Esters Dimethyl Phthalate Research Articles

Adsorption of phthalic acid and its esters onto high-area activated carbon-cloth studied by in situ UV-spectroscopy

The adsorption behavior of phthalic acid and its three esters dimethyl phthalate, diethyl phthalate and diallyl phthalate onto high-area activated carbon-cloth was studied by in situ UV-spectroscopic technique. The effect of ionization of phthalic acid on its adsorption was examined by carrying out the adsorption process in three media; water, 1 M H 2SO 4 and 0.005 M NaOH. Maximum adsorption was observed in 1 M H 2SO 4 and almost no adsorption in 0.005 M NaOH. These results were discussed in terms of electrostatic and dispersion interactions between the adsorbate species and the carbon-cloth surface taking the point of zero charge (pH pzc) of the carbon-cloth into account. The adsorption process for the phthalate species studied was found to follow the first-order rate law, and the rate constants were determined. The isotherm data for the adsorption of phthalic acid and its esters were derived experimentally and fitted to Langmuir and Freundlich isotherm equations. Both equations were found to represent the experimental isotherm data almost equally well.

{\rtf1\ansi\ansicpg1250\deff0\deflang1038\deflangfe1038\deftab708{\fonttbl{\f0\froman\fprq2\fcharset238{\*\fname Times New Roman;}Times New Roman CE;}} \viewkind4\uc1\pard\f0\fs20 Saturation determination of micellar systems using isothermal titration calorimetry \par }

A novel method for the determination of the point of micellar saturation has been developed. To exemplify the theory a model system was considered, this being the saturation of two aqueous micellar solvents with dimethyl phthalate ester (DMP). Upon addition of a hydrophobic compound to an aqueous micellar system partitioning will occur. On further addition, the inner hydrophobic regions will eventually be unable to accommodate any more DMP and, at this specific concentration, the micelle is saturated. With a comparatively large enthalpy change upon partitioning the point of saturation can be determined by a corresponding significant reduction in enthalpy change.

Dimethyl phthalate ester degradation by two planktonic and immobilized bacterial consortia

Abstract Degradation of the plasticizer ortho-dimethyl phthalate ester (DMPE) was investigated using two reconstituted consortia under aerobic conditions. The consortia consisting of two and three bacterial cultures showed capability in the complete degradation of DMPE in less than 5 days at an initial concentration of 400 mg l −1 . Consortium I, comprised of Pseudomonas fluorescens, P. aureofaciens and Sphingomonas paucimobilis, appeared to be more effective in degradation than Consortium II consisting of Xanthomonas maltophilia and S. paucimobilis. The Gompertz function and the Richards function were modified and used to fit the DMPE degradation data and the results indicated that the modified Richards model was always better than the modified Gompertz model in fitting the experimental data. In addition, microorganisms capable of degrading DMPE were subsequently immobilized on the microporous hollow fibres using calcium alginate entrapment techniques. The efficiency of DMPE degradation by the immobilized bacteria of Consortium I was compared with the batch culture system. The results showed that immobilization of microorganisms could further improve the rates of degradation. Our data suggest that microbial degradation of DMPE can be described by the modified Richards model and the plasticizer DMPE can be mineralized by consortia of bacteria either in planktonic culture or immobilized on surfaces.

Microbial degradation of endocrine-disrupting organic compounds and environmental residues of pharmaceutical compounds

Synthetic organic pollutants are not only toxic and accumulative but also able to induce malformation and mutation. Contamination of synthetic compounds in environment disrupts the endocrine system in organisms including human beings. Developed countries have established regulations to limit and control the amount of these compounds in water and food chain. It is clearly known that some herbicides and insecticides (e.g. atrazine and DDT), and plasticizers are all endocrine-disrupting organics, which have adverse effect on the normal development of organisms. These compounds, however, present widely in the environment. The concentration could be extremely high under special circumstance. For example, as high as 10 g · L-1 of phthalic acid and dimethyl phthalate ester (DMPE) were found in landfill leachate. According to our investigation on microbial degradation of phthalic acid and DMPE, enrichment culture obtained from activated sludge and mangrove can mineralize this kind of compounds within short period of time. It is also found that single bacterial species is not able to completely degrade DMPE. Consortium of two or three pure species could mineralize DMPE at a concentration of 500 mg·L-1 within one week. Two degradation intermediates were isolated and identified, and degradation pathway has been established in our investigation. It has been approved that environmental hormone such as DMPE could be mineralized by microorganisms. On the other hand, environmental residues of pharmaceutical compounds are an emerging problem and more attention should be paid to conduct research in this field.

Aerobic degradation of phthalic acid by Comamonas acidovoran Fy-1 and dimethyl phthalate ester by two reconstituted consortia from sewage sludge at high concentrations

Microbial degradation of phthalic acid (PA) and dimethyl phthalate ester (DMPE) under aerobic conditions was investigated using a pure species of bacteria and two consortia from sewage sludge. Five morphologically distinct microorganisms were obtained in pure culture and identified, and tested for the capability of degrading phthalate and DMPE. Comamonas acidovorans strain Fy-1 showed the highest ability to degrade high concentrations of phthalate (2600 mg/l) within 48 h. Two reconstituted consortia of microorganisms, one comprising Pseudomonas fluorescens, P. aureofaciens and Sphingomonas paucimobilis, and the other of Xanthomonas maltophilia and S. paucimobilis, were effective in completely degrading DMPE (400 mg/l) in 48–96 h. The three-species consortium appeared to be more effective in the degradation of DMPE, and both consortia proceeded via formation of mono-methyl phthalate (MMP) and then phthalatic acid before mineralization. This study suggests that high concentrations of the endocrine-disrupting chemicals phthalate and DMPE can be mineralized in wastewater treatment systems by indigenous microorganisms.

