Henry's law constant, octanol-air partition coefficient and supercooled liquid vapor pressure of carbazole as a function of temperature: application to gas/particle partitioning in the atmosphere

The Henry's law constant for carbazole was experimentally determined between 5 and 35 degrees C using a gas-stripping technique. The following equation was obtained for dimensionless Henry's law constant (H') versus temperature (T, K): ln H' = -3982(T,K)(-1) + 1.01. Temperature-dependent octanol-air partition coefficients (KOA) and supercooled liquid vapor pressures (PL,Pa) of carbazole were also determined using the GC retention time method. The temperature dependence of KOA and PL were explained by the following: log KOA = 4076/(T,K) - 5.65, log PL(Pa) = -3948(T,K)(- 1) + 11.48.The gas and particle-phase carbazole concentrations measured previously in Chicago, IL in 1995 was used for gas/particle partitioning modeling. Octanol based absorptive partitioning model consistently underpredicted the gas/particle partition coefficients (Kp) for all sampling periods. However, overall there was a good agreement between the measured Kp and soot-based model predictions.     

Temperature dependence of hydroxyl radical formation in the hv/Fe3+/H2O2 and Fe3+/H2O2 systems

The thermal enhancement of the formation of *OH by the hv/Fe(III)/H2O2 system (including the Fe(III)/H2O2 system) was quantitatively investigated with reaction temperatures ranging from 25 to 50 degrees C. A temperature dependent kinetic model for the hv/Fe(III)/H2O2 system, incorporating 12 major reactions with no fitted rate constants or activation energies, was developed, and successfully explained the experimental measurements. Particularly, the thermal enhancement of Fe(OH)2+ photolysis which is the most significant step in the hv/Fe(III)/H2O2 system was effectively explained by two factors; (1) the variation of the Fe(OH)2+ concentration with temperature, and (2) the temperature dependence of the quantum yield for Fe(OH)2+ photolysis (measured activation energy=11.4 kJ mol(-1)). Although in both the hv/Fe(III)/H2O2 and Fe(III)/H2O2 systems, elevated temperatures enhanced the formation of *OH, the thermal enhancement was much higher in the dark Fe(III)/H2O2 system than the hv/Fe(III)/H2O2 system. Furthermore, it was found that the relative thermal enhancement of the formation of *OH in the presence of *OH scavengers (tert-butyl alcohol) was magnified in the Fe(III)/H2O2 system but was not in the hv/Fe(III)/H2O2 system.     

A review of Henry's law coefficients for chlorine-containing C1 and C2 hydrocarbons

Experimentally determined Henry's law coefficients of 18 chlorinated C(1) and C(2) hydrocarbons reported in the literature as a function of temperature and at the single temperatures 20 and 25 degrees C were compiled and converted to common units of concentration and pressure: K(H) (moldm(-3)atm(-1)). The individual values are plotted in the ln(K(H)) versus reciprocal absolute temperature coordinate frame, data not in harmony with others were deleted, and the resulting data sets treated by linear regression analysis to derive averaged parameters in the general equation ln(K(H))=A+B/T. The quality of the evaluation was further checked by comparison of values calculated from the resulting parameter values with averages obtained from the direct measurements at 20 degrees C. Good agreement was observed for 15 compounds, larger discrepancies arise only for chloroethane, 1,2-dichloroethane and hexachloroethane. In all three cases the data base is poor and needs to be improved. The results are used to derive heats of solution for the C(1) and C(2) chlorinated hydrocarbons in water, Gibbs energies of solution and standard Henry's law coefficients at 298.15K. Henry's law coefficients calculated from the ratio of solubility of the compound in water and the saturation vapor pressure of the pure compound reported by Sangster [Sangster, J.M., 2003. Henry's law constants for compounds stable in water. In: Fogg, P.G.T., Sangster, J.M. (Eds.), Chemicals in the Atmosphere - Solubility, Sources and Reactivity. Wiley, Chichester, West Sussex, England, pp. 255-397] provide good agreement with the experimental data in eight out of eleven cases treated.     

