Analytical methods Results and discussion Comparison

2.5. Analytical methods
3. Results and discussion
3.1. Comparison between different DZNep reagents for efficacy of quenching total chlorine
Fig. 1. Lab tap water quenched with different reducing agents (initial residual chlorine concentration = 0.60 mg/L as Cl2; quenching condition pH = 7.0, phosphate buffer concentration = 5 mM, temperature = 25 ± 1 °C).Figure optionsDownload full-size imageDownload as PowerPoint slide
3.2. Reactions of NaAsO2 with free chlorine, NH2Cl and NHCl2
In order to investigate the quenching ability of NaAsO2 in finished water from DWTPs, the individual reaction of NaAsO2 to free chlorine, NH2Cl and NHCl2, respectively, should be considered first. Based on previous studies, the reducing power of NaAsO2 can be controlled by adjusting its dose and solution pH, and the reactions to free chlorine and NH2Cl are sedimentary rock shown in Eqs. (1) and (2)[24].equation(1)NaOCl+AsO2-→AsO3-+Na++Cl-equation(2)NH2Cl+AsO2-+H2O→NH4++Cl-+AsO3-