Development of gold plasmonic nanoparticles for detection of polydiallyldimethylammonium chloride at Umgeni water treatment plants: An optimised study and case application

Sabelo B Mthembu; Damilola Caleb Akintayo; Brenda Moodley; Bhekumuzi P Gumbi

doi:10.1016/j.heliyon.2023.e17136

Development of gold plasmonic nanoparticles for detection of polydiallyldimethylammonium chloride at Umgeni water treatment plants: An optimised study and case application

Heliyon. 2023 Jun 9;9(6):e17136. doi: 10.1016/j.heliyon.2023.e17136. eCollection 2023 Jun.

Authors

Sabelo B Mthembu¹, Damilola Caleb Akintayo^{1

2}, Brenda Moodley¹, Bhekumuzi P Gumbi¹

Affiliations

¹ School of Chemistry and Physics, University of KwaZulu-Natal, 54 University Road, Durban, 4001, South Africa.
² University of Colorado, Aurora, CO, United States.

Abstract

Background: Polydiallyldimethylammonium chloride (poly-(DADMAC) is used in many drinking water treatment plants in most parts of the world as a flocculant to remove suspended solids from raw water. However, it is very important that residual poly-(DADMAC) is monitored because it disintegrates into a carcinogenic compound known as N-nitrosodimethylamine (NDMA) during the treatment of drinking water.

Methods: In this work, the gold nanoparticle method is optimised for the detection of poly-(DADMAC), where the gold nanoparticles were stabilised with trisodium citrate and then used in quantifying poly-(DADMAC) by Ultraviolet-Visible-Near Infrared spectrophotometry. The optimised method was able to measure poly-(DADMAC) at low concentrations of 1.000 μg L^-1 in drinking water with limits of detection and limits of quantification of 0.3302 and 1.101 μg L^-1, respectively.

Significant results: The method was applied to two different water treatment plants and the concentration of poly-(DADMAC) found during stages of the water treatment process ranged from 1.013 to 33.63 μg L^-1. The average poly-(DADMAC) concentrate concentration that is dosed for coagulation in Umgeni Water plant A was 7.889 μg L^-1 while in plant B was 19.28 μg L^-1. Residual poly-(DADMAC) concentration in drinking water was within the accepted limit of 50.00 μg L^-1, regulated by the World Health Organisation (WHO).

Keywords: AuNPs; Drinking water; Poly-(DADMAC); UV–Vis spectrophotometry; Water treatment.