GC Investigation of the Solubility Parameters of Water-Soluble Homopolymers and Double-Hydrophilic Diblock Copolymers

Solubility parameters of water-soluble 2-(diethylamino)ethyl methacrylate (DEA) homopolymer and [2-(diethylamino)ethyl methacrylate]-[2-(dimethylamino) ethyl methacrylate] (DEA–DMA) diblock copolymer were analyzed by inverse gas chromatography and values were compared to the solubility parameters of 2-(dimethylamino) ethyl methacrylate (DMA) homopolymer. Sorption thermodynamic parameters of some aliphatic, alicyclic and aromatic hydrocarbons, weight fraction activity coefficients, Flory–Huggins interaction parameters and solubility parameters for both hydrocarbons and polymers were calculated. It was observed that sorption thermodynamic parameters on (co)polymers depend on the molecular structures of hydrocarbons. Evaluating both the calculated values of the weight fraction activity coefficients and Flory–Huggins interaction parameters, the solving ability of the hydrocarbons for DEA, DMA homopolymers and DEA–DMA diblock copolymer decreased in the following sequence: aromatic > alicyclic > aliphatic hydrocarbons.     

Thermodynamic interactions of water-soluble homopolymers and double-hydrophilic diblock copolymer

Thermodynamic interaction parameters of water-soluble poly[2-(dimethylamino)ethyl methacrylate] (DMA) and poly[2-(N-morpholino)ethyl methacrylate] (MEMA) homopolymers and their diblock copolymer (DMA–MEMA) were investigated at the temperatures above their glass-transition temperatures (T_g) by inverse gas chromatography (IGC) method. Sorption thermodynamic parameters of some aliphatic, alicyclic and aromatic hydrocarbons, weight fraction activity coefficients, Flory–Huggins interaction parameters, and solubility parameters for hydrocarbons and polymers were calculated. It was observed that sorption thermodynamic parameters on (co)polymers depend on the molecular structures of hydrocarbons. Evaluating both the calculated values of the weight fraction activity coefficients and Flory–Huggins interaction parameters, the solving ability of the hydrocarbons for DMA, MEMA homopolymers, and DMA–MEMA diblock copolymer decreased in the following sequence: Aromatic > alicyclic > aliphatic hydrocarbons.     

A modified square well model in obtaining the surface tension of pure and binary mixtures of hydrocarbons

A model based on the perturbation theory of fluids was proposed to correlate the experimental data for surface tension of pure hydrocarbons in a wide range of temperature. The results obtained for the pure hydrocarbons were directly used to predict the surface tension for binary hydrocarbon mixtures at various temperatures. In the proposed model, a modified form of the square well potential energy between the molecules of the reference fluid was taken into account while the Lennard–Jones dispersion energy was considered to be dominant amongst the molecules as the perturbed term to the reference part of the model. In general, the proposed model has three adjustable parameters which are chain length, m, size, σ, and energy, ε/κ, parameters, but in some cases the number of parameters was reduced to two, thereby setting the chain length to be unity for pure hydrocarbons. The regressed values of these parameters were obtained using the experimental data for pure hydrocarbons at different temperatures. The results showed that these parameters can be related to the molar mass of hydrocarbons. The model was also extended to predict the surface tension of binary hydrocarbon mixtures using the parameters obtained for the pure compounds. It is worth noting that no additional parameter has been introduced into the model in the extension of the model to the mixtures studied in this work. The results showed that the proposed model can accurately correlate the surface tension of pure hydrocarbons. Also the results showed that the surface tension for binary mixture of hydrocarbons can be accurately predicted using the proposed model over a wide temperature range.     

