Analysis of methane production inhibition for treatment of sewage sludge containing sulfate using an anaerobic continuous degradation process

The inhibition of methane production in the continuous anaerobic degradation process for the treatment of sewage sludge containing sulfate was investigated. Also, the competition between sulfate-reducing bacteria (SRB) and methane-producing bacteria (MPB) with COD/sulfate ratio was explained in terms of electron flow. The methane production rate was 0.07, 0.13, 0.24, 0.31 and 0.33 l-CH₄ g-COD⁻¹ when the initial COD/sulfate ratio was 3.3, 5.0, 6.7, 10 and 20, respectively. The numbers of SRB and MPB were counted after the continuous reactor reached steady state and the two bacteria showed opposite growth behaviors with COD/sulfate ratio. The inhibition by sulfate compounds was found to follow the uncompetitive model and inhibition constants were 24.57 and 87.99 mg l ⁻¹ for SRB and MPB, respectively. These results can be useful data for the efficient treatment of sewage sludge in a continuous anaerobic degradation process.     

Irradiated sewage sludge for production of fennel plants in sandy soil

A field experiment was conducted to study the impact of irradiated and non-irradiated sewage sludge applied to sandy soil on the productivity of fennel plants (Foeniculum vulgare L.). Four rates of irradiated and non-irradiated sewage sludge application were used (20, 40, 60, and 80 t ha⁻¹). Samples analysis included the biomass production at the vegetative and flowering stages, seed production, volatile oil content, volatile oil constituents, chlorophyll content, total and reducing sugars, and the heavy metals content of the shoots and seeds. The biomass production increased as the sludge application rate increased for both irradiated and non-irradiated plots. However, the increase was significantly higher under all irradiated treatments than the corresponding rates of non-irradiated treatments at both the vegetative and flowering stages. At the vegetative stage, the biomass values ranged from 10.2 to 34.1 g plant⁻¹ at 80 t ha⁻¹ for non-irradiated and irradiated sewage sludge, respectively. Whereas at the flowering stage, the values ranged from 23.9 to 65.1 g plant⁻¹ at 80 t ha⁻¹ for non-irradiated and irradiated sewage sludge, respectively. Total sugars, reducing sugar, non-reducing sugar and chlorophyll content increased as the sludge application rate increased. At the 80 t ha⁻¹ of irradiated sludge application rate, the reducing sugar content was 29.39 mg g⁻¹ DW (dry weight) at the vegetative stage and 37.85 mg g⁻¹ DW at the flowering stage. Regarding heavy metals, sewage sludge was a good source to provide fennel plants with essential micronutrients (Zn and Fe) in the meantime, the translocation of (Pb and Cd) to the shoot system was very low. A linear gradual increase in seed yield was observed as the sludge application rate increased. Irradiated sewage sludge treatments showed a higher fennel seed yield than non-irradiated sewage sludge treatments. Volatile oil percentages exhibited no observable variations due to the use of sewage sludge. A few and limited fluctuations could be observed. However, total oil content (l ha⁻¹) increased due to the increase in seed yield. The magnitude of increase in volatile oil production in response to the sewage sludge application was parallel to the increase in seed yield. The GLC measurements of the fennel volatile oil reveal that the t-anethole is the predominant fraction. However, fenchone was detected in a relatively moderate concentration. The applied sewage sludge treatment induced some variations in fennel volatile oil constituents. The t-anethole is relatively higher in volatile oil obtained from plants grown on sandy soil fertilized with non-irradiated sewage sludge than that fertilized with irradiated sewage sludge. In the meantime, the increase in t-anethole was accompanied by a decline in fenchone content. Under all sludge application rates iron and zinc concentrations of fennel seeds were within the normal plant concentration range, whereas there were only traces of Cd concentration.     

