Interactions Between Ozone,Halogens and Organic Compounds

During drinking-water treatment, ozone used as a preoxidant and chlorine required for final disinfection, lead to competing chemical reactions, in the case of raw water containing both organic compounds and inorganic salts (such as bromides and ammonia).

The study of the interactions between those reactants has been made according to the following main topics :

As for THM formation, experiments conducted on simple organic compounds or on natural fulvic acids show important decreases in THM or TCAA formation after ozonation. It may be noticed, however, that the ozonation of surface waters may induce the formation of haloform precursors, usually with a low level of reactivity.

In water supplies containing bromide ions, oxidation of the latter through hypobromous acid may take place during the ozonation stage. Failing preozonation treatment, hypobromous acid is generated very rapidly during chlorination, thus inducing the formation of chloro- brominated organic compounds.

During the ozonation of fulvic acid solutions, the presence of small amounts of bicarbonate was found to improve precursor removal significantly.

It can be concluded that the partial analogy of the action of ozone or chlorine on aromatic structures, whether simple or complex (such as humic and fulvic acids), seems to indicate that the consequence of preozonation is the destruction, at least in part, of the most reactive sites for THM production, thus leading to a decrease of the volatile organochlorinated compounds formed during the post-chlorination. However, some ozonation products of natural waters are THM precursors, though of low reactivity. Then, in the presence of bromide ions, the formation of volatile organobrominated compounds may be observed during ozonation.     

High temperature corrosion mechanisms and effect of alloying elements for materials used in waste incineration environment

Corrosion products on two typical materials, SA213-T12 steel and alloy 625 exposed to the actual combustion gas, were analyzed in addition to laboratory tests for penetration of corrosive matter. It has been clarified that corrosion products of oxides containing a little chlorides and sulphides show lamellar structures and that at the alloy-scale interface, chlorination, sulphidation, and oxidation occur under a low P_O2-high P_Cl2 condition. The formation of scale structures and the effect of corrosion-resistant alloying elements can be explained according to the stability tendencies of metals, chlorides, and oxides in the M-Cl-O equilibrium diagrams. The severity of corrosion environments at the interface is influenced by the penetration extent of corrosive matters through deposits and scales, and the protective effects of oxide films derived from alloying elements play an important role in preventing the corrosion. On the other hand, it has been shown that thermal fluctuation characterized in this kind of environment makes the lamellar scale structures and sometimes breaks and peels off the scale, and thus accelerates the corrosion. On the basis of the above mentioned knowledge, a new corrosion model is presented.     

Comparative Analysis of Chlorine Dioxide, Free Chlorine and Chloramines on Bacterial Water Quality in Model Distribution Systems

Drinking water utilities may be required to change disinfectant to improve water quality and meet more stringent disinfection regulations. This research was conducted to assess and compares chlorine dioxide to free chlorine and chloramines on bacterial water quality monitored within model distribution systems (i.e., annular reactors). Following colonization with nondisinfected water, annular reactors containing either polycarbonate or cast iron coupons were treated with free chlorine, chlorine dioxide or chloramines. Two disinfectant doses (low/high) were tested for each disinfectant. Under specific environmental conditions, bacterial inactivation varied as a function of the disinfectant type and dose, sample type (bulk water versus biofilm bacteria) and coupon material. The ranking by efficiency was as follows: chlorine dioxide > chlorine > chloramines. On preformed biofilms of 106–107?cfu/cm2, the continuous application of a disinfectant led to a log removal of heterotrophic bacteria concentrations for suspended and biofilm bacteria ranging from 1.1 to 4.0, and from 0.2 to 2.5, respectively. Doubling the amount of disinfectant doses led to an additional log inactivation of 1–2.5 of heterotrophic bacteria levels. This study demonstrates that bacterial inactivation in distribution systems is governed by various inter-related parameters. The data indicate that chlorine dioxide represents a viable alternative for secondary disinfection in distribution systems.     

