Mthembu Sabelo B, Akintayo Damilola Caleb, Moodley Brenda, Gumbi Bhekumuzi P
School of Chemistry and Physics, University of KwaZulu-Natal, 54 University Road, Durban, 4001, South Africa.
University of Colorado, Aurora, CO, United States.
Heliyon. 2023 Jun 9;9(6):e17136. doi: 10.1016/j.heliyon.2023.e17136. eCollection 2023 Jun.
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.
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 in drinking water with limits of detection and limits of quantification of 0.3302 and 1.101 μg L, respectively.
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. The average poly-(DADMAC) concentrate concentration that is dosed for coagulation in Umgeni Water plant A was 7.889 μg L while in plant B was 19.28 μg L. Residual poly-(DADMAC) concentration in drinking water was within the accepted limit of 50.00 μg L, regulated by the World Health Organisation (WHO).
在世界大部分地区，许多饮用水处理厂使用聚二甲基二烯丙基氯化铵（聚 -（DADMAC））作为絮凝剂，以去除原水中的悬浮固体。然而，监测残留的聚 -（DADMAC）非常重要，因为它在饮用水处理过程中会分解成一种致癌化合物，即N - 亚硝基二甲胺（NDMA）。
在这项工作中，对金纳米颗粒法进行了优化，用于检测聚 -（DADMAC），其中金纳米颗粒用柠檬酸钠稳定，然后用于通过紫外 - 可见 - 近红外分光光度法定量聚 -（DADMAC）。优化后的方法能够测量饮用水中低至1.000μg/L浓度的聚 -（DADMAC），检测限和定量限分别为0.3302和1.101μg/L。
该方法应用于两个不同的水处理厂，在水处理过程各阶段发现的聚 -（DADMAC）浓度范围为1.013至33.63μg/L。Umgeni水厂A用于混凝的聚 -（DADMAC）平均投加浓度为7.889μg/L，而水厂B为19.28μg/L。饮用水中残留的聚 -（DADMAC）浓度在世界卫生组织（WHO）规定的50.00μg/L的可接受限值内。
