Recent Review on Adsorption Techniques for the Removal of Heavy Metals

This paper provides a detailed review of adsorption techniques for the removal of heavy metals from aqueous systems, with particular focus on batch and continuous flow operations. The fundamental concepts of adsorption, including physisorption and chemisorption, are discussed to highlight the interaction between adsorbents and adsorbates. Various adsorbent materials applied to the treatment of heavy metals such as Cr, Cd, Pb, Ni, Co, Cu, and Mn are examined, reflecting the diversity and efficiency of approaches reported in literature. The review compares experimental designs for both batch and column adsorption systems, drawing attention to the distinct operating mechanisms and performance indicators associated with each method. For continuous flow processes, operational parameters such as inlet ion concentration, flow rate, and bed height are evaluated, while batch systems are analyzed in terms of contact time, pH, temperature, and adsorbent dosage. In addition, adsorption isotherm and kinetic models relevant to both systems are reviewed, offering insights into mechanistic understanding and predictive capabilities. The paper further highlights practical challenges that hinder large-scale application, including adsorbent regeneration, process cost, and system design limitations. By consolidating current knowledge, this review underscores the potential of adsorption as a viable technique for heavy metal removal while identifying research gaps and future directions necessary for advancing its practical implementation in water treatment.