Preparation and characterization of ternary Cu/Cu2O/C composite: An extraordinary adsorbent for removing anionic organic dyes from water

Abstract

To find an expeditious adsorbent for removing residual organic dyes is an urgent task, because the protection of water resource does not permit of any delay. In this work, the ternary Cu/Cu2O/C composite with ultrahigh anionic dyes adsorption capacity was synthesized by a simple solvent-free method. The crystalline structure, chemical composition and adsorption feature of the Cu/Cu2O/C composite were systematically studied. The maximum monolayer adsorption capacity of Cu/Cu2O/C for methyl orange (MO) and acid blue 93 (AB93) is 1408.7 and 5385 mg g−1, respectively. Besides, the Cu/Cu2O/C composite can selectively adsorb anionic dyes from mixture of different dyes. A soaking process of hot water can easily release the loaded anionic dyes, and the adsorption capacity of invalid Cu/Cu2O/C composite can be recovered by a baking process. The equilibrium and kinetic studies indicate that the adsorption process is consistent with the Langmuir isotherm theory and pseudo-second-order model. The thermodynamics parameters (ΔG°, ΔH° and ΔS°) show that the adsorption process is spontaneous and exothermic in nature. Based on the experimental data and the characterization of Cu/Cu2O/C composite, it can conclude that the physical and chemical synergism effect co-exist in adsorption process, and chemisorption is the main rate limiting step. The excellent adsorption ability of Cu/Cu2O/C composite is mainly attributed to the interaction between sulfonic group and Cu (Cu0 or Cu1+). This work may shed light on developing high adsorption capacity of adsorbent for toxic organic pollutants removal and some special anion separation.