Heterojunction CuO thin coated CaO drived from eggshell waste for fast removal of organic pollutants from water under visible light

Abstract

The conversion of food and agro-industrial wastes to produce useful products is one of the goals of economic and sustainable development, as also evidenced in the 2030 Agenda for Sustainable Development, adopted by all United Nations Member States in 2015. This work aims to study the transformation of CaCO3 based eggshell waste (ES) into a face centered cubic oxide form (namely, CaO), followed by CuO coating to be used as photocatalytic material (ES@CuO) for fast removal of basic fuchsin (BF) dye from water under visible light. Different ES@CuO samples with different CuO amounts (2.5, 5 and 10%, respectively) and calcined at different temperatures (600, 800, and 1000 °C) were prepared by hydrothermal method. Samples with CuO from medium to high amounts (5 and 10%) demonstrated excellent photocatalytic activity, as compared to low CuO amount (2.5%). In addition, the samples calcined at higher temperature (800 and 1000 °C) exhibited superior degradation rates, reaching 88.11% and 88.33%, respectively. The effect of operating parameters was investigated to understand the behavior of ES@CuO under different conditions. ES@CuO shows rapid removal of BF which combines adsorption and photooxidation, wherein the removal rate reaches up 99% for a BF dye concentration of 100 ppm within 30 min using 75 mg/L of ES@CuO5%. ES@CuO exhibits superior adsorption ability and excellent photoproduced charges transfer which provide synergistic effects to boost the quick removal of dye from water. The finding of this investigation encourages valorizing food wastes into sustainable materials for water remediation. Graphical abstract