Preparation method of starch grafted acrylamide flocculating agent

Abstract

The invention provides a preparation method of a starch grafted acrylamide flocculating agent, which comprises the following concrete step of polymerizing starch and acrylamide in a reversed emulsion formed by liquid paraffin, water and a compounded emulsifying agent to form a graft copolymer of the starch and the acrylamide, wherein potassium permanganate is used as an initiator, and the compounded emulsifying agent comprises span 80, Tween 80 and alkylphenol polyoxyethylene (4) in a mass ratio of 7-9:0.1-0.5:0.9-2.5. The method adopts the compounded emulsifying agent comprising the span 80, the Tween 80 and the alkylphenol polyoxyethylene (4) for preparing the reversed emulsion, thereby stabilizing the system of the reversed emulsion, providing a stable reaction environment for polyreaction, and being helpful for improving the stability of products. In addition, in the method, the potassium permanganate is also selected as the initiator, thereby effectively improving the efficiency of initiating the polyreaction.

Description

technical field [0001] The invention relates to the field of organic chemistry, in particular to a polymer compound obtained by reacting only carbon-carbon unsaturated bonds. Background technique [0002] Organic flocculants refer to natural or synthetic organic molecular substances that can produce flocculation. Natural organic flocculants are protein or polysaccharide compounds, such as starch, protein, animal glue, sodium alginate, sodium carboxymethylcellulose, etc.; synthetic organic flocculants include polyacrylamide, sodium polyacrylate, polyethylene Pyridinium salt, polyethyleneimine, etc. These flocculants are all water-soluble linear polymer substances, most of which can be ionized in water, and are polymer electrolytes. According to the characteristics of their dissociated groups, they can be divided into anion, cation and amphoteric types. After the flocculant is ionized in water, its chain molecules can produce bonding and bridging effects, and the charged gro...

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Problems solved by technology

However, the aqueous solution polymerization method is difficult to control the production process due to the difficulty of heat dissipation during the polymerization process, and the production process is difficult to control, and there are many by-products, and the resulting product has poor stability.

[0004] The inverse emulsion polymerization method is a new polymerization method that has attracted much attention in recent years. It is characterized in that the water-soluble monomer is dispersed in a non-polar liquid with the help of an emulsifier, and then polymerized after forming a water-in-oil state. This This method has the advantages of high polymerization rate, high product solid content, large molecular weight and narrow distribution, and mild reaction conditions. The method of amide graft copolymer, this method is: will be based on Span80 composite emulsifier and liquid paraffin mix, add the mixture of 30% starch milk and 40% monomer acrylamide under stirring to form inverse emulsion, generally Inject high-purity nitrogen for 30 minutes, raise the temperature to 35-55°C, slowly add the initiator ammonium persulfate dropwise and react for 4 hours. The oil-water ratio of the emulsion is 0.8-1.6, the concentration of the emulsifier is 2-10%, the concentration of the initiator is 1-7mmol / L, and the ratio of monomer to starch is 0.8-1.8. The stability of the inverse emulsion system is inverse The key to the success or failure of emulsion polymerization, and the determinant of the stability of the emulsion system is the emulsification system. Although the article claims that the emulsification system in its method is a compound emulsifier, it only discloses one of the components of the compound emulsifier— —Span80, those skilled in the art can't repeat the method and reach the effect claimed by the paper without knowing the remaining components of the emulsifier. In addition, the method of the paper adopts ammonium persulfate as the initiator of polymerization, although ammonium persulfate can The graft copolymerization reaction of starch acrylamide is effectively initiated, but the efficiency of the initiation reaction is low, resulting in a relatively low grafting rate (up to about 85%) and grafting efficiency (less than 60%) of the copolymer.

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