Lead contamination in wastewater presents a major environmental and public health concern due to its toxicity, persistence, and non-biodegradable nature. Although conventional treatment methods such as chemical precipitation and membrane filtration are commonly used, they often come with drawbacks including high operational costs, energy demands, and secondary pollution. As a sustainable alternative, this study investigates the potential of Azolla, an aquatic macrophyte, as a low-cost and eco-friendly bio-adsorbent for lead removal from contaminated water. The Azolla biomass was pre-treated with hydrochloric acid for five hours to improve its surface area and activate functional groups. Its lignocellulosic structure, rich in hydroxyl and carboxyl groups, supports effective lead adsorption via complexation and ion exchange mechanisms. A 2-Level Factorial Design was used to optimize key adsorption parameters including pH, contact time, and initial lead concentration. The highest removal efficiency of 93.69% was achieved at pH 10, a lead concentration of 250 ppm, and a contact time of 10 minutes. Adsorption isotherm analysis indicated that the process followed the Freundlich isotherm model, suggesting multilayer adsorption on a heterogeneous surface with multiple binding sites. These findings demonstrate the effectiveness of Azolla as a promising bio-adsorbent for lead removal. Further research is recommended to explore its long-term performance and scalability for industrial wastewater treatment applications
Supian et al. (Sun,) studied this question.