The effect of rolling at different temperatures on the fracture toughness anisotropy of a C-Mn structural steel

Abstract

The toughness of rolled plates of a plain C-Mn steel was evaluated for three sections, at different temperatures, by means of small-scale Wedge Open Loading (WOL) specimens. These were machined to orient the fracture plane parallel to the rolling plane, the transverse plane or the longitudinal plane which, according to the ASTM Standards code (12) are termed the S-L, the L-T and the T-L orientations, respectively. In addition, small tensile specimens having the tensile axis perpendicular to the rolling plane were tested at different temperatures.

The plates had been soaked at various temperatures between 1200°C and 680°C (finishing temperatures ～980°C to ～680°C) and then continuously rolled to the final thickness of 3/4-in. (10). The observed toughness depended on finishing temperature and also on specimen orientation; the S-L orientation being the least and the L-T orientation the most tough in any given plate. Brittle fractures were observed on the rolling-plane (S-L orientation) of WOL specimens made from. plates that had been soaked at temperatures ≤800°C (finishing temperatures ≤760°C) and these were attributed to the microstructure and texture. Scanning electron micrographs disclosed that elongated MnS inclusions were principally responsible for the fracture toughness anisotropy for higher soaking and finishing temperatures.

Résumé

La résistance de plaques laminées d'un acier au carbone et manganèse fut évaluée à differentes températures, selon les trois orientations possibles du plan de rupture par rapport au plan de laminage. Les éprouvettes ont été usinées conformément à une homothétie: reduite de la géométrie WOL (wedge open loading) et de sorte que le plan de rupture soit parallèle au plan de laminage, au plan transversal ou au plan longitudinal Ces orientations sont appelées S-L, L-T, et T-L respectivement, suivant les normes de l'ASTM (12). De plus, de petites éprouvettes de traction dont les axes de traction sont perpendiculaires au plan de laminage, furent expérimentées a differentes températures.

Les plaques ont été maintenues à differentes températures entre 1200°C et 680°C (températures finales de 980°C a 680°C), puis laminées en continue jusqu'à une épaisseur finale de 3/4 po. (10). On trouve que la resilience observee depend de la température finale et de 1'orientation de l'eprouvette. L'orientation S-L a été la moins résiliente tandis que 1'orientation L-T a été la plus résiliente de toutes les plaques expérimentées. Des cas de rupture fragile ont été observés sur le plan de laminage (orientation S-L) d' éprouvettes WOL obtenues de plaques ayant été maintenues à des températures ≤ 800°C (températures finales ≤760°C), et ceux-ci sont attribués à la microstructure et la tex ture du rnateriau. Des micrographics obtenues du microscope électronique a balayage révélèrent que des inclusions allongées de MnS étaient en grande partie responsables de l'anisotropie de la résistance a la rupture pour de plus hautes températures de maintien et températures finales.     

氯化 Ti3AlC2 陶瓷制备碳化物衍生碳的结构表征

以三元碳化物陶瓷Ti_3AlC_2为原料,在500°C~1000°C温度范围内氯化制备具有纳米孔结构的碳化物衍生碳(Ti_3AlC_2-CDC)。高温氯化制备得到的Ti_3AlC_2-CDC由无定形碳和石墨组成。氯化温度越高,石墨化程度越明显,石墨有序度越高。Ti_3AlC_2-CDC的结构与前驱体Ti_3AlC_2的层状结构保持一致。但随着温度升高,Ti_3AlC_2-CDC会逐渐裂解为单片层或多片层。采用N2吸附技术研究了700°C、800°C和1000°C下制备的Ti_3AlC_2-CDC的孔隙结构特征,通过分析试样的吸附等温线特征和孔径分布探讨了温度对CDC孔结构的影响。     

危险工艺自控改造中氯化反应控制方案的实现

根据国家安全监管总局关于公布首批重点监管的危险化工工艺目录的通知,各地对危险化工工艺正进行自控改造。本文以氯反应为例对自控方案的改造加以阐述。     

Occurrence of nine nitrosamines and secondary amines in source water and drinking water: Potential of secondary amines as nitrosamine precursors

