Adsorption of cadmium (II) by chitin

The feasibility of using chitin as an adsorbent for cadmium (ii) was examined. the adsorption characteristics were studied as a function of solution ph,temperature,contact time et. al.,maximum uptake amount of cadmium (ii) was estimated to 93.9 mg/g · chitin by saturated capacity method at ph 5.41 in the hac-naac system. the isotherm data for cadmium (ii) at ph 5.41 fitted well to a langmuir equation with a sorption capacity of 94.3 mg/g · chitin which was in accordance with the maximum uptake amount by means of the saturation method. the apparent adsorption rate constant was k288k = 3.34×10-5s-1,k298k= 4.60×10 -5s-1,k308k= 635×10-5s -1 and k318k= 9.89×10-5s-1. the apparent activation energy was 63.1 kj/mol,thermodynamic parameters,δ298k was calculated to be -19.5 kj/mol,δh and δs were found to be 10.6 kj/mol and 101 j/mol·k,respectively. adsorption mechanism was also proposed using infrared spectroscopy technique (ir).