The formation of organic peroxides in the Cl\|atom\|initiated photooxidation of CH\-4 in O\-2\|N\-2 mixtures at 101 325 Pa and 298 K was studied with HPLC and FT\|IR methods. Four peroxidic products were detected, whi...
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The formation of organic peroxides in the Cl\|atom\|initiated photooxidation of CH\-4 in O\-2\|N\-2 mixtures at 101 325 Pa and 298 K was studied with HPLC and FT\|IR methods. Four peroxidic products were detected, which were H\-2O\-2, hydroxymethyl hydroperoxide (HOCH\-2OOH; HMHP), methyl peroxide (CH\-3OOH; MHP) and dimethyl peroxide (CH\-3OOCH\-3). A chromatogram peak at retention time of 8.08 min was assigned tentatively to peroxyformic acid (HC(O)OOH). The identification of HMHP in the reaction system showed that one of the reaction paths for the self\|reaction of CH\-3OO· led to producing Criegee intermediate ·CH\-2OO·. The formation mechanism of organic peroxide in the photooxidation of CH\-4 is more complicated than it was assumed before. Photooxidation of CH\-4 is probably an important source of organic peroxides in the troposphere.
Microorganisms capable of degrading di-n-butyl phthalate (DBP) were immobilized by polyvinyl alcohol (PVA) and used for DBP degradation. The characteristics of DBP degradation by immobilized and free cells were invest...
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Microorganisms capable of degrading di-n-butyl phthalate (DBP) were immobilized by polyvinyl alcohol (PVA) and used for DBP degradation. The characteristics of DBP degradation by immobilized and free cells were investigated. The experimental results showed that the degradation rate of immobilized cells was higher than that of free cells. The optimal pH and temperature for DBP degradation were determined to be 7.0 and 25 degrees C, respectively. The semi-continuous degradation test demonstrated that high-frequency feeding of low concentration (50 mg/L) was more favourable than low-frequency feeding of high concentration (150 mg/L) for DBP degradation. The main intermediates of DBP degradation by immobilized cells were identified using a gas chromatography/mass spectrometry method. The results revealed the presence of monobutyl phthalate, phthalic acid, and protocatechuate. A tentative pathway for DBP degradation was proposed, which demonstrated that the metabolic mechanism of immobilized cells remained the same as that of the free cells. (C) 1997 Elsevier Science Ltd.
The biodegradation of di-n-butyl phthalate (DBP) in soil microcosoms by indigenous microbial population and a DBP degrading inoculum as well as DBP adsorption by soil was investigated. The results demonstrated that th...
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The biodegradation of di-n-butyl phthalate (DBP) in soil microcosoms by indigenous microbial population and a DBP degrading inoculum as well as DBP adsorption by soil was investigated. The results demonstrated that the adsorption of DBP by soil conformed to Freundlich equation. The indigenous bacteria were capable of degrading phthalate in soil. The innoculation of the soil with DBP degrader enhanced the DBP degradation rate. The enumeration of microorganisms indicated a good correlation between phthalate degradation and microbial counts. (C) 1997 Elsevier Science Ltd.
Activated sludge obtained from a coke-plant wastewater treatment plant was acclimated and used as seeding microbes to investigate the kinetics of biodegradation of di-n-butyl phthalate (DBP), one of the most frequentl...
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Activated sludge obtained from a coke-plant wastewater treatment plant was acclimated and used as seeding microbes to investigate the kinetics of biodegradation of di-n-butyl phthalate (DBP), one of the most frequently identified phthalic acid esters in diverse environments and the most widely used plasticizer in China. DBP biodegradation conformed to the first-order model with respect to its concentration and the rate constant was independent of the initial concentration when the initial DBP concentration was less than 200 mg/litre. (C) 1997 Elsevier Science Ltd.
A new cell immobilization method based on the replacement of KCl by KCl+chitosan as the gelling agent was developed. The experimental results showed that through addition of chitosan into gelling agent, the mechanica...
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A new cell immobilization method based on the replacement of KCl by KCl+chitosan as the gelling agent was developed. The experimental results showed that through addition of chitosan into gelling agent, the mechanical strength and the thermal stability of the carrageenan gel were greatly improved. The new immobilization method was used to entrap a chlorophenol degrading microorganism. The immobilized microbial cells were applied for chlorophenol biodegradation. The experiments demonstrated that immobilized cells exhibit a higher bioactivity in the degradation of chlorophenol than free cells.
A fast and efficient adaptive sampling algorithm to obtain the response surface of multivariable objective function is presented. The algorithm is divided into two stages. First, starting with a low-rank interpolation...
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