Reaction Period Research Articles

A strategy for the controllable generation of organic superbases from benchtop-stable salts.

Organic superbases are a distinct class of strong base that enable numerous modern reaction applications. Despite their great synthetic potential, widespread use and study of superbases are limited by their air sensitivity and difficult preparation. To address this, we report air-stable carboxylate salts of BTPP and P2-t-Bu phosphazene superbases that, when added to solution with an epoxide, spontaneously generate freebase. These systems function as effective precatalysts and stoichiometric prereagents for superbase-promoted addition, substitution and polymerization reactions. In addition to improving the synthesis, shelf stability, handling and recycling of phosphazenes, this approach enables precise regulation of the rate of base generation in situ. The activation strategy effectively mimics manual slow addition techniques, allowing for control over a reaction's rate or induction period and improvement of reactions that require strong base but are also sensitive to its presence, such as Pd-catalyzed coupling reactions.

A two dimensional Co(OH)2 catalytic gravity-driven membrane for water purification: a green and facile fabrication strategy and excellent water decontamination performance.

Cobalt-based materials are reported to be the most efficient catalysts in sulfate radical advanced oxidation processes (SR-AOPs). A green and facile method was developed in this work to prepare uniform Co(OH)2 hexagonal nanosheets, which was void of any organic solvents via mere ambient temperature stirring. The obtained nanosheets were assembled into a catalytic gravity-driven membrane, through which the removal efficiency of a typical pharmaceutical contaminant, ranitidine (RNTD), could reach ∼100% within 20 min. Meanwhile, the catalytic membrane also demonstrated effective removal performance towards various pollutants. In order to augment the long-term stability of catalytic membranes, Co(OH)2/rGO composites were fabricated using the same strategy, and a Co(OH)2/rGO catalytic membrane was prepared correspondingly. The Co(OH)2/rGO membrane could maintain a ∼100% removal of RNTD over a constant reaction period lasting for up to 165 hours, which was approximately 11 times that of the sole Co(OH)2 membrane (15 h). Analysis of element chemical states, metal ion concentration in filtrates, and quenching experiments suggested that the combination with rGO could promote the electron transfer to accelerate the Co(II) regeneration, restrain the cobalt dissolution to alleviate the active site loss, and contribute to the production of 1O2via synergistic effects of oxygen-containing groups in rGO. Toxicity assessment was performed on RNTD and its degradation intermediates to confirm the reduction in ecotoxicity of the treated feed. Overall, this work not only offered guidance for the application of nanosheets in AOP membranes, but also had implications for the environmentally-friendly preparation protocol to obtain functional metal hydroxides.

Facile preparation of Fe2O3 catalyst and assessment of its photodegradation performance for industrial effluent purification

This study focuses on synthesizing nano-scaled Fe2O3 particles using Araucaria columnaris (Cook's pine) leaf extract under atmosphere circumstances. These extracts serve as both a reductant and a stabilizer. Fe2O3 nanoparticle synthesis was confirmed through a comprehensive characterization process using many analytical techniques. The analysis of XRD patterns indicated that the examined samples consisted of nanoparticles of γ-Fe2O3, exhibiting a cubic crystal structure with a high degree of crystallization. Furthermore, the calculated crystallite size was resolute to be 24.5 nm. The scanning electron microscopy pictures revealed that the created samplesexhibited a combination of spherical and polyhedral morphologies. The investigation of optical characteristics, such as light absorption and bandgap width, was conducted usingUV–visible spectroscopy, employing a bandgap energy value of 3.78 eV. The study aimed to assess the removal effectiveness of Eosin yellow, Malachite green, Reactive black, and Rhodamine 6G dyes using Fe2O3 nanoparticles synthesized as a photocatalyst which exhibited remarkable photocatalytic efficacy in the breakdown of dyes when exposed to sunlight, and the reaction period of 90 min resulted in a maximum degradation rate of 97.4 %. Considering the promising results, utilizing Fe2O3 nanoparticles as a photocatalyst for degrading dyes in wastewater is feasible. Additionally, Araucaria columnaris leaf extract can be an environmentally friendly and economically viable method for synthesizing Fe2O3 nanoparticles.

Slatted floor reduces the welfare and increases the foot pad dermatitis and growth performance of Turkeys under Egyptian conditions.