Elutriation and attrition of char form a large fluidized bed

Previous correlations for elutriation of particle fines did not fit the present data obtained in a large fluidized bed using char/sand mixture as the bed material. A new form of correlation (after Zenz and Weil [1]) for the elutriation rate constants, E_i, has been developed which gives a good agreement with the experimental data: E/?_gU_g = 9.43 × 10^?4 (U²_g/gd_p)^1.65.The attrition rate of production of fines of char particles in char/sand fluidized bed has been found to increase with U_g—U_mf as an exponential function: k_a = ae^{b(U_g—U_mf)}. The dependence of attrition rate constant on d_p appears small, if it is present at all. Attrition would appear to be occuring only in the bubble wakes.A small char layer (without sand) was found on the char/sand bed surface when it was fluidized. The elutriation rate was found not to be significantly influenced by this thin char layer. This is a unique confirmation of the theory of entrainment that the majority of ejected particles originate from the wakes of bubbles which have grown as they rise through the bed.     

Non-steady state estimation of biodegradability of dyeing wastewater using respirometer

Dyeing wastewater is notorious for its non-readily-biodegradability because it contains various kinds of refractory chemicals. To set up a strategy for controlling the dyeing wastewater discharged into conventional wastewater treatment plants, obtaining bio-kinetic information such as maximum specific growth rate (μ _max ) and half saturation constant (K _s ) should first be done. To estimate the biodegradability of the dyeing wastewater, bio-kinetic constants of the artificially formulated dyeing wastewater containing 33 different dyes and auxiliaries were determined by using a respirometer. Activated sludge acclimated to the artificial dyeing wastewater was inoculated to the respirometer and the bio-kinetic constants were determined from oxygen uptake data. The μ _max was found to 0.06 hr⁻¹, which is 3 to 15 times smaller than that of the typical activated sludge for sewage treatment. The K _s was found to 210 mg/L, which was 3.5 to 21 times higher than that of the normal activated sludge.     

Kinetic study of the reaction between tocopheroxyl radical and unsaturated fatty acid esters in benzene

A kinetic study of the reaction between a tocopheroxyl radical and unsaturated fatty acid esters has been undertaken. The rates of allylic hydrogen abstraction from various unsaturated fatty acid esters (ethyl oleate2, ethyl linoleate3, ethyl linolenate4, and ethyl arachidonate5) by the tocopheroxyl radical (5,7-diisopropyltocopheroxyl6) in benzene have been determined spectrophotometrically. The second-order rate constants, k₃, obtained are 1.04×10⁻⁵ M⁻¹s⁻¹ for2, 1.82×10⁻² M⁻¹s⁻¹ for3, 3.84×10⁻² M⁻¹s⁻¹ for4, and 4.83×10⁻² M⁻¹s⁻¹ for5 at 25.0°C. Thus, the rate constants, k_abstr/H, given on an available hydrogen basis are k₃/4=2.60×10⁻⁶ M⁻¹s⁻¹ for2, k₃/2=9.10×10⁻³ M⁻¹s⁻¹ for3, k₃/4=9.60×10⁻³ M⁻¹s⁻¹ for4, and k₃/6=8.05×10⁻³ M⁻¹s⁻¹ for5. The k_abstr/H values obtained for the polyunsaturated fatty acid esters3,4, and5 containing H-atoms activated by two π-electron systems are similar to each other, and are about three orders of magnitude higher than that for the ethyl oleate2 containing H-atoms activated by a single π-system. From these results, it is suggested that the prooxidant effect of α-tocopherol in edible oils and fats may be induced by the above hydrogen abstraction reaction.     

Assessment of CH4 and N2O fluxes in a Danish beech (Fagus sylvatica) forest and an adjacent N-fertilised barley (Hordeum vulgare) field: effects of sewage sludge amendments

