Performance evaluation of sustainable adsorbents for heavy metal removal from municipal landfill leachate: batch...

To address the high cost of high-performance treated adsorbents, this study investigates a sustainable, environmentally friendly removal method. This study investigates the efficacy of readily available, low-cost raw adsorbents-specifically biochar, Fly ash, and bagasse ash-for the removal of heavy metal ions (Cr, Cu, Fe & Zn) from municipal landfill leachate. The influence of pH, dosage, and contact time on adsorption efficiency was determined through batch experiments. To determine the best-fitting kinetic model (Pseudo-First-Order-PFO, or Pseudo-Second-Order-PSO, Webber & Morris Intraparticle diffusion or Elovich), four error functions- the sum of the square of the errors (ERRSQ), the hybrid fractional error function (HYBRID), average relative error deviation (ARE), and the sum of the absolute errors (EABS)- were calculated and subsequently normalized using the Set of Normalized Errors (SNE) method. The kinetic model with the lowest SNE value was found to provide the best statistical fit to the experimental data. Adsorption kinetics for biochar showed PFO for Cr, Cu, and Zn, and PSO for Fe. Fly ash followed PFO for Fe and Zn, and PSO for Cr and Cu. Bagasse ash kinetics showed PFO for Cr and PSO for Cu, Fe, and Zn. The maximum adsorption removal efficiencies for Cr, Cu, Fe, and Zn obtained were 82%,54%, 72% & 62% for biochar, 77%, 50%, 62%, 64% for Fly ash, and 87%, 42%, 79%, 72% for bagasse ash. These findings demonstrate that low-cost, waste-derived adsorbents can effectively remove heavy metals from complex solutions, such as landfill leachate, with high efficiency. This research not only provides a sustainable solution for wastewater treatment but also supports a circular economy by transforming agricultural and industrial waste into valuable resources for pollution control.