Advancing the development of nanocomposite adsorbent through zinc-doped nickel ferrite-pinecone biochar for removal of chromium (VI) from wastewater

Abstract

Leather and textile industrial effluents are the main disseminating routes for chromium contamination of water bodies, causing adverse impacts on public and environmental health. The attempt to remediate chromium through conventional wastewater treatment methods is inefficient. Therefore, this study aims to synthesize zinc-doped nickel ferrite pinecone biochar (Zn-NiF@PBC) nanocomposite for the removal of chromium from wastewater systems. The Zn-NiF@PBC nanocomposite was synthesized via the co-precipitation method. The properties of zinc-doped nickel ferrite (Zn-NiF) were effectively modified by blending with biochar at 1, 5, 10, and 15 % (w/w) which was successfully embedded with Zn-Ni ferrite nanoparticles. This was characterized and confirmed by typical adsorbent properties such as a high surface area of 104 m²/g, conducive pore volume of 0.117 cm³/g and pore size of 3.41 nm (BET), interactive multi-functional groups (FTIR), surface charge determination (pH_pzc,), crystalline structure (XRD) and very rough surface morphology (SEM). The maximum chromium adsorption was found to be 95 % at the specific experimental condition of pH 3, adsorbent dose 1 g/50 mL, contact time 120 min, and initial chromium concentration 100 mg/L. The adsorption experimental data was best fitted with the Langmuir isotherm at R² 0.98 indicating the adsorption process was homogeneous and monolayer whereas the kinetics adsorption was resembling the second-order kinetic at R² 0.99. Moreover, the adsorption thermodynamics was spontaneous, endothermic, and increased the change in entropy. Finally, the regeneration of Zn-NiF@PBC was found to be effective up to five 5 cycles but gradually degrading in terms of removal efficiency after 3 cycles. In general, Zn-NiF@PBC can remediate chromium from wastewater with huge potential for scale-up and extend to other pollutants clear-up.