Oxygen, an odorless and colorless gas constituent of the atmosphere, is a vital gas component for the Earth, as it makes up 21% of the composition of the air we breathe. Apart from the importance of oxygen for human breathing, its highly pure form is demanding for industrial applications. As such, several technologies have been established to increase the oxygen purity from 21% to somewhat higher than 95%. One of the competitive technologies for producing this high-purity oxygen from the air is through pressure swing adsorption (PSA), which has the advantages of low cost and energy while being highly efficient. Also, PSA is a simple and flexible system due to its ability to start up and shut down more rapidly since its operation occurs at ambient temperature, which is enabled through the use of adsorbents to bind and separate the air molecules. The enhancement of the PSA’s performances was reported through the modification of PSA step cycles and material (zeolite) tailoring. A simplified complete set of a mathematical model is included for modelling the PSA system, aiming to ease the experimental burden of the process design and optimization of an infinite modification of PSA step cycles. Finally, some technological importance of oxygen production via PSA, particularly for onboard oxygen generation system and oxy-enriched incineration of municipal solid waste, was discussed. Continuous development of PSA will make significant contributions to a wide range of chemical industries in the near future, be it for oxygen production or other gas separation applications.

Optimizing the volute performance can effectively improve the efficiency of a centrifugal fan by changing the volute geometric parameter, so the self-adaption Kriging surrogate model is used to optimize the volute geometric parameter. Firstly, volute radius Rd, the radius of tongue r, and outlet angle of the volute θ are selected as the optimization parameters of the volute, and latin hypercube sampling is used to configure the initial sample points, the corresponding three-dimensional aerodynamic model under each sample point configuration is constructed. CFD software is used to simulate the aerodynamic efficiency and total pressure of the centrifugal fan under each initial sample point configuration. Secondly, the Kriging surrogate model of initial sample point configuration parameters, aerodynamic efficiency, and total pressure of volute is constructed, and sample points are added by expectation improvement (EI) method to improve the fitting accuracy of Kriging surrogate model. Finally, the high-precision Kriging surrogate model is used as the fitness function of NSGA-II algorithm to find the Pareto optimal solution under multiobjective optimization, and the optimization target are aero dynamical efficiency and total pressure. The rationality of the above method is verified by optimizing the 9–19.4A type centrifugal fan volute. The efficiency of the optimized fan under working conditions is increased by 1%, and the total pressure under working conditions is not reduced. The optimized volute can effectively improve the overall performance of the centrifugal fan. This study is helpful to promote the application of numerical optimization design method in the volute of centrifugal fan. It provides reference for the optimization design of high-performance centrifugal fan.

The thermodynamic properties of pure compounds are relevant data for process systems engineering. Different first-order group contribution models have been reported in the literature to calculate these properties and they are also widely employed in commercial process simulators. However, they may have some limitations and, consequently, a reliable comparison of these models is required to analyze their performance and to determine the best alternative for the calculation of pure compound properties. This paper reports the implementation and evaluation of several first-order group contribution models to calculate the normal boiling point and critical properties (temperature, pressure, and volume) of pure compounds. The performance of these models was characterized and compared for several compound families using a standardized approach to determine their group contributions and parameters. An artificial neural network model was also applied and assessed to improve the estimations obtained with the best group contribution models. Results showed that the calculation of critical temperature was challenging for several compound families where AARD values ranged from 0.05 to 56.28%, while the group contribution models were more accurate to estimate the critical volume with AARD values ranging from 0.48 to 35.99%. This study allows us to identify the limitations and gaps of this type of thermodynamic models with the objective of improving its performance for the calculation of pure compound thermodynamic properties. The findings of this study can help to enhance the capabilities of thermodynamic models for the calculation of the normal boiling point and critical properties of pure compounds, which are relevant for the process systems engineering of new operations and products.

In this study, a mathematical model of the copolymerization of AN-VA in a continuous stirred tank reactor (CSTR) was developed considering charge-transfer complexes (CTCs). CTC formation between acrylonitrile (AN) and vinyl acetate (VA) was demonstrated using UV-VIS spectrophotometry and molecular orbital theory. The rate constants and equilibrium constants of the complexes were calculated from a model of the simultaneous participation of complexes and free monomers and the molar ratio method. Furthermore, the participation of CTCs in propagation was included because of their high reactivity. All the simultaneous equations defined to analyze the reactor parameters were analytically solved, and the results of the model were in terms of operative variables such as monomer conversion, average molecular weight, and the mole fraction of monomer 2 (i.e., VA) in the polymer formed. The results of the predictions of the developed model were compared with the experimental data for validation. This prediction was also compared with the reactor model solution without considering the CTC, which showed deviations that were more significant than those of the CTC model. These results represent a quantitative way to analyze the order of magnitude of the impact of the formation of the complexes in the analyzed polymerization system.

