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In this study, a new sacrificial anode comprised of scrap iron packaged in a polyethylene mesh chamber for Furan-2-carbaldehyde removal using the electrocoagulation (EC) process was fabricated. Therefore, the influences of different operational parameters, such as solution pH, current intensity, initial Furan-2-carbaldehyde concentration, and detention time on the process performance at the batch hydraulic reactor were investigated. Due to the large surface area of the anode, the applied current intensity was low, which led to high efficiency for the Furan-2-carbaldehyde removal (> 97%) at low operating voltage and energy consumption (5.4 kWh/m3). The experimental results corresponded well to the first-order kinetic model. The mineralization values for Furan-2-carbaldehyde using the EC process were 46.5% and 75.5% for total organic carbon (TOC) and chemical oxygen demand (COD), respectively. Moreover, the EC process shows the biodegradability was significantly increased compared to the initial solution after 120 min of reaction time. Based on the LC-MS analysis, the major produced intermediates and the degradation pathway of Furan-2-carbaldehyde were proposed. Consequently, on the contrary plate electrodes, the use of scrap iron as a sacrificial anode increases efficiency and reduces the total required operating costs for energy and electrodes. [ABSTRACT FROM AUTHOR]

Removal of textile dyes from wastewater is essential from an environmental perspective. White rot fungi are effective in azo dye degradation through a process mediated by the action of specific enzymes. Three diffusers, air stone diffuser, coiled tube sparger, and circular plate diffuser, were used to evaluate the effect of the aeration regime on ligninolytic enzyme activities and the consequent degradation process of reactive black 5 in 1-L reactor cultures of Trametes versicolor immobilized in polyurethane foam. The main changes in dye structure occurred during the first 72 h with different patterns in each culture; however, after 144 h, total color removal did not have a significant difference (> 98%) between cultures. In all cases, versatile peroxidase was the enzyme with the highest titers, relative to manganese peroxidase and laccase. Dye degradation was analyzed by the changes in absorbance peaks at 596, 311, and 257 nm in the absorption spectrum of reactive black 5. A multivariate two-way ANOVA test showed that the air diffuser had a significant effect (p < 0.05) on enzyme activity and, consequently, on dye degradation. Multilinear regression analysis indicated that laccases and versatile peroxidase positively correlated with reactive black 5 decolorization and degradation, and laccases were the most efficient for decolorization. [ABSTRACT FROM AUTHOR]

Propene polymerization kinetic profiles with a diether-based Ziegler–Natta MgCl2-supported catalyst were investigated in a stainless-steel batch reactor. The initial 10 min period characterizes various temperature levels with a constant volume of liquid propene. The lowest temperature level corresponds to the usual prepolymerization temperature (10 °C), and the highest level corresponds to the usual main polymerization temperature (70 °C). The effects of the starting temperature levels were evaluated through polymerization kinetic patterns computed namely from the second polymerization period carried out at 70 °C for the next 90 min. Based on the heat transfer data, the kinetic profiles were fitted to suitable semi-empirical equations derived from fundamental kinetic approaches using the first and second orders of the catalyst active sites decay. Both approaches adequately describe the dependence of the initial activities and deceleration constants on the temperature during the initial period. [ABSTRACT FROM AUTHOR]

This comprehensive study explores the kinetics of adsorption and its photocatalytic degradation of methyl orange (MO) using an advanced copper-decorated photocatalyst in the form of hollow fibers (HFs). Designed to boost both adsorption capacity and photocatalytic activity, the photocatalyst was tested in batch experiments to efficiently remove MO from aqueous solutions. Various isotherm models, including Langmuir, Freundlich, Sips, Temkin, and Dubinin–Radushkevich, along with kinetic models like pseudo-first and pseudo-second order, Elovich, Bangham, and Weber–Morris, were utilized to assess adsorption capacity and kinetics at varying initial concentrations. The results indicated a favorable MO physisorption on the nanocomposite photocatalyst under specific conditions. Further analysis of photocatalytic degradation under UV exposure revealed that the material maintained high degradation efficiency and stability across different MO concentrations. Through the facilitation of reactive oxygen species generation, oxygen played a crucial role in enhancing photocatalytic performance, while the degradation process following the Langmuir–Hinshelwood model. The study also confirmed the robustness and sustained activity of the nanocomposite photocatalyst, which could be regenerated and reused over five successive cycles, maintaining 92% of their initial performance at concentrations up to 15 mg/L. Overall, this effective nanocomposite photocatalyst structured in the form of HF shows great promise for effectively removing organic pollutants through combined adsorption and photocatalysis, offering valuable potential in wastewater treatment and environmental remediation. [ABSTRACT FROM AUTHOR]

Tyrosinase, an enzyme involved in browning reactions in plants/crops exposed to mechanical injury, was isolated from the pulp of some different locally available bananas (M. cavendish, M. acuminata, and M. paradisiaca). Tyrosinase from the pulps was extracted, purified, immobilized, and characterized. Thereafter, the potentials of the immobilized tyrosinase in the possible production of l-3,4-dihydroxyphenylalanine (L-DOPA) in an improvised batch reactor was exploited using tyrosine and ascorbate as the substrates. L-DOPA production was monitored via thin-layer chromatography and spectrophotometry (Arnow's method). L-DOPA is a drug that is used in the treatment of Parkinson's disease. Hence, this study exploited a non-chemical route for its synthesis using the tyrosinase obtained from the banana pulps. The purified tyrosinase had an optimum pH and temperature of 6.5 and 7.0, respectively. The molecular weight of the purified tyrosinase was 45 kDa. Quercetin and resorcinol both competitively inhibited the purified tyrosinase from the three cultivars. Immobilized M. cavendish tyrosinase produced the highest concentration (0.60 mM) of L-DOPA after 8 h in an improvised batch reactor. The tyrosinase in the banana pulps serves as a cheap and readily available green route for the possible production of L-DOPA. [ABSTRACT FROM AUTHOR]

