Preparation of Modified Chitin for the Removal of Chromium(VI)

ABSTRACT

Chitin was chemically modified into various forms for enhancing chromium sorption. The modified forms of chitin, viz., protonated chitin (PC), carboxylated chitin (CC), and grafted chitin (GC), possessed enhanced chromium sorption capacities (SCs) of 2812, 3010, and 3770 mg/kg, respectively, than the raw chitin (C), which showed the SC of 2316 mg/kg. The sorption experiments were carried out in batch mode to optimize various influencing parameters, viz., contact time, pH, common ions, and temperature. The sorbents were characterized by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The modified forms of chitin removes chromium by means of electrostatic adsorption coupled reduction and complexation. The adsorption data were fitted with Freundlich and Langmuir isotherms. The calculated values of thermodynamic parameters indicate the nature of chromium sorption. The dynamic studies demonstrated that the sorption process follows pseudo-second-order and intraparticle diffusion models. The suitability of these modified chitin has been tested with field sample collected from a nearby industrial area.

KEYWORDS:

• chitin
• chromium
• isotherm
• kinetics
• sorption

ACKNOWLEDGMENTS

The authors are thankful for the financial support from Defence Research and Development Organization (No.ERIP/ER/0703670/M/01/1066), New Delhi, India.