Preparation method of polyvinyl alcohol/chitosan gel bead

Abstract

The invention discloses a preparation method of a polyvinyl alcohol / chitosan gel bead. The preparation method of the polyvinyl alcohol / chitosan gel bead comprises the steps of using polyvinyl alcoholand chitosan as raw materials, using NaOH as a physical cross-linking agent, using saturated boracic acid and CaCl2 as a chemical cross-linking agent and adopting physical and chemical alternate cross-linking, enabling polyvinyl alcohol molecules and chitosan molecules to be entangled by using a physical hydrogen bond and chemical ester bond double bonding structure to form a stable gel bead withdiameter of about 3 mm. Firstly, the NaOH is adopted to reinforce a hydrogen bond between the polyvinyl alcohol molecules and the chitosan molecules through physical cross-linking, so that the gel forms a uniform pore structure from inside to outside; and secondly, through chemical cross-linking of the boracic acid and the CaCl2, ester bond bonding between the polyvinyl alcohol and the chitosan isformed, so that the strength and elasticity of the gel are improved. The preparation method of the polyvinyl alcohol / chitosan gel bead, disclosed by the invention, has the advantages that a shortcoming that the gel bead obtained by one-step physical cross-linking is likely to dissolve out and break is overcome, and phenomenons that the gel beads are likely to adhere to each other and form a compact shell layer on the surfaces due to one-step chemical cross-linking is avoided.

Description

technical field [0001] The invention belongs to the field of environmental engineering, and in particular relates to a preparation method of polyvinyl alcohol / chitosan gel beads. Background technique [0002] Gel beads are a new type of polymer material with high bio-affinity, which can be used as a biological carrier for the cultivation of high-quality granular sludge, thereby promoting the rapid start-up and high-load stable operation of wastewater biological treatment reactors. [0003] Polyvinyl alcohol gel particles are a new type of organic polymer material that is widely used. It has the advantages of high mechanical strength, chemical stability, anti-microbial decomposition, non-toxic, and low price. The preparation methods of polyvinyl alcohol gel particles include physical cross-linking method and chemical cross-linking method. Physical cross-linking often adopts the freeze-thaw cycle method, which refers to the process of using intramolecular hydrogen bonds in po...

AI Technical Summary

Problems solved by technology

The currently commonly used cross-linking agents are saturated boric acid and CaCl 2 solution, although the chemical cross-linking agent can effectively cross-link the polymer, but the pure chemical cross-linking has some disadvantages: first, the cross-linking method often makes the carrier form a dense and non-porous surface shell structure, which hinders the external nutrition The infiltration of substances and the effective contact between microorganisms and reaction substrates lead to the formation of dead zones inside the gel, and the decline and loss of microbial metabolic activity

And if the gas produced by microbial metabolism has no smooth outlet, it will easily cause the material to swell and rupture.

Secondly, the polyvinyl alcohol-based gel particles after cross-linking have high water-swellability and are prone to stick to each other, making the gel material difficult to store

Finally, the cross-linked polyvinyl alcohol gel particles form irregular hydrogels when they meet water, which limits their application in biological wastewater treatment