Herein, we synthesized AgI/ZIF-8/g-C3N4 ternary composites as a highly efficient heterojunction photocatalyst. Various techniques such as XRD, N2 adsorption-desorption isotherm, DRS, PL, TEM, and FE-SEM were examined to analyse several properties of the synthesized g-C3N4, ZIF-8, AgI, ZIF-8/g-C3N4, and AgI/ZIF-8/g-C3N4 photocatalysts. The photodecomposition of Rh.B dye was investigated under visible-light exposure over fabricated materials in a simple batch and split-plate airlift photocatalytic reactors. The findings showed that the photodegradation efficiency of the AgI/ZIF-8/g-C3N4 heterojunction was excellent, due to the synergistic effect between g-C3N4, AgI, and ZIF-8, simplifying the fast charge transfer. Notably, the degradation efficiency of AgI/ZIF-8/g-C3N4 heterojunction in the airlift photoreactor was higher and more rapid (98.8 %) compared to the batch reactor (92 %). The photocatalytic activity is significantly enhanced by the high self-mixing under air flow and dissolved O2, and thus further O2− radicle generation. Various factors affecting the efficiency of the efficiency of the AgI/ZIF-8/g-C3N4 photocatalyst were studied including the pH, Rh.B concentration, and the AgI/ZIF-8/g-C3N4 amount. The AgI/ZIF-8/g-C3N4 cocomposite exhibited outstanding steadiness and recyclability even after five cycles, so it is probable to be very beneficial in treatment of contaminated water.

4‐Chlorophenol is present as an essential compound of various organic compounds found in different kinds of hazardous waste. It can be easily eliminated from the industrial effluents by different physical and chemical treatment methods although best technique is bioremediation. To separate a potent bacterial strain from the soil that can dispose of 4‐chlorophenol from contaminated water, soil sample was collected from a hospital zone. Isolated bacterial colonies were segregated by the technique of soil enrichment with 500 mg/L 4‐chlorophenol and after that the enriched soil sample was serially diluted and transferred to petri plates with agar media. Twenty‐seven colonies were isolated and the most potent strain was selected in 50 mL liquid medium that was enriched previously with 500 mg/L of 4‐chlorophenol. C19 was found to be the most potent strain and it had the ability to reduce almost 99.97% of 4‐chlorophenol within 24 h, 37°C temperatures as well as in shaking condition (140–150 rpm) and pH 6.8–7.2. After the isolation, the strain was acclimatized in mineral salt medium (MSM) from lower concentration to higher concentration of 4‐chlorophenol to increase its removal capacity as well as to prepare the inoculums. Then parameter optimization study was performed where optimum temperature and pH was found to be 25°C and 6.5°C, respectively, 400 mL media volume and 8% inoculums were found to be most effective and finally 24 h time period was optimized. All these five optimum parameters were applied together to remove higher conc. of 4‐chlorophenol where almost 99.3% removals were obtained when the conc. was 600 mg/L. Moreover, more than 90% removals were obtained in case of 700, 800, and 900 mg/L concentration. Morphological, biochemical, nucleotide homology, and phylogenetic investigation of the strain was made which revealed that it was a rod shaped (Bacillus type), gram +ve, spore forming and motile bacterial strain and therefore, the selected strain was found to exhibit most extreme similarities (91.73%) with Bacillus cereus strain MK789657. [ABSTRACT FROM AUTHOR]

This study was conducted to investigate the combined two‐stage biological‐treatment‐process using consortium of bacteria and microalgae for removal of soluble chemical oxygen demand (SCOD), ammonium‐nitrogen (NH4+‐N), nitrate‐nitrogen (NO3−‐N), phosphorus (PO43−‐P) from dairy wastewater in suspended‐growth batch‐reactor (SGBR). The study also investigated the removal of SCOD, NH4+‐N, NO3−‐N, PO43−‐P under different process parameters, like initial SCOD, NH4+‐N,NO3−‐N, PO43−‐P, MLSS, pH and react time using response surface methodology (RSM) with a five‐factor‐three‐level Central Composite Design(CCD). The experimental results were analyzed by ANOVA and second‐order polynomial mathematical‐models were developed with high correlation efficiency for SCOD, NH4+‐N removal, NO3−‐N, PO43−‐P removal using bacterial and microalgal‐consortia respectively in SGBR. Individual and combined effects of process variables on responses were studied using three‐dimensional response surface plots. Under the optimum conditions (initial SCOD, NH4+‐N, pH, MLSS of 720 mg L−1, 55 mg L−1 as N, 7 and 1500 mg L−1, respectively and react time of 24 h) highest removal efficiencies of SCOD (98.61%) and NH4+‐N (97.42%) were obtained using bacterial consortium and in second‐phase using micro‐algal consortium under optimum conditions highest removal efficiencies of nitrate nitrogen and phosphorus 98.64% and 90.53%, respectively. Optimization of process‐parameters by RSM study is supposed to be helpful for the treatment of real life dairy wastewater in effluent treatment plants. [ABSTRACT FROM AUTHOR]

The study presents a parametric study of pyrolysis of poultry litters under isothermal heating conditions using a two-stage pyrolysis scheme and a downer separation technique. The study aims to increase the yield of biochar through pyrolysis using a two-stage kinetic process. The thermo-physical properties of mild steel and poultry litter were used to develop a simulation with a finite element method and COMSOL multiphysics to predict biochar yield at different temperatures and residence time. The numerical model was validated by comparing the predicted and the experimental results from the literature with a percentage difference of 1.3 to 11% and an R2 value of 0.9124. Further parametric studies showed that for the pyrolysis of 0.5 kg of poultry litters, a maximum yield of biochar of 42.9% was obtained at a lower temperature of 573.15oK with a residence time of 9000 s. Higher temperature favoured gas yield while biochar yield declined. [ABSTRACT FROM AUTHOR]

This research focuses on the development of a state observer for performing indirect measurements of the main variables involved in the soybean oil transesterification reaction with a guishe biochar-based heterogeneous catalyst; the studied reaction takes place in a batch reactor. The mathematical model required for the observer design includes the triglycerides' conversion rate, and the reaction temperature. Since these variables are represented by nonlinear differential equations, the model is linearized around an operation point; after that, the pole placement and linear quadratic regulator (LQR) methods are considered for calculating the observer gain vector L(x). Then, the estimation of the conversion rate and the reaction temperature provided by the observer are used to indirectly measure other variables such as esters, alcohol, and byproducts. The observer performance is evaluated with three error indexes considering initial condition variations up to 30%. With both methods, a fast convergence (less than 3 h in the worst case) of the observer is remarked. [ABSTRACT FROM AUTHOR]

