Adsorption Technique: A Narrative Review

The adsorption technique is a widely utilized process in environmental and industrial applications for the removal, separation, and purification of substances from liquids or gases. This surface phenomenon involves the accumulation of atoms, ions, or molecules from a fluid phase onto a solid surface, known as the adsorbent. Activated carbon, silica gel, zeolites, and bio-based materials are commonly used adsorbents due to their high surface areas and specific affinity for various adsorbates. Adsorption can be classified into physical adsorption, driven by van der Waals forces, and chemical adsorption, involving stronger covalent or ionic bonding. This technique is extensively applied in wastewater treatment, air purification, gas storage, and catalysis, particularly for removing pollutants like heavy metals, dyes, and volatile organic compounds. Factors influencing adsorption efficiency include temperature, pH, surface area, pore size distribution, and the nature of both the adsorbent and adsorbate. Isotherm models, such as Langmuir and Freundlich, help describe the adsorption behavior and capacity of systems under various conditions. Recent advancements focus on developing novel nanomaterials and bio-adsorbents that enhance adsorption capacity, regeneration ability, and environmental sustainability. The adsorption technique remains a cost-effective, efficient, and versatile method with growing potential in environmental protection and resource recovery, highlighting its continued significance in scientific and industrial sectors.