Adduct formation between phthalate esters and Li + in the gas phase: a thermochemical study by FT-ICR mass spectrometry

The lithium-cation basicity (LCB=Gibbs energy of adduct dissociation) of methyl benzoate, and the three isomeric dimethyl phthalates (phthalate, iso- and tere-phthalate) has been determined by Fourier transform ion cyclotron resonance (FT-ICR), using the kinetic method. The dimethyl phthalate ester appears to be a relatively strong base toward Li +, as compared to the other isomers and to methyl benzoate. This is attributed to the chelation effect of the two carboxyl groups. The previously unknown protonic gas-phase basicity of dimethyl phthalate was also determined. Chelation makes also dimethyl phthalate a much stronger base than the two other isomers toward H +, but its protonated form decomposes readily by loss of a methanol molecule.

Adsorption of phthalate esters on soil at near saturation conditions

Batch studies were performed to determine the adsorption behavior of dimethyl phthalate ester and diethyl phthalate ester on two sandy New Jersey soils at near saturation conditions. One soil had a very low organic matter content (<0.012%) while the other was quite higher (1.33%). Both esters displayed BET type adsorption to the high organic content soil, while little adsorption was displayed to the low organic matter soil. Linear, Langmuir, Freundlich, BET, and a composite isotherm proposed by Marinas and Li were fitted to the data. The composite isotherm fir best in all cases. The diethyl phthalate evidence a greater tendency to adsorb than the dimethyl phthalate.

Anaerobic biodegradability of phthalic acid isomers and related compounds.

All three phthalic acid isomers (ortho, meta and para benzene dicarboxylic acid) are produced in massive amounts, and used in the chemical industry as plasticizers or for the production of polyester. Wastestreams generated during the production of phthalate isomers generally contain high concentrations of aromatic acids. To study the potential biodegradability of these primarily anthropogenic compounds in anaerobic bioreactors, biodegradability studies were performed. Compounds tested were benzoate, ortho-phthalate, isophthalate, terephthalate, dimethyl phthalate, dimethyl terephthalate, para-toluate and para-xylene. Seed materials tested were two types of granular sludge and digested sewage sludge. It was found that all phthalate isomers and their corresponding dimethyl-esters, could be completely mineralized by all seed materials studied. Lag phases required for 50% degradation of these compounds, ranged from 17 to 156 days. The observed degradation curves could be explained by growth of an initially small amount of organisms in the inoculum with the specific ability to degrade one phthalate isomer. The observed order in the length of the lag phases for the phthalate isomers is: phthalate < terephthalate < isophthalate. This order appears to be related to the environmental abundancy of the different phthalate isomers. The initial step in the degradation pathway of both dimethyl phthalate esters was hydrolysis of the ester sidechain, resulting in the formation of the corresponding mono-methyl-phthalate isomer and phthalate isomer. The rate limiting step in mineralization of both dimethyl phthalate and dimethyl terephthalate was found to be fermentation of the phthalate isomer. Para-toluate was degraded only by digested sewage sludge after a lag phase of 425 days. The observed degradation rates of this compound were very low. No mineralization of para-xylene was observed. In general, the differences in the lag phases between different seed materials were relatively small. These results indicate that the time needed for the start-up of anaerobic bioreactors treating wastewaters containing phthalic acid isomers, depends little on the microbial composition of the seed material applied, but may take several months.

Post-column extraction system for use with high-performance liquid chromatography

A simple system for on-line sample extraction following reversed-phase high-performance liquid chromatographic ( HPLC) analysis is presented. The system can be used to prepare samples for direct probe insertion mass spectrometry ( MS), infrared analysis or other techniques. The extraction cell has also been used for continuous on-line HPLC-MS. The system is based on post-column chloroform extraction of the eluted compounds from polar mobile phases consisting of methanol or acetonitrile-0.1 M potassium dihydrogen orthophosphate buffer or water. The organic solvent is mixed with the column effluent using a commercially available post-column reaction device. The non-polar phase is separated by pressurized filtration through a Teflon membrane, which acts as a barrier to the aqueous portion of the eluent. The extracted solutes are detected using an ultraviolet spectrophotometer. A portion of the organic solvent that contains the eluted component can be collected easily, examined by other analytical techniques or, as will be shown, the solvent can be applied to a moving belt interface for introduction into a mass spectrometer. The system has been used for the extraction and detection of four model compounds (dimethyl, diethyl, diisobutyl and diamyl phthalate esters). The linear range of detection by on-line mass spectrometry was shown to extend to at least 1.2 μg of each ester.

Toxic effect of a normal series of phthalate esters on the hatching of shrimp eggs

The purpose of this work is to show the toxic order of phthalate esters on the hatching of shrimp eggs. Five phthalate esters (dimethyl phthalate ester, diethyl phthalate ester, dibutyl phthalate ester, dihexyl phthalate ester, and dioctyl phthalate ester) were tested for the hatching of brine shrimp ( Artemia salina) eggs. The toxic order of three phthalate esters was dibutyl phthalate > diethyl phthalate > dimethyl phthalate. The water solubility of the phthalate esters was not related to their toxicity.