Application of Nano-Al2O3 Powder for Removal of Hexavalent Chromium from Aqueous Solutions

Background & Objectives: Pollution due to heavy metals is one of the most serious environmental problems nowadays. Extensive application of Cr (VI) leads to discharge a large amount of chromium containing wastewater into the environment. The aim of this research was evaluation of alumina nanoparticles efficiency to remove chromium (VI) from aqueous solutions through adsorption. Methods: This fundamental and practical study was performed in batch conditions and room-temperature. The structure of the sorbent was characterized by TEM technique. Residual concentrations of Cr (VI) were measured by a spectrophotometer at 540nm. Effects of the process parameters such as Al2O3 loading (0.5–2 g/L), contact time (5-90 min), and pH (5-9) were investigated. Results: The results showed that removal efficiency of Cr (VI) increase with increasing of contact time and pH. The optimum pH was found to be 5 with decreasing of removal efficiency afterward. The value of qm (mg/L) in this work was 30.3 for each gram of nano-alumina adsorbent. Furthermore, chromium sorption kinetics was well fitted by pseudo-second-order kinetic model, and well explained by Freundlich isotherm (R2>0.992). Conclusion: In general, alumina nanoparticle powder is recognized as an effective sorbent to remove chromium (VI) from aqueous solutions