Virgin volcanic rocks: kinetics and equilibrium studies for the adsorption of cadmium from water.
This study was initiated to investigate the adsorption of cadmium from aqueous solution by two different rock types-Pumice (VPum) and Scoria (VSco), which are readily available in Ethiopia and other countries. The influence of operational conditions, such as particle size, adsorbent/solution ratio, contact time, cadmium initial concentration, and pH was analyzed. The competition between metals was also evaluated. The Cd(II) removal capacity was predominantly affected by the pH conditions, being increased under alkaline conditions. For both adsorbents, when particle size was 0.075-0.425 mm, the maximum Cd(II) adsorption was observed at pH 6.0 (contact time=24h, shaking speed=200 rpm, adsorbent dose=50 g L(-1)). Adsorption process revealed that the initial uptake was very fast during the first 1h. The kinetics of the interactions follows pseudo second-order. Equilibrium assays confirm that VPum has a larger capacity and affinity for Cd(II) adsorption than VSco. Both Langmuir and Freundlich models described equally well the experimental data. VPum and VSco were found to be promising material for the removal of cadmium from metal bearing water.
Institute for Land Use, Rostock University, 18059 Rostock, Germany. esayas16@yahoo.com
Esayas
E
Alemayehu
Bernd
B
Lennartz
D000327:Adsorption; D002104:Cadmium / Q000302:isolation & purification*; D019015:Geologic Sediments; D006863:Hydrogen-Ion Concentration; D010316:Particle Size; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods
D014874:Water Pollutants, Chemical; D002104:Cadmium