Preparation method of chitosan type crude oil desalting demulsifier

The invention relates to a preparation method of a chitosan type crude oil desalting demulsifier. The preparation method includes the steps of firstly, performing epoxidation modification on methoxy polyethylene glycol; secondly, preparing glycidyl dimethyl alkyl ammonium chloride; thirdly, preparing quaternization carboxy alkyl chitosan; fourthly, allowing the modified methoxy polyethylene glycol to react with the quaternization carboxyl alkyl chitosan to obtain methoxy polyethylene glycol grafted quaternization carboxy alkyl chitosan. The preparation method has the advantages that chitosan type natural high-molecular compounds are used as the raw materials, the method is wide is source, natural, nontoxic and sustainable, and the product of the method is good in biocompatibility, degradable, and the like; the prepared demulsifier is good in demulsifying and dewatering effect, the demulsifier has high combining capacity to electronegative ions such as metal cations and naphthene acid radicals and electronegat