High specific surface area γ-Al₂O₃ nanoparticles synthesized by facile and low-cost co-precipitation method

Alumina (Al₂O₃) nanoparticles (NPs) are particularly adsorbent NPs with a high specific surface area (SSA) that may well be utilized to clean water. In this study, pure γ-alumina NPs are successfully synthesized by the co-precipitation method, and the effect of ammonium bicarbonate concentration on the synthesized NPs is studied to find the optimum concentration to provide the highest capacity of copper ions removal from water. The results declare that spherical alumina NPs with average diameters in the range of 19-23 nm are formed with different concentrations of precipitation agent, and the concentration has no significant effect on the morphology of NPs. Furthermore, the precipitating agent concentration influences the optical characteristics of the produced alumina NPs, and the bandgap energies of the samples vary between 4.24 and 5.05 eV. The most important impact of precipitating agent concentrations reflects in their SSA and capacity for copper ion removal Ultra-high SSA = 317 m²/g, and the highest copper removal at the adsorbate concentration of 184 mg/L is achieved in an alkalis solution followed by a neutral solution. However, admirable copper removal of 98.2% is even achieved in acidic solutions with 0.9 g/L of the alumina NPs synthesized at a given concentration of ammonium bicarbonate, so this sample can be a good candidate for Cu ions removal from acidic wastewater.