Kinetics and mechanism of the decomposition ofN-bromoalcoholamines in aqueous solution

A Critical Review on Chemical Speciation of Chlorine-Produced Oxidants (CPOs) in Seawater. Part 1: Chlorine Chemistry in Seawater and Its Consequences in Terms of Biocidal Effectiveness and Environmental Impact

Seawater chlorination has three main industrial uses: disinfection of water and installations, control of biofouling, and preventing the transport of aquatic invasive species. Once in contact with seawater, chlorine reacts rapidly with water constituents (e.g. bromide ions, ammonia, and nitrogen-containing compounds) to form a range of oxidative species (e.g. bromine and N-haloamines), termed "chlorine-produced oxidants" (CPOs) or "total residual oxidants" (TRO). The chemical nature of CPOs and their concentration are a function of two categories of parameters related to treatment modality (e.g. chlorine dose) and water quality (e.g. temperature, pH, ammonia concentration, and organic constituents). The chlorination process may result in continuous or intermittent releases of CPOs in seawater. The reactivity and potential ecotoxicity of CPO species largely depend on their physical and chemical properties. Therefore, evaluation of the biocidal effectiveness of chlorination and its potential impacts requires not only determining the sum of CPOs (via a bulk parameter), but also their chemical speciation. The aim of this article - which is the first of a trilogy dedicated to the chemical speciation of CPOs in seawater - is to provide an overview of current knowledge about chlorine chemistry in seawater and to discuss the biocidal efficacy and the environmental fate of resulting CPOs. The 2nd and 3rd articles delineate a comprehensive and critical review of analytical methods and approaches for the determination of CPOs in seawater.

A Critical Review on Chemical Speciation of Chlorine-Produced Oxidants (CPOs) in Seawater. Part 2: Sampling, Sample Preparation and Non-Chromatographic and Mass Spectrometric-Based Methods

Chlorination of seawater forms a range of secondary oxidative species, collectively termed "chlorine-produced oxidants" (CPOs). These compounds do not have the same biocidal efficacy, the same fate and behavior in the marine environment, the same potential formation of chlorination by-products (CBPs), nor the same effects on marine organisms. Their chemical speciation is an important step toward an accurate assessment of the effectiveness of chlorination and the potential impacts of its releases, among others. The aim of this paper - which is the second of a trilogy dedicated to the chemical speciation of CPOs in seawater - is to cover all aspects related to CPOs analysis in seawater, from sampling to instrumental determination. First, it discusses the procedures involved in synthesis, storage, and standardization of analytical standards. Second, it deals with sampling and sample preparation, addressing all relevant issues related to these two key steps. Third, it provides a comprehensive and up-to-date overview of the colorimetric, titrimetric, and electrochemical methods used for CPOs determination and thoroughly discusses their advantages and limitations. Finally, this review ends with some recommendations for progress in the field of CPO analysis with the three aforementioned approaches. Chromatographic and mass spectrometric-based methods will be covered in the third and final article (Part III).

Organic chloramines in chlorine-based disinfected water systems: A critical review

This paper is a critical review of current knowledge of organic chloramines in water systems, including their formation, stability, toxicity, analytical methods for detection, and their impact on drinking water treatment and quality. The term organic chloramines may refer to any halogenated organic compounds measured as part of combined chlorine (the difference between the measured free and total chlorine concentrations), and may include N-chloramines, N-chloramino acids, N-chloraldimines and N-chloramides. Organic chloramines can form when dissolved organic nitrogen or dissolved organic carbon react with either free chlorine or inorganic chloramines. They are potentially harmful to humans and may exist as an intermediate for other disinfection by-products. However, little information is available on the formation or occurrence of organic chloramines in water due to a number of challenges. One of the biggest challenges for the identification and quantification of organic chloramines in water systems is the lack of appropriate analytical methods. In addition, many of the organic chloramines that form during disinfection are unstable, which results in difficulties in sampling and detection. To date research has focussed on the study of organic monochloramines. However, given that breakpoint chlorination is commonly undertaken in water treatment systems, the formation of organic dichloramines should also be considered. Organic chloramines can be formed from many different precursors and pathways. Therefore, studying the occurrence of their precursors in water systems would enable better prediction and management of their formation.