18 褐炭による有害重金属の除去(褐炭利用,熱分解ガス,鉱物構造)

抄録

In this study, the influence of experimental conditions (reaction time, solution pH, initial concentration of metallic ion) on ion-exchange properties of Pb^<2+> and Cd^<2+> by an Australian brown coal was investigated. In order to change the cation-exchange properties, brown coal was heated up to 300℃ and the behavior of the cation exchange was also examined. In all samples, the adsorbed amount of metallic ions increased with contact time, after 60 min the amount of M^<2+> adsorbed reached an equilibrium. Moreover, the amount of M^<2+> adsorbed increased with increasing solution pH and initial concentration of M^<2+>. The maximum adsorbed amount of Pb^<2+> and Cd^<2+> from the aqueous solutions at pH 6 was 1.5 and 0.7 mmol/g, respectively. The amount of carboxyl groups in the brown coal decreased by heat-treatment. In the cation-exchange experiment from the solution containing Pb^<2+>, Cd^<2+> and so on, the heat-treated brown coal adsorbed Pb^<2+> preferentially.