This cluster of papers focuses on the adsorption of contaminants in water and wastewater, with a specific emphasis on surface area evaluation, pore size distribution, biochar as a sorbent, removal of heavy metals and dyes, use of nanomaterials, and biosorption techniques. The papers cover various aspects of adsorption kinetics, isotherm models, low-cost adsorbents, and the application of different materials for efficient water treatment.