Preparation method of polyether-grafted chitosan derivative crude oil desalting demulsifier

The invention relates to a preparation method of a polyether-grafted chitosan derivative crude oil desalting demulsifier. The preparation method comprises the following specific steps: firstly, performing formylation modification on polyethylene glycol monoethylether; secondly, preparing glycidyl dimethyl alkyl ammonium chloride; thirdly, preparing quaternarization carboxyalkyl chitosan; fourthly, enabling formylation modified polyethylene glycol monoethylether to react with carboxy alkyl chitosan to obtain the polyether-grafted chitosan derivative crude oil desalting demulsifier. The polyether-grafted chitosan derivative crude oil desalting demulsifier disclosed by the invention is prepared by taking chitosannatural polymeric compounds as raw materials, and has the advantages of wide sources, naturalness, no toxicity, sustainability, good biocompatibility of a product, degradability and the like. The prepared demulsifier is good in demulsifying and dehydrating effect; meanwhile, a demulsifying molecule conta