1, characterized in that, In the preparation method of biochar, in step (1), the mass concentration of the sodium silicate solution is 7-10%.

5. The method for preparing the flocculant for papermaking wastewater according to claim 1, characterized in that, The preparation method of the papermaking wastewater flocculant is as follows: add polyaluminum chloride, aluminum sulfate, anionic polyacrylamide and biochar to water, introduce nitrogen gas, raise the temperature to 70-80℃, keep it at the temperature for 20-30 minutes, add ammonium persulfate and react for 15-20 minutes, stop introducing nitrogen gas, stir for 3-4 hours, and obtain the finished product.

6. The method for preparing a flocculant for papermaking wastewater as described in claim 5, characterized in that, The amount of ammonium persulfate added is 15-20 mmol / L.

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