Comparisons of PCBs dechlorination occurrences in various contaminated sediments

A comparison was made of reductive dechlorination occurrences of polychlorinated biphenyls (PCBs) by microorganisms collected from contaminated sediments including Er-Jen River (Tainan, Taiwan), Hudson River (Ft. Edward, NY), Silver Lake (Pittsfield, MA) and Puget Sound (Washington State). Comparisons was made in terms of chromatographic data (referring to the biological activity, including microbial availability) and thermodynamic data (demonstrating the selectivity of anaerobic microorganisms in the dechlorination of chlorinated compounds). Chromatographic data was established in terms of difference in relative retention time (delta ln RRT) and thermodynamic data was estimated as heat of reaction (delta H(r)0). Both were calculated and correlated to occurrences of dechlorination reactions. Observed dechlorination reactions for individually introducing PCB congener had delta ln RRT levels measured as >0.47 (Er-Jen River), >0.29 (Hudson River), >0.36 (Silver Lake) and >0.45 (Puget Sound, for Aroclor 1254 dechlorination). Critical of delta H(r)0 and delta ln RRT values showed that Hudson River and Silver Lake microorganisms were capable of dechlorinating PCBs through reactions with larger H(r)0 value (lower levels of released energy) and smaller delta ln RRT value compared with those found in Er-Jen River and Puget Sound sediments. Differences in the critical delta ln RRT values of these sediments may be due to differences in their levels of PCB contamination.     

Temperature dependent properties of environmentally important synthetic musks

Environmental fate determining physical properties including their temperature dependence for five nitro musks and for seven polycyclic musks were estimated. The properties evaluated were vapor pressure in a solid and liquid state (PS and PL), solubility in water (S), Henry's law coefficient (H = PL/S) and log octanol-water partition coefficient (log KOW). Gas chromatography for starting values of vapor pressure estimation and HPLC experiments at 5-20 degrees C for comparison of the theoretical versus experimental solubilities in water were performed. The values of temperature (T) dependence coefficients (Ai and Bi) in equations: log (Property)i = Ai - Bi/T were determined. Values of properties were compared with literature-based data, and an example of their use in environmental hazard estimation by fate modeling was given.     

Kinetics of OH radical reactions with dibenzo-p-dioxin and selected chlorinated dibenzo-p-dioxins

The pulsed laser photolysis/pulsed laser-induced fluorescence (PLP/PLIF) technique has been applied to obtain rate coefficients for OH + dioxin (DD) (k1), OH + 2-chlorodibenzo-p-dioxin (2-CDD) (k2), OH + 2,3-dichlorodibenzo-p-dioxin (2,3-DCDD) (k3), OH + 2,7-dichlorodibenzo-p-dioxin (2,7-DCDD) (k4), OH + 2,8-dichlorodibenzo-p-dioxin (2,8-DCDD) (k5), OH + 1,2,3,4-tetrachlorodibenzo-p-dioxin (1,2,3,4-TCDD) (k6), and OH + octachlorodibenzo-p-dioxin (OCDD) (k7) over an extended range of temperature. The atmospheric pressure (740 +/- 10 Torr) rate measurements are characterized by the following Arrhenius parameters (in units of cm3 molecule(-1) s(-1), error limits are 1 omega): k1(326-907 K) = (1.70+/-0.22) x 10(-12)exp(979+/-55)/T, k2(346-905 K) = (2.79+/-0.27) x 10(-12)exp(784+/-54)/T, k3(400-927 K) = 10(-12)exp(742+/-67)/T, k4(390-769 K) = (1.10+/-0.10) x 10(-12)exp(569+/-53)/T, k5(379-931 K) = (1.02+/-0.10) x 10(-12)exp(580+/-68)/T, k6(409-936 K) = (1.66+/-0.38) x 10(-12)exp(713+/-114)/T, k7(514-928 K) = (3.18+/-0.54) x 10(-12)exp(-667+/-115)/T. The overall uncertainty in the measurements, taking into account systematic errors dominated by uncertainty in the substrate reactor concentration, range from a factor of 2 for DD, 2-CDD, 2,3-DCDD, 2,7-DCDD, and 2,8-DCDD to +/- a factor of 4 for 1,2,3,4-TCDD and OCDD. Negative activation energies characteristic of an OH addition mechanism were observed for k1-k6. k7 exhibited a positive activation energy. Cl substitution was found to reduce OH reactivity, as observed in prior studies at lower temperatures. At elevated temperatures (500 K < T < 500 K), there was no experimental evidence for a change in reaction mechanism from OH addition to H abstraction. Theoretical calculations suggest that H abstraction will dominate OH reactivity for most if not all dioxins (excluding OCDD) at combustion temperatures (>1000 K). For OCDD, the dominant reaction mechanism at all temperatures is OH addition followed by Cl elimination.     

