Adsorptive removal of p-nitrophenol on microporous activated carbon by FeCl sub(3) activation: equilibrium and kinetics studies

Microporous activated carbon from biomass wastes, date pits, has been utilized as adsorbent for removal of p-nitrophenol (PNPh) from aqueous solutions. The chemical activation with FeCl sub(3) was adopted for preparation and the characteristics of prepared carbon (FAC) represented by iodine number, surface area, micropores volume, and mesopores volume were 761.40 mg/g, 780.06 m super(2)/g, 0.468 cm super(3)/g, and 0.105 cm super(3)/g, respectively. The effect of variables represented by pH, adsorbent dose, contact time, and initial concentration on efficiency of FAC for PNPh removal was studied. Maximum removal efficiency of 94% was obtained at best conditions. Equilibrium adsorption data were analyzed by the Langmuir, Freundlich, and Sips isotherm models. The results showed that the best fit was achieved with the Sips isotherm equation, giving a maximum PNPh adsorption capacity of 184.86 mg/g. The adsorption kinetic data were well described by the pseudo-second-order model and the analysis of data showed that intraparticle diffusion cannot be considered as the rate-limiting step.