In a biogas plant, the acetic acid concentration is a major component of the substrate as it determines the pH value, and this pH value correlates with the volume of biogas produced. Since it requires specialized laboratory equipment, the concentration of acetic acid in a biogas substrate cannot be measured on-line. The project aims to use NIR sensors and machine learning algorithms to estimate the acetic acid concentration in a biogas substrate based on the measured intensities of the substrate. As a result of this project, it was possible to determine whether the acetic acid concentration in a biogas substrate is higher or lower than 2 g/l using machine learning models.

The present study successfully produced a highly effective and stable organ phosphorus-doped tungsten trioxide (P-WO3) photocatalyst by a combination of hydrothermal and postcalcination methods. The crystallites, morphologies, and optical properties of the produced WO3 and P-WO3 crystals were investigated. The results indicated that P was consistently doped into the WO3 lattice in a pentavalent-oxidation state (P5+). Additionally, charge carrier traps capable of accepting photoelectrons were created. Additionally, the optical band gap was reduced from 2.4 to 2.33 eV. The degradation of methyl blue by photocatalysts was utilized to evaluate the photocatalytic performance of the synthesized P-WO3 samples at varied P concentrations (MB). The sample containing 6% -P-WO3 exhibited the best photocatalytic performance, degrading 96 percent of MB in 120 minutes, which was more than four times faster than the pure WO3 sample. The practicality of the synthesized P-WO3 was determined using samples from two residential wastewater treatment plants. When treating real wastewater with low organic matter concentrations, the P-WO3 demonstrated strong photodegradation performance. The creation of hydroxyl radicals (OH) and photography-created holes (h+) could be the key protagonists of photocatalytic activity in the P-WO3.

Tannery hair wastes are becoming a challenge for tanners regarding environmental pollution control and human health. In this study, an experiment had been designed to hydrolyse sheep hair in an alkaline medium, and the operational condition for the alkaline extraction of KH has been modeled and optimized. The structure, morphology, functional groups, particle size, and molecular mass of the KH extracts were evaluated experimentally by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), particle size analysis, and SDS-PAGE analysis, respectively. FTIR analysis of the extract confirmed the presence of carboxylic, amide, and aldehyde functional groups and alkyl side chains of amino acids. The molecular weight of the extracted keratin ranges between 3–15 kDa, and X-ray diffraction (XRD) analysis showed an amorphous form of structure with two peaks at 2 theta of 9.36° and 21.16° due to -helix and - sheet structure in keratin. Response surface methodology (RSM) coupled with BOX-Behnken design was applied as a statistical tool to investigate the effect of extraction time, the concentration of the hydrolysing agent, and temperature on the response variable (yield of keratin protein). The concentration of the hydrolysing agent was found to be the most significant factor affecting the speed of extraction, but its gradual increase tends to affect the protein content of the extract. Optimum parameters of 0.5 N, 80°C, and 3.5 hr were obtained for the concentration of NaOH, temperature, and extraction time, respectively, with a maximum average protein yield of 91.5% and a percentage total nitrogen content of 14.6% using the Kjeldahl method and 86.57% using the biuret test method.

Dry reforming of methane has exhibited significant environmental benefits as it utilizes two major greenhouse gases (CO2 and CH4) to produce synthesis gas, a major building block for hydrocarbons. This process has gained industrial attention as catalyst deactivation due to coke deposition being a major hindrance. The present study focuses on the dry reforming of methane over Ni-supported mesoporous zirconia support. Ni metal was loaded over in-house synthesized mesoporous zirconia within the 0–15 wt% range using the wet impregnation method. The physicochemical properties of the synthesized catalysts were studied using various characterization techniques, namely, XRD, SEM, FTIR, TGA, and N2 adsorption-desorption techniques. The activity of all the catalysts was evaluated at 750°C and gas hourly space velocity (GHSV) of 72000 ml/h/gcat for 9 hours (540 min). The deactivation factor indicating a loss in conversion with time is reported for each catalyst. 10 wt% Ni/ZrO2 showed the highest feed conversion of about 68.8% for methane and 70.2% for carbon dioxide and the highest stability (15.1% deactivation factor and 21% weight loss) for dry reforming of methane to synthesis gas.