In this article, a mathematical model of diffusion reaction in kinetically controlled cephalexin synthesis in the batch reactor with penicillin acylase immobilized in glyoxyl-agarose is analyzed. The kinetic model is a non-linear non-stead-state reaction–diffusion equation with non-linear terms related to the Fick’s law. We have presented the approximate analytical expression for the non-steady-state non-linear reaction–diffusion equation by utilizing the Laplace homotopy perturbation method (LHPM) and for steady-state by using LHPM and Adomian decomposition method (ADM). The approximate analytical solution obtained from these methods proved that they are fit for every values of the reaction–diffusion and kinetic parameters. We also present the numerical solution of the considered reaction–diffusion equation by using pdepe tool in MATLAB software. When comparing the semi-analytical solution with the numerical solution, a satisfactory result is noted for all the possible values of the parameters. The closed-form analytical expressions for the effectiveness factor in non-steady and steady-state conditions are obtained and analyzed using LHPM and ADM.

Oxidative leaching, as a basic step of the hydrometallurgical process of pure copper production from chalcopyrite, is a slow process in which mineral acids with strong oxidants addition are usually used as a leaching medium. It was found experimentally that the copper leaching from chalcopyrite in the H2SO4–H2O2–H2O system, in the presence of isopropanol (IPA) and under other conditions (H2O2 concentration, rate of mixing and temperature), takes place with satisfactory rate and efficiency. To quantify how much the change of these crucial variables affects the rate of the process, experimentally obtained kinetic curves (conversion over time) were analyzed using a Shrinking Core Model (SCM). The determined values of the copper leaching rate constants (kobs) confirmed the positive influence of increasing IPA and H2O2 concentrations as well as the temperature on the kinetics and efficiency of the leaching. The kinetic studies were also supported by using X-ray diffraction (XRD), 57Fe Mössbauer spectroscopy, scanning electron microscopy (SEM), and adsorption measurements. The positive influence of IPA was explained by its stabilizing role for iron compounds (hematite, magnetite, and pyrite), which are catalysts during the Cu dissolution, as well as H2O2 protection from decomposition during free radical reactions. Finally, the optimal conditions for efficient leaching, the rate-limiting step as well as the mechanism suggestion of the copper dissolution, were given. [ABSTRACT FROM AUTHOR]

Esters are versatile compounds with a wide range of applications in various industries due to their unique properties and pleasant aromas. Conventionally, the manufacture of these compounds has relied on the chemical route. Nevertheless, this technique employs high temperatures and inorganic catalysts, resulting in undesired additional steps to purify the final product by removing solvent residues, which decreases environmental sustainability and energy efficiency. In accordance with the principles of "Green Chemistry" and the search for more environmentally friendly methods, a new alternative, the enzymatic route, has been introduced. This technique uses low temperatures and does not require the use of solvents, resulting in more environmentally friendly final products. Despite the large number of studies published on the biocatalytic synthesis of esters, little attention has been paid to the reactors used for it. Therefore, it is convenient to gather the scattered information regarding the type of reactor employed in these synthesis reactions, considering the industrial field in which the process is carried out. A comparison between the performance of the different reactor configurations will allow us to draw the appropriate conclusions regarding their suitability for each specific industrial application. This review addresses, for the first time, the above aspects, which will undoubtedly help with the correct industrial implementation of these processes. [ABSTRACT FROM AUTHOR]

Copper poses a major health risk when present in excessive amounts in drinking water and daily feeding. Mahogany chips were used in the batch and fixed bed reactors to study the removal of copper from synthetically prepared solutions. The experimental parameters were the initial solution pH, adsorbent dose, temperature, concentration, duration, volumetric flow rate and bed heights. It was found that pH (5), adsorbent dose (10 g/L), time (60 min) and temperature (250°C) were the best conditions for the batch reactor. A volume flow of 0.5 mL/min, a bed height (15 cm) and a concentration (50 mg/L) were determined as fixed bed parameters for maximum removal, since the breakthrough time increased with these settings. The results can be explained by the pseudosecond-order kinetic model used to study the kinetics of the batch reactor using the pseudo-first-order and pseudo-second-order models. The Yoon-Nelson and Thomas models received the fixed bed reactor kinetic data and the column reactor data were fitted to both models. Activation energy was calculated to be 40.747 kJ/mol at 75 mg/L initial concentration. As a result of experiments with pH: 5, 10 g/L adsorbent dosage for batch studies and 60 minutes for 25°C temperature, a copper removal of 65.7% was obtained using mahogany chips under optimal conditions. It was concluded that the mahogany tree shavings were a suitable biosorbent for copper removal from wastewaters. [ABSTRACT FROM AUTHOR]

Liquid organic hydrogen carriers (LOHCs) are considered a promising hydrogen storage technology. Heat must be exchanged with an external medium, such as a heat transfer fluid, for the required chemical reactions to occur. Batch reactors are simple but useful solutions for small-scale storage applications, which can be modelled with a lumped-parameter approach, adequately reproducing their dynamic performance. For such reactors, power is consumed to circulate the external heat transfer fluid and stir the organic liquid inside the reactor, and heat transfer performance and power consumption are two key parameters in reactor optimisation. Therefore, with reference to the hydrogen release phase, this paper describes a procedure to optimise the reactor thermal design, based on a lumped-parameter model, in terms of heat transfer performance and minimum power consumption. Two batch reactors are analysed: a conventional jacketed reactor with agitation nozzles and a half-pipe coil reactor. Heat transfer performance is evaluated by introducing a newly defined dimensionless parameter, the Heat Transfer Ratio (HTR), whose value directly correlates to the heat rate required by the carrier's dehydrogenation reaction. The resulting model is a valid tool for adequately reproducing the hydrogen storage behaviour within dynamic models of complex and detailed energy systems. • Thermal design of hydrogen storage systems based on LOHC batch reactors is analysed • Design is optimised to ensure effective heat transfer and minimum power consumption • Novel dimensionless parameter (Heat Transfer Ratio, HTR) is introduced • A threshold HTR value is identified, above which only marginal gains are achieved • The lumped-parameter model can be deployed in complex energy system dynamic models [ABSTRACT FROM AUTHOR]

