Simultaneous Removal of Eriochrome Black T and Chromate Anions from Aqueous Solution Using Functionalized Hybrid Magnetic Polymers

Textile wastewater containing heavy metal ions has become a severe environmental problem worldwide. The combined uptake of heavy metals and dyes from wastewater discharged by different sectors is a challenging concept. This study explores the use of hybrid adsorbent based on magnetic chitosan (MC) and magnetic poly glycidyl methacrylate (Mp(GMA)) in adsorption technology, for simultaneous removal of Eriochrome Black T (EBT) dye and chromate anions from their binary aqueous solution. The adsorbent material was functionalized by loading diethylenetriamine (DETA) or dithizone to improve their adsorption capacity (R-DETA or R-Dithizone). The physicochemical characteristics of the materials have been characterized by a wide variety of analytical techniques. Pseudo-second order kinetic model and Langmuir adsorption isotherms were the best-fit models in the binary adsorption system. The co-presence of these anions in the binary solution increases the adsorption capacity of chromate and diminishes the EBT adsorption capacity of the investigated adsorbents (R-DETA and R-Dithizone). The adsorption capacity at monolayer saturation capacities (Langmuir) of R-DETA in binary system were 0.782 and 4.11 mmol g⁻¹ towards EBT and chromate anions respectively, while R-Dithizone adsorbent recorded lower monolayer sorption capacity for EBT (0.490 mmol g⁻¹ ) and higher sorption capacity for chromate 5.93 mmol Cr(VI) g⁻¹ in the binary solution. The effects of competitive anions Cl⁻, NO₃⁻, SO₄²⁻, and MnO₄⁻ on the adsorption of EBT and chromate anions in their binary mixture were examined. The good sorption ability of EBT and Cr(VI) anions against ionic interference supported their use in wastewater treatment applications. NaOH (0.5 M) proved the most effective for desorption from their binary mixture.

Graphical abstract