Removal of eriochrome black T from aqueous solution using coffee husk as bioadsorbent

The eriochrome black T dye belongs to the azo dye class and is often used as an indicator in complexometric titrations and as a fiber dye in industrial processes. It constitutes a direct threat to human health and the environment due to its toxic and carcinogenic nature. Separating this dye from wastewater is essential before its release into water bodies. In this work, the adsorption capacity of eriochrome black T in aqueous solution conferred on the chemically modified or unmodified coffee husk fibers was evaluated. Adsorption experiments were performed in triplicate and batch. The results obtained were adjusted and presented as adsorption isotherms using the Langmuir-Freundlich model. The mass value of adsorbed dye was 483.9 mg ± 17.35 mg and 547.2 mg ± 22.98 mg of eriochrome black T per gram of unmodified and chemically modified coffee husk, respectively, indicating great potential of coffee husk as an adsorbent for the removal of anionic azo dyes in aqueous solution.