Mutagenicity of eluent by hot water extraction of various coals: Effect of chlorination

Six kinds of powdery coals (two bituminous coals, two sub-bituminous coals, and two lignites) were extracted by hot water, and the eluents obtained were analyzed for total organic carbon (TOC), absorbance at 260 nm (A₂₆₀), and pH. The TOC in the eluents decreased in the order, lignites > sub-bituminous coals > bituminous coals. The eluents of lignite gave high A₂₆₀/TOC values and fairly low pH compared to other coals. Chemical structure of the organic matter eluted from coals was discussed with the aid of FTIR analysis. The coal eluents were analyzed by the Ames mutagenicity assay using Salmonella typhimurium TA100 and TA98 strains, and no mutagenicity was observed for all of the six coals. However, especially for the lignites, chlorination of the eluents produced an appreciable mutagenicity, and the expression of mutagenicity was dependent upon the type of coal. The mutagenicity was extinguished when metabolic activation (rat liver homogenate, +S9) was applied.     

Hydrocracking Brazilian Marlim vacuum residue with natural limonite. Part 1: catalytic activity of natural limonite

An experimental study examined the catalytic effects of natural Australian (AL) and Brazilian (BL) limonites used in hydrocracking Brazilian Marlim vacuum residue (ML-VR). The catalytic behavior of the limonites was compared with a conventional NiO-MoO₃-Al₂O₃ (NiMo) catalyst. Diphenylmethane (DPM) and 1-methylnaphthalene (1-MN) were used as standards. The order in which coke and gas formation were suppressed during hydrocracking of ML-VR was NiMo>BL>AL, which is the same order as for the hydrogenation activity observed with the standard compounds. By contrast, the limonite catalysts exhibited relatively higher conversions and distillate yields in ML-VR hydrocracking than did the NiMo catalyst with the order of conversion and distillate yield (yield of the fraction with boiling point of 540 °C) being AL>BL>NiMo, which is the same order obtained for catalytic cracking of the two standards. Coke formation was effectively suppressed at high hydrogen pressures. The limonite catalysts showed lower activities for nitrogen and sulfur removal than did NiMo, but both proved to have a larger activity for nickel removal.     

Comparative chemical composition and biological activity of single- and two-stage coal liquefaction process streams

Samples from several integrated two-stage coal liquefaction (ITSL) process streams were collected under both normal and off-normal operating conditions. Selected crude materials were tested for their ability to initiate tumorigenicity in the initiation/promotion assay in mouse skin. Crude materials and their chemical class fractions were assayed for microbial mutagenic activity in the standard Ames test with S. typhimurium TA98, and selected samples were also subjected to the Chinese hamster ovary mammalian cell assay for mutagenicity. Mass spectral and gas chromatographic—mass spectral (g.c.—m.s.) analyses were carried out on these materials. Results were compared with those for analogous materials from solvent refined coal (SRC) single stage liquefaction processes. In general, the ITSL distillates were of higher molecular weight, higher hydroaromatic content, lower nitrogen content and were somewhat less alkylated than the analogous SRC materials. Compared to the SRC coal liquefaction materials, the ITSL distillates and bottoms materials collected under normal run conditions were substantially less active in both the microbial and mammalian cell mutagenicity assays. These same materials were also less active than ITSL samples collected under off-normal conditions. G.c.—m.s. analyses showed that ITSL materials collected under normal operating conditions were substantially reduced in amino polycyclic aromatic hydrocarbon content when compared to both the off-normal ITSL, and SRC materials. Activity of the ITSL materials as initiators of tumorigenesis was greater than expected, based on results from the in vitro assays and not significantly different than that of the SRC materials. The higher initial boiling point of the ITSL distillates probably accounts for much of their greater than expected initiating activity compared to the SRC materials.     

