In this study, orange peel (OP) biochar was used as a bio-sorbent for the removal of copper and lead from wastewater in single and binary systems. The equilibrium and kinetic studies were conducted at a pH value of 5, which was the maximum adsorption pH value for both metal ions. The equilibrium studies were investigated at a varying initial concentration (10–200 mg/L) with a constant dosage of 0.1 g, while the kinetic studies were conducted at a fixed initial concentration of 200 mg/L with a constant dosage of 1 g/L for both single and binary systems. The maximum adsorption capacity of the orange peel biochar was 28.06 mg/g, 26.83 mg/g, 30.12 mg/g and 27.71 mg/g for single Cu²⁺, binary Cu²⁺, single Pb²⁺ and binary Pb²⁺ systems, respectively. The Langmuir isotherm model fitted the experimental data, suggesting that adsorption occurred on a monolayer, while the pseudo-second-order model performed well with the kinetic data. The point of zero charge (pH_pzc) of the orange peel biochar was found to be 10.03, which revealed that the surface of the bio-sorbent contains basic groups. A Fourier infrared transform (FTIR) spectroscope and scanning electron microscope, coupled with energy dispersive x-ray (SEM-EDX) and x-ray diffraction analyses, were used to determine the functional groups, surface morphology, and inorganic elements present on the surface of the bio-sorbent, respectively. The results obtained have shown that orange peel biochar is efficient for the removal of Cu²⁺ and Pb²⁺ ions from an aqueous solution.

Heavy metals are toxic substances which are hazardous to plant, animal and human health. The presence of these pollutants in the environment can have adverse effects that can threaten human health if inhaled or absorbed. The bioremediation of heavy metals using fruit wastes offers the application of agricultural wastes and low-cost biomaterial and is eco-friendly for the treatment of wastewater. Fruit peels are promising and sustainable waste material for the effective treatment of wastewater, which support the concept of circular economy and environmental sustainability. This chapter provides an overview of bioremediation of heavy metals while highlighting the application of fruit peels as a promising waste material for effective treatment of wastewater. Given the success of bioremediation using agricultural wastes, the mechanisms involved in the biosorption process are discussed. Challenges and prospects for the efficient application of fruit wastes for the bioremediation of heavy metals are discussed.