Method for preparing environment-friendly plasticizer by recycling waste resources

The invention relates to a method for preparing an environment-friendly plasticizer by recycling waste resources. The method comprises the following steps of transferring alkali-reduction wastewater containing sodium terephthalate into an acid precipitation tank with a stirring device and adding sulfuric acid to further precipitate terephthalic acid (PTA) solids; carrying out plate-frame filtration on the mixed solution to obtain a crude PTA material; adding the recovered crude PTA material into an esterification reactor with an alcohol-water separation device, adding iso-octanol, heating and dehydrating, adding tetrabutyl titanate as a catalyst and carrying out esterification reaction; after water is no longer produced, stopping reaction and dealcoholizing to obtain a crude DOTP (Dioctyl Terephthalate) product; rectifying the prepared crude DOTP product in a packing-type rectifying tower to obtain a rectified product, adding the rectified product into a neutralization reaction kettle, adding sodium hydroxide lye, stirring and washing with alkali; standing, precipitating and discharging the aqueous solution in the lower layer, adding hot water, stirring and washing with water, standing, precipitating and discharging the moisture in the lower layer, carrying out temperature-raising dehydration, adding an inorganic filter aid and filtering to obtain the pure DOTP product. By the method, the recycling of the waste resources is achieved.