Removal of arsenite by reductive precipitation in dithionite solution activated by UV light

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

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Abstract

This study investigates the removal of arsenite (As(III)) from water using dithionite activated by UV light. This work evaluated the removal kinetics of As(III) under UV light irradiation as affected by dithionite dose and light intensity, and characterized the nature of the precipitated solids using XPS and SEM-EDS. Photolysis of dithionite was observed by measuring dithionite concentration using UV absorbance at 315 nm. This study also investigated the effect of UV light path length on soluble As concentrations to understand resolubilization mechanisms. Total soluble As concentrations were observed to decrease with reaction time due to reduction of arsenite to form solids having a yellow-orange color. The removal mechanism was found to be reductive precipitation that formed solids of elemental arsenic or arsenic sulfide. However, these solids were observed to resolubilize at later times after dithionite had been consumed. Resolubilization of As was prevented and additional As removal was obtained by frequent dosing of dithionite throughout the experiment. As(III) removal is attributed to photolysis of dithionite by UV light and production of reactive radicals that reduce As(III) and convert it to solid forms.

Original languageEnglish
JournalJournal of Environmental Sciences (China)
DOIs
Publication statusAccepted/In press - 1 Jan 2018

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Keywords

  • and Ultraviolet light
  • Arsenite
  • Reductive precipitation
  • Sodium dithionite

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Environmental Science(all)

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