Synthesis of zeolite-A/Fe₃O₄/biochar composite for removal of Cr(VI) from aqueous solution

Disposal of Cr(VI) into water bodies from industrial effluent has a detrimental effect on human health and aquatic life. To minimize the risks, decreasing of Cr(VI) content via adsorption processes is paramount. In present work, Zeolite-A/Fe₃O₄/Biochar (Z-A/Fe₃O₄/BC) adsorbent was synthesized for the adsorption of Cr(VI) from aqueous solution. The synthesized Z-A/Fe₃O₄/BC composite was characterized using FT-IR, EDX, BET, SEM, and XRD to get information about the functional group, elemental composition, surface area, morphology, and crystallinity, respectively. The batch adsorption of the as-synthesized adsorbent was also tested by optimizing adsorption parameters. The best adsorption capacity (46.93 mg/g) was achieved at 15 mg/L of initial concentration, 0.3 g/L of adsorbent dose, 180 min of contact time, and pH 4. The adsorption isotherm and kinetic are followed the Langmuir and pseudo-second-order models, sequentially. The Z-A/Fe₃O₄/BC adsorbent was also applied for adsorption of Cr(VI) from real sample taken from Batu Tannery PLC and resulted in 99.24 mg/g adsorption capacity from initial concentration of 36.27 mg/L at optimized conditions. Furthermore, the recyclability study was conducted for five successive runs and resulted in 46.93, 42.98, 41.09, 38.435 and 33.76 mg/g adsorption capacity for 1st, 2nd, 3rd, 4th and 5th run, respectively. This suggests that Z-A/Fe₃O₄/BC composite is cost effective and promising for Cr(VI) adsorption that could be applied for practical application.