It is essential and important to determine the adsorption mechanism as well as removal efficiency when using an adsorption technique to remove toxic heavy metals from wastewater. In this research, the removal efficiency and mechanism of chromium removal by a silica-based nanoparticle were investigated. A PEI-silica nanoparticle was synthesized by a one-pot technique and exhibited uniformly well-dispersed PEI polymers in silica particles. The adsorption capacity of chromium ions was determined by a batch adsorption test, with the PEI-silica nanoparticle having a value of 183.7 mg/g and monolayer sorption. Adsorption of chromium ions was affected by the solution pH and altered the nanoparticle surface chemically. First principles calculations of the adsorption energies for the relevant adsorption configurations and XPS peaks of Cr and N showed that Cr(VI), [HCrO4]- is reduced to two species, Cr(III), CrOH2+ and Cr3+, by an amine group and that Cr(III) and Cr(VI) ions are adsorbed on different functional groups, oxidized N and NH3 +.
Bibliographical noteFunding Information:
This research was supported by the Korea Institute of Science and Technology (KIST) institutional program (Grant No. 2E28120) and the Korea Ministry of Environment (MOE) as “Public Technology Program based on Environmental Policy (E416-00020-0606-0)”. J.H.L. at UNIST was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (2015R1C1A1A01055760). This study was also partly supported by a Korea CCS R&D Center (Korea CCS 2020 Project) grant funded by the Korean Government (Ministry of Science, ICT & Future Planning) in 2017 (KCRC-2014M1A8A1049315).
© 2018 The Author(s).
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