The partitioning of protease from Calotropis procera latex by aqueous two-phase systems and its hydrolytic pattern on muscle proteins

The protease from the latex of Calotropis procera was isolated by an aqueous two-phase system (ATPS). Polyethylene glycol (PEG 1000, 2000 and 3000) at a concentration of 12, 15, and 18% (w/w) with salts ((NH₄)₂SO₄, K₂HPO₄ and MgSO₄) at a concentration of 14, 17, and 20% (w/w) were investigated. The highest protease recovery (74.6%) was found in the PEG-rich phase of the system (p < 0.05), comprising of 18% PEG 1000 and 14% MgSO₄. Protein patterns and activity staining showed that the isolated protease had a molecular weight of ∼31 kDa without the oligosaccharide attached to the molecule. Degradation of muscle proteins in beef, farmed giant catfish, and squid was observed by the electrophoresis of sodium dodecyl sulphate polyacrylamide gel (SDS-PAGE). The degradation of myofibrillar proteins (myosin heavy chain: MHC and actin: AC) of farmed giant catfish was higher than that of beef and squid muscles as indicated by the degradation proteins with lower molecular weight.     

Kinetics of asphaltene thermal cracking and catalytic hydrocracking

A pentane-insoluble asphaltene was processed by thermal cracking and catalytic hydrocracking over NiMo/γ-Al₂O₃ in a microbatch reactor at 430 °C. Kinetic analysis shows that the first-order kinetics fits the data of conversion in reaction times ≤ 30 min approximately, but deviates from the data of times over 30 min significantly; whereas the second-order kinetics fits the data of the reaction times up to 60 min adequately, to give the apparent rate constants of 1.704 × 10⁻² and 9.360 × 10⁻² wt frac⁻¹min⁻¹ for the two cracking processes. Furthermore, a three-lump kinetic model is proposed to include parallel reactions of asphaltenes to produce liquid oil (k₁) and gas + coke (k₃), and consecutive reaction from liquid to gas + coke (k₂). The evaluated value of k₁ is 1.697 × 10⁻² and 9.355 × 10⁻² wt frac⁻¹min⁻¹, k₂ is 3.605 × 10⁻² and 6.347 × 10⁻³ min⁻¹ , and k₃ is 6.934 × 10⁻⁵ and 4.803 × 10⁻⁵ wt frac⁻¹min⁻¹ for asphaltenes thermal cracking and catalytic hydrocracking, respectively. Selectivity analysis shows that the catalytic hydrocracking process promotes liquid production and inhibits coke formation effectively.     

Thermal catalytic cracking of buriti oil (Mauritia flexuosa L.) over LaSBA-15 mesoporous materials

In order to obtain a fuel with properties similar to diesel, the thermal catalytic cracking (TCC) of buriti oil was accomplished over LaSBA-15 mesoporous materials. In function of the Lewis acid sites and the unidirectional pore system of the LaSBA-15, this material presented good deoxygenating activity for TCC of the oil, resulting in a reduction of the oxygenate content in the organic liquid (OL) collected above 190 °C, obtaining as main product, a mixture of hydrocarbons similar to mineral diesel, called green diesel.     

A novel conceptional process for residue catalytic cracking and gasoline reformation dual-reactions mutual control

Based on the subsidiary riser FCC (SRFCC) process for gasoline reformation [Y.H. Bai, J.S. Gao, S.C. Li, C.M. Xu, Petrol. Process. Petrochem. (China) 35 (2004) 17–21, J.S. Gao, C.M. Xu, Y. Mao, et al., Petrol. Refin. Eng. (China) 35 (2005) 7–9], a novel conceptional process for residue catalytic cracking and gasoline reformation dual-reactions mutual control (DMC) was proposed and relevant experimental researches were carried out in a Technical Pilot Scale Riser (TPSR) FCC apparatus. The goals of DMC were to improve product quality and increase desirable product yield in residue catalytic cracking as well as in FCC gasoline upgrading. The experiments showed that the decrease of temperature difference between feedstock and regenerated catalysts in DMC by directly leading the cooled regenerated catalysts into riser reactor or feeding gasoline into riser reactor in vapor phase could decrease the amount of dry gas and coke and obtain a better quality of upgraded gasoline. Moreover, the spent catalysts still retaining high level of activity could be recycled to the base of the main riser reactor treating heavy oil and mixed with regenerated catalysts in DMC, it allows residue catalytic cracking to operate at high catalyst-to-oil ratio and the relatively low inlet catalysts temperature. The experimental results also showed that the mixed catalysts could improve the product selectivity in residue catalytic cracking, especially for light oil (gasoline and diesel). In addition, compared with the routine RFCC, the product distribution from the residue catalytic cracking in DMC contains more liquid products, less dry gas, and a better gasoline quality.     

