STUDIES ON DECOLORIZATION OF ORANGE PEEL PECTIN BY USING CORNCOB ACTIVATED CARBON (CAC), KINETICS AND THERMODYNAMICS OF INTERACTIONS

Activated carbon was prepared from the corncob by using phosphoric acid activation and microwave irradiation. Corncob activated carbon (CAC) is a new functional adsorbent, with superior adsorption properties, as the adsorbents for the decolorization of orange peel pectin. Microwave assisted method was investigated for decolorization of orange peel pectin using response surface methodology (RSM). The decolorization rate could reach 70.23% under the optimal conditions for decolorization (i.e., temperature of pectin is 40°C, pH value is 2, microwave time is 60 s, CAC dose is 0.4 g). The equilibrium adsorption data of the pectin pigments from orange peel were analyzed by Langmuir and Freundlich models. Adsorption data were modeled using the pseudo-first-order, pseudo-second-order and intra-particle diffusion kinetics equations. It was shown that pseudo-second-order kinetic equation could best describe the adsorption kinetics. The thermodynamic analysis indicated that the exothermic nature of the adsorption process, which means the adsorption of orange peel pectin by CAC is a type of spontaneous physical adsorption.