Fluxes of CH₄ and N₂O were measured regularly in an agricultural field treated with 280 g m⁻² of sewage sludge. In a nearby beech forest N₂O and CH₄ fluxes were measured in a well-drained (dry) area and in a wet area adjacent to a drainage canal. We observed brief increases of both CH₄ and N₂O emissions immediately following soil applications of digested sewage sludge. Cumulated values for CH₄ emissions over the course of 328 days after sludge applications indicated a small net source in sludge treated plots (7.6 mg C m⁻²) whereas sludge-free soil constituted a small sink (-0.9 mg C m⁻²). The CH₄ emission amounted 0.01% of the sludge-C. Extrapolated to current rates of sludge applications in Danish agriculture this amounts to 0.1% of the total agricultural derived CH₄. Sludge applications did not affect cumulated fluxes of N₂O showing 312 mg N₂O–N m⁻² and 304 mg N m⁻² with and without sludge, respectively. Four months after the sludge applications a significant effect on CO₂ and NO emissions was still obvious in the field, the latter perhaps due to elevated nitrification. Nitrous oxide emission in the beech forest was about six times smaller (45 mg N m⁻²) than in the field and independent of drainage status. Methane oxidation was observed all-year round in the forest cumulating to -225 mg C m⁻² and -84 mg C m⁻² in dry and wet areas. In a model experiment with incubated soil cores, nitrogen amendment (NH₄Cl) and perturbation significantly reduced CH₄ oxidation in the forest soil, presumably as a result of increased nitrification activity. Sludge also induced net CH₄ production in the otherwise strong CH₄ oxidising forest soil. This emphasises the potential for CH₄ emissions from sewage sludge applications onto land. The study shows, however, that emissions of N₂O and CH₄ induced by sewage sludge in the field is of minor importance and that factors such as land use (agriculture versus forest) is a much stronger controller on the source/sink strengths of CH₄ and N₂O. This revised version was published online in August 2006 with corrections to the Cover Date.     

Reaction between Hydrosulfide and Iron/cerium (hydr)oxide: Hydrosulfide Oxidation and Iron Dissolution Kinetics

Hydrosulfide oxidation and iron dissolution kinetics were studied at normal pressure, under inert (N₂) atmosphere, in a liquid–solid mechanically-stirred slurry reactor. The kinetic variables undergoing variations were: hydrosulfide initial concentration (0.90–3.30 mmol/L), oxide initial surface area (16–143 m²/L) and pH (8.0–11.0). The hydrosulfide consumption and products (thiosulfate and polysulfide) formation were quantified by means of capillary electrophoresis, while iron dissolution was monitored through atomic absorption spectroscopy. Most of Fe(II) produced at pH = 9.5 remained associated with the oxide surface in the time-scale of the experiments. The hydrosulfide oxidation by the iron/cerium (hydr)oxide was found to be surface-controlled, with rates (R_i) of both sulfide oxidation and Fe(II) dissolution expressed in terms of an empirical rate equation: R_i = k_i[HS⁻]_t=0^−0.5[A]_t=0[H⁺]_t=0^−0.5 , where k_i represents the apparent rate constants for the oxidation of HS⁻ (k_HS) or the dissolution of Fe(II) (k_Fe), [HS⁻]_{t = 0} is the initial hydrosulfide concentration, [A]_{t = 0} is the initial Fe/Ce (hydr)oxide surface area and [H⁺]_{t = 0} is the initial proton concentration. The rate constant, k_HS, for the oxidation of hydrosulfide at pH = 9.5 was (3.4219 ± 0.65) × 10⁻⁴ mol² L⁻¹ m⁻² min⁻¹, with the rate of hydrosulfide oxidation being ca. 10 times faster than the rate of Fe(II) dissolution (assuming a 1:2 stoichiometric ratio between HS⁻ oxidized and Fe(II) produced; k_Fe = (3.9116 ± 0.41) × 10⁻⁵ mol² L⁻¹ m⁻² min⁻¹).     

CO2 gasification of wood charcoals derived from vacuum and atmospheric pyrolysis

The gasification of biomass derived char obtained via vacuum and atmospheric pyrolysis of Populus tremuloides has been studied in the ranges of 725–960°C and 0.1 to 6 MPa. CO₂ was used as the oxidizing gas. The results show that char reactivity is influenced by the preheating rates and that pressure effects are significant between 850°C and 950°C. A correlation based on the expression: df/dt = k₀{exp(-E/RT)}(1 - f)^af^βP^yCO₂ was used to fit the experimental data. In general, vacuum pyrolysis derived char showed a higher reactivity than atmospheric pyrolysis chars. An explanation based on a higher oxygen content of the vacuum pyrolysis char is suggested.     