Data analysis, modeling and control performance enhancement of an industrial fluid catalytic cracking unit

Considerable fluctuations were observed in the riser temperature of one of the fluid catalytic cracking (FCC) unit of a Southeast Asian refinery. This undesired occurrence has an adverse effect on the performance of the process unit. In the present study, several statistical tools are developed and then used, for the first time, for analyzing routine operating data in order to characterize the dynamics of the riser temperature and other critical variables that may be affecting the riser temperature. Subsequently, a first-principles-based dynamic model of the FCC unit is implemented to closely simulate the FCC unit under investigation. The model is validated by predicting the measured operating data of the FCC unit. This facilitated an in-depth study of the FCC unit, leading to the identification of several strategies for improving the control loop performance of the riser temperature.     

Effect of primary amine hydrocarbon chain length for the selective catalytic reduction of NOx from diesel engine exhaust

The effect of increasing primary amine hydrocarbon chain length on the SCR of NO_x from diesel engine exhaust was investigated and compared to ammonia. Methylamine (CH₃NH₂), ethylamine (CH₃CH₂NH₂), propylamine (CH₃CH₂CH₂NH₂) and butylamine (CH₃CH₂CH₂CH₂NH₂) were tested using a 12 cell mini core NH₃ - SCR catalyst cut from a 400 cpsi block. There is a steady decrease in NO_x conversion as the length of the hydrocarbon chain increases (from 50% for methylamine to 26% for butylamine). For the same number of carbons in the amine, primary amines are more active reductants than methyl substituted secondary or tertiary amines. For example, ethylamine (NO_x conversion of 45%) is more active than dimethylamine (NO_x conversion of 34%).Since the amines are reactive in the gas phase in the temperature range of diesel engine exhaust, gas phase conversions were estimated by replacing the mini core SCR catalyst with an equivalent length of quartz beads. There was no smooth transition in gas phase NO and NO_x conversions with increasing hydrocarbon chain length. The results suggest a different mechanism for gas phase reactions depending on the nature of the amine.     

The thermal cracking of soybean/canola oils and their methyl esters

Triacyl glycerides (TGs) are naturally occurring oils produced by a significant variety of crops, microorganisms (bacteria and algae), and animals (certain fats). The diversity and prevalence of the sources of these compounds suggest that they may serve as an attractive alternative to crude oil as the feedstock for the production of transportation fuels and certain industrial chemicals — organic compounds with carbon chain lengths in the range of C₇ to C₁₅. In the present study a series of batch thermal cracking reactions was performed using soybean oil and canola oil under reaction conditions leading towards attractive yields of potentially valuable (as fuels and/or chemicals) shorter chain products. An attractive yield of alkanes and fatty acids (from oil cracking) or esters (from biodiesel) was obtained. From a parametric study reaction temperature, followed by residence time, was found to have the most significant effect. Significantly, cracking under increased pressures in a hydrogen atmosphere did not improve the yields of desirable species.     