Mechanochemistry and oleochemistry and their combination have been known for centuries. Nevertheless, bioeconomy and circular economy concepts is much more recent and has motivated a regain of interest of dedicated research to improve alternative technologies for the valorization of biomass feedstocks. Accordingly, this review paper aims essentially at outlining recent breakthroughs obtained in the field of mechanochemistry and oleochemicals such as triglycerides, fatty acids, and glycerol derivatives. The review discusses advances obtained in the production of small chemicals derived from oils with a brief overview of vegetable oils, mechanochemistry and the use of mechanochemistry for the synthesis of biodiesel, lipidyl-cyclodextrine, dimeric and labelled fatty acids, calcium diglyceroxide, acylglycerols, benzoxazine and solketal. The paper also briefly overviews advances and limits for an industrial application. [ABSTRACT FROM AUTHOR]

The global charcoal trade is steadily growing, with high-income countries importing significant quantities of this material from regions where its production is often associated with severe environmental issues, including forest overexploitation, illegal logging, and environmental pollution. Promoting local charcoal production in high-income countries is crucial to addressing these challenges. In this study, we have chosen to focus on the European context, specifically emphasizing Italy as a case study. Our study aimed to comprehensively compare five distinct charcoal production systems, including both traditional and modern solutions, with a specific focus on evaluating the quality of the resulting charcoal. Additionally, improvements were evaluated to enhance production efficiency. Traditional systems cannot satisfy production requests, resulting in inefficiencies in manpower, costs, times, and yield. Conversely, recent innovations consider mobile and stationary kiln prototypes. Mobile kilns offer flexibility and cost savings but require operator expertise, limit automation, and have long cycles. In contrast, stationary systems operate continuously, increasing productivity and efficiency, despite higher investment costs. Notably, charcoal quality showed minimal differences. These findings highlighted the potential of new technologies to enhance efficiency, reduce cost and environmental impact, and promote sustainable charcoal production. [ABSTRACT FROM AUTHOR]

It is postulated that waste, if managed effectively, can transform from a liability to a resource. Among various waste management techniques, such as incineration, composting, recycling, and re-use, depolymerization of municipal plastic waste demonstrated superior environmental performance by circumventing the release of harmful gases and facilitating wealth creation. A batch reactor, designed to operate at an internal pressure of 51.34 bar, a maximum temperature of 500°C, and with a reactor thickness of 6 mm, was fabricated using locally available materials. Safeguards were incorporated by ring reinforcing the reactor to prevent burst incidents due to thermal expansion. Further, a sensor was integrated to stabilize the temperature, thereby enabling optimal function at a preset temperature. A shell-in-tube heat exchanger and a sub-cooler, with Log Mean Temperature Differences (LMTDs) of 280.15°C and 174.53°C respectively, were designed and constructed. The system's performance was evaluated by introducing approximately 2 kg of raw, washed, sun-dried, Polyethylene Terephthalate (PET) samples, and combusted in the energy conversion system for three and a half hours under a nitrogen atmosphere. For each run, 10 g of either calcium oxide (CaO) or activated carbon (AC) catalysts were added to the feedstock. Measurements of the temperature, pressure, and flow rate of the pyrolyzed product from the reactor were taken and recorded. The retention times for the depolymerization of catalyzed PET with activated carbon and calcium oxide were observed to be 38 and 45 minutes, respectively. The maximum flow rates of the vaporized product from the reactor were measured at 0.1985L/min and 0.1768L/min, at temperatures of 171°C and 182°C, and pressures of 37.6 kPa and 36.8kPa, respectively. Fuel conversion efficiencies of 49.2%, 66.6%, and 80.0% were recorded for uncatalyzed PET, CaO catalyzed PET, and activated carbon catalyzed PET, respectively, corroborating previous research but at temperatures below 400°C. [ABSTRACT FROM AUTHOR]

In this work, a comparative kinetic study of the transesterification reaction of rapeseed oil with methanol was carried out in two reactors: the first was a batch reactor, and the second was a continuous reactor. The operating conditions of the reaction were a molar ratio of 6:1 (methanol to oil) at temperatures of 40, 50, and 60 °C, with 1% of KOH used as a catalyst. The continuous reactor is composed of a chaotic mixer followed by a plug flow reactor to increase the residence time and ensure complete conversion of the reaction. Mixing is provided by the effects of motion inertia created by chaotic advection in the mixer reactor. A scheme of three reversible reactions was used to model the apparent kinetics of the transesterification reaction. The chaotic mixer is used as an intensifier for the transesterification reaction. The results showed that this technology has reduced the apparent activation energies of the reaction. This kinetic model was applied on used cooking oil for validation. The experimental results show good agreement with the kinetic model with a maximum difference (RMSE) egal to 11% between the experimental results and the simulation. The effect of mixing intensity and temperature on the transesterification reaction in the two systems has been studied. [ABSTRACT FROM AUTHOR]

