Preparation of cellulose-base amphoteric flocculant and its application in the treatment of wastewater

An amphoteric flocculant, MCC(pAA-co-pDMC) was synthesized through an environmental friendly process. Methacryloxyethyltrimethyl ammonium chloride (DMC) and acrylic acid (AA) were grafted onto the skeleton of microcrystalline cellulose (MCC) in NaOH/urea homogeneous system. Orthogonal tests were carried out to achieve the optimal conditions of the polymerization process. Influential factors, which included reaction temperature, reaction time, molar ratio between MCC, acrylic acid and DMC were investigated. The degree of substitution (DS) of AA and DMC were 0.52 and 1.01 under the optimal synthesis conditions. Turbidity removal efficiency of the product can reach 99.82% for kaolin suspension with the initial concentration of 5.0 g/dm(3) under pH 7.0. Structural characterization of FT-IR, XPS and elemental analysis were carried out and further confirmed the successful of the polymerization. Influence factors including flocculant dosage, pH and flocculation time were discussed. In addition, two coagulation-flocculation procedures were carried out to dispose kaolin suspension, results found polyaluminum chloride (PAC) (or CaCl2) and MCC(pAA-co-pDMC) have synergy effect in turbidity removal with a significant dosage decrease at high removal efficiency. MCC(pAA-co-pDMC) coupled with ozonation process was used to treat black-middle effluent from pulp and paper mill and exhibited effective result on decolorization and turbidity removal.