Abstract Deep insight into the forces driving chloramine decay in different pipe materials is the key to taking sound action to cope with pipe water quality deterioration. By using the newly developed RTCDM (refined Total Chloramine Decay Model) and pipe section reactor, the role of four typical pipes in disinfection chemistry was qualitatively and quantitatively compared, and the mechanism of pipe wall mediated chloramine decay was further described. As for the four typical pipes studied, the characteristics of deteriorating water quality, especially for accelerating total chloramine decay was in the order of cast iron pipe > steel pipe > cement lined ductile iron pipe > polypropylene-random pipe. Cast iron pipes, cement-lined ductile iron pipes, and steel pipes of long service age are characterized by one or two driving forces leading to TCR decay. Aged cast iron pipes could take up chloramine by Fe(0) and microbes (especially nitrifiers) spreading over the inner wall. Aged steel pipe is characterized by aggressive electrochemical corrosion and weak nitrification. Lime and gypsum leaching is the main cause, and nitrification/denitrification may also occur in aged cement-lined ductile iron pipe. Polypropylene-random pipes have a minimum effect on disinfection chemistry. This knowledge is of value in speculating the reasons leading to TCR loss in the full scale distribution system.
In the present study, Ni / Fe nanoparticles were synthesized using bound micelles as a template and 3, 3 ′ , 4, 4 ′ -tetrachlorobiphenyl (PCB77) as the target contaminant. The dual bound micelles, which are composed of polyvinylpyrrolidone (PVP) and sodium dodecyl sulfate (SDS), were found to be superior to single-component templates for the dispersion of metallic ions and thus directed the synthesis of Ni / Fe nanoparticles with improved properties. After characterization of the different nanoparticles, it was found that the sustained effectiveness of PVP–SDS bound micelles afforded specialized structures with two gradations of Ni / Fe nanoparticles, correlating to more active sites and higher activity. The improved activity of the Ni / Fe nanoparticles was finally exhibited by the higher ratio (99.3% in 72 h) and efficiency (k obs of 0.0674 h -1 ) of PCB77 removal. Herein, the utilization of PVP–SDS bound micelles is proposed as a template for the improvement of iron-based nanoparticles and correlated research.
TiN films growing, Ti films as interlayers were prepared on AZ91C by CMP equipment. Surface topography, microstructure and hardness of the films were analyzed with high resolution SEM, X-ray EDS and CSM microcharacter hardness tester.
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