MJCat 1-2016-7

Competitive adsorption of metals on volcanic ash active sites from multi-metal solutions

Merapi Volcanic Ash (MVA) was used to study the competitive adsorption of several metal cations (Cu2+,Zn2+, Cd2+, Pb2+ and Hg2+) from multi-metal ions solution within various experimental conditions. The properties of adsorbent were characterized with XRD, FESEM-EDX and FT-IR. The influence of pre-treatment condition, contact time, pH of solution, adsorbent dosage, initial metal concentration and temperature on multi-metals adsorption were investigated. The characterization results showed that the MVA exhibited the presence of aluminate, quarts and maghematite. The maximum adsorption capacities for all metal ions were observed at pH 6 and adsorbent dosage of 0.1 g L-1. The adsorption reached equilibrium within 120 minutes. Adsorption equilibrium study showed that Freundlich isotherm model fitted very well with the Zn, Pb, Cd and Cu while adsorption on Hg was best fitted with Langmuir isotherm model. The kinetic of adsorption on multi-metal ions were best described by pseudo-second order kinetic model. The thermodynamic properties confirmed that the adsorption of multi-metal ions onto MVA was spontaneous and endothermic in nature. The activation energy, Ea of the adsorption process showed that it was a chemisorption process. The results showed that MVA could be used as a low-cost material for the adsorption of multi-metals in water treatment.