Modified walnut shell filter material for the enhanced removal of oil from oilfield wastewater

While polymer oil recovery greatly improves oil recovery, the polymer injected into the formation undergoes shearing, degradation, etc., and returns with the output liquid in the form of an anionic polyacrylamide of lower molecular weight, resulting in a production fluid. There is residual polymer, and this kind of polymer–containing wastewater is easy to contaminate the walnut shell filter in the sewage treatment process, resulting in failure of the walnut shell filter material, introduce hydrophilic sulfonic acid groups on the surface of the walnut shell filter material to lipophilic to hydrophilic of the surface. The dosage of NaHSO₃ is 10-20% of the mass fraction of walnut shell filter (mass ratio %). Reflux reaction, and the reaction time was 1-5 h; the surface wettability of the walnut shell reversed. The surface contact angle drops from 95° before modification to 36.75°-66.25°, Its surface hydrophilic oleophobic performance has been significantly improved, Treatment of 150-230 mg/L of oily sewage, filtration and oil removal rate increased from 38.05% to 89.51% by modification; Backwashing and degreasing effect is increased by 4 times.