阅读说明：本技术 一种重金属离子吸附纤维膜材料的制备方法 (Preparation method of heavy metal ion adsorption fiber membrane material ) 是由 李森 徐乃姣 于 2021-08-10 设计创作，主要内容包括：本发明公开一种基于农业秸秆废弃物的重金属离子吸附纤维膜材料的制备方法,将农业秸秆废弃物进行切断与破碎处理后,取粒径于20～100目之间的秸秆纤维进行预处理得到由多层薄纤维网络组成的白色纤维海绵。然后以秸秆纤维海绵为基材,采用胞外聚合物(EPS)、改性葡甘聚糖以及海藻酸对其进行改性并形成具有优良成膜性能的热不可逆凝胶混合物,碳酸钠与海藻酸反应产生的二氧化碳可使纤维膜材料空洞更加丰富,最终经抽滤及干燥固化得到高性能重金属离子吸附纤维膜材料。制备出具有良好的过滤性能,对重金属离子具有高吸附去除效果,以及具有可再生生物质、环境友好、响应性好等特点的高性能纤维膜材料。(The invention discloses a preparation method of a heavy metal ion adsorption fiber membrane material based on agricultural straw waste, which comprises the steps of cutting and crushing the agricultural straw waste, and pretreating straw fibers with the particle size of 20-100 meshes to obtain white fiber sponge consisting of multiple layers of thin fiber networks. Then, the straw fiber sponge is used as a base material, Extracellular Polymer (EPS), modified glucomannan and alginic acid are adopted to modify the straw fiber sponge to form a heat irreversible gel mixture with excellent film forming performance, carbon dioxide generated by the reaction of sodium carbonate and alginic acid can enrich the cavities of the fiber membrane material, and finally, the high-performance heavy metal ion adsorption fiber membrane material is obtained through suction filtration, drying and solidification. The high-performance fiber membrane material which has good filtering performance, high adsorption and removal effects on heavy metal ions, renewable biomass, environmental friendliness, good responsiveness and the like is prepared.)

1. A preparation method of a heavy metal ion adsorption fiber membrane material based on agricultural straw waste is characterized by comprising the following steps:

(1) cutting and crushing the agricultural straw waste, taking straw fibers with the particle size of 20-100 meshes, then soaking the straw fibers with hydrogen peroxide with the concentration of 10% -30%, simultaneously converting the hydrogen peroxide into hydroxyl free radicals by matching ozone aeration and ultrasonic induction, reconnecting the fibers to obtain white straw fiber sponge consisting of a plurality of layers of thin fiber networks, and then drying the white straw fiber sponge to constant weight at the temperature of 50-90 ℃;

(2) dissolving glucomannan powder in water, stirring until the glucomannan powder is dissolved to obtain a homogeneous glucomannan solution, then adding alkali liquor into the solution to adjust the pH value to 9-12, and continuously stirring for 0.5h to obtain a deacetylated glucomannan solution;

(3) soaking the white straw fiber sponge in the step (1) in deionized water until the white straw fiber sponge is completely wetted, then adding extracellular polymeric substances and sodium carbonate into the white straw fiber sponge, continuously and violently stirring the mixture for about 0.5 to 3 hours, then adding the deacetylated glucomannan in the step (2) into the mixed solution, and continuously and violently stirring the mixture for 1 to 5 hours at the temperature of 50 to 90 ℃ to obtain a white mixture;

(4) and (4) dropwise adding alginic acid into the white mixture obtained in the step (3) until bubbles are generated and dissipated, finally washing with deionized water and carrying out suction filtration to obtain a yellow mixture with rich pores, taking out the yellow mixture, and then placing the yellow mixture in a drying furnace at 90-120 ℃ for drying and curing for 1-5 hours to obtain the heavy metal ion adsorption fiber membrane material.

