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Published in Salmi Tapio, Mikkola Jyri-Pekka, Wärnå Johan, Chemical Reaction Engineering and Reactor Technology, 2019
Salmi Tapio, Mikkola Jyri-Pekka, Wärnå Johan
The reaction should be carried out adiabatically in a semibatch reactor, feeding hexanol into the liquid maleic acid. The reactor volume is 500 dm3, and no solvent is used. Maleic acid melts at 53°C. A maximum temperature of 100°C may not be exceeded due to the formation of by-products. The reaction is of second order, and the rate constant is expressed as k=1.37×1012exp−12,628KTdm3/mols.
Ring-opening pathway of 2, 4, 6-trichlorophenol initiated by OH radical: an insight from first principle study
Published in Molecular Physics, 2020
Subrata Paul, Ramesh Chandra Deka, Nand Kishor Gour, Abhishek Singh
Because of poor biodegradability and carcinogenicity of chlorophenols, 2, 4, 6-TCP is among the priority contaminants of major environmental concern. The strong C–Cl bond and the position of Cl atom relative to the hydroxyl group are the main reason for its toxicity and their persistence in the biological environment [22]. It is important to note that due to structural stability, toxicity and persistence, it is difficult to remove from the biological environment. When 2, 4, 6-TCP is heated, it emits corrosive fumes of hydrochloric acid and other toxic gases in the atmosphere. Benitez et al. [23] first performed the experimental study using batch reactor on the kinetics of the decomposition of 2, 4, 6-TCP by ozonation and by Fenton’s reagent reaction and found the rate constant of 5.48 × 109 M−1, s−1 at 25°C for the direct reaction between 2, 4, 6-TCP and hydroxyl radicals (•OH). Further, the decomposition pathway of the ozonation of 2, 4, 6-TCP in aqueous solution was investigated by Yunzheng et al. [24]. They proposed that in the presence or absence of OH• radicals the molecular ozone firstly oxidised 2, 4, 6-TCP to chlorinated quinine, which is subsequently degraded to formic acid and oxalic acid. Mayani et al. [25] further investigated the oxidative degradation of 2-CP, 4-CP, and 2, 4, 6-TCP by Co(II) and Ni(II) impregnated SBA-15 catalyst in an aqueous medium. They reported that in the catalytic oxidation of 2, 4, 6-TCP formed 2, 6-dichloro-1, 4-benzoquinone, maleic acid, fumaric acid, oxalic acid and glyoxylic acid.
Synthesis, colloidal-chemical and petroleum collecting properties of new counterion coupled gemini surfactants based on hexadecylbis(2-hydroxypropyl)amine and dicarboxylic acids
Published in Journal of Dispersion Science and Technology, 2020
Ziyafaddin H. Asadov, Saida M. Huseynova, Gulnara A. Ahmadova, Ravan A. Rahimov, Seyran U. Sharbatov, Fedor I. Zubkov, Rana A. Jafarova
Increasing the length of the alkyl chain results in an increase of hydrophobicity of the cocogem surfactants because more molecules become able to approach the interface. It results in a decrease in Γmax and an increase in Amin. As the length of the alkyl chain increases in the spacer, more ions acquire ability to approach the air-water interface. Therefore, the unit area covered per molecule increases during adsorption across water/air boundary. In the case of cis- and trans-isomerism, as it is seen in maleic and fumaric acids, Γmax depends on the type of the isomerism. Γmax of the maleic acid which is in cis-position is lower than the corresponding parameter of fumaric acid which is in trans-position. The reason behind this is that when the spacer group contains the cis-position chain in the adsorption process, surfactant molecules and adsorbates hinder each other. That’s why the area occupied by the molecules is larger which means a higher value of Amin and a lower value of Γmax.
Removal mechanism of persistent organic pollutants by Fe-C micro-electrolysis
Published in Environmental Technology, 2022
Dajun Ren, Yongwei Huang, Sheng Li, Zhaobo Wang, Shuqin Zhang, Xiaoqing Zhang, Xiangyi Gong
Under acidic conditions, 2,4-DCP undergoes substitution and reduction reactions. The chlorine or hydrogen on the benzene ring is substituted to produce 3,5-dichlorocatechol, 2-Chlorohydroquinone and 4-chlorophenol. These compounds are further dechlorinated and dehydroxylated to form phenol. The formation of Maleic acid and Glyoxylic acid is because •OH and O• destroy the structure of phenol, which makes the phenol ring-open and break. And then Maleic acid and Glyoxylic acid continue to be degraded until they are completely mineralized into CO2 and H2O.