Utilization of Lemon Peel Adsorbent for Efficient Nickel Removal from Synthetic Wastewater

Abstract

Heavy metals in water are considered pollutants and represent a worldwide environmental issue. Common heavy metal ions with high toxicity and carcinogenicity, such as nickel, are often found in contaminated water. The increasing presence of human-made sources of nickel, introduced into water bodies through industrial discharge, agricultural runoff, and wastewater treatment plants, as well as natural sources, underscores the importance of removing nickel from water before consumption. Adsorption is a widely used method for removing nickel ions from contaminated water. Different adsorbents have been produced from waste of various materials and applied to eliminate nickel ions. In this study, natural biosorbent was prepared using lemon peel to remove nickel ions from simulated wastewater in a batch reactor mode. Various parameters influencing the adsorption process of the current study were examined. These parameters involved the application of a pH value range of 2 to 7, a contact time range of 30 to 120 minutes, and an adsorbent mass range of 0.25 g to 3 g per 100 mL, with a constant initial concentration of nickel (II). Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to analyze and evaluate the surface and the functional groups of the raw and used adsorbent. Significant changes in the surface morphology of the used adsorbent were observed, indicating high adsorption of nickel ions. The influence of the temperature on the adsorption process was also investigated. The results elucidated that increasing the temperature enhanced the nickel (II) removal percentage, suggesting that the process is endothermic. Moreover, different isotherm models and kinetic parameters, such as Langmuir and Freundlich, were used to further describe the adsorption characteristics of the biosorbent. Overall, the results indicate that lemon peel shows significant potential as a low-cost biosorbent for removing nickel (II) ions.