Atenolol (ATN) is a drug that is widely used to treat some heart diseases, and since it cannot be completely decomposed in the human body, some amounts of it are found in surface water. These amounts may bring risks to the environment and humans, and for this reason, its removal is a must. In the present study, the combined sono-electro-persulfate method was used for ATN removal. Based on the design of the experiment conducted by response surface methodology (RSM), the effects of 5 main factors (pH, time, PS concentration, current intensity, and initial ATN concentration) have been investigated at 5 levels. After passing the test steps in different conditions, the remaining amount of ATN has been measured by high-performance liquid chromatography (HPLC). Finally, an adaptive neuro-fuzzy inference system (ANFIS) with 99.63% accuracy and a genetic algorithm (GA) were used to analyze and interpret data and predict optimal conditions. The obtained results indicate the possibility of a maximum efficiency of 99.8% in the mentioned conditions (Ph of 7.4, time of 18 min, PS concentration of 2000 mg/L, current intensity of 3.35 A, and initial ATN concentration of 11.2 mg/L). According to the obtained results, the initial concentration of ATN can be considered as the most effective factor in this process, and the best Ph range for this experiment was the neutral range. The sono-electro persulfate process can be mentioned as a new and effective method for removing ATN from water sources.

A better understanding of the reaction mechanism and kinetics of dry reforming of methane (DRM) remains challenging, necessitating additional research to develop robust catalytic systems with high catalytic performance, low cost, and high stability. Herein, we prepared a zirconia-alumina-supported Ni-Fe catalyst and used it for DRM. Different partial pressures and temperatures are used to test the dry reforming of methane reaction as a detailed kinetic study. The optimal reaction conditions for DRM catalysis are 800°C reaction temperature, 43.42 kPa CO2 partial pressure, and 57.9 kPa CH4 partial pressure. At these optimal reaction conditions, the catalyst shows a 0.436 kPa2 equilibrium constant, a 0.7725 /gCat/h rate of CH4 consumption, a 0.00651 /m2/h arial rate of CH4 consumption, a 1.6515 /gCat/h rate of H2 formation, a 1.4386 molCO/gCat/h rate of CO formation. This study’s findings will inspire the cost-effective production of robust catalytic systems and a better understanding of the DRM reaction’s kinetics.

High concentrations of fluoride (F−) in drinking water represent a public health threat, and consequently, effective and sustainable methods are required to improve the water quality, mainly in developing and low-income countries. This study focused on the thermodynamics of fluoride adsorption on bone char regenerated with NaOH for water defluoridation. A detailed analysis of the number of fluoride adsorption/desorption cycles, their impact on the performance and surface chemistry of bone char using different NaOH concentrations, and modeling of the adsorption mechanism using statistical physics theory was carried out. The results showed that 0.075 mol/L NaOH was effective in recuperating the defluoridation properties of bone char with a regeneration efficiency higher than 90% during five adsorption/desorption cycles. Bone char regeneration efficiency decreased up to 64% after ten adsorption/desorption cycles with a maximum fluoride adsorption capacity of 0.18 mmol/g. NaOH restored the bone char surface properties for ligand exchange of the fluoride anions via the hydroxyapatite functionalities contained in this adsorbent. It was calculated that around 0.25–0.46 mmol/g hydroxyapatite ligand exchange sites of regenerated bone char samples could be involved in the fluoride adsorption, which was also expected to be a mono-ligand mechanism. The reduction in defluoridation properties of bone char during the regeneration cycles was attributed to the decrease in the ligand exchange capacity as well as the deactivation and blocking of some functional groups of hydroxyapatite, which limited their participation in consecutive adsorption processes. This study contributes to the optimization of the recycling and reuse of bone char for fluoride removal from water to reduce the operating defluoridation costs, thus enhancing the application of this technology in low-income areas where fluorinated water represents a threat to public health.

Herein, a kind of three-dimensional hollow Mg-Ca-Al hydrotalcite-like compounds (HTLCs) microsphere was prepared by self-assembly of hydrotalcite-like nanosheets. Mg-Ca-Al HTLCs microsphere (MS) has large specific surface area and large pore size, and the modification of KF·2H2O increases numerous alkaline active sites on the surface of the catalyst. The prepared catalyst has excellent catalytic effect for the production of biodiesel by transesterification. Under the optimal conditions of the catalyst addition amount which accounts for 2% of the weight of oil, the biodiesel yield of the best catalyst is as high as 92% within 30 minutes. This article also provides a paradigm of a rational structural design for regulating the morphology of HTLCs.

