Binary Adsorption of Phenol and 2-Chlorophenol on Chitosan Derived from Pink Shrimp Shell

Abstract

The binary adsorption of phenol and 2-chlorophenol in a synthetic industrial wastewater was investigated using extracted optimized chitosan from pink shrimp shell wastes as adsorbent. The effects of operational parameters on the binary adsorption system were studied. The equilibrium adsorption data for the binary system were analyzed using extended Langmuir, extended Sips, extended Redlich-Peterson and Fritz-Schlüender adsorption isotherms. The Fritz-Schlüender isotherm fitted the adsorption data excellently wherein the maximum adsorption capacities for phenol and 2-chlorophenol were obtained as 6.7431 and 14.7493 mg/g respectively for the optimized chitosan at pH=4, adsorbent dose of 1 g, initial concentration of phenol and 2-chlorophenol = 25-250 mg/L, contact time of 120 min, agitation speed of 150 rpm, particle size of 250 microns and temperature of (28 ± 2)°C. The kinetic modelling of the phenol-2-chlorophenol adsorption system showed that pseudo second-order kinetic model gave the best fit amongst the investigated kinetic models. The simultaneous adsorption of phenol and 2-chlorophenol on the prepared adsorbent was chemisorption and film-diffusion controlled. The thermodynamic parameters of the binary adsorption system indicated that the simultaneous adsorption of phenol and 2-chlorophenol on the extracted optimized chitosan was relatively favourable, non-spontaneous, endogenic and exothermic with changes in Gibb’s free energy, G ∆ , positive, entropy, S ∆ , approximately zero (though negative), and enthalpy, H∆, negative.