Cadmium removal from aqueous solution using nano/milli-sized particles of cedar leaf ash

Heavy metals in water resources are one of the important environmental problems. These metals have hazardous effects on human health. This study was conducted to investigate the comparison between adsorption of cadmium from aqueous solution using nano/milli-sized adsorbents of cedar leaf ash by batch experiments and with variation of impressive parameters such as pH, contact time, and adsorbent amount. The results showed, the optimum pH of adsorption was 5. Adsorption equilibrium times for nano/milli-sized adsorbents were obtained in 30 and 45min, respectively. With increasing the amount of milli-sized adsorbent, adsorption efficiency increased but increasing of nanosized adsorbent at first, caused the increase in adsorption efficiency and then adsorption efficiency decreased because of clogging phenomenon of adsorbent in aqueous solution. The experimental data were analyzed using two isotherm models (Langmuir and Freundlich) and two kinetic models (pseudo-first-order and pseudo-second-order). Based on the results, adsorption of cadmium followed from the models of pseudo-second-order kinetic and Langmuir isotherm well. Adsorption capacity of nanosized adsorbent was about two times more than adsorption capacity of milli-sized adsorbent. This case indicated the high ability of nanoparticles in adsorption of cadmium from aqueous solution.