Application of arrhenius kinetics to evaluate oxidative stability in vegetable oils by isothermal differential scanning calorimetry

In this study, 10 different vegetable oils were oxidized at four different isothermal temperatures (383, 393, 403, and 413 K) in a differential scanning calorimeter (DSC). The protocol involved oxidizing vegetable oils in a DSC cell with oxygen flow. A rapid increase in evolved heat was observed with an exothermic heat flow appearing during initiation of the oxidation reaction. From this resulting exotherm, the onset of oxidation time (T _o) was determined graphically by the DSC instrument. In our experimental data, linear relationships were determined by extrapolation of the log (T _o) against isothermal temperature. The rates of lipid oxidation were highly correlated with temperature. In addition, based on the Arrhenius equation and activated complex theory, reaction rate constants (k), activation energies (E _a), activation enthalpies (ΔH ^‡), and activation entropies (ΔS ^‡) for oxidative stability of vegetable oils were calculated. The E _a′, ΔH ^‡, and ΔS ^‡ for all vegetable oils ranged from 79 to −104 kJ mol⁻¹, from 76 to −101 kJ mol⁻¹, and from −99 to −20 J K⁻¹ mol⁻¹, respectively. Based on the results obtained, differential scanning calorimetry appears to be a useful new instrumental method for kinetic analysis of lipid oxidation in vegetable oil.     

Effect of crop-specific field management and N fertilization on N2O emissions from a fine-loamy soil

Agricultural soils are a major source of atmospheric N₂O. This study was conducted to determine the effect of different crop-specific field management and N fertilization rates on N₂O emissions from a fine-loamy Dystric Eutrochrept. Fluxes of N₂O were measured for two years at least once a week on plots cropped with potatoes (Solanum tuberosum) fertilized with 50 or 150 kg N ha⁻¹ a⁻¹, winterwheat (Triticum aestivum) fertilized with 90 or 180 kg N ha⁻¹ a⁻¹, corn (Zea mays) fertilized with 65 or 130 kg N ha⁻¹ a⁻¹, and on an unfertilized, set-aside soil planted with grass (mainly Lolium perenne and Festuca rubra). The mean N₂O emission rate from the differently managed plots was closely correlated to the mean soil nitrate content in the Ap horizon for the cropping period (April to October, r ² = 0.74), the winter period (November to March, r ² = 0.93, one outlier excluded), and the whole year (r ² = 0.81). N₂O emissions outside the cropping period accounted for up to 58% of the annual emissions and were strongly affected by frost-thaw cycles. There was only a slight relationship between the amount of fertilizer N applied and the annual N₂O emission (r ² = 0.20). The mean annual N₂O-N emission from the unfertilized set-aside soil was 0.29 kg ha⁻¹. The annual N₂O-N emission from the fertilized crops for the low and the recommended rates of N fertilization were 1.34 and 2.41 kg ha⁻¹ for corn, 2.70 and 3.64 kg ha⁻¹ for wheat, and 5.74 and 6.93 kg ha⁻¹ for potatoes. The high N₂O emissions from potato plots were due to (i) high N₂O losses from the interrow area during the cropping season and (ii) high soil nitrate contents after the potato harvest. The reduction of N fertilization (fertilizer was applied in spring and early summer) resulted in decreased N₂O emissions during the cropping period. However, the emissions during the winter were not affected by the rate of N fertilization. The results show that the crop-specific field management had a great influence on the annual N₂O emissions. It also affected the emissions per unit N fertilizer applied. The main reasons for this crop effect were crop-specific differences in soil nitrate and soil moisture content. This revised version was published online in June 2006 with corrections to the Cover Date.     

