The Research Of Arsenic Removal By Ferric Chloride And The Mechanism

There are many arsenic containing compounds getting into the water environmentthrough natural and man-made pathway. Most of the arsenic containing compounds inwater are inorganic and toxic. Drinking high-arsenic water for a long period willseriously affect the health of human beings. Therefore it’s very important to study theremoval of inorganic arsenic, its influencing factors and mechanism.In this paper, zeta potential and the removal rate of arsenite and arsenate afterprecipitation and filtering in the pH range from5to10were investigated. Themechanism of arsenic removal by coagulating process of ferric chloride was analyzed.The influences on the effect of coagulation in the presence of background solutionsodium chloride from1mM to10mM, calcium hydroxide50mg/L, or magnesiumchloride64.31mg/L were compared and analyzed.First of all, this paper studied the detection method of determination of arseniccontent by high performance liquid chromatorgraphy. Through many experiments,20mM NH4H2PO4solution (when its pH value was6.0) and methanol solution wereused as mobile phase of HPLC-ICP-MS. Arsenite and arsenate were separated wellwhen the mobile phase ratio was97%:3%.The results show that the zeta potential increased first and then decreased, theisoelectric point was reached when pH ranged from7to8; and that the removal rate ofarsenite increased in high pH, but it decreased in low pH, arsenate was just the opposite.If calcium ions and magnesium ions were added into the solution, the zeta potentialdecreased but the removal rate of arsenate increased under alkaline conditions, while theremoval rate of arsenite was not affected. The arsenic removal rate was highest whenthe solution’s pH value was9and metal ions were added into the solution.