When Turkeys' legscome in contact with their dropping during the growing stage results in footpad dermatitis condition which affects the poult's welfare and productivity. Our experiment aimed to detect the impact of various bedding substrates on the wellbeing, and performance of growing Turkey under Egyptian conditions. 180-day-old Turkey poults were allocated into three treatments. In treatment I, the poults [60 each with three replicates (n = 20 birds)] were kept on wood shavings (WS); in the second treatment, the poults were housed on chopped wheat straw (CWS). However, in the third treatment, they kept on a plastic slatted floor (PSF). The greater feed intake and body weight were recorded in poults reared in PSF compared with those kept in other treatments (WS and CWS). Feed conversion ratio did not show any significant difference. The mortality percentage was higher in the PSF group than in the WS one. The frequency of feeding and drinking behavior was higher in poults reared on WS treatment compared with other treatments CWS and PSF. On the other hand, resting behavior showed the highest frequency in poults kept in PSF. Contrary, the lowest frequency of walking behavior was recorded in poults reared in PSF treatment. In addition, the poults kept in WS had a longer tonic immobility reaction period followed by those kept in PSF and CWS. Concerning foot-pad dermatitis, the highest score of 0 was observed in the CWS group, while the highest score of 1 was recorded among poults kept in the WS group. On the other side, the highest score 2, 3, and 4 was observed in the poults reared in the PSF group. Heterophil/Lymphocyte ratio of Turkey poults was higher in PSF. While T3 and T4 concentrations in blood were not affected by using different bedding materials. It is concluded that the slatted floor was good for Turkey producers from the point of performance but, it is the worst from the point of welfare.

Tailored sulfonated carbons: unraveling enhanced catalytic dynamics for fructose dehydration under conventional and microwave heating

Cooperation among active sites within a strongly acidic carbon allowed 80% conversion at 120 °C within a 5-minute reaction period.

Insight into the long-term nonoxidative immobilization of thallium on birnessite

Birnessite has been considered as a potential thallium (Tl)-oxidizing mineral and Tl scavenger in natural and engineered systems. However, the birnessite aging that occurs during Tl sorption may severely limit the long-term effectiveness of Tl immobilization on birnessite. In this study, kinetic experiments were performed in batch coupled stirred-flow systems to investigate the effects of Tl(I) loading and pH on Tl(I) retention during short- and long-term Tl-birnessite interactions. Spectral analysis, microscopic observations, and theoretical calculations revealed a change in the Tl(I) binding mode to birnessite with time. In the short term, low levels of Tl(I) could be effectively immobilized through adsorption to birnessite vacancies. Structural disruption and vacancy occupation in birnessite resulted in the migration of adsorbed Tl(I) toward the edges of the mineral during a 24-d reaction period. Under acidic to neutral conditions, the migration of vacancy-bound Tl(I) induced sustained Tl(I) release (10–45%) from birnessite over the long-term. Under alkaline conditions, hydroxide ions contributed to the formation of Tl(I)–OH species with double edge sharing, which enhanced the binding ability (α ≈ 7 × 10−4 min−1) and stable retention of Tl(I) on birnessite. Understanding Tl(I) retention dynamics during long-term Tl-birnessite interactions elucidates the Tl cycle in Mn oxide-containing systems.

Efficient hydrogen production from high-concentration aqueous formic acid over bio-based γ-Mo2N catalysts

Formic acid is regarded to be one of the most prospective hydrogen carriers. Effective screening of the fitting non-noble-metal-based heterogeneous catalysts to substitute the expensive noble-metal-based ones for FA dehydrogenation is considered as a key to the commercial application for hydrogen economics. Herein, dehydrogenation of liquid neat FA achieved a gas production value of 1753.5 mL/gcat./h at 94 °C by using a biomass-derived γ-Mo2N based catalyst synthesized from the earth-abundant molybdenum and soybean with a facile pyrolysis process. The effect of material ratio, pyrolysis temperature on the catalytic performance of FA dehydrogenation were studied in details. In particular, the catalyst obtained at a pyrolysis temperature of 700 °C, weight ratios of ammonium molybdate to soybean of 0.2/1 exhibited the highest activity. In addition, the catalytic activity increased with the increase of FA concentration, but conversely, the dehydrogenation selectivity decreased with the increasing FA concentration. Moreover, it was found that the Bio-Mo2N catalyst was rather stable over the 40 h continuous reaction period.

