Study On The Synthesis And Flocculation Efficiency Of Polymeric Ferric Base Modified Composite Flocculants Pfdms

The exacerbating environment and shortage of water resource, which threatening both people's lives and the sustainable development of economy, has become a global issue of global concern. Water treatment chemicals are gaining more and more attention, research and development of new highly efficient flocculants is of significant meanings to water pollution control. Being new type of highly efficient flocculants, inorganic-organic composite flocculants possess both organic flocculants and inorganic flocculants'merits, and will be an important direction and hot field of research.In this study, by-product copperas(FeSO4·7H2O) of a given titanium dioxide factory were used to compound Polymeric ferric sulfate(PFS),then poly-diallyldiethylammoniu-chloride(PDAC) which passed the toxicity test of the U.S. Federal Department of Public Health and was the first polymer approved to use in the treatment of drinking water, was used to modify PFS to synthesized a highly efficient organic-inorganic composite flocculants PFDMS,which possess both organic flocculants and inorganic flocculants' merits. The best synthesis condition was ascertained as flowing:concentration ratio of FeSO4 and PDAC (mass ratio) was 20:1,the reaction system pH value 2.3, temperature 60℃,reaction time 3 hours.And the final product was brown viscous liquid, with the density of 1.207 g·mL-1, pH value 2.1 or so.200NTU,1 000NTU and 5 000NTU diatomite suspension were used as simulated wastewater to test and evaluate the flocculation efficiency of PFDMS. The results showed that, PFDMS could better play its flocculation performance when used to deal with high turbidity wastewater; Compared with conventional flocculants such as PFS, PAC, PFDMS was superior to them in flocculation efficiency. At a relatively low dosage, the flocs were larger, settling velocity faster, and easier to separate from solid-liquid system.PFDMS was used in the treatment of a given coking factory's wastewater, and UV254 was used as a comprehensive indicator to reflex the content of organic pollutants. Through trials and curve fitting, an obvious linear relationship between the COD and UV254 values of the wastewater was discovered, linear equation y=0.047x-0.3124, R2=0.9911, so UV254 could be used to predict the concentration of COD, and to give rapid reflection of COD changes during the treatment process. When the dosage of PFDMS was 40mg·L-1, within the pH value of 6.0 to 10, there were higher removal rate of UV254 and turbidity, the highest removal rates could separately reach as high as 63%and 74%, and was far higher than those of PFS,PAC and FeCL3 under the same experimental conditions. The COD could be significantly reduced, which was beneficial to the subsequent biochemistry treatment procedure. So using of PFDMS to treat coking-plant wastewater, provided a effective and practical pretreatment method for the treatment of coking-plant wastewater.The cause of the higher efficiency of composite flocculant PFDMS lies in as flowing:①trengthening it's ability of charge neutralizing;②nhancing the molecular weight of the composite flocculant, thereby the ability of bridge-putting-up and net-catching were also enhanced at the same time;③he existence of PDAC increased the activity of the reactive group, strengthened the bridge-putting-up adsorption and swept flocculation to colloid matters;④ue to modification, the modality and structure of PFDMS were changed, the surface action between flocculant and contaminant particles was optimized, the specific adsorption and exclusive chemical role were strengthened. In addition, the comparison of different adding method of flocculants, shows that PFDMS is not just a simple mixture of PFS and PDAC, but exists synergy between the two components, which make PFDMS possess outstanding flocculation ability.Composite flocculants has overcome the shortcoming of producing the gel or insoluble precipitation when general organic and inorganic flocculants were used together just after simply mixed, and possess the reinforcement flocculation effect and merits of both inorganic flocculants and organic flocculants; The performances of PFDMS exceeds several conventional flocculants mentioned above, the flocs produced is larger, settling velocity faster, and easier to separate from solid-liquid system; At the same time, PFDMS exhibits good stability and low cost, and also good value and prospects, so PFDMS possesses upstanding applicational values and an encouraging prospect for development. And this study also provide a new method and thought for the resource reutilization of spin-off copperas from titanium dioxide production.