2. The preparation method of the heavy metal ion adsorption fiber membrane material based on the agricultural straw waste, according to claim 1, is characterized in that in the preparation method, 50-80 parts by weight of white straw fiber sponge, 10-30 parts by weight of extracellular polymeric substance, 1-10 parts by weight of deacetylated glucomannan, 1-5 parts by weight of sodium carbonate and 1-10 parts by weight of alginic acid are used.

3. The method for preparing the heavy metal ion adsorption fiber membrane material based on the agricultural straw waste as claimed in claim 1, wherein the agricultural straw waste in the step (1) is one or a mixture of two or more of rice straw, corn stalk, bagasse and wheat straw.

4. The preparation method of the heavy metal ion adsorption fiber membrane material based on the agricultural straw waste as claimed in claim 1, wherein the alkali solution in the step (2) is an aqueous solution of NaOH or KOH.

Technical Field

The invention relates to the field of purification treatment of sewage containing various heavy metals and the field of resource utilization of wastes, in particular to a preparation method of a heavy metal ion adsorption fiber membrane material based on agricultural straw wastes and extracellular polymeric substances of activated sludge wastes.

Background

In recent years, the research and engineering applications of polymer materials have gradually shifted to functionalized fiber composites. The composite materials mainly comprise carbon fiber, aramid fiber, glass fiber and other composite materials, and are widely applied to the fields of spaceflight, traffic, buildings, environmental protection and the like. However, these types of composite materials suffer from several serious drawbacks, such as recycling problems, post-processing problems, and sustainable development problems of the material. The raw materials of carbon fiber and aramid fiber are petroleum-based materials, petroleum is a non-renewable resource, and glass fiber is a high-energy consumption material, and the defects are fatal to the sustainable development of the raw materials. With the continuous consumption of non-renewable resources, the development and utilization of renewable resources are particularly important for the sustainable development of national economy, the sustainable development of the material field and carbon emission reduction. According to statistics, the annual yield of the straws in China currently exceeds 8 hundred million t, wherein the recoverable straw resource is about 7 hundred million t; the straw resources can be recovered, about 15.0 percent of the straw resources which are directly returned to the field, about 30.7 percent of the straw resources which are used for producing animal feed, about 17.9 percent of the straw resources which are used for industrial energy, only 5.25 percent of the straw resources which are used for other project fields such as material preparation and the like, and the proportion of the directly abandoned and burnt straw resources is as high as 31.6 percent. Therefore, the method has important significance for improving the material utilization rate of the recyclable straw resources. Meanwhile, the preparation of the nano-functional fiber material by using the straw fiber is a new high-tech industrial development direction. The fiber-based environment-friendly material based on the agricultural straw waste is successfully applied to solving the problems of environmental pollution and the like, and provides a relevant technical support for the national low-carbon green development and beautiful Chinese construction.

However, the existence of hydrogen bonds inside plant fibers greatly restricts the reactivity of the fibers, so that the natural agricultural straw fibers have poor adsorption performance on substances such as water, oil and heavy metals if being directly used as an adsorption material, and due to the existence of a large amount of hydroxyl and other polar groups, huge interaction force exists inside macromolecules and among molecules in the natural fibers, which inevitably brings great obstruction to the research and preparation of modified fibers.

The extracellular polymeric substance has a large number of anionic groups (carboxyl, hydroxyl, amino, sulfate radical and phosphate anion), and the groups enable the extracellular polymeric substance not only to have ion exchange characteristics, but also to interact with metal ions, so that heavy metals can be selectively and efficiently combined from the environment, and the coordination activity of the extracellular polymeric substance and the heavy metals is even better than that of chitosan. At present, domestic researches on heavy metal adsorption of extracellular polymeric substances focus on investigating the adsorption effect of extracellular polymeric substances extracted from specific strains on the heavy metal, and reports on the preparation of heavy metal adsorption materials with excellent chemical stability by compounding the extracellular polymeric substances with plant fibers are not found.

Disclosure of Invention

The invention provides a preparation method of a heavy metal ion adsorption fiber membrane material based on agricultural straw waste, which is used for preparing a high-performance fiber membrane material with good filtering performance, high adsorption and removal effects on heavy metal ions, renewable biomass, environment friendliness, good responsiveness and the like.

