Preparation of a new inorganic–organic composite flocculant used in solid–liquid separation for waste drilling fluid

In this study, a new inorganic–organic composite flocculant CSSAD was prepared by the reaction of corn starch (st), acrylamide (AM), and (2-methacryloyloxyethyl) trimethyl ammonium chloride (DMC) with a previously prepared SiO2 sol by using the aqueous solution polymerization process. The different factors affecting the preparation were investigated and the optimal synthesis conditions were established: polymerization temperature was 70 °C, reaction time was 4 h, w(DMC):w(st) was 1.5, w(AM):w(st) was 3, and the ratio of initiator to acrylamide was 0.5 wt.%. CSSAD was characterized by FTIR spectroscopy, scanning electron microscopy, and gel permeation chromatography. The different factors affecting the flocculating ability of CSSAD for waste drilling fluid were studied. These factors included the dose, stirring rate, and time. When the dosage of CSSAD was 0.3 g (per 100 g waste drilling fluid) with a stirring rate of 60 r/min and a stirring time of 2 min, the water content of the flocculated precipitate was the lowest at 21.34%. And CSSAD showed better flocculating ability than other flocculants in the same dose (0.3 wt.%).