Selenium removal from water and its recovery using iron (Fe3+) oxide/hydroxide-based nanoparticles sol (NanoFe) as an adsorbent

This study relates to an adsorption method process for treating a fluid containing undesired selenium contaminants (Se4+ and Se6+) in order to clean the fluid of the contaminant and develop a process for recovering the adsorbent material. The approach for this purification process was made using iron (Fe3+) oxide/hydroxide nanoparticles sol (NanoFe) as an adsorbent.The technique provides an efficient and cost-effective method for selenium removal from water. A strong effect was shown of iron (Fe3+) oxide/hydroxide nanoparticles-based concentration and pH level of polluted water on removal efficiency. The exceptional adsorption properties of synthesized NanoFe adsorbent are demonstrated. This technique achieved residual selenium concentration less than 0.01 ppm, which is acceptable by water quality regulations and at least 95–98% regeneration efficiency of the selenium with the proposed adsorbent. The selenium adsorption capacity on the iron(3) oxide particles at an equilibrium concentration of 0.01 ppm as Se in the solution is about one order of magnitude higher than these values reported in the literature. This technique enables the recovery of the adsorbent by producing concentrated selenium solution that may be treated further to obtain selenium-containing crystals while recovering the cleaning solution.

► This article demonstrates fast removal of selenium from water by adsorption at affordable pH level.
► Removal is done according to water quality restrictions.
► Complete recovery of the adsorbent for reuse was shown, followed by contaminant removal as solid barium selenate.
► Relatively high adsorption of the selenium ions, at the permitted concentration level was demonstrated, in comparison with other reported works.
► The finding may be a basis for a non-expensive process for complete removal of selenium anions from solutions.