Detoxification of cadmium from industrial effluents using solid waste generated after sea nodule processing

Abstract

This paper deals with studies on the utilization of a solid waste generated during the recovery of copper, nickel and cobalt form polymetallic manganese nodules from Indian ocean, for the detoxification of industrial effluents/waste waters from cadmium for its safe disposal to the river or land. The influence of various parameters such as contact time, solution pH, and initial metal concentration in solution, temperature and adsorbent quantity, on cadmium removal were studied. The linear forms of the Langmuir and Freundlich equations were utilized for experiments with metal concentrations of 200mg/l for Cd(II) as functions of solution pH (2.0-6.0). First order rate equation and pseudo second order rate equations were applied to study adsorption kinetics. The adsorption capacity of sea nodule residue(SNR) was found to be 19.8mg of Cd/g of SNR. Under the optimized conditions cadmium level was brought down from 100ppm to nil and 200ppm to 2ppm making wastewater safe for disposal. Desorption studies were also performed to see the elution of cadmium from the loaded adsorbent from the point of view of its recycling/safe disposal with or without treatment.