A study on soil remediation of hexavalent chromium pollution using nano-sized zinc oxide and Miscanthus lutarioriparius

Abstract

Hexavalent chromium (Cr(VI)) pollution poses significant health and ecological risks warranting cost-effective remediation. This study investigated the efficacy of zinc oxide nanoparticles (nZnO) and Miscanthus lutarioriparius synergism for Cr(VI) immobilization and stabilization. nZnO characterized by XRD, SEM-EDS and DLS was amended to 3 mg kg⁻¹ Cr(VI) spiked soil pots at 0.5 % and 1 %. M. lutarioriparius seedlings were then transplanted and grown for 3 months. Results showed increase in residual soil Cr(III) from negligible to 68.9 % upon 1 % nZnO indicating reduction of Cr(VI). Maximum decline of 76.3 % in total Cr(VI) confirmed immobilization. Batch adsorption experiments revealed rising Cr(VI) removal from 61.3 % to 83.7 % by increase in nZnO dose from 0.2 to 1 g L⁻¹. M. lutarioriparius demonstrated hyperaccumulator ability uptaking 208.3 and 156.8 mg kg⁻¹ Cr in roots and shoots respectively. Restricted root-shoot translocation factor of 0.79 aided suitability for phytostabilization. The plant-nZnO synergy enhanced remediation efficiency as confirmed by tolerance index restoration from 38.6 % to 100 %. Increased growth performance reflected mitigation of toxicity by restricted bioavailability. Overall, the nanoremediation strategy displayed high potential for effective in situ stabilization of Cr(VI) contamination combining favorable properties of nZnO and plant tolerance mechanisms.