Kinetic Study of Selenium Removal Using Advanced Reduction Process with Dithionite

Yuhang Duan, Vishakha Kaushik, Bahngmi Jung, Bill Batchelor, Ahmed Abdel-Wahab

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

This article reports on the application of an advanced reduction process (ARP) that combines ultraviolet (UV) irradiation and dithionite to remove selenium from solution. Batch kinetic removal of selenite (Se(IV)) and selenate (Se(VI)) with the dithionite/UV ARP at different pH were evaluated under anaerobic conditions and a removal mechanism was proposed. Resolubilization of selenium was observed for all pH (7, 8, and 9) after 15 to 20 min, which was the time when dithionite was completely consumed. A hypothesis was proposed that selenium first was reduced to elemental Se by radicals formed from photolysis of dithionite. Then, it was resolubilized by reaction with oxidizing radicals formed by photolysis of dithionite degradation products. A kinetic model for dithionite photolysis and a second-order model for precipitation of selenium were developed to describe selenium removal. Experimental data were used in nonlinear regressions to estimate quantum yields and second-order rate constants. Lowest quantum yields were observed at pH 8 for experiments with both selenite and selenate. The rate of selenite removal from solution was not affected by pH, but the rate of selenate removal was faster at pH 8 than at pH 7 and 9.

Original languageEnglish
Pages (from-to)169-175
Number of pages7
JournalEnvironmental Engineering Science
Volume35
Issue number3
DOIs
Publication statusPublished - 1 Mar 2018

    Fingerprint

Keywords

  • advanced reduction processes
  • dithionite
  • reducing radicals
  • selenium
  • UV irradiation

ASJC Scopus subject areas

  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution

Cite this