Sulfidic schists are important rock formations due to their trace metal and metalloid (TMM) content and carry the potential for pyrite and pyrrhotite to hydrate and oxidize leading to acid-enhanced chemical weathering. The objectives of this study were to compare TMMs in sulfidic schists to other co-occurring bedrock, evaluate conditions that optimize TMM rock weathering, and examine streamwater TMMs in relation to bedrock lithology and human development in eleven streams across central Massachusetts. Sulfidic schists samples had the highest As (72 ± 46 mg kg−1), Cu (63 ± 21 mg kg−1), and Pb (63 ± 33 mg kg−1) concentrations. Electron Probe Microanalysis (EPMA) images show As and Pb were widely distributed across silicate and sulfide minerals in both the mica schist and sulfidic schists, not exclusively hosted in sulfide minerals as hypothesized. Batch reactors had TMM dissolution rates an order of magnitude higher for sulfidic schists than granite and mica schists. Furthermore, TMM dissolution was greatest under pH 9 than pH 7 or pH 5 and dissolution rates were two times greater under anoxic conditions compared to oxic conditions. Streamwater concentrations of As (0.01 to 10.3 μg L−1), Cu (0.2 to 206 μg L−1), and Pb (0.001 to 8.3 μg L−1) were below Massachusetts Surface Water Quality Standards. Across the eleven watersheds, % sulfidic schists were positively correlated with mean streamwater S and Cu concentrations and area-normalized annual export. Streamwater As and Pb concentrations were significantly correlated with %Developed land and %Mica schist, which strongly covaried. Our study confirmed the elevated abundance of TMMs in sulfidic schists but laboratory experiments suggest the precipitation of amorphous Fe oxyhydroxide phases decreased dissolved TMMs during oxic weathering. Future work will need to incorporate groundwater and stable isotope systems to separate anthropogenic and geogenic analyses. [ABSTRACT FROM AUTHOR]

Modeling of core-shell catalytic pellets with inert shell was performed assuming three different particle shapes such as sphere, cylinder, and slab. For isothermal irreversible first order reaction, A→B, analytical solutions of intra-particle concentration of reactant were derived by solving reaction-diffusion equations, considering thickness of catalytically active core (r2), when the pellets were immersed in infinitely large medium. Unlike conventional pellets or core-shell pellets with inert core, effectiveness factor (η) was affected by r2 as well as ratio of effective diffusivity in inert shell and active core (Υ), and η could be enhanced by increasing Υ. η increased in the order of sphere > cylinder > slab due to surface area per unit volume of medium, and η increased with increasing Biot number (Bi), because of decreased external film resistance. For series reaction, A→B→C, transient change of the concentration of starting reactant (CA) and intermittent product (CB) in bulk fluid of reactor could be predicted by solving material balance equations assuming pseudo-steady state approximation and equal value of Thiele modulus for both reactions in batch reactor and CSTR. When B is desirable product, CB increased by increasing Υ and decreasing r2. Similar to conventional pellets, CB in batch reactor decreased by increase of distribution coefficient of B on surface of pellet, KB, due to increased adsorption, and increased in the order of sphere

Mathematical modeling of catalytic reaction was performed for hollow cylindrical pellets with infinitely long or finite length. For isothermal irreversible first order reaction, intra-particle concentration could be predicted from analytical solutions obtained by solving reaction-diffusion equations. Both intra-particle diffusional and surface film resistance were considered in the modeling equations. Factors affecting distribution of reactant concentration inside hollow cylindrical pellet surrounded in infinitely large medium were studied by adjusting thickness of hollow core (x’), aspect ratio (γ0), Thiele modulus (Φ), and Biot number (Bi). Transient concentration inside hollow cylindrical pellet with infinitely long and finite length was also derived by solving unsteady-state partial differential equation using separation of variables and eigenfunction expansion method, respectively. Analytical solutions could be also derived for effectiveness factor (η), which was increased with increasing x’ and decreasing γ0 due to decrease of active volume of the pellet. For hollow cylindrical pellet with finite length, η was derived as two different mathematical expressions, which are advantageous to evaluate eigenvalues for various x’ or γ0. For series reaction (A→B→C), secondary effectiveness factor (ηB→C) was derived for hollow cylindrical pellet for the first time to apply pseudo steady-state approximation for batch and fixed bed reactors. The performance of the catalytic reactors was predicted for consecutive reaction by adjusting x’ and Φ. Maximum concentration of intermittent product in batch reactor could be increased using hollow cylindrical pellets, compared to conventional cylindrical pellets. For simple reaction (A→B), transient concentration of reactant in exit stream was also predicted for fixed bed containing hollow cylindrical pellet with finite length. Reaction conversion at steady state was enhanced using the hollow pellets with smaller γ0, while pressure drop in bed was reduced, compared to conventional cylindrical pellets.

The production of prebiotic fruit juices has been extensively investigated, mainly by the enzymatic route. However, studies involving agitated reactors and other important parameters are lacking. This work evaluated the effect of temperature and agitation on the synthesis of oligosaccharide and dextran in orange juice using dextransucrase. The syntheses in orange juice were carried out in magnetic and mechanic stirred-tank reactors at 25 (MAG25, MEC25) and 30°C (MAG30, MEC30) for 24 h. A low final sucrose concentration was found at 6h for magnetic stirring and low temperatures. The reducing sugar concentration decreases at 25°C and increases at 30°C throughout the process. Results showed higher oligosaccharide and dextran production at 25°C. Magnetic agitation (MAG) favored the dextran synthesis over the mechanic agitation (MEC) at the same temperature. MAG25 and MEC25 provided similar concentrations of oligosaccharides at 6h. Although MAG25 and MEC25 were the best conditions to synthesize oligosaccharides and dextran in orange juice, MEC25 is more suitable and feasible for large-scale production.

The electrochemical synthesis of ammonia has emerged as a sustainable alternative to the traditional Haber-Bosch process. This review provides a comprehensive examination of the transition from batch reactors to flow reactors in the context of lithium-mediated nitrogen reduction for electrochemical ammonia synthesis. It underscores the advances made in mechanistic understanding, reactor design, and the exploration of key variables such as pressure, Li salts, proton shuttles, and additives. The advantages and disadvantages of both reactor types are critically assessed, offering insights into their suitability for scaling up production. Moreover, this review elucidates the role of various factors in enhancing Faradaic efficiency and energy efficiency, thus contributing to the development of more efficient, sustainable, and economically viable electrochemical ammonia synthesis methods. The synergy between fundamental research and engineering advancements in this field is highlighted, providing a roadmap for future research endeavors and industrial applications.