The specific technical scheme is as follows:

a preparation method of a heavy metal ion adsorption fiber membrane material based on agricultural straw waste is characterized by comprising the following steps:

(1) cutting and crushing the agricultural straw waste, taking straw fibers with the particle size of 20-100 meshes, then soaking the straw fibers with hydrogen peroxide with the concentration of 10% -30%, simultaneously converting the hydrogen peroxide into hydroxyl free radicals by matching ozone aeration and ultrasonic induction, reconnecting the fibers to obtain white straw fiber sponge consisting of a plurality of layers of thin fiber networks, and then drying the white straw fiber sponge to constant weight at the temperature of 50-90 ℃;

(2) dissolving glucomannan powder in water, stirring until the glucomannan powder is dissolved to obtain a homogeneous glucomannan solution, then adding alkali liquor into the solution to adjust the pH value to 9-12, and continuously stirring for 0.5h to obtain a deacetylated glucomannan solution;

(3) soaking the white straw fiber sponge in the step (1) in deionized water until the white straw fiber sponge is completely wetted, then adding extracellular polymeric substances and sodium carbonate into the white straw fiber sponge, continuously and violently stirring the mixture for about 0.5 to 3 hours, then adding the deacetylated glucomannan in the step (2) into the mixed solution, and continuously and violently stirring the mixture for 1 to 5 hours at the temperature of 50 to 90 ℃ to obtain a white mixture;

(4) and (4) dropwise adding alginic acid into the white mixture obtained in the step (3) until bubbles are generated and dissipated, finally washing with deionized water and carrying out suction filtration to obtain a yellow mixture with rich pores, taking out the yellow mixture, and placing the yellow mixture in a drying furnace at 90-120 ℃ for drying and curing for 1-5 hours to obtain the high-performance heavy metal ion adsorption fiber membrane material.

Wherein: 50-80 parts of white straw fiber sponge, 10-30 parts of extracellular polymer, 1-10 parts of deacetylated glucomannan, 1-5 parts of sodium carbonate and 1-10 parts of alginic acid.

Preferably, the agricultural straw waste is one of rice straw, corn stalk, bagasse and wheat straw, or a mixture of two or more of the above;

preferably, the alkali liquor is an aqueous solution of NaOH or KOH.

According to the invention, sodium carbonate is used for replacing a pore-foaming agent, sodium alginate generated in the process is used as a cross-linking agent, deacetylated glucomannan is used as a film-forming agent, hydroxyl carried by the substances can also strengthen the adsorption of heavy metals, and the fibers are assisted to construct a three-dimensional structure.

Based on rich functional groups and three-dimensional hole structures of plant straw fiber sponges, the coordination adsorption behavior of the straw fiber materials to heavy metal ions can be effectively enhanced by using Extracellular Polymer (EPS), modified glucomannan and alginic acid, so that the adsorption and ion exchange processes of pollutants can be controlled, carbon dioxide gas generated by decomposition of sodium carbonate escapes from the materials and can greatly increase adsorption pore channels of the materials, and sodium alginate generated in the process is used as gel and cross-linking agent to better assist the fiber sponges to construct a three-dimensional network structure to become an excellent collector in the adsorption process of the heavy metal ions. More importantly, the konjac glucomannan has good film forming property after being modified, and can form a heat irreversible film with adhesive force and high density after being heated and dehydrated under the alkaline condition. The fiber membrane material has the characteristics of environmental protection, waste utilization, easy material obtaining, excellent adsorption performance, stable chemical performance and the like.

The heavy metal ion adsorption fiber membrane material based on agricultural straw waste has the characteristics of high removal effect on heavy metal ions, high adsorption capacity, good solid-liquid separation effect, long service life, easily available raw materials, low cost, biodegradability and the like. Can simultaneously adsorb and remove heavy metal ions and filter and remove heavy metal-containing suspended matters, so the method has huge application prospect in the field of heavy metal-containing sewage treatment.

