Polychlorinated Terphenyls (PCTs): Backbone Angle of ortho and nonortho Chlorination

Polychorinated Terphenyls is considered as one of persistent organic pollutants (POPs) and have been banned in the use mostly in United State and Europe countries. A study of the ortho chlorination toward backbone angle has been done in order to obtain the information of –C-C- angle of between aromatic groups of terphenyls. Five hexachlorinated terphenyl standards have been deployed for the purpose. Firstly, five terphenyl standards of 2,2",3,3",5,5"-hexachlorinated-meta-, 2',3,3",5,5',5"-hexachlorinated- para-, 2',3,3",4,4",5'-hexachlorinated-para-, 2,2”,3,3”,5,5”-hexachlorinaated-para-, 3,3´,3”,5,5´,5”-hexachlorinated-para- have been measured by GC-FTIR. From the data obtained, IR spectra of each standard were then compared to the theoretical calculation with Gaussian Program. The result showed that IR spectra of all five standard congeners were fit to the each spectra of the theoretical calculation. Based on the theoretical IR spectra obtained, furthermore, backbone angle of each five standards were able to be obtained related to the position of the chlorination pattern of the backbone. The angle between aromatics groups because of ortho chlorination or without ortho chlorination was clearly different. The ortho chlorination contributed to angle resulted in the lowest structure energy level around 51°-58°. Without ortho chlorination, the angle is around 36°

Recovery of actinides from actinide-aluminium alloys by chlorination: Part I

Pyrochemical processes in molten LiCl–KCl are being developed in ITU for recovery of actinides from spent nuclear fuel. The fuel is anodically dissolved to the molten salt electrolyte and actinides are electrochemically reduced on solid aluminium cathodes forming solid actinide–aluminium alloys. A chlorination route is being investigated for recovery of actinides from the alloys. This route consists in three steps: Vacuum distillation for removal of the salt adhered on the electrode, chlorination of the actinide– aluminium alloys by chlorine gas and sublimation of the formed AlCl3. A thermochemical study showed thermodynamic feasibility of all three steps. On the basis of the conditions identified by the calculations, experiments using pure UAl3 alloy were carried out to evaluate and optimise the chlorination step. The work was focused on determination of the optimal temperature and Cl2/UAl3 molar ratio, providing complete chlorination of the alloy without formation of volatile UCl5 and UCl6. The results showed high efficient chlorination at a temperature of 150 °C

Iron(III)-catalyzed chlorination of activated arenes

A general and regioselective method for the chlorination of activated arenes has been developed. The transformation uses iron(III) triflimide as a powerful Lewis acid for the activation of N-chlorosuccinimide and the subsequent chlorination of a wide range of anisole, aniline, acetanilide and phenol derivatives. The reaction was utilized for the late-stage mono- and di-chlorination of a range of target compounds such as the natural product nitrofungin, the antibacterial agent chloroxylenol and the herbicide chloroxynil. The facile nature of this transformation was demonstrated with the development of one-pot tandem iron-catalyzed dihalogenation processes allowing highly regioselective formation of different carbon-halogen bonds. The synthetic utility of the resulting dihalogenated aryl compounds as building blocks was established with the synthesis of natural products and pharmaceutically relevant targets

Contribution of the antibiotic chloramphenicol and its analogues as precursors of dichloroacetamide and other disinfection byproducts in drinking water

Dichloroacetamide (DCAcAm), a disinfection byproduct, has been detected in drinking water. Previous research showed that amino acids may be DCAcAm precursors. However, other precursors may be present. This study explored the contribution of the antibiotic chloramphenicol (CAP) and two of its analogues (thiamphenicol, TAP; florfenicol, FF) (referred to collectively as CAPs), which occur in wastewater-impacted source waters, to the formation of DCAcAm. Their formation yields were compared to free and combined amino acids, and they were investigated in filtered waters from drinking-water-treatment plants, heavily wastewater-impacted natural waters, and secondary effluents from wastewater treatment plants. CAPs had greater DCAcAm formation potential than two representative amino acid precursors. However, in drinking waters with ng/L levels of CAPs, they will not contribute as much to DCAcAm formation as the μg/L levels of amino acids. Also, the effect of advanced oxidation processes (AOPs) on DCAcAm formation from CAPs in real water samples during subsequent chlorination was evaluated. Preoxidation of CAPs with AOPs reduced the formation of DCAcAm during postchlorination. The results of this study suggest that CAPs should be considered as possible precursors of DCAcAm, especially in heavily wastewater-impacted waters

Pilot scale study of chlorination-induced transport property changes of a seawater reverse osmosis membrane

A pilot-scale study was performed to assess variations of reverse osmosis (RO) membrane water permeance (A) and salt retention (Robs) induced by chlorination and to compare them with those observed at the lab-scale. A chlorination protocol was adapted to expose only the surface active layer (an aromatic polyamide)of a composite RO membrane to consecutive free chlorine doses ranging from 40 to 4000 ppm h, at pH 6.9. Along the long-term filtration of seawater, performed with a 4" spiral wound RO module, we monitored the variations of A, the decrease of Robs and the rate of increase of A with time, and found themquantitatively similar to those reported in previous studies performed at the lab-scale under accelerated exposure conditions. The elemental analysis of the feed and permeate streams revealed that the rejection of divalent ions remained constant (ca. 100%), irrespective of the free chlorine dose reached, whereas the rejection of monovalent ions of the seawater (mainly sodium, chloride and bromide ions) decreased as the exposure dose increased. Overall, transposing the characterization procedure to the pilot-scale further supports that chlorination of PA, under pH conditions usually found in desalination plants (6.9 to 8.0), is controlled by the concentration of HOCl, as observed from elemental analysis of the surface by XPS

A Systematic Review of the Evidence for the Sustainability of Household Water Treatment Interventions

This systematic review assesses the quantity and quality of evidence for the sustainability of household water treatment (HWT) since the World Health Organization (WHO) recently endorsed HWT based on growing evidence of HWT's ability to improve microbial water quality, effectiveness at reducing diarrheal disease, cost-effectiveness, and rapid application and acceptance. A large portion of the world population still relies on unsafe sources of drinking water, but whether HWT can support scaling-up efforts and be considered sustainable, it remains to be seen. Ultimately this systematic review found limited evidence of a sustained uptake and usage of HWT interventions, and results from studies that found high levels of confirmed usage after one year must be considered alongside their methodological quality

Fluidized bed desulfurization

High sulfur content carbonaceous material, such as coal is desulfurized by continuous fluidized suspension in a reactor with chlorine gas, inert dechlorinating gas and hydrogen gas. A source of chlorine gas, a source of inert gas and a source of hydrogen gas are connected to the bottom inlet through a manifold and a heater. A flow controler operates servos in a manner to continuously and sequentially suspend coal in the three gases. The sulfur content is reduced at least 50% by the treatment