Surface water H-bonding network is key controller of selenate adsorption on [0 1 2] α-alumina: An Ab-initio study

Srishti Gupta, Ngan Anh Nguyen, Christopher L. Muhich

Research output: Contribution to journalArticlepeer-review

Abstract

Selenate adsorption onto metal oxide surfaces is a cost-effective method to remove the toxin from drinking water systems. However, the low selectivity of metal oxides requires frequent sorbent replacement. The design of selective adsorbents is stymied because the surface factors controlling selenate adsorption remain unknown. We calculate adsorption energies of selenate on the (0 1 2) α-Al2O3 surface using density functional theory to unravel the physics that controls adsorption. Our model is validated against experiment by correctly predicting selenate removal efficiency as a function pH. We find that the selenate adsorption energy on the anhydrous α-Al2O3 surface is surprisingly anti-correlated with the fully solvated adsorption energy; therefore, the direct interaction between adsorbate and sorbent is eliminated as the controlling mechanism. Rather, the change in number of surface hydrogen bonds after adsorption is the factor most correlated with the adsorption energy (R2 > 0.8); and is thus determined to be the factor controlling selenate adsorption. We find that pH affects adsorption by controlling the number of surface protons available for H-bonding to selenate. This work demonstrates that adsorption prediction should not be made based on gas phase sorption energies and suggests that surface engineering which increases surface protonation may be an effective strategy for increasing selenate sorption.

Original languageEnglish (US)
Pages (from-to)136-146
Number of pages11
JournalJournal of Colloid And Interface Science
Volume617
DOIs
StatePublished - Jul 2022
Externally publishedYes

Keywords

  • Adsorption
  • Interfacial phenomena
  • Selenate
  • Solvation
  • Water treatment
  • pH effects

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Surfaces, Coatings and Films
  • Colloid and Surface Chemistry

Fingerprint

Dive into the research topics of 'Surface water H-bonding network is key controller of selenate adsorption on [0 1 2] α-alumina: An Ab-initio study'. Together they form a unique fingerprint.

Cite this