Response Surface Methodology Process Optimization of Biodiesel Production from Castor Seed Oil

The increasing demand for energy and the depletion of fossil fuel resources has led to the search for an alternative energy source. The search for such alternative fuel sources has oriented biodiesel synthesis as the ultimate alternative energy resource of the future. The purpose of this study was to produce castor oil and optimize biodiesel production using full factorial central composite design (CCD) through the response surface methodology (RSM) approach. The castor oil was extracted using a mechanical press, and free fatty acids were reduced with acid esterification and biodiesel produced through the transesterification process using homogeneous catalysts. The physicochemical properties of extracted castor oil and biodiesel including density, kinematic viscosity, saponification number, free fatty acid, acid number, cetane number, and iodine number were determined. The ideal conditions for producing biodiesel from castor oil are anticipated to be a reaction period of 105 min at a temperature of 50°C, a catalyst loading weight of 1.5%, and a methanol-to-oil ratio of 5 : 1. The biodiesel yield obtained was 95.0%, and the results of the measured parameters of biodiesel were compared with the international standards of the European norms (EN14214) and the American Society Test Material (ASTM) D6751. The weight composition of both fatty acid and methyl ester was determined by gas chromatography-mass spectroscopy (GC-MS). The study concluded that the results of this research are beneficial in optimizing the parameters for making biodiesel from extracted castor oil.

A rapid and large volume synthesis of mono-, di-, tri-, and tetra-substituted imidazole derivatives via ultrasonic radiation-driven technique

Sonochemistry under controlled conditions has proven effective in medicinal chemistry and drug development. It can substantially shorten reaction timelines from days or hours to minutes. A convenient one-pot synthesis of 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted imidazole derivatives catalyzed by PTSA and benzenesulfonic acid in ethanol as solvent, under ultrasonic irradiation and without ultrasound irradiation at 50° C has been achieved successfully. These 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted imidazole derivatives synthesis were also accomplished using different solvents viz., Methanol, Ethanol, DCM, DMF, Acetonitrile and THF and PTSA as the catalyst. This method yielded the highest % synthesis of 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted imidazole derivatives with PTSA as the catalyst in solvent ethanol. These reactions were also optimized for % of PTSA catalyst required to obtain the maximum yield of 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted imidazole derivatives with and without ultrasound irradiation at 50° C. Synthesis of 2,4,5-trisubstituted Imidazole derivatives reaction follows first-order rate kinetics while that of 1,2,4,5-tetrasubstituted Imidazole derivatives reaction follows the second-order rate kinetics. Furthermore, sonochemistry has higher yields, lower cost, easier workups, and higher purity than conventional thermal organic synthesis, which has lower yields, tedious workups, longer reaction periods, lower purity, and numerous byproducts.

Research progress on the influencing factors and enhancement mechanism of CH4/CO2 mixture separation process by hydrate‐based technology: A review

AbstractThe separation of mixed gas by hydrate method can realize the efficient separation of CO2 gas from biological gas. However, the long period, slow rate, and low selectivity of hydration reaction have become the critical problems restricting the efficient separation of the gas mixture by hydrate method. In this review, the formation characteristics of CH4/CO2 mixed gas hydrate are systematically summarized, and the kinetic process and influencing factors of CH4/CO2 mixed gas hydrate formation are comprehensively analyzed. On this basis, the influence mechanism and law of temperature, pressure, gas–liquid ratio, gas component ratio, additives, and other factors on the CH4/CO2 mixed gas hydrate formation progress were described in detail, and the enhancement mechanism of CH4/CO2 mixed gas hydrate formation under the influence of different factors was analyzed. Finally, the shortcomings and future development directions of the purification and separation technology of CH4/CO2 mixed gas by hydrate method are pointed out. Further research is needed to understand the kinetic mechanism and enhancement mechanism of the CH4/CO2 mixture separation process by hydrate method. The relative results will provide valuable guidance for the separation of mixture gas by a hydrate‐based method.

