Synthesis of Al2O3@Fe2O3 core–shell nanorods and its potential for fast phosphate recovery and adsorption of chromium (VI) ions from contaminated wastewater

Abstract

Wastewater and agricultural runoff contain phosphate and chromium ions, which are common pollutants. In particular, industrial wastewater can contain excessive untreated pollutants, leading to eutrophication. Therefore, it is crucial to treat wastewater to recover phosphate ions and remove chromium before releasing it into aquatic systems. In this study, we engineered a core–shell nanorod structure, Al2O3@Fe2O3 via a three-step method. To evaluate the effectiveness of the as-prepared Al2O3@Fe2O3 nanorods, in recovering and removing contaminants, we investigated various factors on phosphate recovery. The Al2O3@Fe2O3 nanorods exhibited a maximum Langmuir adsorption capacity of 106.2 mg/g for the phosphate recovery, which was 11.29 and 1.85 times greater than that of pure aluminum oxide and ferrous oxide samples, respectively. The pseudo-second-order and the Elovich diffusion kinetic models resulted in the greatest correlation constants. Desorption of the phosphate adsorbed on the Al2O3@Fe2O3 sample was effectively achieved using a sodium carbonate solution. Furthermore, our findings revealed that the Al2O3@Fe2O3 sample showed a supreme chromium adsorption capacity of 476.2 mg/g. According to thermodynamic analyses, the route for chromium adsorption was impulsive and endothermic. This paper offers a thorough summary of the potential application of core–shell nanorods in wastewater treatment.