Life cycle assessment, kinetic, and isothermic studies of grape stalks for Zn(II) biosorption: From waste to resource

Abstract

This study investigates the application of grape stalks, a byproduct of winemaking, as an effective biosorbent for removing zinc ions from water. The research addresses the challenges of heavy metal contamination while promoting sustainable waste management. Optimization of the biosorption process was conducted using a Box-Behnken design within the framework of Response Surface Methodology, focusing on the influence of variables such as biosorbent dosage, pH, contact time, and initial Zn(II) concentration. The experimental results demonstrated that optimal biosorption efficiency (up to 99.38 %) was achieved at pH 8 and higher dosages of biosorbent. Adsorption kinetics aligned closely with the pseudo-second-order model, suggesting chemisorption as the governing mechanism. The equilibrium data fits well with the Langmuir isotherm, revealing a maximum adsorption capacity of 238.1 mg/g. A Life Cycle Assessment highlighted the environmental trade-offs, favoring a scenario that balanced high Zn(II) removal efficiency with lower resource consumption. The findings demonstrate the viability of grape stalks as an eco-friendly and cost-effective solution for zinc ion remediation, supporting circular economy principles in the wine industry and promoting advancements in sustainable wastewater treatment.