Biosorption of cadmium from aqueous solution by shell dust of the freshwater snail Lymnaea luteola

• Biosorption of cadmium by shell dust of L. luteola (LSD) was evaluated under laboratory condition.
• Biosorption maxima of LSD was 20.00 mg/g, which fitted to Langmuir and Freundlich equations.
• Biosorption kinetics fitted to pseudo-second order and Lagergren models.
• FTIR and EDX analyses indicate ion exchange involving different functional groups.
• LSD can be considered as low cost biosorbent for cadmium removal.

An assessment of the metal biosorption potential of shell dust of the freshwater snail (Lymnaea luteola) was made using cadmium as model metal. Artificial Neural Network (ANN) model was constructed for portraying the biosorption process under varied conditions. Under optimal conditions, the shell dust of L. luteola (LSD) exhibited a biosorption capacity of 20.00 mg g−1 at pH 6. The adsorption data at equilibrium fitted significantly more to Langmuir (R2=0.997R2=0.997) than Freundlich equation (R2=0.790R2=0.790). The kinetics for the biosorption process followed the pseudo-second order model (R2=0.998R2=0.998) better than the Lagergren model (R2=0.835R2=0.835). Confirmation of cadmium adsorption by LSD was further revealed through EDX studies, and the experimental results fitted well with the predicted pattern of biosorption based on ANN model (R2=0.924R2=0.924). It appears that shell dust of the snail L. luteola (LSD), a waste biomaterial, can be used as a low cost and environment friendly biosorbent for cadmium removal from aqueous solution.

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