Application of the thermal DeNOx process to diesel engine DeNOx: an experimental and kinetic modelling study

Diesel DeNO_x experiments have been conducted using the selective noncatalytic ‘thermal DeNO_x’ process in a diesel fuelled combustion-driven flow reactor which simulated a single cylinder (966 cm³) and head equipped with a water-cooling jacket and an exhaust pipe. NH₃ was directly injected into the cylinder to reduce NO_x emissions. A wide range of air/fuel ratios (A/F=20-40) was selected for NO_x reduction where an initial NO_x of 530 ppm was usually maintained with a molar ratio (β=NH₃/NO_x) of 1.5.The results indicate that a 34% NO_x reduction can be achieved from the cylinder injection in the temperature range, 1100-1350 K. Most of the NO_x reduction occurs within the cylinder and head section (residence time<40 ms), since temperatures in the exhaust are too low for additional NO_x reduction. Under large gas quenching rates, increasing β values (e.g. 4.0) substantially increase the NO_x reduction up to 60%, which is comparable with those achieved under isothermal conditions. Experimental findings are analysed by chemical kinetics using the Miller and Bowman mechanism including both N/H/O species and CO/hydrocarbon reactions to account for CO/UHC oxidation effects, based on practical nonisothermal conditions. Comparisons of the kinetic calculations with the experimental data are given as regards temperature characteristics, residence time and molar ratio. In addition, the effects of CO/UHC and branching ratio (α=k₁/(k₁+k₂)) for the reaction NH₂+NO=products are discussed in terms of NO reduction features, together with practical implications.     

Growth of Escherichia coli and Salmonella typhi inhibited by fractal silver nanoparticles supported on zeolites

Silver nanoparticles were dispersed on clinoptilolite zeolite. These materials were evaluated as biocides for Escherichia coli and Salmonella typhi. Ag-zeolites were shown to be efficient in eliminating both E. coli and S. typhi present in nutritive media. Particularly, E. coli was eliminated at very short times. In the presence of a zeolite free of silver, bacteria use the zeolite to reproduce rapidly.     

催化裂化废剂的处置和再利用

本文介绍了国内外催化裂化废剂的处理和利用技术,为其处置和再利用提供参考。     

重油催化裂化吸收稳定系统降低液态烃C_2含量的分析

举例分析了重油催化裂化装置吸收稳定系统降低液态烃C2含量的可行性,对装置实际生产数据进行分析并提出优化方案,为装置生产创造经济效益。     

Five-lump kinetic model with selective catalyst deactivation for the prediction of the product selectivity in the fluid catalytic cracking process

The effective simulation of the fluid catalytic cracking (FCC) operation requires a good understanding of many factors such as, reaction kinetics, fluid dynamics, and feed and catalyst effects. The different product slates that can be obtained are the consequence of a complex reaction scheme including cracking, isomerization, hydrogen transfer, oligomerization, etc. Furthermore, the catalyst deactivation may affect each one of the reactions in different ways, which creates an additional reason for different variation with time-on-stream of the yield to each product. On the basis of the experimental data of the FCC pilot plant operated in Chemical Process Engineering Research Institute (CPERI, Thessaloniki, Greece), a lumping model was developed for the prediction of the FCC product distribution. The lumped reaction network involved five general lumps (gas oil, gasoline, coke, liquefied product gas, and dry gas) to simulate the cracking reactions and to predict the gas oil conversion and the product distribution. The paths of catalyst deactivation were studied and a selective deactivation model was adopted that enhances the fundamentality and accuracy of the lumping scheme. The hypothesis of selective catalyst deactivation was found to improve the product slates prediction. Models with different assumptions were examined, regarding the behavior of the catalyst, as deactivated, and its effect on the reactions of the lumping scheme. A large database of experiments, performed in the FCC pilot plant of CPERI was used to verify the performance of the models in steady state unit operation. The simulation results depict the importance of incorporating selective catalyst deactivation functions in FCC lumping models.     

Solubility of Jatropha and Aquilaria oils in supercritical carbon dioxide at elevated pressures

This study investigated experimental equilibrium solubilities of Jatropha curcas and Aquiliaria crassna oils dissolved in supercritical carbon dioxide at temperatures of 318-338 K and pressures of 20, 25, 30, 35 MPa. The highest solubility of J. curcas and A. crassna oil were 29.8 and 28.4 mg L⁻¹, respectively, at 338 K and 35 MPa. The oil solubilities and the concentration of triglycerides both increased with increasing temperature and pressure. Triglyceride molecules surrounded by carbon dioxide molecules may be proposed since solubilities increased with the flux of supercritical carbon dioxide. The solubility of these two oils linearly increased with the density of supercritical carbon dioxide. Experimental data of the oil solubility were successfully correlated by the Chrastil equation.     

