Intrinsic properties of cupric oxide nanoparticles enable effective filtration of arsenic from water

Abstract

The contamination of arsenic in human drinking water supplies is a serious global health concern. Despite multiple years of research, sustainable arsenic treatment technologies have yet to be developed. This study demonstrates the intrinsic abilities of cupric oxide nanoparticles (CuO-NP) towards arsenic adsorption and the development of a point-of-use filter for field application. X-ray diffraction and X-ray photoelectron spectroscopy experiments were used to examine adsorption, desorption, and readsorption of aqueous arsenite and arsenate by CuO-NP. Field experiments were conducted with a point-of-use filter, coupled with real-time arsenic monitoring, to remove arsenic from domestic groundwater samples. The CuO-NP were regenerated by desorbing arsenate via increasing pH above the zero point of charge. Results suggest an effective oxidation of arsenite to arsenate on the surface of CuO-NP. Naturally occurring arsenic was effectively removed by both as-prepared and regenerated CuO-NP in a field demonstration of the point-of-use filter. A sustainable arsenic mitigation model for contaminated water is proposed.

Figure 1. Adsorption schematic and XPS analysis.

(a) Adsorption and desorption phenomenon of CuO-NP in water. (b) XPS spectra at the As3d peak of CuO-NP following initial reaction with As. (c) XPS spectra at the As3d peak of CuO-NP following regeneration. (d) XPS spectra at the As3d peak of regenerated CuO-NP following reaction with As. (e) XPS spectra of the Os1 peak for CuO-NP as-prepared and following regeneration after reaction with either As(III) or As(V).

Figure 2. Point-of-use arsenic filter design, field results, and proposed model.

(a) Point-of use arsenic removal filter set-up and regeneration set-up. (b) Removal of arsenic from Torrington domestic groundwater sample with point-of use arsenic removal filter. (c) Removal of arsenic from Jackson domestic groundwater sample with point-of use arsenic removal filter. (d) A model for sustainable arsenic mitigation process.