The textile industry is a common and relevant sector worldwide that generates significant environmental pollution via the discharge of dye-containing wastewater. In this direction, the electrospinning technology can be used to produce adsorbing nanofibers for the treatment of wastewater polluted by dyes and other toxic compounds. The nanofibers obtained by this technology are light and thin, thus providing several advantages (e.g., high surface area) to improve the efficacy of adsorption processes. In this direction, this study reports the preparation of nanofibers from polyvinyl butyral (PVB) and bentonite via electrospinning. This study also reports PVB/bentonite nanofiber mat and its application in adsorbing the cationic dye (methylene blue) from an aqueous solution. The morphology and water contact angles of these nanofibers were analyzed. Results showed that the maximum dye adsorption of these nanofibers was 66.63 mg/g along with 32% removal at pH 9 and 27 ± 2°C. The dye adsorption on these nanofibers was exothermic and pH-dependent, with the best adsorption capacities obtained under alkaline conditions. The adsorption mechanism of this dye molecule on these PVB/bentonite nanofiber mats was associated with van der Waals forces, hydrogen bonding, and electrostatic interactions. This novel composite is an interesting material with improved properties that can be applied to the removal of cationic dyes from wastewater.

Almost every metal and alloy corrodes when used in high-temperature applications. To combat this problem, ceramic coatings on the metals can be deposited for better thermal and corrosion behavior. The present study applies an alumina-titania (Al2O3-TiO2) ceramic coating to the stainless steel (SS) surface using a detonation spray process. The surface of the coated SS is probed by optical microscopy (OM), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The clear differences between coated and uncoated SS have been observed based on the SEM images. The XRD pattern indicates that the Al2O3-TiO2 coating on SS has been successfully deposited. The hardness of coated and uncoated SS surfaces is determined by using the Micro Vickers hardness tester, which claims that the hardness of the SS surface has decreased after coating. Salt spray tests were used to examine the corrosion behavior of coated and uncoated SS after 12 and 24 hours. After 12 hours, no corrosion was observed on the SS. After 24 hours, however, significant corrosion of uncoated SS is observed, and the coated SS shows negligible corrosion. Based on the study, it is claimed that an Al2O3-TiO2 coating on SS has improved its corrosion behavior significantly.

Increased urbanization and consumerism have resulted in the excessive release of food waste and municipal solid waste. Such wastes contain abundant organic matter that can be transformed into energy, addressing the twin challenges of waste management and energy insecurity. In recent years, different studies have investigated ways of producing biogas through the codigestion of organic wastes. In this work, different food wastes were codigested and the biogas yield was determined. The effect of feedstock mixing ratios, temperature, and pH was studied. A mixing ratio of 1 : 1 produced the highest biogas yield (2907 ± 32 mL), nearly twice, which was obtained at a ratio of 1 : 4 (1532 ± 17 mL). The biogas yield increased with the temperature rise. The lowest yield of 2907 ± 32 mL was obtained at 20°C, while the highest yield of 4963 ± 54.6 mL was obtained at 40°C. Regarding pH, the yield was 2808 ± 31 mL at pH 6.5 and 7810 ± 86 mL at pH 7.3. This indicated a 178.1% increase in the biogas yield. The CN ratio for tuber waste and fruit waste was 18 and 28, respectively, while the corresponding pH was 6.7 and 6.9. A positive synergy index of 4.5 was obtained, which is higher than what is reported in the literature of codigested substrates. Irish potato peels and banana peels produced the highest biogas yield and are recommended for use as codigested feedstock.

Ionic liquids (ILs) are proposed as potential “green” solvents with remarkable properties. Deep eutectic solvents (DESs) are a new type of ILs with additional properties, such as higher biodegradability and a lower price. ILs and DESs are “green” absorbents for various gas separations, such as CO2/N2, CO2/H2/CO, H2S/CH4, and N2O/N2. Due to their large number, the screening of ILs is crucial. Although ILs with high absorption capacities were screened using gas solubility and selectivity, it is important to consider the energy and solvents used in the process. In this paper, the absorbent amount and the energy consumption were used for screening absorbents for various gas separation processes. The results reveal that physical IL [Bmim][DCA] and chemical IL [Eeim][Ac] are screened for CO2/N2 and CO2/H2/CO separation, physical IL [Omim][PF6] for H2S/CH4 separation, and physical IL [P66614][eFAP] for NO/N2 separation. The screened ILs offer some advantages over commercial absorbents in terms of lower energy consumption or amount.

