부산대학교 도서관

In the previous paper the co-precipitation process with ferric hydroxide was investigated to remove As contained in waste water.Since fine MnO2powder obtained by electrolysis at lowtemperature was fou nd effective to remove the As ions, the optimum conditions were studied in this paper for both arsenous and arseni c solutions.When the solution containing 10ppm As wastreated with MnO22g/l, the minimum content of As in the solution such as 0.15ppm was reached at pH 2 regardless of As3+or As5+. The As absorbed on MnO2may be leached out by 2N-NaOH solution with a yield of high As content solution and the active MnO 2 applicable tof urther treatment. In the same way the iron precipitate in low As contentand high As solution were obtained by treating the precipitate of ferric hydroxide containing As with 0.5N-NaOH solution.As the co-precipitation process with ferric hydroxide suggested that the better result was expected when As in the solution was oxidized to As5+ion, the oxidizing effect for As3+was studied by using NaOCI and Ca (OCl) 2.