The Henry's law coefficient of 2-nitrophenol over the temperature range 278-303 K

Although 2-nitrophenol has been identified as an important environmental chemical there is scarcity in the literature regarding the temperature dependence of its Henry's law coefficient, H. Here a bubble purge method was used to measure H for 2-nitrophenol over the temperature range 278-303 K. A novel approach in the data treatment allowed correction of the data for non-equilibrium partitioning in the apparatus to obtain the true equilibrium H value. The experimentally derived temperature-dependent expression for H of 2-nitrophenol is lnH (M atm(-1)) = (6290/T (K)) - 16.6. The standard enthalpy and entropy of gas-to-liquid transfer for 2-nitrophenol in aqueous solution are -52.3 +/- 8.1 kJ mol(-1) and -138 +/- 28 J mol(-1) K(-1), respectively. (Errors are 95% confidence intervals.)     

Solubility of volatile organic compounds in aqueous ammonia solution

The Ostwald solubility coefficient, L of 17 volatile organic compounds (VOCs) from the gas phase into water and dilute aqueous ammonia solutions was determined by the equilibrium partitioning in closed system-solid phase micro extraction (EPICS-SPME) method at 303 K and at 0-2.5 mol dm(-3) ammonia concentrations. Ammonia increased the solubility of all VOCs nearly linearly, but to a different extent. The difference in the solubility values in aqueous ammonia solutions (Lmix) compared to pure water (L) is explained on the basis of a Linear Solvation Energy Relationship (LSER) equation made applicable for solvent mixtures, logLmix - logL = x((sNH3 - sH2O)pi2H + (aNH3 - aH2O)Sigma2H + (bNH3 - bH2O)Sigmabeta2H + (vNH3 - VH2O)Vx). sNH3 - sH2O, aNH3 - aH2O, bNH3 - bH2O, vNH3 - vH2O are the differences of solvent parameters, x is the mole fraction, pi2H is the solute dipolarity-polarizability, Sigmaalpha2H is the effective hydrogen bond acidity of the solute, Sigmabeta2H is the effective hydrogen bond basicity of the solute and Vx, the McGowan characteristic volume. The most significant term was v, the phase hydrophobicity. The solubility behavior was explained by the change in structure of the aqueous solution: the presence of ammonia reduces the cavity effect. These findings show that the presence of compounds such as ammonia, frequently observed in environmental waters, especially wastewaters, affect the fugacity of VOCs, having consequences for the environmental partitioning of VOCs and having technical consequences towards wastewater treatment technologies.     

电催化氧化法处理染料废水的影响因素及动力学

以钛涂膜极板为阳极、石墨极板为阴极、Fe2O3/γ-Al2O3为多相催化剂,构建电-多相催化氧化体系,研究了该体系对酸性大红模拟染料废水中COD的去除效果及其影响因素,优化了实验条件,并初步探讨了COD的降解机理。结果表明,在槽电压20 V,pH 4,曝气量0.24 m3/h,极板间距3 cm的条件下,COD的去除率最高,达到64.5%;COD的降解近似符合一级动力学方程:ln(C0/C)=0.0034t+0.719。在电-多相催化氧化体系中,废水中的有机物被直接矿化或降解为小分子有机物。     

O_3/BAF工艺系统中有机物生物降解数学模型

研究臭氧预氧化/曝气生物滤池（O3/BAF）联合工艺深度处理实际城市污水二级出水过程中,后续BAF系统中有机物的生物降解数学模型。以有机底物浓度、填料层高度两个基本变量为控制条件,研究BAF的总体运行常数和填料特性常数,得出BAF有机物生物降解动力学方程为（Se/S0）=exp（（-Kn/qSh0））。出水与进水COD浓度比值（Se/S0）的对数与反应器填料高度（h）之间可表达成一次函数关系。在不同的进水浓度（S0）下,根据ln（Se/S0）~h和关系式m=（K/qS0n）,得到方程ln（qm）=-nln（S0）＋lnK。BAF总体运行常数K和填料特性常数n分别为1.708和0.5063。该模型对BAF工艺有如下指导意义：可以根据设计流量、进水有机物浓度和出水浓度,初步确定BAF的尺寸（如横截面积、高度等）。     

H(2) production through anaerobic mixed culture: effect of batch S(0)/X(0) and shock loading in CSTR