Ultra-deep desulfurization of coker and straight-run gas oils: Effect of lowering feedstock 95% boiling point

Production of diesel fuels with ultra-low-sulfur levels by deep desulfurization of gas oil feeds has received considerable importance in the petroleum refineries in recent years. The type of the gas oil feed and its distillation temperature play a key role in the deep desulfurization process. In the present research project, the effect of lowering the 95% distillation temperature (T₉₅) of two gas oil feeds, namely, straight-run gas oil (SRGO) and coker gas oil (CGO), on deep desulfurization to ultra-low-sulfur levels was investigated. The results showed that for both types of feeds a higher degree of desulfurization was achieved with reduction of T₉₅ from > 360 °C to < 340 °C. The refractory alkyl dibenzothiophenes boiling above 320 °C were present in very low concentrations in the low-boiling cuts and deep HDS to ultra-low-sulfur levels (< 50 ppm) was achieved at low severity operating conditions. Among the two feeds, the CGO that contained high nitrogen content, high concentrations of sterically hindered alkyl DBTs and high aromatics content (low feed saturation) was more difficult to desulfurize than SRGO.     

Toxicological evaluation for bioremediation processes of TNT-contaminated soil by Salmonella mutagenicity assay

This research was performed to evaluate the toxicity for composting and slurry phase bioreactor processes of TNT (2,4,6-trinitrotoluene)-contaminated soils by Salmonella mutagenicity assay. For composting, the percentage reductions of final composts in strain TA98 and TA100 with S9 metabolic activation were 90.3?C93.7% and 96.7?C97.5%, respectively. For slurry phase bioreactor processes, the percentage reductions of final residuals in strain TA98 and TA100 with S9 metabolic activation were 95.0% and 99.1% for anaerobic, 96.2% and 99.2% for anaerobic/aerobic, and 96.6 and 97.4% for anaerobic treatment. Slurry phase treatment showed higher mutagenicity reduction than composting. It was implied that slurry phase treatment was a more effective process than composting in reducing toxicity. This research has the advantage of speed and ease of performance in comparison to testing of other higher life forms due to the shorter life cycles of microorganisms.     

Systematic characterization of petroleum residua based on SFEF

Supercritical fluid extraction and fractionation (SFEF) has been used to separate a variety of petroleum residua and other heavy oils into narrow-cut fractions with total yields up to 75-90%. Any insoluble material, or end-cut, corresponds to the asphaltene fraction in the parent oil. The narrow-cut fractions were analyzed comprehensively and separated into the solubility classes of saturate, aromatic, resin, and asphaltene fractions. The boiling points were measured up to 700 °C and correlations were established with the key factors such as density and molecular weight. This allows extrapolation of boiling points of residue fractions up to 1000 °C. Unlike bulk property measurements, the narrow-cut characterization data show increasing concentrations of key contaminants as the fractions become heavier. The solubility parameter for each narrow-cut fraction was measured using high-pressure fluid phase equilibrium with propane. The corresponding values for the end-cuts were obtained by the conventional precipitation method. The distribution and reactivity of sulfur species were determined by XPS in the bitumen pitch fractions and the corresponding residua produced during thermocracking and hydrocracking. The average structures for the narrow-cuts were constructed from molecular weight and elemental analyses together with FTIR, ¹H-NMR and ¹³C-NMR data. The results were used to develop a generalized feedstock characteristic index, K_R. This index shows good correlation with feedstock hydrocarbon constituents and can be used to assess feedstock reactivity and processability. Downstream refiners can use the narrow-cut data and K_R values for process optimization by either cutting deeper into residua bottoms to increase yield or by selecting the most appropriate process units for the various residue fractions. This information can also be used by upstream operators to determine the economic feasibility of utilizing the end-cut onsite.     

