Selective removal of bromide and iodide from natural waters using a novel AgCl-SPAC composite at environmentally relevant conditions

Mohamed Ateia; Cagri Utku Erdem; Mahmut Selim Ersan; Marcel Ceccato; Tanju Karanfil

doi:10.1016/j.watres.2019.03.028

Selective removal of bromide and iodide from natural waters using a novel AgCl-SPAC composite at environmentally relevant conditions

Water Res. 2019 Jun 1:156:168-178. doi: 10.1016/j.watres.2019.03.028. Epub 2019 Mar 20.

Authors

Mohamed Ateia¹, Cagri Utku Erdem¹, Mahmut Selim Ersan², Marcel Ceccato³, Tanju Karanfil⁴

Affiliations

¹ Department of Environmental Engineering and Earth Science, Clemson University, SC, 29634, USA.
² Department of Environmental Engineering and Earth Science, Clemson University, SC, 29634, USA; Water Quality Research and Development Division, Southern Nevada Water Authority, P.O. Box 99954, Las Vegas, NV, 89193-9954, USA.
³ Carbon Dioxide Activation Center (CADIAC) - Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000, Aarhus C, Denmark; Department of Chemistry, Aarhus University, Langelandsgade 140, 8000, Aarhus C, Denmark.
⁴ Department of Environmental Engineering and Earth Science, Clemson University, SC, 29634, USA. Electronic address: tkaranf@clemson.edu.

PMID: 30913420
DOI: 10.1016/j.watres.2019.03.028

Abstract

The removal of bromide (Br^-) and iodide (I^-) from source waters mitigates the formation of brominated and iodinated disinfection by-products (DBPs), which are more toxic than their chlorinated analogues. In this study, we report on our recently developed environmental-friendly method for the preparation of novel silver chloride/superfine activated carbon composite (AgCl-SPAC) to rapidly and selectively remove Br^- and I^- from surface waters. The material characteristics were tracked, before and after treatment, using scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), X-ray diffraction (XRD), and X-ray photoelectron spectra (XPS) spectroscopies. The results showed very fast removal kinetics of Br^- and I^- by AgCl-SPAC with equilibrium times at 150 s and <10 s, respectively (i.e., 2-3 orders of magnitudes faster than previously tested Ag-based composites). In addition, AgCl-SPAC was evaluated under eight different Cl^- concentrations up to 400 mg/L and exhibited high removal efficiencies for I^- (i.e., >90% at all tested conditions) and Br^- (i.e, >80% at Cl^- = 0.5-200 mg/L, and 60-75% at extreme Cl^- conditions = 300-400 mg/L). Unlike previous Ag-based composites, AgCl-SPAC performance was not affected by elevated concentrations of two types of natural organic matter (2-16 mg-NOM/L). The superior performance was further confirmed in four different surface waters and one groundwater. After the removal of Br^- and I^- from all waters by AgCl-SPAC, the subsequent DBPs formation (trihalomethanes, haloacetic acids, and haloacetonitriles), total organic halogens (TOX), bromine substitution factor (BSF), and calculated cytotoxicity under the uniform formation conditions (UFC) decreased significantly. Overall, this novel composite represents a promising alternative approach, to be integrated continuously or seasonally, for controlling the formation of brominated and/or iodinated DBPs at water treatment plants.

Keywords: Bromide; Disinfection by-products; Iodide; Silver chloride; Superfine activated carbon; Water toxicity.

MeSH terms

Bromides
Disinfection
Halogenation
Iodides
Trihalomethanes
Water Pollutants, Chemical*
Water Purification*

Substances

Bromides
Iodides
Trihalomethanes
Water Pollutants, Chemical