Investigation on processes for removal of chloramines from saturated sodium chloride brine solution

Abstract

ERCO Worldwide, a division of Superior Plus LP, Saskatoon facility ("ERCO Worldwide-Saskatoon") is a manufacturer of caustic soda, chlorine, hydrochloric acid and sodium chlorite. The brine solution as produced from the brine wells contains 26% sodium chloride. The saturated brine is purified and supplied to the electrolyzer system to produce caustic soda, chlorine, hydrochloric acid, and sodium chlorate. During the electrolysis of brine to produce sodium hypochlorite, chloramines are produced as undesirable products. These are chlorine contaminant which are detrimental to electrolysis process. Hence, it is essential to develop an efficient, and environmentally benign process to remove chloramines from brine. The objective of this project is to develop a suitable process to remove chloramines from brine. This project focuses on the evaluation of various processes available to remove chloramine from brine, test them in bench scale and recommend a process, which is adaptable with the existing ERCO operation. This study is divided into two phases: the first phase involves the application of ultraviolent radiation (UV) treatment to remove chloramines. The effects of solution pH (3-11), reaction time (15-45 min), concentrations of chloramines and ammonia to chlorine ratio (1:3 – 1:7) on chloramine removal were studied using the central composite design (CCD). Maximum chloramine removal of 100% was obtained at 30 mins reaction time, pH 3 and ammonia to chlorine ratio of 1:5. In the second phase, activated carbon (AC) was used for chloramines removal in an adsorption column. The influence of the mass dosage of AC (0.5 -1.5 g), flow rate (5-7 mL/min) and ammonia to chlorine ratio (4:20 – 7:35) on chloramine removal was studied. Maximum chloramines removal of 92% was observed at flow rate of 6 mL/min, 1 g AC dosage and ammonia to chlorine ratio of 1:5. Based on the results, UV treatment was found more effective in chloramine removal from synthetic solution.