Sorption and desorption kinetics of chlorophenols in hexadecyltrimethyl ammonium-montmorillonites and their model analysis

Sorption and desorption kinetics of chlorophenols, 2-chlorophenol (2-ChP), 2,4-dichlorophenol (2,4-DChP) and 2,4,5-trichlorophenol (2,4,5-TChP), in montmorillonite modified with hexadecyltrimethyl ammonium cations (HDTMA-mont) were investigated by using laboratory batch adsorbers. To investigate the effect of chemical concentration and sorbent weight on the sorption or desorption rate constants, the initial chemical concentration and sorbent weight were varied from 50 to 150 mg/L and from 0.2 to 1.0 g, respectively. A one-site mass transfer model (OSMTM) and two compartment first-order kinetic model (TCFOKM) were used to analyze kinetics. The OSMTM applicable to desorption rate analysis was newly derived. As expected from the number of model parameters involved, the three-parameter TCFOKM was better than the two-parameter OSMTM in describing sorption and desorption kinetics of chlorophenols in HDTMA-mont. The mass transfer coefficient for sorption (k_s) in OSMTM generally increased as K _ow value increases, except for 2,4,5-TChP, while the mass transfer coefficient for desorption (k _d ) consistently increases as K _ow value decreases, due to the weaker hydrophobic interaction between the solute and the organoclay. Since most sorption and desorption complete in an hour and half an hour, respectively, k _d values were found to be greater than k _s values for all three solutes studied. The fraction of the fast sorption (or desorption) and the first-order sorption (or desorption) rate constants for the fast and slow compartments in TCFOKM were determined by fitting experimental data to the TCFOKM. The results of kinetics reveal that the fraction of the fast sorption or desorption and the sorption rate constants in the fast and slow compartments were in the order 2,4,5-TChP>2,4-DChP>2-ChP, which agrees with the magnitude of the octanol-water partition coefficient, K _ow . The first-order sorption rate constants in the fast and slow compartments were found to vary 10¹–10² hr⁻¹ and 10⁻³–10⁻² hr⁻¹, respectively. However, the desorption rate constants in the fast and slow compartments were not correlated well withK _ow . The first-order desorption rate constants in the fast compartment (10¹−10² hr⁻¹) were found to be much larger than those in the slow compartment (10⁻³–10⁻⁴ hr⁻¹). Sorption affinity and desorption resistance of each chlorophenol in 50% HDTMA-mont were found to show the same tendency: the weakly-sorbed chlorophenol (i.e., 2-ChP) was easily desorbed, while the strongly-sorbed chlorophenol (i.e., 2,4,5-TChP) was rather resistant to desorption.     

Sewage treatment for chromium(VI) disposal by combined reduction with sodium sulfite in the presence of solid adsorbents

To improve the existing procedure for the purification of low concentration (50–150 mg/l) sewage from Cr(VI) using sodium sulfite, it was suggested that sewage should be passed through an adsorbent layer. An alternative method is to pass sewage through the adsorbent layer placed in the interelectrode space of an electrochemical cell. Both methods increase the degree of purification for sewage with pH ≥ 6 and allow pH of purified water to be maintained at 6.5–8.0 in accordance with sanitary requirements. It was shown that combined adsorption-reagent and electrochemical reduction can be used by reducing Cr(VI) with sodium sulfite on adsorbents such as Fe₂O₃, kaolin, and activated coal (AC) and passing electric current through an AC adsorbent layer. The degree of purification varied from 80 to 94% for combined processes. The theoretical rate constants were calculated for adsorbent-reagent reduction (4.0–4.7 min⁻¹), and the transfer coefficients were calculated for electrochemical reduction (1–4 mm/s⁻¹).     

Bleaching kinetics of sunflowerseed oil

The bleaching process for sunflowerseed oil follows a rate formula, log (A/A ₀)=−κ , according to absorbance measurements. The dark color of crude oil converts to a light color as the absorbance value decreases. The activation energy E _a was calculated from the Arrhenius equation as 3 kJ, and other activation thermodynamic parameters were determined as ΔS ^⊄=−4.4 J K⁻¹, ΔH ^⊄=−31.2 J mol⁻¹, and ΔG ^⊄=1.6 kJ mol⁻¹. The study showed that the bleaching process was exothermic, presented a decrease of entropy, and was a nonspontaneous process during activation.     

