In situ fabrication of hierarchical biomass carbon-supported Cu@CuO-Al2O3 composite materials: Synthesis, properties and adsorption applications

Abstract

Hierarchical Cu-Al2O3/biomass-activated carbon composites were successfully prepared by entrapping a biomass-activated carbon powder derived from green algae in the Cu-Al2O3 frame (H-Cu-Al/BC) for the removal of ammonium nitrogen (NH4+-N) from aqueous solutions. The as-synthesized samples were characterized via XRD, SEM, BET and FTIR spectroscopy. The BET specific surface area of the synthesized H-Cu-Al/BC increased from 175.4 m2 g-1 to 302.3 m2 g-1 upon the incorporation of the Cu-Al oxide nanoparticles in the BC surface channels. The experimental data indicated that the adsorption isotherms were well described by the Langmuir equilibrium isotherm equation and the adsorption kinetics of NH4+-N obeyed the pseudo-second-order kinetic model. The static maximum adsorption capacity of NH4+-N on H-Cu-Al/BC was 81.54 mg g-1, which was significantly higher than those of raw BC and H-Al/BC. In addition, the presence of K+, Na+, Ca2+, and Mg2+ ions had no significant impact on the NH4+-N adsorption, but the presence of Al3+ and humic acid (NOM) obviously affected and inhibited the NH4+-N adsorption. The thermodynamic analyses indicated that the adsorption process was endothermic and spontaneous in nature. H-Cu-Al/BC exhibited removal efficiency of more than 80% even after five consecutive cycles according to the recycle studies. These findings suggest that H-Cu-Al/BC can serve as a promising adsorbent for the removal of NH4+-N from aqueous solutions.