Sorption of Zn(II) ion onto the surface of activated carbon derived from eucalyptus bark saw dust from industrial wastewater: Isotherm, kinetics, mechanistic modeling, and thermodynamics

Abstract

The activated carbon was derived from base (0.2 M NaOH)-mediated activation of biomass followed by thermal treatment at 1,123 K. The utmost metal ion uptake capacity and sorption percentage of activated carbon derived from eucalyptus biomass were 1.42 mmol g-1 and 93.42%, respectively. Freundlich isotherm model proved to be superior with higher linear correlation coefficient R2 = 0.96-0.98. Similarly, it was observed that pseudo-second-order reaction model with lower ?2 (0.002703-0.009351) and sum of square errors (0.0001-0.0144) value together with higher R2 (0.98-0.99) ruled in all the possibilities of sorption of Zn(II) ion on activated carbon surface as chemisorption. Bangham's model (R2 = 0.93-0.95) applicability in the present investigation demarcated the fact that the main rate-controlling step in the sorption of Zn(II) ions on activated carbon surface was film diffusion rather than intraparticle diffusion. The results of diffusivity coefficients (Df = 7.16 × 10-6 cm2 s-1) reproduced the analogous viewpoint that film diffusion is quite a dominant step in the biosorption of Zn(II). ?G, ?H, and ?S values obtained through the thermodynamic study of Zn(II) biosorption system were-9798 kJ mol-1, -34.74 kJ mol-1, and -107.63 kJ mol-1 K-1, respectively. © 2012 Desalination Publications. All rights reserved.