Removal of Cadmium from Polluted Aqueous Solutions Using Agricultural Wastes

Abstract

Heavy metals are among the most toxic contaminants of surface water. The main sources of heavy metals are industrial wastes from processes such as electroplating, metal finishing, chemical manufacturing, and nuclear fuel processing. Since most of heavy metals are non degradable, these concentration must be reduced to acceptable levels before discharging them into environment. The goal of this research is to examine the ability of different media to reduce the concentration of cadmium ions in aqueous solution. The application of low-cost adsorbents obtained from plant wastes as a replacement for costly conventional methods of removing cadmium ions from wastewater has been reviewed. Langmuir and Freundlich adsorption isotherms found to be applicable to the absorption process and their constants are found. The single component adsorption of heavy metal ions named Cadmium (II) onto powdered activated carbon (PAC), palms karab, rice husks and corncobs from water aqueous solution has been investigated using batch system. In batch tests, the effects of pH, dosage of adsorbent, contact time, initial concentration, mixing (stirring) speed and particle size diameter are studied. The optimum values of pH is 5.5, dosage adsorbent is 1g sorbent/100ml of Cd (II), contact time is 30min, initial concentration is 125 mg/L and for mixing (stirring) speed is 100 rpm.