Fischer-Tropsch synthesis to α-Olefins with low CO2 selectivity on a Co2C catalyst

A Co2C catalyst with low CO2 selectivity for the Fischer-Tropsch to Olefins (FTO) was derived from a precursor catalyst prepared by a “melting” method. Co-Mn composite oxide, MnCo2O4.5, was identified as the dominant composition in the catalytic material before it was activated. The catalyst showed a weak interaction between Co and Mn with the presence of Na. Therefore, Co could be liberated easily from MnCo2O4.5 with H2 reduction at a usually used condition for Co-based catalyst for the Fischer-Tropsch Synthesis (FTS). A clear carburization of Co0 to Co2C was observed during the initial period of reaction, and this transformation could be achieved within 6 h. Four different crystal facets, (210), (020), (111), and (101) for Co2C, were identified once Co0 has been successfully carburized during the reaction. A limited amount of Co0 also transformed to Co3O4 during Co2C formation when H2O was produced by the FT reaction. The prepared catalyst demonstrated outstanding performance in terms of product selectivity. Its selectivity to lower olefins (C2-C4) was as high as 60.26 % with an average olefin/paraffin ratio of 26.69. Additional to high olefin selectivity, the CO2 selectivity was as low as 11.49 %, and that of C1 (CO2 + CH4) could be controlled at 16.44 % with optimal Co/Mn ratio and operating conditions. It was also found that transient state Co0 with Mn and Na as promoters demonstrated similar high olefin to paraffin ratios when compared to Co2C.

The role of various preparation techniques and nickel loadings in ethanol steam reforming over mesoporous nanostructured Ni–Al2O3 catalysts

This study involved the preparation of Al2O3 support and Ni/Al2O3 catalysts through different methods such as mechanochemical, impregnation, and co-precipitation. These prepared samples were then assessed for their performance in the ethanol steam reforming (ESR) process. The results indicated that the 10Ni/Al2O3 catalyst, which was created using the impregnation method and exhibited a high BET surface area of 200.8 m2/g along with well-dispersed nickel, displayed exceptional performance in the ethanol steam reforming reaction. When compared to other catalysts, it exhibited greater activity and stability. A series of Ni/Al2O3 catalysts were prepared with nickel contents ranging from 2.5 to 20 wt%. The study showed that increasing the amount of nickel from 2.5 to 12.5 wt% led to a boost in the catalysts' ability to be reduced, which in turn resulted in improved catalytic performance. However, increasing the nickel content beyond 12.5 wt% led to a decline in catalytic performance. This decrease could be attributed to weaker Ni–Al2O3 interactions, an increase in particle size from 2.7 to 7.8 nm, and a significant reduction in the BET surface area from 198.3 m2/g to 166.4 m2/g. Temperature-programmed oxidation (TPO) profiles revealed that the carbon deposits on the catalyst's surface exhibited a whisker-like structure, and higher nickel contents correlated with increased oxidation peak temperatures and intensities. Moreover, the 12.5Ni/Al2O3 catalyst demonstrated remarkable stability over a 550-min reaction period. The study's findings indicated that as the Tcal. rose from 500 to 700 °C, the catalytic activity gradually lessened. The 12.5Ni/Al2O3 catalyst calcined at 500 °C, characterized by a small particle size and moderate Ni–Al2O3 interaction, exhibited the most favorable catalytic activity.

Drying behavior of solid digestate and reaction kinetics of ammonium degradation during laboratory-scale drying

Fundamental knowledge of the drying behavior and ammonia emission from digestate is required in order to properly design efficient drying processes. In this study, laboratory-scale drying experiments with two different digestates (D1 and D2) were conducted at four different drying temperatures (50, 60, 70, and 80 °C). The solid digestate D1 mainly consisted of plant silage (88.7%), while D2 comprised primarily of manure (55.9%). The drying experiments were performed in a controlled drying chamber using relatively small-sized samples of digestate (30 g for D1, 37 g for D2). These samples were characterized by an initial moisture content of about 74% wb (D1) and 78% wb (D2). This sample size mass was deliberately chosen to ensure homogeneous drying conditions within a thin layer and to facilitate precise laboratory quality measurements of parameters including water content, nitrogen contents (N-total, NH4-N), and pH values before and after the drying process. Both types of digestate exhibited a similar kinetics of drying and ammonium degradation. The first period of constant drying rate was followed by two periods with decreasing rates. Similarly, the ammonium degradation was characterized by three periods with decreasing reaction rates. Considering only the first reaction period herein, ammonium degradation was determined as a first-order reaction. The activation energy for this reaction period was obtained to be 20.00 kJ mol−1 for digestate D1 and 18.44 kJ mol−1 for digestate D2. The results of this study may serve as a basis for the conceptualization and design of optimized, continuous drying processes tailored to digestate materials.