Compared with the prior art, the invention has the beneficial effects that:

(1) the method is characterized in that hydrogen peroxide with the concentration of 10% -30% is used for dipping, meanwhile, ozone aeration and ultrasonic induction are matched to convert the hydrogen peroxide into hydroxyl free radicals, lignin in straw fibers is removed through the strong oxidizing property of active free radicals, the fibers are reconnected to obtain the white straw fiber sponge consisting of multiple layers of thin fiber networks, the technology is environment-friendly, free of secondary pollution and easy to operate, and the straw fiber sponge is strengthened to have rich functional groups such as the hydroxyl free radicals and a three-dimensional hole structure.

(2) The fiber membrane is prepared by adopting two solid wastes of agricultural straw fiber and extracellular polymeric substances extracted from sewage treatment activated sludge as main raw materials and is used for adsorbing and separating heavy metals from water, so that the aim of treating wastes with processes of wastes against one another is fulfilled. And the deacetylated glucomannan is used as a film forming agent to combine the deacetylated glucomannan and the deacetylated glucomannan to form a chemically stable thermal irreversible film.

(3) The raw materials are white straw fiber sponge, extracellular polymer, deacetylated glucomannan, sodium carbonate and alginic acid, all of which are derived from natural components, and no secondary pollution hidden trouble exists. And sodium carbonate is used to replace pore-forming agent, and sodium alginate generated in the process can also be used as cross-linking agent.

(4) A large number of anionic groups (carboxyl, hydroxyl, amino and phosphate radicals) existing in extracellular polymers and abundant hydroxyl groups contained in deacetylated glucomannan can be used for strengthening coordination sites and coordination performance of heavy metals in the structure and strengthening the adsorption effect of heavy metals on fiber membranes.

The specific implementation mode is as follows:

example 1

Cutting and crushing the agricultural straw waste rice straws, taking straw fibers with the particle size of 40 meshes, then soaking the straw fibers with the concentration of 30% hydrogen peroxide, simultaneously, matching with ozone aeration and ultrasonic induction to convert the hydrogen peroxide into hydroxyl free radicals, reconnecting the fibers to obtain white rice straw fiber sponge consisting of a plurality of layers of thin fiber networks, and then drying the white rice straw fiber sponge at the temperature of 50 ℃ to constant weight. Dissolving glucomannan powder in water, stirring until dissolving to obtain homogeneous glucomannan solution, adding sodium hydroxide into the solution to adjust pH to 10, and continuously stirring for 0.5h to obtain deacetylated glucomannan solution. And (2) soaking the obtained white fiber sponge into deionized water until the white fiber sponge is completely wetted, then adding the extracellular polymeric substance and sodium carbonate into the white fiber sponge, continuously and vigorously stirring the mixture for about 1h, then adding the deacetylated glucomannan into the mixed solution, and continuously and vigorously stirring the mixture for 2h at 90 ℃ to obtain a white mixture. And (3) dropwise adding alginic acid into the obtained white mixture until bubbles are generated and dissipated, finally washing with deionized water and carrying out suction filtration to obtain a yellow mixture with rich pores, taking out the yellow mixture, and then placing the yellow mixture in a drying furnace at 102 ℃ for drying and curing for 5 hours to obtain the high-performance heavy metal ion adsorption fiber membrane material. Wherein: 70 parts of white straw fiber sponge, 10 parts of extracellular polymer, 10 parts of deacetylated glucomannan, 2 parts of sodium carbonate and 8 parts of alginic acid.

The obtained heavy metal ion adsorption fiber membrane material is directly used for mercury adsorption and demercuration treatment of mercury sewage containing high chlorine, the content of chloride ions reaches 91831mg/L, the mercury ion removal effect can be directly treated from 300ppb to 0.4ppb, and the removal efficiency reaches 99.87%.