Mechanochemistry and oleochemistry and their combination have been known for centuries. Nevertheless, bioeconomy and circular economy concepts is much more recent and has motivated a regain of interest of dedicated research to improve alternative technologies for the valorization of biomass feedstocks. Accordingly, this review paper aims essentially at outlining recent breakthroughs obtained in the field of mechanochemistry and oleochemicals such as triglycerides, fatty acids, and glycerol derivatives. The review discusses advances obtained in the production of small chemicals derived from oils with a brief overview of vegetable oils, mechanochemistry and the use of mechanochemistry for the synthesis of biodiesel, lipidyl-cyclodextrine, dimeric and labelled fatty acids, calcium diglyceroxide, acylglycerols, benzoxazine and solketal. The paper also briefly overviews advances and limits for an industrial application.

Many research papers describe selective hydrogenation of functional groups, such as nitro groups, carbonyl groups, or unsaturated carbon bonds to obtain fine chemicals or precursors of pharmaceuticals. Quite often, the catalyst performance is investigated in batch or continuous flow reactors without finding advantages and disadvantages of this or that regime. At the same time, the transition from batch processes to continuous flow occurs on the industrial scale. However, the batch process can be preferable for some reactions, in spite of its drawbacks. This review article aims to identify all publications that consider selective hydrogenation of functional groups in organic compounds, both in batch and continuous flow reactors, at the same reaction conditions that allow making conclusions about the benefits of one of the regimes in a particular case. [ABSTRACT FROM AUTHOR]

Niobium oxide supported on ZrO2 and mixed oxide of NbOx-ZrO2 was prepared and characterized. Mechanical treatment was followed by the microwave heating procedure of catalysts with more advanced textural parameters. The amount of Lewis (LAS) and Brønsted (BAS) acid sites rose with the increasing Nb content in the catalysts. The catalytic properties of samples of niobia-zirconia (NbZr samples, NbZr catalysts) were studied in a cellulose hydrolysis–dehydration reaction at 453 K under an inert Ar atmosphere in a batch reactor. Glucose and 5-hydroxumethylfurfural (5-HMF) were the major products. The initial reaction rate could be tuned by the density of acid sites on the surface of solid. At a low density of acid sites (0.1–0.3 µmol·m−2), the initial reaction rate had a pronounced inverse correlation. Increasing the LAS/BAS from 0.3 to 2.5 slightly stimulated the formation of the target products. The catalytic properties of NbZr catalysts prepared by microwave treatment were studied in cellulose transformation in a flow set-up. Glucose was found to be the major product. The maximum yield of glucose was observed in the presence of the sample of 17%Nb/ZrO2. Increasing Nb content resulted in the formation of Nb-associated acid centers and, in turn, increasing catalyst acidity and activity. [ABSTRACT FROM AUTHOR]

Acid-modified red mud supported by peanut shells (MRP) catalysts were prepared for the catalytic wet persulfate oxidation (CWPO) process of dyes wastewater (containing methyl orange (MO), NH3-N, and Cr6+) in batch and continuous fixed bed reactors. Importantly, the influence of NH3-N and Cr6+ on the catalytic performance of the MRP catalyst was primarily studied. In the CWPO process, the reactors had a remarkable degradation efficiency (72–97%) of MO in the dyes wastewater. In the batch reactor, with the increase of NH3-N concentration (5–20 mg L−1), the degradation efficiency of MO was maintained at 93%. When NH3-N, Cr6+, and MO coexist, the degradation of MO had slight inhibition with 87.24%, which indicated that MO concentration was still controlled by MRP under the coexistence system, and the order of the removal effect of MRP on the three pollutants in the reactors was as follows: MO > NH3-N > Cr6+. Furthermore, in the fixed reactor, with the increasing of NH3-N or Cr6+ concentration, the MO degradation removal decreased to about 84%. The results showed that the degradation effect of MO in a fixed bed is still considerable. Then, the SEM and FTIR results indicated that SO4·−, ·OH, and O2−· generated in the CWPO process and Fe2+ and oxygen-containing functional groups on MRP played a major role on the degradation of pollutants. This study showed that this novel MRP is a promising catalyst with promising applications in composite dyes wastewater. [ABSTRACT FROM AUTHOR]

In the present work, a reaction methodology was implemented using a batch reactor, which synthesized glycerol carbonate (GC) using glycerin and CaCO3. A crystallographic analysis of CaCO3 was performed to determine its crystalline form. The obtained product was characterized by infrared spectroscopy, thermogravimetric analysis and nuclear magnetic resonance (1H and 13C). Our analysis demonstrated that the obtained product with the implemented reaction methodology has GC, FTIR showed the signals of the carbonyl groups, and the NMR spectrum confirmed the presence of cyclic carbonate structure in addition to linear carbonates. The thermogravimetric study showed that the thermal stability of the product is highly similar to that reported for GC. These results exhibit that the synthesis process produces linear and cyclic carbonates.

The partial replacement of fossil fuels with biomass provides an alternative to producing cleaner and more sustainable energy and fuels. Conventional shale oil production infrastructure can potentially be used in co-pyrolysis with biomass to reduce the use of oil shale and decrease its environmental impact. The effect of adding 10 and 30 wt% woody biomasses (spruce, alder, pine, and birch) into oil shale was studied through intermediate co-pyrolysis. The experiments were carried out in a batch reactor at 520 °C, with a 20 min residence time, in CO2, CO2-H2O 1:1, and Ar gas atmospheres. The solid products were collected and analyzed for elemental composition and surface area, while the composition of the gases was determined through gas chromatography. The difference in experimental and theoretical mass balances of fuel blends was lower than 2.5 wt% in all gas environments, indicating slight interactions between the fuels. CO2 atmospheres contributed to increased decomposition, with up to 2.6 wt% lower solid products. Biomass increased the production of combustible gases, especially CO yields, from 0.42 to 1.30 vol%. The addition of biomass and the use of alternative atmospheres can improve pyrolysis through increased fuel decomposition and a lower share of residual mass from 74.4 wt% for oil shale to 58–70 wt% for oil shale and biomass blends. [ABSTRACT FROM AUTHOR]

