Preparation Of Solid Polyferric Aluminum Ferric Sulfate And Its Performance

A new type flocculant—polymeric aluminum ferric sulfate was prepared. The main material was bauxite in western guangxi, which acid by sulfuric acid under certain temperature, and then the calcium hydroxide was added into the mixed liquid. By using the hydrolisis polymerization curing, we can obtain it. The major factors which influenced the synthesis of polymeric aluminum ferric sulfate were:the concentration and amount of sulfuric acid, reaction time, reaction temperature, baking temperature, baking time, the amount of alkalization agent and aging time. The effects of concentration and amount of sulfuric acid,action time and temperature were investigated and the optimum conditions were given in the experiment:the ratio of sulfuric acid and raw materials was 1.40:1, the concentration of sulfuric acid was 8 mol·L-1, the reaction time was 100 min, the reaction temperature was 115℃. Under these conditions,the iron oxide content can be up to 5.59%, the aluminum oxide content of 6.65% and the basicity of prepared polymeric aluminum ferric sulfate was 57.35%.which were in line with the national standard (GB15892-2003 and GB14591-2006). In addition, polymeric aluminum ferric sulfate under the conditions of this system which carried on the coagulation experiment to the heavy rainstorms waste water, car wash waste water, the printing waste water. Experimental results showed that the flocculating effect was superior to other traditional flocculants. The removal rate of turbidity to heavy rainstorms waste water was 99.74% under the dosage of 250 mg·L-1; the removal rate of turbidity to car wash waste water was 97.89% under the dosage of 120 mg·L-1; the color removal to printing waste water was 93.43% under the dosage of 240 mg·L-1.The macrostructure characteristics with macromolecular network structure of PAFS were studied by SEM; X-ray diffraction analysis showed that the polymeric aluminum ferric sulphate coagulant may be the macromolecular phase, it was a mixture of mineral crystals,with iron polymer single aluminum and aluminum oligomer.The Ferron method was used in measuring the species distribution and transformation of the compound flocculant.The results denoted that the contents of [Al+Fe]a decreased 5.58%, [Al+Fe]c decreased 3.86%, whereas [Al+Fe]b increased 9.44% with introducing aluminum ions. However, the contents of [Al+Fe]a decreased 5.97%, [Al+Fe]b increased 9.60%, [Al+Fe]c decreased 3.73% with introducing phosphate ions. It could be estimated that the original 21.47%of (Al+Fe)a and 5.07%of (Al+Fe)b equated roughly to 26.54% of (Al+Fe)c with the increase of aging time. But it had little change in coagulation, which could stay at least six months.