Example 2

Cutting and crushing the agricultural straw waste corn straw, taking straw fiber with the particle size of 50 meshes, then soaking the straw fiber with the concentration of 20% by using hydrogen peroxide, simultaneously matching ozone aeration and ultrasonic induction to convert the hydrogen peroxide into hydroxyl free radicals, reconnecting the fiber to obtain white corn straw fiber sponge consisting of a plurality of layers of thin fiber networks, and then drying the white corn straw fiber sponge at the temperature of 60 ℃ to constant weight. Dissolving glucomannan powder in water, stirring until dissolving to obtain homogeneous glucomannan solution, adding potassium hydroxide into the solution to adjust pH to 11, and stirring for 0.5 hr to obtain deacetylated glucomannan solution. And (2) soaking the obtained white fiber sponge into deionized water until the white fiber sponge is completely wetted, then adding the extracellular polymeric substance and sodium carbonate into the white fiber sponge, continuously and vigorously stirring the mixture for about 2 hours, adding the deacetylated glucomannan into the mixed solution, and continuously and vigorously stirring the mixture for 3 hours at the temperature of 80 ℃ to obtain a white mixture. And (3) dropwise adding alginic acid into the obtained white mixture until bubbles are generated and dissipated, finally washing with deionized water and carrying out suction filtration to obtain a yellow mixture with rich pores, taking out the yellow mixture, and placing the yellow mixture in a drying furnace at 100 ℃ for drying and curing for 4 hours to obtain the high-performance heavy metal ion adsorption fiber membrane material. Wherein: 65 parts of white straw fiber sponge, 15 parts of extracellular polymer, 5 parts of deacetylated glucomannan, 5 parts of sodium carbonate and 10 parts of alginic acid.

The obtained heavy metal ion adsorption fiber membrane material is directly used for adsorption and deleading ion treatment of lead-containing sewage with high COD, the COD content in the sewage reaches 85707mg/L, the lead ion removal effect can be directly treated from 10ppm to 0.028ppm, and the removal efficiency reaches 99.72%.

Example 3

Cutting and crushing the agricultural straw waste bagasse, taking straw fibers with the particle size of 80 meshes, then soaking the straw fibers with 25% of hydrogen peroxide, simultaneously converting the hydrogen peroxide into hydroxyl free radicals by matching ozone aeration and ultrasonic induction, reconnecting the fibers to obtain white bagasse fiber sponge consisting of multiple layers of thin fiber networks, and then drying the white bagasse fiber sponge at the temperature of 70 ℃ to constant weight. Dissolving glucomannan powder in water, stirring until dissolving to obtain homogeneous glucomannan solution, adding sodium hydroxide into the solution to adjust pH value to 12, and continuously stirring for 0.5h to obtain deacetylated glucomannan solution. And (2) soaking the obtained white fiber sponge into deionized water until the white fiber sponge is completely wetted, then adding the extracellular polymeric substance and sodium carbonate into the white fiber sponge, continuously and vigorously stirring the mixture for about 3 hours, adding the deacetylated glucomannan into the mixed solution, and continuously and vigorously stirring the mixture for 5 hours at 70 ℃ to obtain a white mixture. And (3) dropwise adding alginic acid into the obtained white mixture until bubbles are generated and dissipated, finally washing with deionized water and carrying out suction filtration to obtain a yellow mixture with rich pores, taking out the yellow mixture, and placing the yellow mixture in a drying furnace at 110 ℃ for drying and curing for 4.5 hours to obtain the high-performance heavy metal ion adsorption fiber membrane material. Wherein: 60 parts of white straw fiber sponge, 25 parts of extracellular polymer, 5 parts of deacetylated glucomannan, 1 part of sodium carbonate and 9 parts of alginic acid.

The obtained heavy metal ion adsorption fiber membrane material is directly used for adsorption treatment of copper-containing sewage with high mineralization degree, the mineralization degree content reaches 101447mg/L, the copper ion removal effect can be directly treated from 50ppm to 0.008ppm, and the removal efficiency reaches 99.98%.

Although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that various changes in the embodiments and/or modifications of the invention can be made, and equivalents and modifications of some features of the invention can be made without departing from the spirit and scope of the invention.