Adsorption Kinetics, Equilibrium, and Thermodynamics of Copper From Aqueous Solutions using Silicon Carbide Derived from Rice Waste

Abstract

Adsorption of Cu (II) from aqueous solution on a novel adsorbent, silicon carbide ash (SiC ash) was studied using batch technique. The adsorbent was prepared by pyrolysis of Egyptian rice waste (rice straw and rice husk) and was characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDAX), Fourier transform infra-red spectroscopy (FTIR), x-ray diffraction (XRD) and surface area analysis by BET. The influence of pH, contact time, initial Cu(II) concentration, adsorbent dose, agitation speed and temperature was investigated. Adsorption kinetics was analyzed using the pseudo first order, the pseudo second order and intra particular diffusion model. The adsorption process was found to follow a pseudo second order rate mechanism. The adsorption isotherm data could be well described by the Langmuir and Freundlich than DubininRadushkevich adsorption model. The adsorption capacity of 22.06 mg/g for SiC ash was obtained at pH =5 and temperature of 298 K. Thermodynamic parameters, change in the free energy (∆G°), the enthalpy (∆H°), and the entropy (∆S°)) were also calculated. The overall adsorption process was exothermic, spontaneous in nature and proceeds with decreased randomness as the entropy is negative value. Adsorption process was successfully applied to remove Cu(II) from an industrial waste water sample. Downloaded by [Stockholm University Library] at 07:25 24 August 2015 2

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