Abstract:
Attention of the researchers, at present, is deserved by the heavy metal burden on the
mankind and the environment. The issue is specially triggered with continuous
anthropogenic inputs of chemical substances supposed to be rich in heavy metals. In
particular, heavy metals such as cadmium (Cd) and arsenic (As) are considered as one of
the causes of the Chronic Kidney Diseases of uncertain etiology (CKDu) in Sri Lanka.
Consequently, management of such heavy metal inputs to the environment and also
amputation of them are accounting priority area of research. Naturally forming
aquaculture pond waste material (aqua waste) has demonstrated promising adsorption
characteristics adding a value to the waste and reducing the burden of Cd in aqueous
phase at ambient conditions simultaneously. This duality approach showed that under
the optimized conditions of as little contact time and settling time as 30 minutes,
unmodified aqua waste showed 98% removal of Cd from 10 mg dm-3 aqueous solution at
1:20 adsorbent/solution ratio. Amongst different adsorption isotherm models, the
Freundlich model in its linear form depicted validity of the adsorbent- adsorbate (Cd)
adsorption system at equilibrium with a high regression coefficient of 0.933. Such an
adsorption is characterized by non-ideal sorption on heterogeneous surfaces, which
explains multilayer sorption. Thus, the aqua waste exhibits its potential towards real
time applications as an adsorbent for heavy metal Cd from aqueous solutions without
prior modification of the material
