Preparation And Characterization Of Flocculant Agents For Removal Of Heavy Metal Ions

Abstract:Polyaluminium chloride, which is one of the inorganic polymer flocculatants, is used in the matter of water coagulation treatment widely nowadays. The main function of polyaluminium chloride are turbidity removal, decoloration, deodorization and so on. In this paper, the application of removal of heavy metal ions by polyaluminium chloride was researched.There are two aspects research in this paper. One is used aluminum hydroxide Al(OH)3and hydrochloric acid HCl as main raw materials to prepare polyaluminium chloride solution, the other one is used the red mud and hydrochloric acid HCl as main raw materials to prepare inorganic materials water treatment agent.Using aluminum hydroxide Al(OH)3and hydrochloric acid HCl as main raw materials, the basic polyaluminium chloride solution was prepared. We investigate the influences of HCl concentration, the ratio of the quality of Al(OH)3to the volume of HCl, reaction temperature and reaction time on the solubility of Al(OH)3powders. Then the sodium aluminate NaAlO2as regulator of basicity was prepared, in which we analyze the influences of the ratio of aluminum oxide to sodium carbonate and calcination temperature on the synthesis of sodium aluminate. In the last step, polyaluminium chloride solution was prepared by slow titration, and we investigate the influences of different pH and coagulant dosage on the removal of heavy metal ions, simultaneously, the probable chemical compositions and crystallines structure of Al13in polyaluminium chloride was investiged by XRD and FT-IR analysis.The result showed that, basis polyaluminium chloride solution was prepared by Al(OH)3and HCl when the concentration of HC1is20%, the ratio of the quality of Al(OH)3to the volume of HCl is0.6, reaction temperature is80℃and reaction time is3h, and the solubility of Al(OH)3can achieve98.61%. NaA102was prepared at1300℃when the ratio of Al2O3to Na2CO3is1:1. The polyaluminium chloride solution of colorless and transparent was prepared by slow titration of NaA102solution under2500r/min strong agitation, heating at80℃, pH3.5and curing24h. The white or beige polyaluminium chloride solid was got by drying at40℃. The Al13Cl15(OH)24-37.5H2O and its structure were checked by XRD and FT-IR analysis. Finally, the removal efficiency of heavy metal ions for polyaluminium chloride was measured and the good result is71.10%when pH is4-7and the coagulant dosage is between200mg/L and300mg/L.Using the red mud and hydrochloric acid HCl as main raw materials, the inorganic materials water treatment agent was prepared. In this research we investigate the discrepancy of different pretreatment temperature of red mud, the ratio of the quality of red mud to the volume of HCl and the ratio of acid solution to alkali solution on the removal of heavy metal ions, and the probable chemical compositions and crystallines structure in the water treatment agent was also investiged by XRD and FT-IR analysis. The result showed that, the removal efficiency of heavy metal ions when pretreatment temperature of red mud is700℃is better than the removal efficiency when pretreatment temperature is500℃and900℃, the ratio of the quality of red mud to the volume of HCl of1:8is better than1:10and the ratio of acid solution to alkali solution of1:1is better than1:0. We have synthesized the deep yellow water treatment agent, which only can achieve48.84%on the removal of heavy metal ions. The probable chemical compositions and crystallines structure of Al5Cl3(OH)12-7.5H2O was investiged by XRD and FT-IR analysis.