烃类化合物在不同色谱柱上的定量结构-保留相关性研究

运用量子化学中的AMI方法计算烃类化合物的分子结构描述参数,借助逐步回归法建立了烃类化合物在不同极性色谱柱上的QSRR模型。结果表明：烷烃、烯烃、二烯烃类化合物在不同极性的色谱柱上的色谱保留与其分子结构描述参数之间具有较好的线性关系,烃类化合物在不同极性固定相上的保留主要与溶质分子的MR有关,即与溶质分子的色散力有关。随着溶质分子的不饱和度的增加,或固定相极性的增强,溶质分子与固定相之间的电荷传递作用随之增强。而且,烃类化合物在不同极性固定相上的色谱保留的QSRR模型均可用量化参数HOMO、LUMO、EICE以及MR参数来描述。所建立的在不同极性色谱柱上的烃类化合物的色谱保留QSRR模型预测烃类化合物的色谱保留值时具有较好的稳定性和准确性。     

Unified kinetic model of soot formation in the pyrolysis and oxidation of aliphatic and aromatic hydrocarbons in shock waves

The formation of soot particles in the pyrolysis and oxidation of various aromatic and aliphatic hydrocarbons in argon behind reflected shock waves has been investigated by computational and theoretical methods. The hydrocarbons examined include methane, ethane, propane (aliphatic hydrocarbons with ordinary bonds), acetylene, ethylene, propylene (aliphatic hydrocarbons with multiple bonds), benzene, toluene, and ethylbenzene (simplest aromatic hydrocarbons). Soot formation in the pyrolysis and oxidation of both aromatic and aliphatic hydrocarbons can be simulated in detail within a unified kinetic model. The predictive power of the unified kinetic model has been verified by directly comparing the calculated kinetic data for the formation of products and reactive radicals in the pyrolysis and oxidation of various hydrocarbons to the corresponding experimental data. In all calculations, all the kinetic parameters of the unified kinetic model were strictly fixed. A good quantitative fit between the data calculated via the unified kinetic model and experimental data has been attained.     

Simultaneous determination of 16 polycyclic aromatic hydrocarbons in reclaimed water using solid‐phase extraction followed by ultra‐performance convergence chromatography with photodiode array detection

A new fast and effective analysis method has been developed to simultaneously determine 16 polycyclic aromatic hydrocarbons in reclaimed water samples by ultra‐performance convergence chromatography with photodiode array detection and solid‐phase extraction. The parameters of ultra‐performance convergence chromatography on the separation behaviors and the crucial condition of solid‐phase extraction were investigated systematically. Under optimal conditions, the 16 polycyclic aromatic hydrocarbons could be separated within 4 min. The limits of detection and quantification were in the range of 0.4–4 and 1–10 μg/L in water, respectively. This approach has been applied to a real industrial wastewater treatment plant successfully. The results showed that polycyclic aromatic hydrocarbons were dramatically decreased after chemical treatment procedure, and the oxidation procedure was effective to remove trace polycyclic aromatic hydrocarbons.     

Computer-assisted retention prediction of polycyclic aromatic hydrocarbons in supercritical fluid chromatography using carbon dioxide as the mobile phase

Summary The dependence of the capacity factor of polycyclic aromatic hydrocarbons on column temperature and on the density of the mobile phase in supercritical-fluid chromatography was investigated using carbon dioxide as the mobile phase. Logarithmic capacity factors of polycyclic aromatic hydrocarbons were obtained as a linear function of the reciprocal column temperature at a constant molar volume of carbon dioxide.The application of the Retention Prediction System to supercritical-fluid chromatography is demonstrated: one can predict the retention of polycyclic aromatic hydrocarbons using equations including column temperature, density and the physico-chemical properties of the solutes as the parameters.     

Retention prediction of large and condensed polycyclic aromatic hydrocarbons in reversed-phase microcolumn liquid chromatography with diphenylsilica stationary phase

The retention behavior of condensed large polycyclic aromatic hydrocarbons has been investigated with diphenylsilica stationary phases in reversed-phase microcolumn liquid chromatography. The results were correlated with two parameters which indicate size and shape of the molecules. Since the resulting equation can be used for retention prediction of large polycyclic aromatic hydrocarbons, computer-assisted “standardless” identification is accomplished for “unknown” compounds contained in the standard.     

化学计量学方法用于多环芳烃液相色谱分离条件优化

本文报道化学计量学方法用于多环芳烃(PAHs)液相色谱分离条件的优化.使用均匀实验设计法,以乙腈在线性梯度展开时的初始浓度和线性梯度的斜率为优化参数,对16种多环芳烃混合体系进行液相色谱分离条件优化,采用遗传算法和退火神经网络方法建立了有效的分离条件预测模型.对模型所预测的最佳分离条件进行试验,分离结果满意.     

