Formation of Halogenated Byproducts upon Water Treatment with Peracetic Acid

Peracetic acid has quickly gained ground in water treatment over the last decade. Specifically, its disinfection efficacy toward a wide spectrum of microorganisms in wastewater is accompanied by the simplicity of its handling and use. Moreover, peracetic acid represents a promising option to achieve disinfection while reducing the concentration of typical chlorination byproducts in the final effluent. However, its chemical behavior is still amply debated. In this study, the reactivity of peracetic acid in the presence of halides, namely, chloride and bromide, was investigated in both synthetic waters and in a real contaminated water. While previous studies focused on the ability of this disinfectant to form halogenated byproducts in the presence of dissolved organic matter and halides, this work indicates that peracetic acid also contributes itself as a primary source in the formation of these potentially carcinogenic compounds. Specifically, this study suggests that 1.5 mM peracetic acid may form around 1-10 μg/L of bromoform when bromide is present. Bromoform formation reaches a maximum at near neutral pH, which is highly relevant for wastewater management

Evaluation of Fenton and modified Fenton oxidation coupled with membrane distillation for produced water treatment: Benefits, challenges, and effluent toxicity

Membrane distillation is a promising technology to desalinate hypersaline produced waters. However, the organic content can foul and wet the membrane, while some fractions may pass into the distillate and impair its quality. In this study, the applicability of the traditional Fenton process was investigated and preliminarily optimized as a pre-treatment of a synthetic hypersaline produced water for the following step of membrane distillation. The Fenton process was also compared to a modified Fenton system, whereby safe iron ligands, i.e., ethylenediamine-N,N′-disuccinate and citrate, were used to overcome practical limitations of the traditional reaction. The oxidation pre-treatments achieved up to 55% removal of the dissolved organic carbon and almost complete degradation of the low molecular weight toxic organic contaminants. The pre-treatment steps did not improve the productivity of the membrane distillation process, but they allowed for obtaining a final effluent with significantly higher quality in terms of organic content and reduced Vibrio fischeri inhibition, with half maximal effective concentration (EC50) values up to 25 times those measured for the raw produced water. The addition of iron ligands during the oxidation step simplified the process, but resulted in an effluent of slightly lower quality in terms of toxicity compared to the use of traditional Fenton

Tragacanth, an Exudate Gum as Suitable Aqueous Binder for High Voltage Cathode Material

he improvements in future-generation lithium-ion batteries cannot be exclusively focused on the performance. Other aspects, such as costs, processes, and environmental sustainability, must be considered. Research and development of new active materials allow some fundamental aspects of the batteries to be increased, such as power and energy density. However, one of the main future challenges is the improvement of the batteries’ electrochemical performance by using “non-active” materials (binder, current collector, separators) with a lower cost, lower environmental impact, and easier recycling procedure. Focusing on the binder, the main goal is to replace the current fluorinated compounds with water-soluble materials. Starting from these considerations, in this study we evaluate, for the first time, tragacanth gum (TG) as a suitable aqueous binder for the manufacturing process of a cobalt-free, high-voltage lithium nickel manganese oxide (LNMO) cathode. TG-based LNMO cathodes with a low binder content (3 wt%) exhibited good thermal and mechanical properties, showing remarkably high cycling stability with 60% capacity retention after more than 500 cycles at 1 C and an outstanding rate capability of 72 mAh g−1 at 15 C. In addition to the excellent electrochemical features, tragacanth gum also showed excellent recycling and recovery properties, making this polysaccharide a suitable and sustainable binder for next-generation lithium-ion batteries