Preparation Of Polysaccharide-based Ionic Flocculants And Their Application In Hot Wash Oil Sludge

The oil industry produces a large amount of dirty sludge every year.If it is discharged directly without treatment,it will cause pollution to the environment and also waste petroleum resources such as aging crude oil and asphaltene in the sludge.Among many treatment methods,the chemical hot washing separation method is commonly used because it has the advantages of low cost and good separation effect.Some flocculants are needed to temper the sludge in the chemical hot washing process.Since traditional flocculants have defects such as toxic monomers or heavy metal residues,this paper designs and prepares polysaccharide-based ionic flocculants instead of traditional flocculants and applies them to the hot washed sludge as follows.1、The cellulose-based cationic modified flocculant CMC-g-PAC was synthesized by free radical polymerization using the positively charged quaternary ammonium salts 3-chloro-2-hydroxypropyltrimethylammonium chloride(CTA)and acrylamide(AM)for graft modification of sodium carboxymethyl cellulose(CMC)and potassium persulfate(KPS)as initiator.The effects of monomer mass ratio,total monomer concentration,initiator concentration,and The effects of monomer mass ratio,total monomer concentration,initiator concentration and polymerization temperature on the grafting rate,grafting efficiency and characteristic viscosity of the product were investigated.The orthogonal experiments were designed based on the results of single-factor experiments and the optimal synthesis conditions were determined by response surface optimization.The optimum flocculation conditions and the flocculation performance under these conditions were also determined using the dosage,temperature and pH as factors.2.In order to further improve the flocculation efficiency,chitosan,the only polysaccharide with positive charge in nature,was selected as the raw material,and the chitosan-based cationic modified flocculant CTS-g-PAD was synthesized by copolymerization with dimethyldiallylammonium chloride(DMDAAC)and AM using ammonium persulfate as the initiator.The optimal monomer mass ratio,total monomer concentration,initiator concentration and polymerization temperature for the reaction were determined.The optimal synthesis conditions were simulated by response surface optimization method.The optimum flocculant dosage,flocculation temperature and pH value were also determined.3.Graphene oxide(GO)was prepared according to the modified Hummers method.The newly prepared GO samples were condensed with chitosan-based flocculant CTS-g-PAD,and finally the environment-friendly CTS-g-PAD/GO composite flocculant was successfully prepared,and the optimum flocculation conditions and the flocculation performance under these conditions were determined with the dosage,temperature and pH as factors.4.Simulating the treatment of dirty oil sludge by hot washing technology,the research results show that the solid-liquid ratio is 1:4,the dosage of emulsion breaker is 2 g/L,the dosage of CTS-g-PAD/GO is 1 g/L,the hot washing temperature is 60 ℃,pH 8,and the agitation intensity is 200 r/min,the best oil removal effect can be achieved,and the oil removal rate is 92.1%.