Excellent adsorptive-photocatalytic performance of zinc oxide and biomass derived N, O-contained biochar nanocomposites for dyes and antibiotic removal

Designing and constructing low cost, environmental, and efficient photocatalysts is essential to remove the organic pollutants in wastewater. In this work, two series of nanocomposites containing zinc oxide and N, O-contained biochar (ZnO/NOC) were smartly fabricated by using biomass peanut shell as carbon source and template, zinc nitrate as Zn source, and ethanol as solvent. Calcination temperature and mass ratio of biomass to ZnO were optimized to be 700 °C and 0.3. As expected, the optimal ZnO/NOC nanocomposite shows an excellent adsorptive and UV/Vis-photocatalytic performance in the removal of diverse pollutants. Particularly, the photocatalytic activities of ZnO/NOC are 3.5 and 20.5 times higher than pure ZnO for methylene blue degradation (10 mg/L) under ultraviolet and visible lights, respectively. Also, the removal efficiencies of ZnO/NOC for antibiotic (30 mg/L) under the same conditions are 5.4 and 7.7 times higher than pure ZnO. The excellent performance is mainly ascribed to large surface area, ample and proper size pore, fast charges transfer, large density and long lifetime of photogenerated charges, and strong interactions between ZnO and N, O-contained biochar, and so on. And Vis-photocatalytic mechanism was proposed.