Determination of chlorinated polycyclic aromatic hydrocarbons in water by solid‐phase extraction coupled with gas chromatography and mass spectrometry

Given the potential risks of chlorinated polycyclic aromatic hydrocarbons, the analysis of their presence in water is very urgent. We have developed a novel procedure for determining chlorinated polycyclic aromatic hydrocarbons in water based on solid‐phase extraction coupled with gas chromatography and mass spectrometry. The extraction parameters of solid‐phase extraction were optimized in detail. Under the optimal conditions, the proposed method showed wide linear ranges (1.0–1000 ng/L) with correlation coefficients ranging from 0.9952 to 0.9998. The limits of detection and the limits of quantification were in the range of 0.015–0.591 and 0.045–1.502 ng/L, respectively. Recoveries ranged from 82.5 to 102.6% with relative standard deviations below 9.2%. The obtained method was applied successfully to the determination of chlorinated polycyclic aromatic hydrocarbons in real water samples. Most of the chlorinated polycyclic aromatic hydrocarbons were detected and 1‐monochloropyrene was predominant in the studied water samples. This is the first report of chlorinated polycyclic aromatic hydrocarbons in water samples in China. The toxic equivalency quotients of chlorinated polycyclic aromatic hydrocarbons in the studied tap water were 9.95 ng the toxic equivalency quotient m^?3. 9,10‐Dichloroanthracene and 1‐monochloropyrene accounted for the majority of the total toxic equivalency quotients of chlorinated polycyclic aromatic hydrocarbons in tap water.     

Conversion of natural gas to C_2 hydrocarbons through dielectric-barrier discharge plasma catalysis

The experiments are carried out in the system of continuous flow reactors with dielectric-barrier discharge (DBD) for studies on the conversion of natural gas to C2 hydrocarbons through plasma catalysis under the atmosphere pressure and room temperature. The influence of discharge frequency, structure of electrode, discharge voltage, number of electrode, ratio of H2/CH4, flow rate and catalyst on conversion of methane and selectivity of C2 hydrocarbons are investigated. At the same time, the reaction process is investigated. Higher conversion of methane and selectivity of C2 hydrocarbons are achieved and deposited carbons are eliminated by proper choice of parameters. The appropriate operation parameters in dielectric-barrier discharge plasma field are that the supply voltage is 20-40 kV (8.4-40 W), the frequency of power supply is 20 kHz, the structure of (b) electrode is suitable, and the flow of methane is 20-60 ml · min-1. The conversion of methane can reach 45%, the selectivity of C2 hydrocarbons i     

Novel kinetic modelling of methanol-to-gasoline (MTG) reaction on HZSM-5 catalyst: Product distribution

A new kinetic model of MTG process on HZSM-5 catalyst, which enables us to predict the distribution of the subdivided product, has been proposed. The new model includes four reaction steps with oxygenates, C₂~C₄ unsaturated hydrocarbons, C₅₊ unsaturated hydrocarbons, C₁~C₄ saturated hydrocarbons, C₅₊ saturated hydrocarbons and aromatics as the product lumps. The kinetic parameters have been calculated using this model. The objective function has been introduced to check the availability of calculation. Based on the above kinetic parameters, a MTG fixed bed process has been simulated kinetically by using Aspen Plus.     

Calculation of heats of formation for carbocyclic compounds

A method previously described is applied to the heats of formation of gaseous saturated and unsaturated alicyclic and aromatic hydrocarbons as well as hydrocarbons with several conjugated double bonds. Some energy parameters of carbon in these compounds are evaluated.     

A new modification of the UNIQUAC equation including temperature dependent parameters

The UNIQUAC equation was modified by introduction of a linear temperature dependence of the volume and surface area parameters, r_i and q_i. The slope of r_i and q_i functions were found to be the same for hydrocarbons and pyridine. The modified equation was used for prediction of vapor–liquid equilibria (VLE) in binary mixtures of hydrocarbons and pyridine with hydrocarbons as well as for the prediction of the excess enthalpy (H^E) in binary mixtures formed by pyridine with aliphatic alkanes. The results obtained were compared with predictions by UNIFAC and further with UNIQUAC equation and its modification involving temperature dependant coordination number z. The proposed temperature dependence of the r_i and q_i parameters enables prediction of the VLE at various temperatures and leads to reasonable values of H^E. The necessary input reduces to one set of isothermal VLE data. One set of UNIQUAC interaction parameters u_ij is sufficient for representation of VLE in a wide range of temperature and to obtain a reasonable prediction of H^E.     

