Studies On The Preparation And Properties Of Two Flocculants

Coagulation process is one of the common water treating technology at present.Because of its simplicity, efficiency and economy coagulation process is considered as the most commonly used separation techniques which determine water quality and effluent treatment costs. Selection of flocculants is the core part of the coagulation process, the types and qualities of flocculants will directly determine the treatment effect of the whole process.Therefore, it is an important subject for researching a water treatment process which have high, affordable, safe and nontoxic flocculants in.In this paper, based on the comprehensive understanding of the development of flocculants, two kinds of efficient flocculants are synthesized, namely boron poly-silicate ferric magnesium and Chitosan-Fe, the optional preparation conditions were investigated through the simulation domestic wastewater, and the flocculants were characterized by infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and X-ray diffraction(XRD). The main research contents are listed as the following:(1)Firstly, the reaction conditions for preparation poly silicate were optimized,polysilicate gel time as the evaluate standard, the effect of concentration of sodium silicate,pH value and reaction temperature were discussed, the optimal preparation conditions is room temperature, concentration of sodium silicate is 0.4 mol/L, polymerization pH is 4.5.After ferric sulfate, magnesium suifate, sodium tetraborate were introduced into the poly(sodium silicate), the optimum preparation conditions of boron iron magnesium silicate flocculants were determined by turbidity, chroma and COD removal rate. The mole ratios are: n(Fe)/n(Si) is 0.25, n(Mg)/n(Si) is 0.4, n(B)/n(Si) is 0.2; By using the boron magnesium iron silicate flocculant and chitosan solution mixture, the flocculant property was improved through the synergies interaction of flocculant, this method showed more environmental protection and lower cost;(2)Chitosan complex iron flocculant was prepared when Fe3+ ion as a modifier, the optimization technology that we achieved is: the modified solution was resolved in water,then Fe3+ as the modifier complex with chitosan, and adjust the acidity to promote the hydrolyzing of complexed Fe3+ ions moderately, the concentration ration of the complex flocculant is CTS:Fe=2:1, the prepared chitosan-ferric flocculant have a good performance on flocculation;(3)The synthesized flocculants were characterized by infrared spectroscopy (FT-IR),scanning electron microscopy (SEM) and X-ray diffraction (XRD). And we observed their morphology and dicssused flocculant mechanism. Experimental and characterization results showed that the two flocculants are not a simple blend, they are formed macromolecular polymers and its morphological become denser. Thus poly silicate boron iron magnesium flocculant and chitosan-ferric have good performance on stability and flocculation.