REMOVAL OF HEXAVALENT CHROMIUM FROM TANNERY WASTEWATER USING MAGNETIC RECOVERABLE ZEOLITE: OPTIMIZATION USING RESPONSE SURFACE METHODOLOGY (RSM)

Abstract

A recoverable adsorbent of magnetic natural zeolite has prepared by co-precipitation techniques for enhanced removal of Cr (VI), from aqueous solution. MZ adsorbents prepared by the technique characterized and its performance evaluated for the removal of Cr (VI) from tannery discharge. Furthermore, the effects of different fractions of MP on the adsorption capacity and recoverability of the adsorbents investigated. Medium fraction of MP (33.3%) give a promising adsorption efficiency and recoverability The optimum adsorbent dose, pH, agitation speed and contact time at which maximum Cr (VI) adsorbed from aqueous solution experimentally determined. Finally, the adsorption kinetic that best fits to the maximum adsorption rate as well as the adsorption isothermal model that well describes the adsorption capacity of the adsorbents were determined. In this study, a response surface methodology (RSM) approach using central composite design (CCD) was investigated to develop a mathematical model and to optimize the effects of pH, adsorbent dose, and initial concentration and contact time related to the hexavalent chromium removal by magnetic zeolite (MZ). The highest removal percentage of 93.57% was found by the predicted model under the optimum conditions (pH of 3, 1.6g of MZ, 30 mg/l of Cr (VI) and 60 min of contact time). The maximum percentage of Cr (VI) removal using natural magnetic Zeolite was found 94.88%. The MZ characterized by FTIR, BET, and analyses. Moreover, a Langmuir isotherm fitted well (R2 =0.9966) with the experimental data, and the maximum adsorption capacity was discovered to be 43.859 mg/g. Kinetic data were well foreseen by pseudo second order. In summary, the Cr (VI) removal onto economic, sensitive and selective MZ was optimized using CCD to study MZ behaviors