Preparation,Characterization And Application Of Hybrid Flocculant PSAF-PDMDAAC

Coagulation is one of the important processes in the conventional water treatment process.Its core technology is the development of flocculants.The performance of flocculants directly affects the effect of water treatment.With the continuous complexity and diversification of water pollution,it is very necessary to develop new efficient and environmentally friendly flocculants.Therefore,a hybrid synthesis method in the field of materials was introduced.The hybrid preparation of organic and inorganic flocculants hybridizes the organic phase and inorganic phase through chemical bonding to achieve molecular level recombination,change its structure and morphology,and make it have better flocculation effect.The new hybrid flocculant polyaluminum ferric silicate-poly dimethyl diallyl ammonium chloride（PSAF-PDMDAAC）was prepared by polyaluminum ferric silicate（PSAF）and dimethyl diallyl ammonium chloride（DMDAAC）as raw materials,ammonium persulfate as the initiator in situ hybridization method.The synthesis conditions of the hybrid flocculant PSAF-PDMDAA were optimized,including reaction time,reaction temperature,monomer mass fraction and initiator mass fraction.The results show that the maximum intrinsic viscosity of the hybrid flocculant is 790.43m L·g^-1.It was observed at the initiator mass fraction of 0.5% and the monomer mass fraction of 30%,the reaction time of 5 h and the reaction temperature of 70℃.Conductivity analysis,infrared spectrum analysis and thermogravimetric-differential thermal analysis methods are used to characterize the hybrid flocculant.It was analyzed that the connection between the inorganic component and the organic component in the hybrid flocculant PSAF-PDMDAAC is formed by the sulfate ion at the polymer chain end of the polydimethyl diallyl ammonium chloride and the positively charged inorganic hydroxyl complex Ionic bond.Scanning electron microscopy showed that the hybrid flocculant PSAF-PDMDAAC had more holes and protrusions,and showed a spatial network structure.The hybrid flocculant PSAF-PDMDAAC was used to treat simulated water samples and Jialing River raw water to explore its flocculation performance and mechanism.The single-factor flocculation experiment results of simulated water samples showed that the hybrid flocculant PSAF-PDMDAAC has the highest turbidity removal rate and a small amount of flocculation agent compared to PSAF,PAC,PAM and compound PSAF-PDMDAAC flocculant.The results of the flocculation experiment on the raw water of the Jialing River showed that when the optimal dosage of the hybrid flocculant was 4 mg/L,the residual turbidity was 0.82 NTU.When the dosage of the compound type,PSAF,and PAC was 6 mg/L,the remaining turbidity were 1.63 NTU,2.09 NTU,and 2.80 NTU,respectively.When the dosage was 6mg/L,the removal rates of UV₂₅₄ of hybrid type,compound type,PSAF and PAC were 54.76%,42.85%,40.48%and 36.90%,respectively.The removal rates of COD_Mn were 71.32%,69.48%,64.33%and 37.5%,respectively.Therefore,the hybrid flocculant can obtain the best effect of removing turbidity and organic matter with less dosage.At the same time,the temperature and p H of the water sample for removing turbidity of the hybrid flocculant have a wide range of applications.The optimal initial temperature was 20～50℃and the optimal initial p H was 7～9.In addition,the experimental results of the analysis of the coagulation mechanism showed that the electric neutralization ability and settling performance of the hybrid flocculant PSAF-PDMDAAC are superior to the compound type and PSAF flocculant.This is because the hybrid flocculant not only plays the role of electrical neutralization of inorganic components,but also plays the role of adsorption and bridging of organic components.The two together produce large and dense flocs,improving the flocculation effect and settling performance.The hybrid flocculant PSAF-PDMDAAC was applied to the decolorization of dye solutions.The results showed that the decolorization effect of the hybrid flocculant PSAF-PDMDAAC on reactive brilliant red X-3B and direct fast turquoise GL was better than the compound flocculants,PSAF and PAC.The highest decolorization rates achieved were 93%and 94.38%,respectively.The optimal p H ranges for the treatment of reactive brilliant red X-3B and direct light fast green Cyan GL with hybrid flocculants were 7～9 and 6～9,respectively.The initial water sample temperature has a wide application range and can be set to room temperature.