Simulation of thermal shock cracking in ceramics using bond-based peridynamics and FEM

The effects of moderate intensity ‘hot’ or ‘cold’ shock in brittle solids have been extensively studied, while much less is known about thermal shock response during large temperature variations. In this study, a combined finite element – peridynamics numerical procedure is proposed for the simulation of cracking in ceramic materials, undergoing severe thermal shock. Initially, Finite Element nonlinear heat transfer analysis is conducted. The effects of surface convection and radiation heat exchange are also included. Subsequently, the interpolated temperature field is used to formulate a varying temperature induced action for a bond-based peridynamics model. The present model, which is weakly coupled, is found to reproduce accurately previous numerical and experimental results regarding the case of a ‘cold’ shock. Through several numerical experiments it is established that ‘cold’ and ‘hot’ shock conditions give rise to different failure modes and that large temperature variations lead to intensified damage evolution.     

Removal of SO2 at low temperature using dead Bacillus licheniformis

In this paper we studied the adsorption and desorption behavior of SO₂ by the dead Bacillus licheniformis R08 biomass. The effects of water vapor, temperature and O₂ on the removal of SO₂ by the biomass were studied. FTIR and XPS were used to characterize the mechanism of the SO₂ adsorption on the biomass. The experimental results showed that water vapor and temperature deeply influenced the adsorption of SO₂ by the biomass. However, O₂ cannot oxidize SO₂ to SO₃ on the biomass. FTIR and XPS results showed that oxygenous and nitrogenous functional groups on the cell walls of biomass may be related to the SO₂ adsorption and three sulfur species were formed on the biomass in adsorption process. In the desorption process, weakly adsorbed SO₂ could be desorbed by increasing temperature and the biomass can be reused for 10 cycles.     

Imidazolium-substituted ionic (co)polythiophenes: Compositional influence on solution behavior and thermal properties

A series of ionic polythiophenes, in homopolymer and random copolymer configurations, is prepared via the Grignard metathesis (GRIM) polymerization protocol and subsequent substitution on the bromohexyl side chains with N-methylimidazole. The introduced structural variations – comonomer ratio, side chain composition, counter ions – allow tuning of the thermal properties and solution behavior of the resulting conjugated polymers. As expected, the solubility depends majorly on the number of ionic groups and the counter ions. The most peculiar behavior is observed for the P3HT-P3(MIM)HT-Br 50/50 random copolymer, which shows organization of the polymer chains in solution and thin film dependent on the preparation conditions. Dynamic light scattering studies confirm that the ordered solid-state structure is somewhat maintained when the copolymer is dissolved in a bad solvent mixture. The ionic (co)polythiophenes are generally more resistant to thermal degradation than their precursors. The precursor polymers all show a clear semi-crystalline behavior, with a decrease in crystallinity upon decreasing the number of regular 3-hexylthiophene units. On the other hand, the studied ionic (co)polythiophenes are fully amorphous. Changes in the counter ions have dramatic effects on the thermal properties. Bromine counter ions render the polymers strongly hygroscopic. The novel materials are of particular appeal in the field of organic photovoltaics, in which the imidazolium-substituted (co)polythiophenes can be beneficially applied as constituents of either active layers or electron transport layers. Their processability from green solvents is also of major importance for the field.     

Preliminary separation and purification of rutin and quercetin from Euonymus alatus (Thunb.) Siebold extracts by macroporous resins

In this study, the performances of rutin and quercetin from Euonymus alatus (Thunb.) Siebold extracts on five macroporous resins with different physical and chemical properties were investigated. The results of static tests indicated that AB-8 resin was the most appropriate and its adsorption data were well fitted to the Langmuir and Freundlich isotherms. In order to optimize the separation process, different pH values of sample solution, different concentrations and pH values of ethanol solution also have been investigated. Column packed with AB-8 resin was used to perform dynamic adsorption and desorption experiments. After the treatment with AB-8 resin and optimal conditions, the contents of rutin and quercetin in the product were 8.45-fold and 13.14-fold increased with recovery yields of 63.1% and 72.3%, respectively. The results showed that the present method was suitable for large-scale preparation of rutin and quercetin from Euonymus alatus (Thunb.) Siebold or other herbal materials.     