An h.p.l.e. and m.s. analysis of distillate fractions of neutral oil from hydrogenated Akabira coal to elucidate chemical structures

Akabira coal-derived neutral oil was separated into 25 narrow boiling range fractions covering 183–423 °C, and subsequently separated into compound class fractions : alkanes, monoaromatics, naphthalene-type diaromatics, fluorene-type diaromatics and tri- and/or tetraaromatics, by high performance liquid chromatography (h.p.l.c.). The compound type analyses of the distillate/h.p.l.c. fractions were performed using electron impact mass spectroscopy (e.i.m.s.) or field ionization mass spectroscopy (f.i.m.s.). Aromatic/hydroaromatic compound types and the alkyl side-chain carbon distribution of the distillate/h.p.l.c. fractions were clarified, based on the separation behaviour of h.p.l.c. and the type analyses according to Z value by m.s. By the distillation/h.p.l.c./m.s. method, coal-derived oil was characterized in terms of the distribution of the numbers of aromatic rings, naphthenic rings and carbons of alkyl groups attached to these rings. The variations in chemical structure in a compound class with distillation temperature are discussed in terms of these chemical structural factors.     

Effect of heat treating gel films on the formation of superhydrophobic boehmite flaky structures on austenitic stainless steel

The effect of heat treating gel films at different temperatures on the formation of the boehmite flaky structures on AISI 316 type austenitic stainless steel is investigated. After heating at different temperatures, the reactivity of the gel films with boiling water to form boehmite flakes was different, which resulted in different morphologies and different contact angle values after coating with hydrolyzed (heptadecafluoro-1,1,2,2-tetrahydrodecyl)trimethoxysilane (FAS). When the gel film was heat treated from 200 to 600 °C, the resulting contact angle was above 150°, indicating superhydrophobic behavior. However, when the gel film was heat treated below 200 °C as well as at 700 and 800 °C, only some boehmite flakes were formed; when the gel film was heat treated at 900 °C, no boehmite flakes were observed. In these cases the surface roughness is insufficient for the superhydrophobicity. The formation condition of the boehmite flakes by reaction of the gel film with boiling water is also tentatively discussed.     

Simultaneous catalytic esterification of carboxylic acids and acetalisation of aldehydes in a fast pyrolysis bio-oil from mallee biomass

This paper reports the simultaneous catalytic esterification and acetalisation of a bio-oil with methanol using a commercial Amberlyst-70 catalyst at temperatures between 70 and 170 °C. The bio-oil was prepared from the pyrolysis of mallee woody biomass in a fluidised-bed pyrolysis reactor under the fast heating rate conditions. Our results show that the conversion of light organic acids and aldehydes to esters and acetals rises significantly with increasing temperature, reaction time and catalysts loading. However, some acetals (e.g. dimethoxymethane) could decompose at higher operating temperatures (>110 °C) and catalyst loadings (>6 wt.%). The medium and heavy fractions of bio-oil also reacted with methanol to result in increases in their volatility (or decreases in boiling points) when their reactive O-containing functional groups were stabilised. The acid-catalysed reactions between bio-oil and methanol also decreased the coking propensity of the bio-oil reaction products.     

Comparison of exhaust emissions and their mutagenicity from the combustion of biodiesel, vegetable oil, gas-to-liquid and petrodiesel fuels

Efforts are under way to reduce diesel engine emissions (DEE) and their content of carcinogenic and mutagenic polycyclic aromatic hydrocarbons (PAH). Previously, we observed reduced PAH emissions and DEE mutagenicity caused by reformulated or newly developed fuels. The use of rapeseed oil as diesel engine fuel is growing in German transportation businesses and agriculture. We now compared the mutagenic effects of DEE from rapeseed oil (RSO), rapeseed methyl ester (RME, biodiesel), natural gas-derived synthetic fuel (gas-to-liquid, GTL), and a reference petrodiesel fuel (DF) generated by a heavy-duty truck diesel engine using the European Stationary Cycle. Mutagenicity of the particle extracts and the condensates was tested using the Salmonella typhimurium mammalian microsome assay with strains TA98 and TA100. The RSO particle extracts increased the mutagenic effects by factors of 9.7 up to 17 in strain TA98 and of 5.4 up to 6.4 in strain TA100 compared with the reference DF. The RSO condensates caused up to three times stronger mutagenicity than the reference fuel. RME extracts had a moderate but significantly higher mutagenic response in assays of TA98 with metabolic activation and TA100 without metabolic activation. GTL samples did not differ significantly from DF. Regulated emissions (hydrocarbons, carbon monoxide, nitrogen oxides (NO_x), and particulate matter) remained below the limits except for an increase in NO_x exhaust emissions of up to 15% from the tested biofuels.     