Microstructure evolution law and dissolution time effect of bituminous coal under acetic acid acidification: Based on Micro-CT image analysis

Undeveloped pores and fractures in coal seams constrain coalbed methane mining and dust disaster prevention significantly. The existing hydraulic fracturing technology has achieved some effects in coal seam modification. Still, there are hidden dangers in inducing microseismicity and other aspects. Applying acidification technology for pore and fracture modification improves the efficiency of coalbed methane mining and dust suppression. In this paper, 75% concentration of acetic acid was utilized to treat columnar coal samples, and the experimental method of X-ray computed tomography was applied to study the role of dissolution time on the microcomponents and structure of samples. The experimental results showed that the porosity increased with the dissolution time; the effect of acetic acid on the pore expansion and mineral dissolution showed three periods, i.e., the beginning of the reaction period (0 ∼ 12 h), the full reaction period (12 ∼ 48 h), and the reaction slowing down period (>48 h). The mineral volume fraction showed an overall decreasing trend; before 36 h, the dissolution of acetic acid on the mineral structure within the coal was faster, making it loose, which in turn accelerated the dissolution of coal, and after 36 h, the dissolution effect of acetic acid weakened, and the mineral was gradually stabilized. Acetic acid first reacts with minerals in large quantities. With the increase of products, the solution's ionic complexity increases, so acetic acid accelerates the ionization of more H+ ions, and the solution's acidity increases. After a while of dissolution, the content of acetic acid decreases, the ionized H+ ions are not enough to continue to react with the minerals, and the rate of the mineral's crystal particle size reduction slows down gradually. In conclusion, acetic acid has the potential for pore and fracture modification of coal reservoirs. It can affect the mineral through dissolution, at the same time, improve the porosity. The research results provide an essential reference for using acidification technology to modify the pores and fractures in coal seams.

Mg1-xNixGayFe2-yO4 nano catalysts for green hydrogen generation with highly efficient photo/electro catalytic water splitting applications

The production of nanomaterials for renewable energy as fossil fuel substitutes is anticipated as a viable solution to the pressing issues of environmental pollution and energy scarcity. We fixated on the development of Mg1-xNixGayFe2-yO4 (x = y = 0.0–0.03; steps: 0.01) nanocatalysts by sol-gel auto-combustion route (SGAC) for the hydrogen generation through overall photo and electrocatalytic water splitting. The spinel cubic phase with Fd3m space geometry was established from XRD results. FESEM images shows cubic and spherical formed grains with definite grain boundaries and grain size of 164 and 184 nm for the MgFe2O4 and Mg0.98Ni0.02Ga0.02Fe1.98O4 nanomaterials. Soft magnetic behavior with superior saturation magnetization (Ms) and moderate coercivity (Hc) of 2.72–29.24 emu/g and 51.23–257.86 Oe was obtained for all of the developed nanocatalysts. According to the research findings, Mg0.98Ni0.02Ga0.02Fe1.98O4 nanocatalyst shows the highest photocatalytic activity of 11.38 mmol gcat−1. The as-synthesised photocatalysts' repeatability and stability were evaluated throughout repeated runs of a 4-h reaction period conducted under identical circumstances. On the other hand, the electrocatalytic studies were carried via 3-electrode arrangement (i.e., working, counter and reference) in 0.5 M H2SO4 and 0.1 M KOH electrolytes for hydrogen evolution reactions (HER) and oxygen evolution reactions (OER). The overpotential for the MgFe2O4, Mg0.99Ni0.01Ga0.01Fe1.99O4, Mg0.98Ni0.02Ga0.02Fe1.98O4, and Mg0.97Ni0.03Ga0.03Fe1.97O4 electrocatalysts at 10 mA/cm2 were −0.866, −0.82, −1.02 and −0.92 V. Consequently, owing to these photocatalytic and electrocatalytic water splitting traits, the prepared nanocatalysts are highly efficient for hydrogen generation. However, MgFe2O4, and Mg0.99Ni0.01Ga0.01Fe1.99O4 nanomaterials show high zone of inhibition (ZOI) against Bacillus subtilis and Pseudomonas aeruginosa and therefore, making it valuable also for biological usages.

