Study On Synthesis And Properties Of Novel Polyacrylamide Flocculant For Treatment Of Fracturing Wastewater

Fracturing process was adopted popularly by oilfields in order to enhance oil production.The fracturing wastewater had high COD value,high viscosity,high oil content,hardly degradating and etc.If the wastewater was discharged without being treated,the environment would be seriously polluted.Therefore developed a good performance flocculant is necessary.A novel cationic monomer acryloxy-2-hydroxypropyl-trimethylammonium chlorides?AHPTAC?wassynthesizedinanewway.Cationiccopolymer acrylamide-acryloxy-2-hydroxypropyl-trimeth-ylammonium chloride?PAM-AHPTAC?was synthesized from acrylamide?AM?and?AHPTAC?by radical polymerization.Its flocculation performance was studied,in order to get a better performance cationic flocculant.AHPTAC was synthesized by using 3-chloro-2-hydroxypropyl-trimethylammonium chloride?CHPTAC?and acrylic acid?AA?.The suitable conditions for synthesis of AHPTAC are:n?AA?:n?CHPTAC?=1:1.1,reactiontime4.5h,reactiontemperature65?,V?water?:V?acetonitrile?=1:1.Under these conditions,yield of AHPTAC was 81.9%.The structure of AHPTAC was identified by FTIR and NMR.AHPTAC and acrylic amide?AM?were used as monomers to synthesize water soluble copolymers of P?AM/AH?,on the basis of synthetic cationic polyacrylamide flocculant process of domestic and foreign.The results showed that the suitable conditions for synthesis of P?AM/AH?are:reaction time 4h,reaction temperature 60?,n?AM?:n?AHPTAC?=1:3,C_initiators?wt%??ammonium persulfate,sodium bisulfite?=0.2%,C_monomers?wt%?=30%,initiators added in three portions.Under these conditions,The removal rates of COD was84.9%.The structure of P?AM/AH?was identified by FTIR and NMR.Through the flocculation experiments of using P?AM/AH?disposing of fracturing wastewater,the result showed that it is better than the commercially available PAC?PAM.P?AM/AH?is a highly efficient organic cationic flocculant.The reaction temperature?n?AM?:n?AHPTAC?have greatest impact on the molecular weight.The reaction temperature?n?AM?:n?AHPTAC??C_monomers?wt%?have greatest impact on the cationic degree.The relationship between molecular weight,cationic degree and P_CODOD were studied:the larger the degree of cation,the less impact on the P_CODOD the molecular weight,and vice versa.According to the water quality of Shengli oilfield fracturing wastewater,the processes of flocculation-Fenton oxidation reaction were studied.The optimum inorganic/organic flocculant and their dosages were:PAC dosage of 280mg/L,P?AM/AH?dosage of 100mg/L.The optimal operating conditions of Fenton oxidation reaction were:pH=3,reaction time 1.5h,reaction temperature 20?,H₂O₂ concentration was 0.125mol/L,FeSO₄ dosage was 0.84g/L.The flocculant-Fenton oxidation reaction were used to treat the fracturing wastewater.The removal rates of COD was 99.21%.The SS content was 13mg/L.The oil content was 5.3mg/L.