Mechanosynthesis,crystal structure and magnetic characterization of M-type SrFe12O19

M-type strontium hexaferrite was prepared by mechanosynthesis using high-energy ball milling. The influence of milling parameters, hematite excess and annealing temperature on magnetic properties of SrFe₁₂O₁₉ were investigated. Commercial iron and strontium oxides were used as starting materials. It was found that mechanical milling followed by an annealing treatment at low temperature (700 °C) promotes the complete structural transformation to Sr-hexaferrite phase. For samples annealed at temperatures from 700 to 1000 °C, saturation magnetization values (M_s) are more sensitive to annealing temperature than coercivity values (H_c). The maximum M_s of 60 emu/g and H_c of 5.2 kOe were obtained in mixtures of powders milled for 5 h and subsequently annealed at 700 °C. An increase in the annealing temperature produces negligible changes in magnetic saturation and coercivity. An excess of hematite as a second phase produces a slight decrease in the saturation magnetization but leads to a significant increase in coercive field, reaching 6.6 kOe.     

Catalytic combustion of methane on substituted strontium ferrites

Sr-hexaferrites prepared by co-precipitation method and calcined at 700-1000 °С have been characterized by thermogravimetric and differential thermal analysis (TG-DTA), Fourier transformed infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), hydrogen temperature-programmed reduction (H₂-TPR), and Ar adsorption techniques. It has been shown that hexaferrite phase formed after calcination at 700 °С is amorphous and its crystallization occurs at 800 °С. Specific surface area (S_BET) of the samples calcined at 700 °С is 30-60 m²/g. Reduction in hydrogen proceeds in several steps, Fe(III) in the hexaferrite structure being practically reduced to Fe⁰. Amount of hydrogen necessary for the reduction of the samples decrease in the order: SrMn₂Fe₁₀O₁₉ > SrFe₁₂O₁₉ > SrMn₆Fe₆O₁₉ > SrMn₂Al₁₀O₁₉. Surface composition of the ferrites differs from bulk. According to XPS data, the surface is enriched with strontium. Sr segregation is most probably explained by the formation of surface carbonates and hydroxocarbonates. The main components on the surface are in oxidized states: Mn³⁺ and Fe³⁺. Maximum activity in the methane oxidation is achieved for the SrMn_xFe_12−xO₁₉ (0 ? x ? 2) catalysts. These samples are characterized by highest amount of the hexaferrite phase, which promotes change of oxidation state Mn(Fe)³⁺ ↔ Mn(Fe)²⁺.     

Synthesis and mutagenic properties of 4,4'-diamino-p-terphenyl and 4,4'-diamino-p-quaterphenyl

4,4'-Diamino- p -terphenyl and 4,4'-diamino- p -quaterphenyl were synthesised from readily available chemical intermediates. These compounds, along with 1,4-diaminophenylene and benzidine were examined in the Salmonella microsome assay with strains TA98 and TA100. The results of this study indicate that the mutagenicity of these diamines was the greatest for 4,4'-diamino- p -terphenyl, followed by diaminophenylene and benzidine, with 4,4'-diamino- p -quaterphenyl showing no mutagenicity.     

