Study On The Synthesis And Flocculation Performance Of Cationic Polyacrylamide

Cationic polyacrylamide (PAM-C), a polymer containing cationic charge, is aderivant of polyacrylamide. As a high-efficiency organic flocculant, cationicpolyacrylamide can make colloidal particles coalesce through “charge neutralization”and “absorption-bridging” effect with anion in waste water, then the water is purified.In the field of sludge dewatering, cationic polyacrylamide is widely favored becauseof its less amount, fast and thorough flocculating characteristic. In addition, thedeposit is loose, the filtering rate is fast and the moisture content of the filter cake isespecially low.The initiator is a key factor that would affect the performance of polymer and thecondition of polymerizing. Here, Ultra-high molecular weight cationic CPAM wasprepared through copolymerization of acrylamide (AM) and dimethyl aminoethylacrylate methyl chloride quarternary (DAC) in aqueous solution with compoundinitiator which comprises of self-made difunctional peroxide as oxidant, sodiumhydrogensulfite as reductant and Water-soluble azoic compound. Six products withdifferent cationic degree (10%-35%) were prepared and the effect of monomerconcentration, initiator concentration (the concentration of oxidant, reductant and azoinitiator, the mass ratio of oxidant and reductant), complexant EDTA concentration,cosolvent urea concentration and chain transfer agent isopropanol concentration onintrinsic viscosity of products were investigated detailedly. The optimalpolymerization process conditions determined through single factor experiment wereobtained as follows: monomer concentration30%, oxidized-reduction initiatorconcentration0.005%(mass fraction), azo initiator concentration0.007%(massfraction), EDTA concentration0.01%(mass fraction), urea concentration0.1%(massfraction) and isopropanol concentration0.18%(mass fraction).The conclusion was applied to pilot plant test of annual output of100tonscationic polyacrylamide. The production equipment and process were introduced. Theintrinsic viscosity and flocculation performance of products were also investigated.The results show that the intrinsic viscosity of pilot plant products is1000-1300ml/L,which is lower than that of miniature experimentation products, but better than otherdomestic products. Beaker flocculation experiments were done to examine the dewatering propertyof the self-made products. On the basis of the best dosage, the Floc size, the moisturecontent of filter cake and the specific resistance of the sludge the self-made productsshowed better performance than both the domestic and imported products. Inconsideration of the sludge dehydration effect of the pilot plant product is more or lessthe same with the domestic product of the same cationic degree.