Effects of taro [Colocasia esculenta (L.) Schott] slices on nutritional quality, sensory quality, and shelf life of Chinese pickled and steamed pork belly.

This study aimed to investigate the influence of different ratios of taro slices (TS) on the nutritional quality, sensory quality, and shelf life of Chinese pickled and steamed pork belly (CPSPB). The study examined various aspects of CPSPB, including its proximate components, fat oxidation, fatty acid composition, protein hydrolysis, oxidation reaction, and induction period (IP). Additionally, the sensory quality and texture analysis were compared simultaneously. The results showed that the addition of TS to CPSPB significantly improved water and lipid loss (p < 0.05), increased the unsaturated/saturated ratio of fatty acids, and reduced lipid and protein oxidation. Additionally, the incorporation of TS extended the IP and enhanced the shelf life of CPSPB. Particularly, the addition of a specific amount of TS (60%) to CPSPB resulted in the highest organoleptic quality. Therefore, these results emphasize the positive impact of TS on the overall quality of CPSPB, highlighting its potential to enhance the nutritional value, sensory attributes, and shelf life.

Nanocrystalline Co/Ga substituted CuFe2O4 magnetic nanoferrites for green hydrogen generation

The research study on the design of cobalt and gallium substituted copper nanoferrites through sol-gel auto-combustion were testify to check the photocatalytic/electrocatalytic water splitting efficiency of prepared nanoferrites for hydrogen generation. XRD study confirms the formation tetragonal phase for all fabricated nanoferrites with no additional phases of impurities. The tetragonal shaped grains with definite grain boundaries were observed from the FESEM study. The magnetic measurements show large hysteresis loop area with high magnetization of 58.45 emu/g for undoped copper nanoferrite. The catalytic behaviors of the fabricated nanocatalysts for the photo-catalytic H2 production was determined by using 0.079 M Na2SO3 and 0.128 M Na2S as the sacrificial agents, that give electron donor site during photo-catalysis under UV–visible irradiation. As compared to other compositions, Cu0.99Co0.01Ga0.01Fe1.99O4 (x = y = 0.01) nano photocatalyst attained the highest photocatalytic activity of 18.11 mmol gcat−1. Also, the as-synthesized photocatalysts repeatability and stability were evaluated throughout repeated runs of 4 h reaction period conducted under identical circumstances. However, all electrocatalytic analysis for hydrogen evolution reaction (HER) activity were performed using three electrode arrangements (reference, counter, and working electrodes) in 0.5 M H2SO4 electrolyte mixture. There was a rise in overpotential at 10 mA/cm−2 cathode current density as concentrations of Co/Ga for the synthesized nanoferrites were increased. It has been showed that CuFe2O4 had a high electrocatalytic HER activity. In addition, the produced nanoferrites were also examined against different type of bacterial strains, where Cu0.99Co0.01Ga0.01Fe1.99O4 indicated maximum zone of inhibition (ZOI) against Bacillus subtilis (20 ± 0.55 mm), Salmonella typhi (12 ± 0.52 mm), Escherichia coli (16 ± 0.49 mm), and Staphylococcus aureus (12 ± 0.54 mm), respectively. Hence, with these efficient overall photocatalytic and electrocatalytic water splitting traits, the prepared nanoferrites are highly useful for the green hydrogen production applications.