Here in the results of simulation of a batch reactor in which the transesterification of triolein is carried out in presence of a heterogenous catalyst. The simulated operation conditions consisted in two levels of temperature (50 and 60 °C), concentration of catalyst (0.5 and 1.0 kg/m3) and two initial concentrations of intermediaries and final products (at 1 and 10 g), keeping the amount of triolein and methanol at 1 kg and 12 mol of alcohol per mol of triolein. For the most severe conditions and lower amount of intermediaries and product in the feedstock, the final concentration of methyl oleate was 1.45 mol/L. At similar conditions of operation of reactor, the effect of reducing the concentration of catalyst was the factor that affected mainly the production of methyl oleate (1.41 mol/L), followed by the effect of temperature (1.44 mol/L of methyl oleate), while no appreciable effect on biodiesel production was observed by increasing the concentration of intermediaries and products in the feedstock. The developed reactor model predicted accordingly the profiles of viscosity and density which are necessary to the mechanical design of reactor. [ABSTRACT FROM AUTHOR]

Food coloring has become one of the main sources of water pollution. Brilliant blue (BB) is one of the dyes used in the food industry. Heterogeneous photocatalysis is increasingly used to decontaminate polluted water from food industries. The objective of this paper was to treat this pollution using a photoreactor at the laboratory (batch) and pilot scales. The photodegradation of the brilliant blue dye, chosen as a model of pollutant, was performed at room temperature in an aqueous solution of titanium dioxide supported on cellulosic paper in the presence of an external UV lamp. The surface morphology of this photoactive tissue was characterized by SEM and FTIR. The performances of two geometric configurations were examined (batch reactor and annular recirculation reactor) in accordance with degradation and pollutant mineralization. The performance of the photocatalytic system was optimized by a parametric study to improve the impact of the different parameters on the efficiency of the degradation process, namely the initial concentration of the pollutant, the TiO2 cycle, the pH of the solution with the recirculating reactor, and the flow rate. The results showed 98% degradation of brilliant blue at the laboratory scale and 93.3% and 75% at the pilot flow rates of 800 and 200 L·h−1, respectively. The supported semiconductor showed good photodegradation ability during BB decomposition, showing that photocatalysis is a promising technique for water purification. [ABSTRACT FROM AUTHOR]

The use of an irradiation source with a homogeneous distribution of irradiation in the volume of the reaction mixture belongs to the essential aspects of heterogeneous photocatalysis. First, the efficacy of six lamps with various radiation intensity and distribution characteristics is contrasted. The topic of discussion is the photocatalytic hydrogen production from a methanol-water solution in the presence of a NiO-TiO2 photocatalyst. The second section is focused on the potential of a micro-photoreactor system–the batch reactor with a micro-reactor with a circulating reaction mixture, in which the photocatalytic reaction takes place using TiO2 immobilized on borosilicate glass. Continuous photocatalytic hydrogen generation from a methanol-water solution is possible in a micro-photoreactor. This system produced 333.7 ± 21.1 µmol H2 (252.8 ± 16.0 mmol.m−2, the hydrogen formation per thin film area) in a reproducible manner during 168 h.

This research focuses on the development of a state observer for performing indirect measurements of the main variables involved in the soybean oil transesterification reaction with a guishe biochar-based heterogeneous catalyst; the studied reaction takes place in a batch reactor. The mathematical model required for the observer design includes the triglycerides’ conversion rate, and the reaction temperature. Since these variables are represented by nonlinear differential equations, the model is linearized around an operation point; after that, the pole placement and linear quadratic regulator (LQR) methods are considered for calculating the observer gain vector L(x). Then, the estimation of the conversion rate and the reaction temperature provided by the observer are used to indirectly measure other variables such as esters, alcohol, and byproducts. The observer performance is evaluated with three error indexes considering initial condition variations up to 30%. With both methods, a fast convergence (less than 3 h in the worst case) of the observer is remarked.

The economic attractiveness of an industrial process depends a large extent on its safe and reliable operation. The inherently safer design can help reduce the potential hazard on a fundamental level and eliminate escalation at the early stage of process development. In this work, an inherently safer design method for batch chemical reactors is proposed, which maximizes the yield of target product while minimizes Dow's fire and explosion index. Process safety time is introduced as criterion to respond to the thermal runaway risk risen by unexpected failures. Finally, two examples for specific reaction systems with given kinetics are performed to demonstrate the feasibility and validity of the proposed method. The results indicate that the product yield optimized with the proposed method is significantly higher than that obtained from literature approach involving temperature limit or divergence criterion under the same PST. With the same yield, the PST optimized with the proposed method is longer. [ABSTRACT FROM AUTHOR]

This work presents for the first time an integrated hydrogen generation system with storage based on aluminum waste from soda cans to supply hydrogen on-demand to a PEM (proton exchange membrane)-type fuel cell for reliable electricity generation. The raw material that feeds the hydrogen generator consists of distilled water, aluminum from soda cans and sodium hydroxide to remove the oxide layer that passivates the aluminum, a technique known as alkaline activation. The design of the generator was done based on the analysis of the mass and energy balance and its experimental verification. The stainless-steel prototype consisted of a vessel with a capacity of 2.1 L batch reactor, which delivers the gas produced to a column of water to scrub the gas. The three components function as a temporary gas storage system while the fuel is delivered at a regulated pressure. The NaOH container has a maximum storage capacity of 0.45 L, enough for 21 g of aluminum to react and produce 25.7 L (at 0 °C and 105 Pa) of hydrogen; the reaction yield in the generator was 97%. Through the evaluation of the electrical performance at a home-made 9 cm2 PEMFC and extrapolation to 45 W, it was calculated that the generator can supply H2 to the cell for 53 min at that power. [ABSTRACT FROM AUTHOR]

This study aims to design and analyze the design of a batch-type reactor to optimize the production of gold nanoparticles on an industrial scale. The method used in the design of this reactor is the computational analysis of the reactor calculations, including stirring and mass balance as initial calculations using the Microsoft Excel application manually. The calculation results show that the designed reactor specifications have a reactor volume of 21.7335 ft3, cylinder height of 13.4612 in, a height of solution in the cylinder of 8.9046 in, vessel diameter of 73.2984 in, design pressure of 9.9978 psig, impeller length of 9.1840 in, shaft length of 10.5418 in, with stirring power 62.5228 Hp. Reactor design analysis is an important stage in the design of production processes on an industrial scale, where the specification results from the designed reactor can be used not only to adjust the reactor to the product but also to be used as a reference for production costs. The results of computational analysis and calculations performed on the reactor design in this study can be used as a reference and can be applied in the design of reactor performance analysis as a learning media, including operating mechanisms in the production process. [ABSTRACT FROM AUTHOR]