Dehydration of red bell-pepper (Capsicum annuum L.): Change in drying behavior, colour and antioxidant content

The sun, oven (50 and 70 °C) and microwave oven (210 and 700 W) drying behaviors of red bell-pepper slices were investigated. Effects of these drying methods in terms of colour indices and antioxidant activity of pepper slices were also studied. “Midilli and Küçük” model exhibited high coefficient of determination (R²) values for all the drying methods used in the assay, ranging between 0.994-0.999, while “Page” and “Modified Page” models fit better for oven drying at 70 °C. The calculated effective diffusivity (D_eff) values (m²/s) of pepper slices for the drying processes ranged between 0.31 and 87.39 × 10⁻⁹. Sun dried and followed by microwave oven (700 W) dried samples revealed the highest L^*, a^* and b^* colour values than the other dried samples. Microwave oven dried (210 W) and oven dried (50 °C) samples exhibited the lowest TEAC and DPPH radical scavenging activities among the dried samples.     

Design and control of an olefin metathesis reactive distillation column

This paper considers the design and control of a reactive distillation column in which one reactant is consumed and two products are formed (A?B+C). The volatilities are α_B>α_A>α_C, i.e. the reactant is intermediate boiling between the two products. The metathesis of 2-pentene is considered as the demonstrative example. The column has a single feed of the intermediate boiling reactant. The distillate contains mostly light component and the bottoms mostly heavy.Three designs are considered: the base case (low-conversion/low-pressure), a low-conversion/high-pressure case and a high-conversion/high-pressure case. The base design is obtained from the literature, and the other two steady-state designs are optimized with respect to the total annual cost. All the designs are found to be openloop stable. Five control structures are studied for the base design. Then the best two structures are applied to the remaining two designs. This category of reactive distillation exhibits less challenging problems than other categories since it uses a single feed, which eliminates the need for the control structure to perfectly balance two fresh feeds.Simulation results demonstrate that effective dynamic control is provided by a control structure that uses two temperatures to maintain the purities of both product streams. No internal composition measurement is required. This structure is found to be robust and stable and rejects loads and tracks setpoints very well.     

Changes of tomato powder qualities during storage

Changes of tomato powder qualities at different storage temperatures (0, 25, and 37 °C) for 5 months were evaluated in this study. Color parameters (L*, a*, b*), glass transition temperature (Tg) and pH decreased significantly, while 5-Hydroxymethylfurfural (HMF), browning degree (BD) and titratable acid (TA) increased significantly (P < 0.05) at 25 and 37 °C after 5 months. The increased HMF and BD followed a combined kinetics model well. There were insignificant changes for these indicators at 0 °C during storage (P > 0.05). Sucrose, fructose and total sugar (TS) exhibited significant reduction (P < 0.05) only at 37 °C. Free amino acids (FAAs), l-ascorbic acid and solubility of tomato powder underwent significant reduction and total color change ^ΔE significantly increased after 5 months regardless of storage temperatures (P < 0.05), while lycopene and total soluble solid (TSS) showed no significant changes (P > 0.05). SEM micrographs indicated that tomato powder tended to aggregate with increasing the storage temperature or time, which conformed to decreased Tg. There were good correlations between HMF and total free amino acids (TFAA), TS, l-ascorbic acid, BD, L*, a*, b* when stored at 25 and 37 °C.     

Separation of ethyl acetate–isooctane mixture by heteroazeotropic batch distillation

This paper studies the separation of an ethyl acetate–isooctane mixture by heterogeneous azeotropic distillation in a batch rectifying column. An initial list of 60 candidates was studied but only methanol and acetonitrile were obtained as potential heterogeneous entrainers. These entrainers form a low boiling heterogeneous azeotrope with isooctane. Experimental verification of the miscibility gap with isooctane was performed at 25 °C for each entrainer giving a smaller region for methanol than for acetonitrile. Feasibility of the heterogeneous azeotropic batch distillation was carried out experimentally in a laboratory batch distillation column having 44 theoretical equilibrium stages and using a high reflux ratio. Several distillate fractions were taken as a function of the temperature at the top of the column. For both methanol and acetonitrile, the main fraction was defined by the condensed vapor providing a liquid–liquid split of the isooctane/entrainer heteroazeotrope into the decanter. Ethyl acetate impurity was detected in both decanted phases, but in much lower amount when using acetonitrile as entrainer. The process with acetonitrile also resulted in a shorter operating time and higher purity and recovery yield of isooctane as the main distillate product. Pure ethyl acetate remained into the boiler at the end of each process.     