Maximizing biodiesel yield of a non-edible chinaberry seed oil via microwave assisted transesterification process using response surface methodology and artificial neural network techniques

In this study, the non-edible Chinaberry Seed Oil (CBO) is converted into biodiesel using microwave assisted transesterification. The objective of this effort is to maximize the biodiesel yield by optimizing the operating parameters, such as catalyst concentration, methanol-oil ratio, reaction speed, and reaction time. The designed setup provides a controlled and effective approach for turning CBO into biodiesel, resulting in encouraging yields and reduced reaction times. The experimental findings reveal the optimal parameters for the highest biodiesel yield (95 %) are a catalyst concentration of 1.5 w/w, a methanol-oil ratio of 6:1 v/v, a reaction speed of 400 RPM, and a reaction period of 3 min. The interaction of the several operating parameters on biodiesel yield has been investigated using two methodologies: Response Surface Methodology (RSM) and Artificial Neural Network (ANN). RSM provides better modeling of parameter interaction, while ANN exhibits lower comparative error when predicting biodiesel yield based on the reaction parameters. The percentage improvement in prediction of biodiesel yield by ANN is found to be 12 % as compared to RSM. This study emphasizes the merits of both the approaches for biodiesel yield optimization. Furthermore, the scaling up this microwave-assisted transesterification system for industrial biodiesel production has been proposes with focus on its economic viability and environmental effects.

A bidirectional kinetic reaction model to predict uranium distribution in permeable reactive bio-barrier with high-sulfate environment

The use of permeable reactive bio-barriers (Bio-PRBs) is a developing method for remediation of uranium groundwater pollution. However, some remediation effects are difficult to estimate when because of the subsurface environment. Advanced knowledge of uranium migration and reactions in Bio-PRBs is crucial for successful practical application. In this study, a bidirectional kinetic reaction model was developed for predicting uranium reduction in a Bio-PRB system. The research demonstrates that the model is able to predict the uranium migration and rapidly evaluate the Bio-PRBs performance. The results show that contact period and microbial growth are the key factors that affect the remediation performance of Bio-PRBs. Microbial growth could lead to a decrease in hydraulic conductivity (K). The hydraulic conductivity loss in the free microorganisms (FM) group was 0.8–2.3 m/d, which was significantly smaller than the immobilized microorganism (IM) group (0.8–5.2 m/d). Compared to the IM group, the simulation results reveal that longer contact reaction period improves the remediation performance of SO42− and uranium by 32.6% and 21.7%, respectively. The bidirectional reaction between microorganisms and pollutants leads to a decrease in the remediation efficiency. In addition, the model can be used to design standard Bio-PRBs for real field of uranium contanminated groundwater. To meet the remediation goal of groundwater, the width of IM group needs to be increased to 250 cm while 500 cm for FM group. Therefore, IM-PRBs save costs significantly. The model has successfully optimized Bio-PRBs and predicted uranium contaminant-plume evolution and microbial growth inhibition in different Bio-PRBs.

Compatibility of high strength silica‐modified microcapsules modified with polydopamine in elastomer substrates

AbstractMicrocapsules with polydopamine composite shell layer were successfully synthesized by functionalizing silica‐modified microcapsules containing isophorone diisocyanate. The components and micromorphology of silica‐modified microcapsules at different reaction periods were studied by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy. The structure of different microcapsules was characterized by FTIR, 1H nuclear magnetic resonance and x‐ray photoelectron spectroscopy. The mechanical performances of different microcapsules were analyzed by nanoindentation technique. The compatibility and self‐healing efficiency of different microcapsules with the substrate were also investigated by the tensile tests. The results showed that the density of the silica‐modified microcapsule shell gradually increased and the mechanical performances were enhanced with the silica source. The hardness and elastic modulus of silica‐modified microcapsules in suitable core fraction (76.5 wt%) were 139.9 MPa and 2.2 GPa, which are 2.3 times and 4.8 times higher than those of untreated microcapsules, respectively. The functionalized modified microcapsules had excellent compatibility with the elastomeric substrate (PU‐PPG2000). At the same time, the self‐healing efficiency of the functionalized modified microcapsules in PU‐PPG2000 was 69.8%, which was 48.9% higher than that of the untreated microcapsules prepared under the same conditions. Silicon modification improved the density of microcapsules, enhancing their mechanical strength. At the same time, functionalization modification improved the interfacial bonding strength of microcapsules, further improving the compatibility with the polymer matrix.Highlights Microcapsules with different silicon sources are characterized. Microcapsules are functionalized with polydopamine. Individual microcapsules are tested for mechanical strength by nanoindentation. The compatibility of the functionalized microcapsules is excellent. The self‐healing efficiency of modified microcapsules is greater than 70%.