An experimental and numerical study was conducted to evaluate the performances of an innovative thermal system composed of a batch reactor surrounded by a helical coil heat exchanger (HX), coupled with a parabolic trough solar collector. It was equipped with K-type thermocouples connected to a laptop to instantaneously record the heat transfer fluid temperatures at the inlet and outlet of the HX. Temperature and pressure of water were also measured inside the reactor. It was found that all temperature profiles follow similar trends as the Direct Normal Irradiation (DNI) variation, and the thermal efficiency does not exceed 20% because of significant thermal losses. The exergy analysis was applied to the mathematically modeled HX and simulated using COMSOL Multiphysics software. Temperatures from the CFD simulation and those measured during experiment tests are in good agreement. The Bejan number varies rapidly from 0.6 to 1 because of the strong dominance of heat irreversibilities. The total entropy generation increases with temperature and DNI until reaching its maximum value, then decreases in the cooling phase. A new heat exchanger design was proposed and simulated to reduce thermal losses. Consequently, the destroyed exergy was considerably reduced, and the efficiency was enhanced by almost 16%. [ABSTRACT FROM AUTHOR]

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Sequential nitrification–autotrophic denitrification (SNaD) was carried out for ammonium removal in synthetic wastewater (SWW) using sulfur as an electron donor in denitrification. Four reactors were operated in batch mode, two with zeolite (1 mm size) used as microbial support and two without support, to assess the effect of the zeolite addition in the SNaD. Aeration, anoxic, and anaerobic cycles were established, where 96% removal of NH4+-N (oxidized to nitrite or nitrate) was achieved in nitrification, along with 93% removal of NO3−-N in denitrification for the SNaD with zeolite. It was observed that the use of zeolite assists in buffering reactor load changes. Inhibition caused by nitrite accumulation in the denitrification stage was minimized by increasing the nitrogen concentration in the SWW. The results obtained in this study are the basis for the development of ammonium removal by simultaneous nitrification–autotrophic denitrification using a single reactor. [ABSTRACT FROM AUTHOR]

Introduction: Almost 18 percent of emitted greenhouse gasses in Iran come from livestock industries, especially from manure decomposition. With the anaerobic digestion of animal wastes, in addition to eliminating its disadvantages, biogas as a clean and renewable energy carrier is produced. In addition, the resulting sludge is a more healthy and nutritious fertilizer for use in agriculture. One of the challenges of the bio-gas industry is to increase gas production efficiency. Various approaches are proposed to enhance manure digestion efficiency and increase biogas production, which can be mentioned below: Changing operating parameters such as temperature, hydraulic retention time (HRT), and particle size of the substrate; adding some effective additives; returning the resulting sludge into the digestion process and using bio-filters. Therefore in this study, in order to increase biogas production from poultry manure, two methods (co-digestion with rumen contents, and chicken intestine and its contents, and returning the slurry into the reactor) were tested. The alkaline composition of chicken manure and its high content of ammonia makes it difficult to digest alone, and co-digestion with high-carbon organic matter improves its digestibility. Materials and Methods: Polyethylene bottles were used as batch reactor units. In order to the possibility of gas exit, as well as taking samples of the digester, two valves were placed on the bottle cap. All digesters were placed in a hot water bath and a 700 watts electric heater and a thermostat were used respectively to supply heat and to keep the temperature constant. A U-shaped tube, connected to the reactor output pipe was used to measure the amount of produced gas. The volume of water removed from the tube was an indicator of produced gas. The experiment was carried out in two stages. In the first stage 21 reactors were used according to the design of the experiment which was a completely randomized design with 7 treatments (adding rumen fluid in three levels (10, 20, and 30 percent of chicken manure (weight basis), respectively), adding chicken intestines and its content in three levels (10, 20, and 30 percent of chicken manure (weight basis), respectively), and control treatment), and three replicates of each treatment. During the whole experiment period, the pH and temperature were kept constant, respectively between 7.2-8.2 and 40-35 °C (mesophilic range). In the second stage of the experiment, after all the treatments reached the end of their hydraulic retention time, the resulting sludge was filtered and the liquid part was returned to the cycle. Three treatments were also provided here (supplying 50% of the water required by sludge liquid, supplying 100% of the water required by sludge liquid, and control treatment (no liquefied sludge). Results and Discussion: Based on the results, although the type of organic supplementation had a significant effect on the amount of biogas production, the quantity of them had not. Treatments of chicken manure + 20%, 30%, and 10% of chicken intestines resulted in the highest amount of biogas production, respectively. But these three treatments were not significantly different. Also, the co-digestion of chicken manure with chicken intestines was more effective than the co-digestion of chicken manure with rumen fluid. The return of sludge, resulted from anaerobic digestion of chicken manure, again into the cycle, in addition to enhancing the amount of produced gas, can reduce the waiting time to start gas production by at least six days (in the treatment of providing 100% of required water from returned sludge). This can lead to continuous gas production and availability of sufficient gas in commercial gas-producing units. The effect of treatments on the time of reaching the cumulative gas production index to 100 mm was significant (α= 5%) and treatment of S100 reduced this duration by approximately 17 days (65%) and S50, for approximately 16 days (74%). Conclusion: According to the results of this study, co-digestion of chicken manure with cow rumen fluid did not have a significant effect on the increase of biogas production, but co-digestion of chicken manure with chicken intestine and its contents (at least by 20% of chicken manure (weight basis)) can have a significant effect on the increase in the production of biogas and can increase the amount of gas at least twice. The highest amount of gas volume was about 305 Ml.gr-1 VSadded and came from the treatment of co-digestion of chicken manure with 20% (weight base) chicken intestine and its contents. The return of the resulting sludge of anaerobic digestion of chicken manure, back into the cycle, in addition to increasing the amount of gas, can minimize the time it takes to start to produce gas and help to produce gas continuously. Moreover, the water used for digestion will also be significantly reduced (at least 50%).