Biological production of H(2) has received considerable attention lately. The present study was undertaken to observe the effects of substrate/seeding ratios (S(0)/X(0)) on batch H(2) generation. The H(2)-producing seeding spores were obtained from the heat treatment (88 degrees C for 12h) of the compost from a grass composting facility. A dehydrated brewery mixture was used as feed substrate. The results indicate that the pattern of the cumulative H(2) production with time is similar to the growth curve with a typical lag, exponential and stationary phase; the results were successfully modeled with a modified Gompertz equation. It appears that maximum H(2) yield potential (27ml g(-1)COD(added)) occurs at an S(0)/X(0) ratio of about 4, whereas the maximum specific H(2) yield (205ml g(-1) VSSd(-1)) occurs at approximately S(0)/X(0)=3. The S(0)/X(0) ratios higher than 4 would inhibit H(2) production. An attempt was made to waste a certain amount of reactor content and replaced it with fresh substrate in order to enhance H(2) production. After this medium replacement, the H(2) production was initially inhibited and the system then exhibited a long lag before it reached an active H(2) production stage. For a continuous-stirred tank-reactor (CSTR) system, the results of replacing 25% of the reactor content indicate that there is still a lag time before a sudden increase in H(2) production after the addition of the new substrate feed. The major low molecular weight acids identified are HAc and HBu with total volatile acids of about 6000-8000mg l(-1). The ratio of HAc/HBu in the present study is relatively constant (about 5) and appears not significantly affected by the medium replacement. The concentration of total alcohols is about 2000mg l(-1). All in all, the CSTR system is able to recover to its previous performance after such a dramatic 25% medium replacement.     

Adsorptive separation of cadmium from aqueous solutions and wastewaters by riverbed sand

Application of riverbed sand for the adsorptive separation of cadmium(II) from aqueous solutions has been investigated. Removal increased from 26.8 to 56.4% by decreasing the initial concentration of cadmium from 7.5 x 10(-5) to 1.0 x 10(-5)M at pH 6.5, 25 degrees C temperature, agitation speed of 100 rpm, 100 microm particle size and 1.0 x 10(-2) NaClO4 ionic strength. Process of separation is governed by first order rate kinetics. The value of rate constant of adsorption, k(ad), was found to be 2.30 x 10(-2)per min at 25 degrees C. Values of coefficient of mass transfer, beta L, were calculated and its value at 25 degrees C was found to be 1.92 x 10(-2)cm/s. Values of Langmuir constant were calculated. Values of thermodynamic parameters delta G0, delta H0 and delta S0 were also calculated and were recorded as -0.81 kcal/mol, -9.31 kcal/mol and -28.10 cal/mol at 25 degrees C. pH has been found to affect the removal of cadmium significantly and maximum removal, 58.4%, has been found at pH 8.5. Process can be used for treatment of cadmium(II) rich wastewaters.     

Stable hydrogen,carbon and chlorine isotope measurements of selected chlorinated organic solvents

Stable hydrogen isotopes of two chlorinated solvents, trichloroethylene (TCE) and 1,1,1-trichloroethane (TCA), provided by five different manufacturers, were determined and compared to their carbon and chlorine isotopic signatures. The isotope ratio for delta2H of different TCEs ranged between +466.9 per thousand and +681.9 per thousand, for delta13C between -31.57 per thousand and -27.37 per thousand, and for delta37Cl between -3.19 per thousand and +3.90 per thousand. In the case of the TCAs, the isotope ratio for delta2H ranged between -23.1 per thousand and +15.1 per thousand, for delta13C between -27.39 per thousand and -25.84 per thousand, and for delta37Cl between -3.54 per thousand and +1.39 per thousand. As well, a column experiment was carried out to dechlorinate tetrachloroethylene (PCE) to TCE using iron. The dechlorination products have completely different hydrogen isotope ratios than the manufactured TCEs. Compared to the positive values of delta2H in manufactured TCEs (between +466.9 per thousand and +681.9 per thousand), the dechlorinated products had a very depleted delta2H (less than -300 per thousand). This finding has strong implications for distinguishing dechlorination products (PCE to TCE) from manufactured TCE. In addition, the results of this study show the potential of combining 2H/1H analyses with 13C/12C and 37Cl/35Cl for isotopic fingerprinting applications in organic contaminant hydrogeology.     