Heterogeneous photocatalytic reduction of Fe(VI) in UV-irradiated titania suspensions: effect of ammonia

Results of the heterogeneous photocatalytic reduction of Fe(VI) in UV-irradiated TiO₂ suspensions in the presence of ammonia are presented. The initial rate of Fe(VI) reduction, R, may be expressed as R = k _Fe(VI)[Fe(VI)]^1.25 where k _Fe(VI) = a[Ammonia]+b), a = 6.0 × 10³ μm ^0.25 s and b = 4.1 × 10⁶ μm ^−1.25s⁻¹. The rate constant, k _Fe(VI), increases with the ammonia concentration. The photocatalytic oxidation of ammonia is enhanced in the presence of Fe(VI). A mechanism involving Fe(V) as a reactive intermediate is presented which explains the faster photocatalytic oxidation of ammonia in the presence of Fe(VI).     

Thermochemical Conversion of Sewage Sludge by TGA-FTIR Analysis: Influence of Mineral Matter Added

Thermal treatments, such as combustion, gasification, and pyrolysis, have been proven to be a convenient alternative to conventional sludge disposal technologies. Today, process development implies scaling up and so improving the reactor's design. In continuously operated reactors, fresh sewage sludge is in contact with solid residues (reacted material rich in mineral matter and char). Mineral matter has been reported to catalyze the thermo-chemical reactions involved but few works focus on this aspect. In this work, sewage sludge residues were added to fresh sewage sludge. Non-isothermal thermo-gravimetric analysis (TGA) coupled with infrared spectrometry (FTIR) showed that added residues reduce the characteristic reaction temperatures during char combustion and gasification (air, air-N₂, and CO₂ atmospheres). However, any considerable influence of residues was observed during pyrolysis experiments (N₂ atmosphere). The analysis of gas produced during those experiments revealed further details about the solid decomposition, showing considerable differences between different atmospheres.     

Kinetic Study of the Prooxidant Effect of α-Tocopherol. Hydrogen Abstraction from Lipids by α-Tocopheroxyl Radical

A kinetic study of the prooxidant effect of α-tocopherol was performed. The rates of allylic hydrogen abstraction from various unsaturated fatty acid esters (ethyl stearate 1, ethyl oleate 2, ethyl linoleate 3, ethyl linolenate 4, and ethyl arachidonate 5) by α-tocopheroxyl radical in toluene were determined, using a double-mixing stopped-flow spectrophotometer. The second-order rate constants (k _p) obtained are <1 × 10⁻² M⁻¹ s⁻¹ for 1, 1.90 × 10⁻² M⁻¹ s⁻¹ for 2, 8.33 × 10⁻² M⁻¹ s⁻¹ for 3, 1.92 × 10⁻¹ M⁻¹ s⁻¹ for 4, and 2.43 × 10⁻¹ M⁻¹ s⁻¹ for 5 at 25.0 °C. Fatty acid esters 3, 4, and 5 contain two, four, and six –CH₂– hydrogen atoms activated by two π-electron systems (–C=C–CH₂–C=C–). On the other hand, fatty acid ester 2 has four –CH₂– hydrogen atoms activated by a single π-electron system (–CH₂–C=C–CH₂–). Thus, the rate constants, k _abstr/H, given on an available hydrogen basis are k _p/4 = 4.75 × 10⁻³ M⁻¹ s⁻¹ for 2, k _p/2 = 4.16 × 10⁻² M⁻¹ s⁻¹ for 3, k _p/4 = 4.79 × 10⁻² M⁻¹ s⁻¹ for 4, and k _p/6 = 4.05 × 10⁻² M⁻¹ s⁻¹ for 5. The k _abstr/H values obtained for 3, 4, and 5 are similar to each other, and are by about one order of magnitude higher than that for 2. From these results, it is suggested that the prooxidant effect of α-tocopherol in edible oils, fats, and low-density lipoproteins may be induced by the above hydrogen abstraction reaction.     

