Insights into Pb (II) adsorption mechanisms using jackfruit peel biochar activated by a hydrothermal method toward heavy metal removal from wastewater

Understanding adsorption mechanisms plays an instrumental role in designing and operating adsorpiton-based wastewater treatment systems. This research systematically demonstrated the comprehensive adsorption mechanism of Pb(II) ions onto biochar synthesized from jackfruit peel in an aqueous solution using theoretical adsorption models and cutting-edge analytical techniques, such as FT-IR, TG-DSC, and EDX. The results showed that the adsorption process followed the Redlich-Peterson isothermal model and the intraparticle diffusion kinetic model under optimized conditions. The key mechanisms contributing to effective Pb(II) adsorption include complexation, ion - exchange, and intradiffusion. Furthermore, using the hydrothermal method to active biochar improves the surface area of JPT, leading to the maximum Pb(II) adsorption capacity of jackfruit peel-derived biochar to be 83.86 mg/g, higher than biochars from other parts of jackfruit waste (seeds and stems) and some materials from different agricultural residues in previous studies. These findings contribute to narrowing the gap in understanding heavy metal adsorption using biomass residues, theoretical models, and their mechanisms. Additionally, these indicate that agricultural by-products such as jackfruit peel are environmentally friendly and economical materials for implementing strategies aimed at mitigating heavy metal pollution in wastewater. • Utilizing agricultural by-products as an economical and environmental material. • The specific surface area of the adsorbent was improved roughly 19 times. • The biochar exhibits a high adsorption capacity for Pb(II) ions (83.86 mg/g). • Kinetic and isothermal models with two and three parameters were analyzed. • The comprehensive adsorption mechanism of Pb(II) ions onto biochar was explored.