Preparation of activated carbon derived from cotton linter fibers by fused NaOH activation and its application for oxytetracycline (OTC) adsorption

► Fused NaOH activation is used to prepare cotton linter-based activated carbon. ► Activated carbon from cotton linter fibers had a large surface area of 2143 m2/g. ► Carbon from cotton linter fibers had a predominantly microporous structure. ► Competitive adsorption took place in the weakly acidic to neutral conditions. ► Strong acid or strong basic hindered the adsorption by electrostatic repulsion.