Dry catalytic partial oxidation of diesel-fuel distillates into syngas

Volatile compounds distilled below 205 °C from diesel fuel are reformed into synthesis gas by dry catalytic partial oxidation using porous membrane reactors, eliminating complex liquid-fuel injectors and fuel-air mixers, greatly simplifying reformers for applications with solid-oxide fuel cells and NO_x traps. For distillates utilizing 20 wt% of the diesel fuel, 88 mol% of the carbon is converted into CO and 75 mol% of the hydrogen into H₂. Rationale is as follows: Long-chain n-alkanes such as n-hexadecane, with normal boiling point, 286.5 °C, but autoignition temperature, 205 °C, are the least thermally stable hydrocarbons in diesel fuel. If attempts are made to vaporize diesel fuel under oxygen-lean conditions without precautions, long-chain n-alkanes crack at autoignition temperatures forming radicals that initiate polymerization. By eliminating more troublesome compounds by distillation, and by effusing cooler air through porous ceramic membranes to react radicals with oxygen, carbon deposition is largely suppressed. A perovskite catalyst, fed pre-heated air at >900 °C, provides a reservoir of mobile lattice oxygen to react with adsorbed carbon. In continuous runs of 72 h, carbon deposition was negligible in the reactor, on the catalyst, and in the exhaust, except for minor graphite deposited onto walls near the catalytic hot zone.     

Changes in pore properties of phenol formaldehyde-based carbon with carbonization and oxidation conditions

Porous carbon beads were prepared by carbonizing at 700 and 1000 °C under N₂ (NN-series) or CO₂ atmospheres (CO-series) and a subsequent oxidization with boiling nitric acid solution (13%, v/v) for 3 h (ANN- and ACO-series). BET surface area of both CO- and NN-series samples tends to increase with increasing carbonization temperature, but CO-series samples show higher BET surface areas (700 °C: 610 m²/g, 1000 °C: 780 m²/g) compared with those of NN-series samples (700 °C: 380 m²/g, 1000 °C: 580 m²/g). After acid oxidation, BET surface areas of NN-series samples increased from 580 to 650 m²/g, whereas those of CO-series samples decreased from 780 to 600 m²/g. On subsequent acid oxidation, acidic surface functional groups increased in both CO- and NN-series samples, but the CO-series samples tend to have much more acidic surface functional groups. Adsorption of halogenated methanes, such as tetra-, tri- and dichloromethanes, onto the samples of CO-, NN-, ACO- and ANN-series was thought to be driven initially by the basicity, but the acidic functional groups that could attract adsorbates via dipole-dipole interaction might hinder the adsorption of subsequently incoming adsorbates.     

Structural investigation relating to the cementitious activity of bauxite residue — Red mud

The cementitious behavior of red mud derived from Bauxite-Calcination method was investigated in this research. Red mud were calcined in the interval 400–900 °C to enhance their pozzolanic activity and then characterized in depth through XRD, FTIR and ²⁹Si MAS-NMR techniques with the aim to correlate phase transitions and structural features with the cementitious activity. The cementitious activity of calcined red mud was evaluated through testing the compressive strength of blended cement mortars. The results indicate that red mud calcined at 600 °C has good cementitious activity due to the formation of poorly-crystallized Ca₂SiO₄. The poorly-crystallized Ca₂SiO₄ is a metastable phase which will transform into highly-crystallized Ca₂SiO₄ with the increase of calcination temperature from 700 °C moving to 900 °C. It is the metastable phase that mainly contributes to the good cementitious activity of red mud. This paper points out another promising direction for the proper utilization of red mud.