Modified nanocrystalline natural zeolite for adsorption of arsenate from wastewater: Isotherm and kinetic studies

This work investigates the efficiency and possibility of modified nanoscale zeolite with baloform for removing of arsenate anions from wastewaters. A combination of scanning electron microscopy, X-ray diffraction, Fourier transform-infrared spectroscopy, Thermogravimetric-differential thermal analysis and Brunauer-Emmett-Teller surface area were used for characterization of zeolitic materials. Effects of different parameters such as pH and dosage of adsorbent, on the arsenate removing yield are studied. The yield of arsenate removing increases by increasing dosage of adsorbent and contact time. The results show that arsenate removal efficiency from wastewaters is higher than 99% at optimum conditions. The adsorption data of the modified zeolite for arsenate removing was consistent with six isotherm equations (Freundlich, Langmuir, Langmuir-Freundlich, Dubinin-Radushkevich, Redlich-Peterson and Toth). The obtained modeling results indicated that, although the three-parameter models, taking into account the surface heterogeneity, provided the closest approach to the measurement data, the parameters estimates could be highly biased. Batch experiments were carried out to study the removal kinetics of arsenate. The kinetic studies proved that the Elovich was the applicable model. (C) 2014 Elsevier Inc. All rights reserved.