Adsorption Removal of Mo(VI) from an Aqueous Solution by Alumina with the Subsequent Regeneration of the Adsorbent

Abstract

Industrial wastewater is the main source of an excessive amount of molybdenum (Mo) in natural ecosystems. It is necessary to remove Mo from wastewater before it is discharged into the environment. Molybdate ion(VI) is the most common form of Mo in natural reservoirs and industrial wastewater. In this work, the sorption removal of Mo(VI) from an aqueous medium was evaluated using aluminum oxide. The influence of such factors as the pH of the solution and the temperature was evaluated. Three adsorption isotherms, namely, Langmuir, Freundlich and Temkin, were used to describe the experimental results. It was found that the pseudo-first order kinetic model better fits the kinetic data of the adsorption process, and the maximum Mo(VI) adsorption capacity was 31 mg/g at 25 °C and pH 4. The thermodynamic parameters indicated that the process of Mo(VI) adsorption on Al2O3 was exothermic and spontaneous. It was shown that the adsorption of Mo strongly depends on pH. The most effective adsorption was observed at pH values below 7. Experiments on adsorbent regeneration showed that Mo(VI) can be effectively desorbed from the aluminum oxide surface into a phosphate solution in a wide range of pH values. After the desorption of Mo(VI) in a phosphate solution, alumina was found to be suitable for repeating the procedure at least five times.

Removal of 2,4-Dichlorophenoxyacetic Acid from Aqueous Solutions Using Al2O3/Graphene Oxide Granules Prepared by Spray-Drying Method

“…The Al 2 O 3 compound combines high mechanical strength, hardness, a developed surface and chemical resistance, while its cost is reasonably low [11,12]. Currently, special attention is paid to adsorbents with alumina, which exhibit very good adsorption properties towards heavy metals [13,14]. In addition, being water-resistant, aluminum oxide is often used as an adsorbent for drying and processing media containing condensed moisture, while the possibility of repeated temperature regeneration by burning ensures the long-term operation of the adsorbent [15].…”