Biochar supported CuFe layered double hydroxide composite as a sustainable adsorbent for efficient removal of anionic azo dye from water

Abstract This study reports the synthesis of date palm waste-derived biochar (B) supported Cu-Fe layered double hydroxides (CuFe LDH) composite by facile co-precipitation method. The adsorption performance of B-CuFe composite was evaluated for the removal of Eriochrome black T (EBT), as a model anionic azo dye, from the aqueous phase. The B-CuFe composites were characterized by FTIR, XRD, TGA, SEM-EDX and BET technique. Characterization results revealed the synergistic effect of biochar and CuFe-LDH has resulted in substantial improvement in physicochemical characteristics (i.e. surface functionality, surface area and surface morphology) of B-CuFe composite, which promotes rapid and improved adsorption of (EBT) from the solution. The B-CuFe composite with 2.5 g loading of biochar onto CuFe LDH layers showed better adsorption performance than that of other B-CuFe composites The adsorption process of EBT onto B-CuFe composite was well described by the RSM models (with R 2 = 0 .964-0.999). Acidic pH (2-5) and higher temperature favored the adsorption of EBT onto B-CuFe composite, and almost (70%–85%) of EBT was removed from the water within the first 15 min. The highest adsorption capacity, 565.32 mg/g of EBT onto B-CuFe composite, was obtained at pH 2.5 and 45 °C. The adsorption mechanism associated with the strong electrostatic and chemical interactions of EBT sulfonated anions (SO 3 − ) with protonated hydroxyl surface groups (-OH 2 + ) of B-CuFe composite. The B-CuFe composite exhibited better EBT removal in the presence of co-existing anions and demonstrated excellent reusability performance (11 % reduction) after five successive cycles. The results demonstrated that the B-CuFe composite showed great potential as a sustainable and cost-effective adsorbent for the purification of dye contaminated water bodies.