Interaction of mercury with chitin: A physicochemical study of metal binding by a natural biopolymer

Chitin is one of the most abundant polymers in nature, it can be found in the exoskeletons of arthropods and in the cell wall of fungi. Chitin presents multiple applications for medical and industrial purposes. In this study, chitin isolated from waste spider crab shells has been used to analyse its interaction with mercury(II). Characterisation of chitin polymer particles was done by means of FTIR, 13C solid-state NMR, nitrogen adsorption isotherm and SEM/EDS analysis. Batch experiments have been done to analyse factors affecting the metal-polymer interaction process such as time of contact between the chitin and the mercury bearing solution, particle size, pH of the solution and initial metal concentration. Results obtained show that the binding process takes place at moderate rate, in 6-7 h equilibrium conditions are nearly achieved. Particle size influences in the process rate but not in the total metal removal obtained at equilibrium. Results indicate that interaction between mercury and chitin is very strong and irreversible.