Waste spider crab shell and derived chitin as low-cost materials for cadmium and lead removal

Crab shell and inexpensive chitin obtained from it have been studied to determine their capability to remove cadmium and lead from aqueous solutions. Factors affecting the process such as pH, metal concentration, time and temperature have been critically analysed. Results show that only cadmium uptake on crab shell is strongly influenced by the pH of the solution. The crab shell was also found to be more efficient. Equilibrium data analysis using the Langmuir isotherm indicates that crab shell can remove at least 1.4 mmol of metal per gram of sorbent at optimum pH. Temperature studies for metal sorption on chitin showed that the effect of temperature is very small for both the kinetic constant of the sorption process and for maximum uptake. (c) 2006 Society of Chemical Industry