Characterization of Oil by Micro-Solid-Phase Extraction and Gas Chromatography–Mass Spectrometry

Micro-solid-phase extraction is reported for the preparation of Bohai crude oil for the determination of hydrocarbons by gas chromatography-mass spectrometry. The operational parameters were optimized. Micro-solid-phase extraction provided higher quantities of low-molecular weight components than conventional liquid chromatography. The concentrations of high-molecular weight n-alkanes, polycyclic aromatic hydrocarbons, and their alkylated homologs obtained were comparable by micro-solid-phase extraction and liquid chromatography. The diagnostic ratios also indicated that there were no significant differences between these methods. Therefore, micro-solid-phase extraction with gas chromatography–mass spectrometry is recommended for the characterization of spilled oil.     

Estimation of boiling and melting points of light,heavy and complex hydrocarbons by means of a modified group vector space method

A modified group vector space (GVS) method was developed for estimating the normal boiling points and melting points of alkanes, alkenes, alkynes, and cyclic and aromatic hydrocarbons including their isomers. The present method, based on group contributions as well as topological contributions, can represent the normal boiling points of isomeric compounds accurately. The group parameters for the modified GVS method were obtained from the correlation of the boiling and melting points of 1115 hydrocarbons.     

Reactions of carbocations with unsaturated hydrocarbons: electrophilic alkylation or hydride abstraction?

Benzhydryl cations were used as reference electrophiles to determine the hydride donor reactivities of unsaturated hydrocarbons. The kinetics of the reactions were followed by UV-vis spectroscopy and conductivity measurements, and it was found that the second-order rate constants for the hydride transfer processes were almost independent of the solvents or counterions employed. The rate constants correlate linearly with the previously published empirical electrophilicity parameters E of the benzhydrylium ions. Therefore, the linear free energy relationship log k(20 degrees C) = s(E + N) could be employed to characterize the hydride reactivities of the hydrocarbons by the nucleophilicity parameters N and s. The similarity of the slopes s for hydride donors and pi-nucleophiles allows a direct comparison of the reactivities of these different functional groups based on their nucleophilicity parameters N. Since nucleophilicity parameters of -5 < N < 0 have been found for a large variety of allylic and bisallylic hydride donors, a rule of thumb is derived that hydride transfer processes may compete with carbon-carbon bond-forming reactions when carbocations are combined with olefins of pi-nucleophilicity N < 0.     

Electronic structure of saturated hydrocarbons in the semiempirical equivalent orbital method

The problem of matrix elements of the Hartree-Fock Hamiltonian for saturated hydrocarbons in the EO method is considered. It is stated, that all the proposed scales of such parameters are incomplete or lead to an incorrect band structure of diamond. It is shown that the data on the band structure of diamond may be useful to obtain the full scale of the parameters for the calculations of the electronic structure of hydrocarbons.     

Production of Carbon Nanotubes over Pre-reduced LaCoO_3 Using Fluidized-bed Reactor

A great amount of research on carbon nanotubes (CNTs) has been carried out since its observation in 19911. It has been predicted that CNTs can be novel materials of semiconductor, electric-field-induced electron emitters, quantum wire, catalysts etc2-5. Nowadays, CNTs can be synthesized by arc discharge6 laser ablation7, and pyrolysis of hydrocarbon gases8. In order to make CNTs of practical importance, the criteria for assessing any synthesis technique must include the feasibility and po…     

Magneto-optische Rotationsdispersion von gesättigten aliphatischen Kohlenwasserstoffen

Magneto-optical rotatory dispersion (MORD.) of saturated aliphatic hydrocarbons can be described very accurately by an equation of the DRUDE type. The two parameters, appearing in such an equation, have been determined from MOR. measurements in the region of 240 to 500 nm by the method of least squares. These parameters show a systematic dependence on the structure of the investigated hydrocarbons. An empirical rule for the approximation of the DRUDE parameters is given which in turn allow the calculation of the VERDET constant for a given structure at any wavelength between 240 and 500 nm.