Improved adsorption properties of a nano zeolite adsorbent toward toxic nitrophenols

In this study, synthesized nano zeolite (NZ) was applied for the removal of 3 nitrophenol isomers (meta, ortho and para) to evaluate its feasibility as an effective adsorbent. NZ was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), inductively coupled plasma optical emission spectroscopy (ICP-OES) and gas adsorption analysis (BET) methods to determine its basic physicochemical properties. Adsorption experiments were carried out as a function of pH, contact time, adsorbent dose and initial nitrophenols concentration. NZ with greatly improved surface area was particularly effective for the removal of nitrophenols. The adsorption of nitrophenols onto NZ reached equilibrium within 150 min. The maximum adsorption capacities of NZ for meta, ortho and para-nitrophenols were 125.7, 143.8 and 156.7 mg/g, respectively. The adsorption behavior of nitrophenols was fitted better by the Freundlich isotherm than by the Langmuir isotherm. The regeneration characteristics of nitrophenol-loaded NZ were analyzed. Even after 5 cycles of adsorption desorption, the percentage removal of o-, m- and p-nitrophenols were maintained at more than 70% of the initial values. The required adsorption cost for treating 1000 kg wastewater containing 300 mg/L of nitrophenols by using NZ was 46.6% lower than that by activated carbon (AC). Based on these findings, NZ, with its low adsorption cost and high adsorption capacity, can be utilized as a more economic and effective adsorbent for nitrophenols removal. (C) 2016 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.