New approach to the formulation of hydrogel beads by emulsification/thermal gelation using a static mixer

A new approach in the formulation of hydrogel beads by emulsification/in situ thermal gelation using static mixer technology is described. κ-Carrageenan was selected as the model hydrogel. The emulsion generated by a Sulzer SMX6 static mixer consisted of warm κ-carrageenan sol (1.5% w/w in water or ) as the dispersed phase, and ambient temperature sunflower seed oil as the continuous phase. Dispersion followed by in situ gelation of κ-carrageenan droplets was possible within a short residence time (1-) in the static mixer, under defined operational conditions, known as the feasibility region. This region was defined as the zone of operation conditions necessary to obtain discrete gel beads, within a defined range of κ-carrageenan solution injection temperature, volume fraction and total flowrate. The temperature boundaries of the feasibility region were determined by the κ-carrageenan gelation temperature and solution viscosity. The resulting beads had a Sauter mean diameter ranging from 350 to , which decreased with the increase of κ-carrageenan injection temperature, total flowrate and/or the number of static mixer elements. Theoretical values of maximal bead diameter and Sauter mean diameter were calculated on the base of critical Weber number, which was demonstrated through good agreement with the experimental values. It was demonstrated that an existing model for the prediction of gel bead diameter in a SMX static mixer is applicable for the new procedure described in this study.     

Self-assembled monolayers-based immunosensor for detection of Escherichia coli using electrochemical impedance spectroscopy

An electrochemical impedance immunosensor for the detection of Escherichia coli was developed by immobilizing anti-E. coli antibodies at an Au electrode. The immobilization of antibodies at the Au electrode was carried out through a stable acyl amino ester intermediate generated by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydrosuccinimide (NHS), which could condense antibodies reproducibly and densely on the self-assembled monolayer (SAM). The surface characteristics of the immunosensor before and after the binding reaction of antibodies with E. coli were characterized by atomic force microscopy (AFM). The immobilization of antibodies and the binding of E. coli cells to the electrode could increase the electro-transfer resistance, which was directly detected by electrochemical impedance spectroscopy (EIS) in the presence of Fe(CN)₆³⁻/Fe(CN)₆⁴⁻ as a redox probe. A linear relationship between the electron-transfer resistance and the logarithmic value of E. coli concentration was found in the range of E. coli cells from 3.0 × 10³ to 3.0 × 10⁷ cfu mL⁻¹ with the detection limit of 1.0 × 10³ cfu mL⁻¹. With preconcentration and pre-enrichment steps, it was possible to detect E. coli concentration as low as 50 cfu/mL in river water samples.     

Production of clean transportation fuels and lower olefins from Fischer-Tropsch Synthesis waxes under fluid catalytic cracking conditions: The potential of highly paraffinic feedstocks for FCC

The potential of Fischer-Tropsch Synthesis (FTS) waxes as a feedstock for fluid catalytic cracking (FCC) has been evaluated with a once-through microriser reactor operating under realistic conditions. The highly paraffinic feedstock has a high reactivity and can be converted under industrial conditions to a high extent (>90 wt%). The product distribution can be optimised by the process parameters and catalyst formulation. A high gasoline fraction (70 wt%) with a very low aromatics concentration can be obtained. As a result of the formation of i-paraffins, n-olefins and i-olefins the gasoline is expected to possess an acceptable octane number. The reaction scheme derived predicts that the degree of branching in the paraffinic diesel-range product is lower than that of the gasoline-range product and that a relatively good diesel is expected. Due to the absence of sulfur and nitrogen in the feed extremely clean transportation fuels are obtained. The addition of ZSM-5 to an equilibrium catalyst allows the production of significant amounts of light olefins, in particular propene (16 wt%) and butenes (15 wt%).