Mesoporous silica based novel conjugate adsorbent for efficient selenium(IV) detection and removal from water

Selenium is a very toxic element that at low concentration can affect human beings and living organisms. In this study, the ligand immobilized conjugate adsorbent was developed and selenium (Se(IV)) detection and removal from water were investigated. The conjugate adsorbent was successfully prepared by direct immobilization of 6-((2-(2-hydroxy-1 naphthoyl)hydrazono) methyl)benzoic acid onto mesoporous inorganic silica. This study was performed to evaluate the several influencing parameters such as solution pH, contact time, initial concentration, and the presence of competitive ions on the monitoring and removal performance. The adsorbent has the specific functionality for Se(IV) detection and removal from aqueous media. Moreover, the adsorbent has large surface area-to-volume ratios and uniformly mesostructures shaped pores that were actively working to capture Se(IV). The point of zero charge of the adsorbent was evaluated to understand the adsorption phenomenon. The limit of detection of the method presented was 2.16 ppb at optimum conditions. The adsorption data were well interpreted by the Langmuir adsorption isotherm and the maximum adsorption capacity was 103.73 mg/g. The adsorbent was capable of Se(IV) removal even in the presence of a high amount of coexisting cations and anions such as sodium, potassium, calcium, chloride, nitrate, sulfate, phosphate and etc. This technique achieved residual Se(IV) concentration less than 10 ppb, which is acceptable by water quality regulations. The adsorbed Se(IV) was eluted with 0.10 M NaOH and simultaneously regenerated into the initial form for the next operation after rinsing with water. Moreover, the adsorbent was retaining functionality in spite of several cycles during sorption elution regeneration operations. Therefore, the solid design adsorbent is efficient and cost-effective for selective Se(IV) detection and removal from water. (C) 2014 Elsevier Inc. All rights reserved.