Preparation And Application Of Polysilicate Aluminium Ferric Lanthanum Sulfate Flocculant

The methods used for dyeing wastewater treatment have flocculation, oxidation, adsorption and biological treatment, etc. Because of flocculation has less land occupied, low cost, easy management, and other advantages, which has become a common method to deal with the printing and dyeing wastewater. Traditional inorganic flocculants have higher decolorization efficiency for the hydrophobic dyes, but less decolorization efficiency for some good water-soluble dyes. So it is crucial to find and develop a new coagulant which has a high decolorizing rate.In this paper, Polysilicate Aluminium Ferric La flocculant (La-PFASS) is a new type of rare earth composite inorganic polymer coagulant. There are sodium silicate, aluminum sulfate, ferric sulfate and lanthanum as raw material, and prepared by a composite copolymer. Preparation method:at room temperature, firstly prepare polysilicate by using sodium silicate under acidic conditions, then add the solution of aluminium-ferro-lanthanum, so La-PFASS is prepared after reaction between polysilicate and aluminium-ferro-lanthanum. By coagulation experiments respectively treat the simulated dye wastewater of reactive blue KN-R, vat scarlet R, disperse red E-4B and direct black FF, study effect of the molar ratio of (Al+Fe)/Si, the molar ratio of Al/Fe, lanthanum dosage and dosage of La-PFASS and pH value of wastewater on the flocculation, Optimize preparation conditions, determine the best working parameters for a variety of wastewater treatment. And the flocculation mechanism of La-PFASS was preliminary discussed.The results show that the La-PFASS flocculation has good flocculation and bleaching performance to treat dyes wastewater. The flocculant has higher decolorization efficiency to deal with non-ionic hydrophobic dyes (vat scarlet R, disperse red E-4B), when the dosage of coagulant was 14mg/L, turbidity removal rate and the decoloration rate could reached over 90%. But for some water-soluble dyes (reactive blue KN-R, direct black FF) have less decolorization efficiency, when the dosage of coagulant was 14mg/L, decolorization rate was only about 80%. The practical printing and dyeing wastewater was treated by La-PFASS has good flocculation effect, when the dosage was 35mg/L, turbidity removal rate and the decoloration rate could reached 81.0%,76.5%.In short, because of its electrostatic neutralization, cohere adsorption and network-capturing effect, the prepared La-PFASS flocculant is a high efficient and a large molecular weight inorganic polymer composite flocculant, which has excellent decolorization performance for more difficult non-ionic dye wastewater of hydrophobic, so La-PFASS is a promising flocculant.