Enhanced selective adsorption ability of Cu2O nanoparticles for anionic dye by sulfur incorporation

Cu2O-based materials are potential adsorbents for the removal of anionic dyes pollutions. Herein, sulfur incorporation is designed to promote adsorption capacity of Cu2O. A series of sulfur-incorporated Cu2O nanomaterials are synthesized by a facile chemical reduction method. Sulfur incorporation favors the formation of small sized S-Cu2O particles in the range of 50–100 nm and their enhanced adsorption performances. The S-Cu2O particles show good adsorption activities for methyl orange solution (75–500 mg L−1) under pH 6–10 at room temperature. A superior adsorption capacity of 1485.24 mg g−1 for the removal of methyl orange is achieved on the S-Cu2O adsorbent. Adsorption behaviors of the S-Cu2O adsorbent fit well with Langmuir isotherm and pseudo-second-order kinetic model. Adsorption thermodynamic results indicate the exothermic and spontaneous adsorption process. Anionic dye can be adsorbed selectively on the S-Cu2O adsorbent and separated from cationic dyes. Density functional theory calculations prove a pronounced electron accumulation on sulfur sites, benefiting to the adsorption on S-Cu2O. A nonmetallic element incorporation for improving adsorption capacity of metal oxide adsorbents is provided as a promising strategy for other adsorbents.