Kinetics of hydrogen peroxide oxidation of alkyl dimethyl amines

We measured the absolute rate constants for the hydrogen peroxide oxidation of two different octyl dimethyl amines in isopropanol/water mixtures at 23°C. The amines were 1-octyl dimethyl amine (1) and 2-ethylhexyl dimethyl amine (2); their structures were analogous to those most often encountered in commercial alkyl dimethyl amine oxide production. The observed first-order rate constants for the disappearance of amine across a range of H₂O₂ concentrations (0.5–8 M) indicated that the overall rate was first-order in amine and 3/2-order in H₂O₂. Calculations showed k ₁=0.16 M⁻¹h⁻¹, k ₂=0.046 M⁻¹h⁻¹, and k ₁/k ₂=3.5. The rates appeared to decrease with increasing steric hindrance around the nitrogen atom. We also investigated the effect of water on the reaction rates. When [H₂O]<∼4.5 M in isopropanol, the rates increased with increasing [H₂O]; for [H₂O]>∼4.5 M, the rates were insensitive to [H₂O].     

The formation of 1-octen-3-ol in soybeans during soaking

The soaking of soybeans in water as a pretreatment for soy milk manufacture was found to result in the production of significant quantities of 1-octen-3-ol. The amount of this compound formed at a soak temperature of 50 C increased with length of soak time and reached a maximum after approximately 6 hr. The rate of formation had a pH optimum of 6–7. A pure fraction of 1-octen-3-ol, isolated by a preparative GLC technique, was found to be levorotatory ([a] _D ¹⁷ = −11.7; [a] _D ¹³ = −11.8). Based on these findings, the mode of formation of 1-octen-3-ol in this case is presumed to be enzymatic. The flavor threshold of 1-octen-3-ol in soy milk was determined to be between 0.5 and 1.0 ppm. New York State Agricultural Experiment Station Journal Paper No. 1654.     

Factors affecting methanol photocatalytic oxidation and catalyst attrition in a fluidized-bed reactor

A resolution IV fractional factorial experimental design explored the effects of seven factors on both the methanol photocatalytic oxidation (PCO) rate and the catalyst particle size distribution using a fluidized-bed reactor. The seven factors were as follows: calcination temperature, calcination time, grinding order, particle size, vibration amplitude, carrier gas humidity, and fluidization velocity. Decreasing calcination temperature from 726 to 623 K increased the activity of TiO₂/Al₂O₃ catalysts for methanol PCO. Attrition during fluidization liberated small TiO₂ particles from the bulk catalyst and the rate of attrition increased with gas velocity. Attrition was the primary cause of catalyst elutriation and not the presence of fine particles initially present in the bed from catalyst preparation. Increasing humidity caused agglomeration of fine particles, which reduced the amount of catalyst carryover. Removal of fines from the catalyst bed prior to fluidization caused an increase in catalyst attrition until the amount of fines present in the bed was similar to that of a bed in which fines were not removed.     

Kinetics of halogen-exchange fluorination of 2,6-dichlorobenzaldehyde

Under the conditions of phase transfer catalysis and nitrobenzene as the solvent, the halogen-exchange fluorination of 2,6-dichlorobenzaldehyde using KF as fluorinating agent was studied. The kinetics was investigated and the reaction rate constants were obtained under the optimum conditions of n(KF):n(2,6-dichlorobenzaldehyde): n(Ph₄PBr):n(acetone-furan crown ether) = 4:1:0.1:0.05 and temperatures of 433 K, 443 K, 453 K and 463 K. The results illustrated the activation energy of the first and the second step is 4.57 × 10⁴ J·mol⁻¹ and 3.53 × 10⁴ J·mol⁻¹, respectively. The pre-exponential factor is 4.50 × 10⁵ h⁻¹ and 1.08 × 10⁴ h⁻¹, respectively. Thus a reliable kinetics data could be obtained for further research. __________ Translated from Chemical Engineering (China), 2007, 35(8): 33–36 [译自: 化学工程]