Removal of molybdenum and indium from water by chemical coagulation process

• Main Authors: Yi-An Su, 蘇憶安
• Other Authors: Shyh-Fang Kang
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/95281962769512729357

碩士 === 淡江大學 === 水資源及環境工程學系碩士班 === 100 === The Environmental Protection Administration (EPA) Taiwan sets regulated limitation of molybdenum (Mo) and Indium (In) as 0.07 mg/L in 2009. However, researches in removal of Mo and In from drinking water by chemical coagulation process are scarcely reviewed. This study investigated removal of Mo and In by coagulation process. The operational parameters of coagulation are type and dosage of coagulant (ferric chloride, aluminum sulfate and poly aluminum chloride), pH and initial concentration of Mo and In. The results show that in the natural water when pH ranging from 5 to 9, the predominant species of Mo is in dissolved form of MoO42- and In in un-dissolved non-charged form of In(OH)3(aq). The removal efficiency of Mo by different coagulants is following the order of ferric chloride> poly aluminum chloride >aluminum sulfate. The removal efficiency of Mo by aluminum is low (lower than 20%), while removal by ferric chloride could reach more than 75% of efficiency. The amount of Mo been removed by unit mass of ferric is 1.6 to 3.5 times larger than aluminum salt. It is recommended that to use ferric chloride as a coagulant to remove Mo. The optimum pH range to remove Mo by ferric salt is from 4.5 to 6.0. The amount of Mo been removed by unit mass of ferric is 2.8 times larger in pH 5.0 than in pH 7.0. The removal of Mo in unit mass of ferric is higher in higher initial concentration of Mo. The removal efficiency of In by different coagulants is the same. The optimum pH range to remove In by ferric salt and aluminum salt is from 7.0 to 9.0 、 6.0 to 8.0(alum) and 8.0 to 9.0(PACL). The capability of removing In by unit mass of ferric and aluminum are higher in higher initial concentration of In.