Due to their high carcinogenicity, the control of nitrosamines, a group of disinfection by-products (DBPs), is an important issue for drinking water supplies. In this study, a method using ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry was improved for simultaneously analyzing nine nitrosamines in source water and finished water samples of twelve drinking water treatment plants (DWTPs) in China. The method detection limits of the nine target analytes were 0.2-0.9 ng/L for the source water samples and 0.1-0.7 ng/L for the finished water samples. Of the nine nitrosamines, six (N-nitrosodimethylamine (NDMA), nitrosodiethylamine (NDEA), N-nitrosomorpholine (NMor), N-nitrosodi-n-butylamine (NDBA), N-nitrosomethylethylamine (NMEA), and N-nitrosodiphenylamine (NDPhA)) were detected. The total nitrosamine concentrations in source water and finished water samples were no detection-42.4 ng/L and no detection-26.3 ng/L, respectively, and NDMA (no detection-13.9 ng/L and no detection-20.5 ng/L, respectively) and NDEA (no detection-16.3 ng/L and no detection-14.0 ng/L, respectively) were the most abundant. Meanwhile, the occurrence of nine secondary amines corresponding to the nine nitrosamines was also investigated. All of them except for di-n-propylamine were detected in some source water and finished water samples, and dimethylamine (no detection-3.9 μg/L and no detection-4.0 μg/L, respectively) and diethylamine (no detection-2.4 μg/L and no detection-1.8 μg/L, respectively) were the most abundant ones. Controlled experiments involving chloramination of four secondary amines confirmed that dimethylamine, diethylamine, morpholine and di-n-butylamine in water can form the corresponding nitrosamines, with diethylamine and morpholine showing significantly higher yields than dimethylamine which has already been identified as a precursor of NDMA. This study proved that diethylamine, morpholine and di-n-butylamine detected in raw water would be one of the important the precursors of NDEA, NMOR and NDBA, respectively, in drinking water.     

铜镍合金氯化渣富集贵金属

针对含贵金属０．１２％的高冰镍磨浮磁选铜合金氯化浸出渣富集贵金属生产流程中的不足,提出了新的工艺流程结构,包括煤油脱除元素硫－熔炼含贵金属高锍－加压酸浸三个步骤,贱金属分离效率（％）：Ｃｕ９９．５、Ｎｉ９９．８、Ｆｅ９４．５、Ｓ９９．６、ＳｉＯ２９８．８;贵金属回收率（％）：Ｐｔ９８．０、Ｐｄ９７．０、Ａｕ９７．０,产出贵金属品位〉３０％,贵贱比〉１的精矿。     

湿法炼锌过程中除铁工艺的进展

本文论述了常规法浸出、高温高酸浸出、氧压浸出等几种湿法炼锌除铁工艺的基本原理,比较分析了各工艺的技术特点。总结了几种优化及创新工艺,探讨了湿法炼锌除铁工艺改革的发展方向。为该类资源的综合利用提供参考依据。     

Investigating the chlorination of acidic pharmaceuticals and by-product formation aided by an experimental design methodology

The degradation of seven acidic drugs and two metabolites during chlorination was investigated by liquid chromatography-mass spectrometry (LC-MS). A triple-quadrupole (QqQ) system was used to follow the time course of the pharmaceuticals and by-products, while a quadrupole time-of-flight (Q-TOF) system was also used for the identification of the by-products. Under strong chlorination conditions (10 mg/L Cl₂, 24 h), only four of the target compounds were significantly degraded: salicylic acid, naproxen, diclofenac and indomethacine. The degradation kinetics of these four compounds were investigated at different concentrations of chlorine, bromide and pH by means of a Box-Behnken experimental design. Depending on these factors, measured pseudo-first order half-lives were in the ranges: 23-573 h for salicylic acid, 13-446 min for naproxen, 5-328 min for diclofenac and 0.4-13.4 min for indomethacine. Also, it was observed that chlorine concentration was the overall most significant factor, followed by the bromide concentration (except for indomethacine), resulting in increased degradation kinetics as they are increased. The degradation path of salicylic acid, naproxen and diclofenac consisted of aromatic substitution of one or two hydrogens by chlorine and/or bromide. Moreover, for diclofenac, two other by-products corresponding to a decarboxylation/hydroxylation pathway from the monohalogenated products were also identified. On the other hand, indomethacine degradation did not lead to halogenation products but to oxidation ones. The investigation of these by-products in real samples by LC-MS/MS (QqQ) showed that the halogenated derivates of salicylic acid occurred in all the drinking water and wastewater samples analysed.