Detoxification of hexavalent chromium using hydrothermally modified agricultural detritus into mesoporous zeolitic materials

• BFA was converted into zeolitic materials with and without electrolyte.
• The synthesized zeolitic materials are mesoporous in nature.
• ECZBFA sorbent shows higher uptake capacity for hexavalent chromium toxic metal.
• The Langmuir isotherm was found to be best fitted model.
• The sorption was physisorption and endothermic in nature.

The present study reports the removal of hexavalent chromium by bagasse fly ash (BFA) – an agricultural detritus and synthesized modified zeolitic materials. The native BFA was successfully converted into mesoporous zeolitic materials with (ECZBFA) and without electrolyte (CZBFA) media using hydrothermal treatment. The proximate analysis and physicochemical analysis were determined by wet analysis methods. The instrumental techniques like XRF, FTIR and SEM were used to determine the chemical composition of sorbents, functional groups and its surface morphology, respectively. The optimum pH, contact time, sorbent dose, initial concentration of Cr(VI) and effect of temperature on sorption were investigated thoroughly to optimize the uptake condition. Pseudo second order model and diffusion models like film diffusion and pore diffusion models were well characterized for Cr(VI) sorption on sorbent. Langmuir, Freundlich, Dubinin–Redushkwich and Temkin isotherm were used to understand the efficiency of zeolitic materials and its nature of sorption. Out of the three mesoporous sorbents ECZBFA shows better uptake capacity of Cr(VI) than that of CZBFA and BFA. The uptake of Cr(VI) was studied by batch and column method.

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