Preparation Of SiO₂-TiO₂ Based Composite Flocculants And Optimization Of Its Flocculation Performance

With the increasingly sharp contradiction between supply and demand of petroleum energy,oil sand resources are exploited in large quantities.It has brought a large amount of oil sand tailings.Long-term storage of oil sand tailings in tailings ponds had caused that large-scale land resources couldn't be used for a long time,a large amount of water resources in oil sand tailings couldn't be reused and the local ecological environment had been seriously damaged.In response to the above problems,a large number of commercial polyacrylamide flocculants have been used to flocculate oil sand tailings.However,these flocculants have critical problems of low flocculation efficiency and severe secondary pollution.In order to solve the problems of commercial polyacrylamide flocculant,three novel organic-inorganic composite high-efficiency flocculants with self-degradable of SiO2-TiO2-PAM,SiO2-TiO2-P(AM-DMC)and SiO2-TiO2-P(AM-DMC-AA)were designed and prepared.The main contents and conclusions of the three organicinorganic composite flocculants are as follows:(1)For the problems of commercial polyacrylamide flocculants,the selfdegradable SiO2-TiO2-PAM composite flocculant was successfully prepared by surface photoinitiated polymerization.In order to study the synthesis process,flocculation performance and degradation characteristics of SiO2-TiO2-PAM composite flocculant,SiO2-TiO2-PAM was characterized by FTIR,TG,SEM,performed flocculation parameters optimization and degradation experiments,respectively.The characterization data of SiO2-TiO2-PAM composite flocculant showed that it was successfully prepared by surface photoinitiated polymerization.The flocculation parameters of SiO2-TiO2-PAM composite flocculant can be optimized by CCD and RSM.The optimum flocculation parameters of SiO2-TiO2PAM are as follows:VTBOT/mSiO2=6.66 mL.g-1,flocculant dosage was 50 ppm and kaolin concentration was 1.5 wt%.Moreover,under the optimal flocculation conditions,the turbidity removal of kaolin suspension by SiO2-TiO2-PAM can reach 99.2%,which is much higher than the flocculation efficiency of the general composite flocculants.The self-degradation experiments of SiO2-TiO2-PAM composite flocculant indicated that the degradation efficiency of SiO2-TiO2-PAM could reach more than 90%after 2h,which was much higher than the degradation efficiency of organic compounds degraded by photocatalyst.Moreover,the selfdegradation process of SiO2-TiO2-PAM composite flocculant accorded with the first-order kinetic reaction,and the first-order reaction rate constant was 2.3×10-2 min-1.(2)For the water property of negative charge of oil sand tailings,the cationic SiO2-TiO2-P(AM-DMC)composite flocculant was successfully prepared by surface photoinitiated polymerization.In order to investigate the synthesis process,synthesis influencing factors and flocculation performance of SiO2-TiO2-P(AMDMC)composite flocculant,SiO2-TiO2-P(AM-DMC)was characterized by FTIR,TG,and XPS,performed preparation of process parameters optimization experiments and executed flocculation parameter optimization experiments,respectively.The characterization data of SiO2-TiO2-P(AM-DMC)cationic composite flocculant showed that SiO2-TiO2-P(AM-DMC)was successfully prepared by surface photoinitiated polymerization.The optimum preparation parameters of SiO2-TiO2-P(AM-DMC)were as follows:mDMC:mAM=5,monomer concentration was 35%,and reaction time was 100 min by using CCD and RSM.Moreover,under the optimal preparation parameters,the intrinsic viscosity of the cationic composite flocculant of SiO2-TiO2-P(AM-DMC)was 734.1 mL.g-1,The optimum SiO2-TiO2-P(AM-DMC)flocculation parameters were obtained by using CCD and RSM as follows:pH=5,the flocculant dose was 30 ppm,and the kaolin concentration was 1.36 wt%.Moreover,under the optimal flocculation conditions,the turbidity removal of the cationic composite flocculant SiO2-TiO2-P(AM-DMC)was 87.5%.(3)In order to expand the application range of the composite flocculant,the amphoteric SiO2-TiO2-P(AM-DMC-AA)composite flocculant was successfully prepared by surface photoinitiated polymerization.In order to analyze the synthesis process and flocculation performance of SiO2-TiO2-P(AM-DMC-AA)composite flocculant,SiO2-TiO2-P(AM-DMC-AA)was characterized by FTIR,TG and TEM and performed flocculation parameter optimization experiments,respectively.The characterization data of SiO2-TiO2-P(AM-DMC-AA)amphoteric composite flocculant showed that SiO2-TiO2-P(AM-DMC-AA)was successfully prepared by surface photoinitiated polymerization.The optimal flocculation parameters of SiO2-TiO2-P(AM-DMC-AA)amphoteric composite flocculant were obtained by CCD and RSM as follows:pH=5.37,flocculant dosage was 39.18 ppm,kaolin concentration was 1.27 wt%.Moreover,under the optimal flocculation conditions,the turbidity removal of SiO2-TiO2-P(AM-DMC-AA)amphoteric composite flocculant was 97.09%.