Temperature-dependent rate coefficients for the reactions of Cl atoms with methyl methacrylate,methyl acrylate and butyl methacrylate at atmospheric pressure

Rate coefficients for the gas-phase reactions of Cl atoms with a series of unsaturated esters CH₂C(CH₃)C(O)OCH₃ (MMA), CH₂CHC(O)OCH₃ (MAC) and CH₂C(CH₃)C(O)O(CH₂)₃CH₃ (BMA) have been measured as a function of temperature by the relative technique in an environmental chamber with in situ FTIR detection of reactants. The rate coefficients obtained at 298 K in one atmosphere of nitrogen or synthetic air using propene, isobutene and 1,3-butadiene as reference hydrocarbons were (in units of 10^?10 cm³ molecule^?1 s^?1) as follows: k_(Cl+MMA) = 2.82 ± 0.93, k_(Cl+MAC) = 2.04 ± 0.54 and k_(Cl+BMA) = 3.60 ± 0.87. The kinetic data obtained over the temperature range 287–313 K were used to derive the following Arrhenius expressions (in units of cm³ molecule^?1 s^?1): k_(Cl+MMA) = (13.9 ± 7.8) × 10^?15 exp[(2904 ± 420)/T], k_(Cl+MAC) = (0.4 ± 0.2) × 10^?15 exp[(3884 ± 879)/T], k_(Cl+BMA) = (0.98 ± 0.42) × 10^?15 exp[(3779 ± 850)/T]. All the rate coefficients display a slight negative temperature dependence which points to the importance of the reversibility of the addition mechanism for these reactions. This work constitutes the first kinetic and temperature dependence study of the reactions cited above.An analysis of the available rates of addition of Cl atoms and OH radicals to the double bond of alkenes and unsaturated and oxygenated volatile organic compounds (VOCs) at 298 K has shown that they can be related by the expression: log k_OH = 1.09 log k_Cl ? 0.10. In addition, a correlation between the reactivity of unsaturated VOCs toward OH radicals and Cl atoms and the HOMO of the unsaturated VOC is presented. Tropospheric implications of the results are also discussed.     

Kinetics of hydrolysis and cyclization of ethyl 2-(aminosulfonyl)benzoate to saccharin

The cyclization of ethyl 2-(aminosulfonyl)benzoate (ASB) to give saccharin was investigated in aqueous solutions at pH between 5.2 and 9.5 and in the temperature range of 296.2-334.2 K. The initial concentration of the reactant was varied between 1.45 x 10(-5) and 3.86 x 10(-4) M. Ultraviolet spectroscopy was used to obtain the kinetic data. The reaction is acid catalyzed and follows pseudo-first-order kinetics. The experimental rate constant, k(obs), increases with temperature and pH. Its dependence on the temperature and pH is well described by: k(obs) = k1 [OH-] = [(2.52 +/- 0.9) x 10(16) exp(-20.2 +/- 1 kcalmol(-1)/RT) s(-1)][OH-] A mechanism is proposed and the half-life of ethyl ASB is calculated.     

Comparison of advanced oxidation processes and identification of monuron photodegradation products in aqueous solution

The photodegradation of monuron (3-(4-chlorophenyl)-1,1-dimethylurea) in aqueous solutions under simulated solar irradiation has been conducted by different advanced oxidation processes (UV/H(2)O(2), UV/H(2)O(2)/Fe(2+), UV/H(2)O(2)/TiO(2), UV/TiO(2), dark H(2)O(2)/Fe(3+)). The degradation rates were always higher for the homogeneous catalysis in photo-Fenton reactions (UV/H(2)O(2)/Fe(2+)) compared to the heterogeneous photocatalytic systems (TiO(2)/UV and UV/H(2)O(2)/TiO(2)). Optimal concentrations of Fe(2+) and H(2)O(2) for the abatement of the herbicide in the photo-Fenton system were found to be 1 mM Fe(II) and 10 mM H(2)O(2). Several intermediary products were identified using large volume injection micro-liquid chromatography with UV detection (mu-LC-UV), mu-LC-MS and GC-MS techniques and a degradation mechanism has been proposed.     

Filtration of Airborne Particulates by Gravel Filters: I. Initial Collection Efficiency of a Gravel Layer

An equation derived for initial collection of efficiency E₀ of a gravel bed filter predicts that — ln(1 — E₀) is proportional to the thickness of the gravel layer, to the — 5/3 power of the diameter of uniform gravels, and to the — 2/3 power of the Darcy airflow velocity. The experimental data obtained from NH₄CI fume removal from dry air at room temperature by sieved gravel fractions generally supported the equation, except that the effect of mean gravel size was represented by the —1.43 power of the average diameter.