The Study Of Flocculation Recovery And Reuse Of The TiO₂ Photocatalyst In Suspension System By PDMDAAC And PDMDAAC-AM

The research of TiO2 photocatalystion is loading system and suspension system.The nano TiO2 has high photocatalytic activity in the suspension system,but it is easy to agglomerate,difficult to separate,difficult to recycle and reuse.The loading system can recover TiO2 well,but the photocatalytic efficiency is decreased obviously.The TiO2 of suspension system is in the presence of colloidal state,The flocculation method can be used to flocculate suspended particles in water.In this study,flocculation technology and photocatalysis technology were combined to establish a route for the recovery of TiO2 from the suspension system and then to the photocatalytic degradation of pollutants.In this paper,PDMDAAC,PDMDAAC-AM as flocculant on flocculation and recovery of high turbidity in suspension systems using TiO2,Set flocculation process 1(200r/min fast mixing 120 s,60r/min slow mixing 10min)and program 2(250r/min fast mixing 90 s,50r/min slow mixing 10min),The different dosage of flocculant and the flocculation experiment of with different pH value were carried out under the condition of program 1&,respectively,And above the supernatant turbidity and Zeta potential value as the evaluation index,so as to investigate the factors of flocculant dosage,pH value,stirring time and velocity effect on the flocculation of TiO2 suspension system of the recovery effect.Based on the above experimental results,the orthogonal experiment was designed,and the optimum flocculation conditions were optimized by orthogonal experiment.Then,using phenol as a model pollutant for flocculation and recovery for the suspension system of TiO2 in the optimum experimental conditions were screened,with suspended flocculation and recovery of the TiO2 as a photocatalyst for photocatalytic degradation of phenol experiment,study the degradation efficiency of phenol on the flocculation and recovery of TiO2.Then the flocculation recycling photocatalytic degradation experiment 10,investigated the photocatalytic efficiency of TiO2 flocculation and recovery of the change after 10 times in the experiment,finally the research group has developed the best effect of PAM flocculant cycles reuse Recyclable suspension system TiO2.In the process of flocculation and flocculation experiment of recycling,the floc particles were characterized by SEM,TEM and particle size analyzer before and after flocculation,to obtain more accurate results.The main results are summarized as follows:(1)flocculant dosage,pH value of the suspension and flocculation stirring time and velocity have significant influence on the flocculation effect of flocculant,PDMDAAC,optimum dosage of PDMDAAC-AM mixing conditions in different flocculation.Under the different conditions of flocculation and agitation,the turbidity of the suspension system TiO2 recovered by PDMDAAC flocculation was in the range of 75 to 120 NTU,and the turbidity of the suspension recovered by PDMDAAC-AM flocculation was from 6 to 23 NTU.Under the condition of flocculation of the procedure 2,the turbidity of the suspension recovered by PDMDAAC+8mg/LPAM flocculation is about 18 ~ 40 NTU.(2)the flocculation effect of flocculant PDMDAAC was the best when the flocculation system was and the dosage was 2.6mg/L in suspension system TiO2,and the turbidity was75 NTU.The flocculation effect of PDMDAAC-AM in suspension system TiO2 was the best when 6NTU was 2 and the dosage was 10mg/L.(3)the flocculant PDMDAAC has a great influence on the pH of the flocculation environment,the effective pH range is greater than or equal to,and the flocculation effect is the best when pH is 11.The pH value of flocculant PDMDAAC-AM was relatively small,the effective pH range was less than or equal to 6,and the flocculation effect was best at pH of 5.(4)the optimum flocculation conditions of flocculant PDMDAAC were as follows: the dosage of pH=7 and PAM was 7mg/L,PDMDAAC dosage was 2.6 mg/L,210r/min fast stirring 120 s,60r/min slow stirring 10 min.The optimum flocculation conditions of PDMDAAC-AM were as follows: the dosage of pH=5,flocculant PDM DAAC-AM was10mg/L,240r/min fast stirring 90 s,50r/min slow stirring 610 s.(5)after 6 factors 5 levels of orthogonal experiment,the optimal conditions of PDMDAAC and PDMDAAC-AM combined flocculation,the flocculation experiment of residual turbidity suspension system corresponding respectively 5.6NTU and 1.79 NTU in the best condition,compared with the original selected under the condicondition of flocculation turbidity decreased by 64.9NTU,4.21 NTU,flocculation the effect has been optimized.(6)the photocatalytic efficiency and suspension system of TiO2 without adding flocculant than by flocculant PDMDAAC and PDMDAAC-AM flocculation after photocatalytic suspension system TiO2 efficiency were decreased,but the catalytic efficiency is still high at 82%,85%.(7)the photocatalytic efficiency of TiO2 suspension flocculation and recovery of different initial concentrations after different,whether PDMDAAC or PDMDAAC-AM flocculant,showed the initial concentration of the catalytic efficiency of TiO2 suspension flocculation and recovery after 1000mg/L was higher than that of 500mg/L.(8)the TiO2 suspension system of flocculant PDMDAAC and PDMDAAC-AM reuse after 10 times,the photocatalytic efficiency of flocculant PDMDAAC recovery of TiO2 decreased by 41%,and repeat the experiment to tenth times when the degradation rate was39%.The photocatalytic efficiency of PDMDAAC-AM recovered by flocculant TiO2 was decreased by 8%,and the degradation rate was up to tenth times,which was up to 77%.(9)the PAM of TiO2 flocculant suspension system by cyclic repeated 34 times,repeated experiments were carried out to 34 times the photocatalytic degradation rate remains unchanged,the degradation rate remained at around 4%.In summary,the nano TiO2 can be recovered by flocculation technology,and the recovered TiO2 can be reused for photocatalytic degradation of pollutants.