Hybridized Co, Mn co-doped ZnO@graphite for photocatalytic degradation of orange G dye: Ecotoxicity and phytotoxicity evaluation

Abstract

This study proposes a novel research investigation into the remediation of orange G dye (acid orange 10) contaminated solution using Co, Mn co-doped ZnO@graphite composite (MC-ZnO/G) material synthesized by a simple hydrothermal route. XRD, FT-IR, EDX, FE-SEM, TEM, BET analysis, UV-Vis DRS spectroscopy and XPS techniques were employed to analyse the physic-chemical characteristics of MC-ZnO/G nanocomposite. MC-ZnO/G shows a higher surface area of 27.4 m2/g than pristine ZnO (12.26 m2/g). Under optimal condition (concentration - 45 ppm, photocatalyst 20 mg and pH - 7), MC-ZnO/G photocatalyst attained a maximum degradation efficiency (MDE) of 97.8 % during 150 min of visible light exposure, whereas pristine ZnO shows a maximum degradation efficiency of 53.5 % only. Furthermore, MC-ZnO/G nanocomposite demonstrated strong stability and reusability, retaining 95.9 % of its stability even after 4 consecutive cycles. The radical studies have been carried out the scavengers, viz., IPA, BQN and EDTA. Under optimal levels, the elimination of OG dye is primarily due to the presence of •OH radicals. The treated effluent was evaluated for its effects on aquatic life, specifically Danio rerio (Zebra fish) by a survival rate of 2 days, and plants, namely Trigonella foenum-graecum (Fenugreek) by a survival rate of 7 days, in order to assess its toxicity.