Molten salt reactor (MSR) is considered a promising 4th generation nuclear power plant because of its safety and suitability for SMR (small modular reactor). Also, molten salts are used in concentrating solar power (CSP) and energy storage system (ESS) as a heat storage medium. So molten salt has recently been researched a lot as heat storage and a transfer medium. However, molten salts’ high operating temperature (>450°C) and high Prandtl number make it hard to perform a thermal-hydraulic experiment in the laboratory. Thus, high Prandtl number and high viscosity fluid, deep eutectic solvents (DES), is chosen as a simulant of molten salts in this study. Thermal-hydraulic experiment using glyceline, which is easy to synthesize and transparent to visualize flow with high viscosity among various DESs, was performed. Also, the friction factor and heat transfer coefficient required for energy system designs were measured. As a result, it was found that glyceline is a Newtonian fluid, and the transition region from laminar to turbulent flow has a lower Reynolds number than water has. In addition, the heat transfer coefficient properties of glyceline were somewhat consistent with the existing correlations. To summarize, glyceline’s friction factor and heat transfer coefficient are predictable in existing theories, but the transition regions for those are different because flow development behavior between hydraulic and thermal boundary layers is different. Therefore, it is estimated that thermal-hydraulic experiments are essential when using high Pr numbers and high viscosity fluids such as DESs and molten salts as heat storage and transfer mediums.

Backgroundand Aim. Natural organic matter (NOM) has become one of the most serious environmental problems due to its persistence in aqueous solutions and the risk of carcinogenesis. In this study, the removal efficiencies of real and synthetic humic acid (HA) by multi-walled carbon nanotubes (MWCNTs) coated with iron oxide were evaluated. Materials and Methods. The MWCNs were synthesized and coated with iron oxide. In addition, the effects of pH, contact time, mixing speed, and adsorbent dose on the removal efficiency of NOM by MWCNTs-Fe3O4 were studied. Then, the removal efficiency of NOM from real samples was investigated at optimal conditions. The MWCNT-Fe3O4 was characterized by scanning electron microscopy (SEM) test and X-ray diffraction (XRD), respectively. Data analysis was performed using Minitab software based on the Taguchi method. Results. The results showed that MWCNTs were coated with Fe3O4. The SEM test shows particle (MWCNTs-Fe3O4) size in the range of 48–143 nm, and the particles have uniform spherical shapes. Enix software was used to identify the phase in this sample. The conditions including , mixing speed = 120 rpm, adsorbent dosage = 1.5 g·L−1, and contact time = 90 minutes were selected as optimal for NOM adsorption. The mean removal efficiencies of NOM in synthetic samples at 5, 10, and 20 mg·L−1 concentrations were 86.6%, 84.87%, and 95.41%, respectively. In addition, the mean removal efficiency of NOM in Choghakhor Wetland was 77%. Conclusion. Our findings demonstrated that the MWCNTs-Fe3O4 can be potentially used as an adsorbent for removing natural organic matter (HA) from aqueous solutions.

A potential and developing green technology for producing renewable energy and treating wastewater is the microbial fuel cell (MFC). Despite several advancements, there are still several serious problems with this approach. In the present work, we addressed the problem of the organic substrate in MFC, which is necessary for the degradation of metal ions in conjunction with the production of energy. The utilization of fruit waste as a carbon source was strongly suggested in earlier research. Hence, the mango peel was used as a substrate in the current study. Within 25 days of operation, a 102-mV voltage was achieved in 13 days, while the degradation efficiency of Cr3+ was 69.21%, Co2+ was 72%, and Ni2+ was 70.11%. The procedure is carried out in the batch mode, and there is no continuous feeding of the organic substrate. In addition, a detailed explanation of the hypothesized mechanism for this investigation is provided, which focuses on the process of metal ion degradation. Lastly, future and concluding remarks are also enclosed.

Maximizing the production of high-value olefins from heavy crude oil is a crucial topic in the downstream refining industry. However, converting heavier fractions is a major challenge due to the small pore size of the zeolites. Therefore, this work aimed to develop extrudate zeolite catalysts posing adequate micromesoporous pore network and moderate acidity by combining microporous zeolite with the boehmite phase of alumina. These extruded zeolite-alumina catalysts are expected to allow sufficient diffusion of heavy fractions, thus leading to high cracking of heavy oil into valuable olefins. Different zeolite-alumina catalysts of varying alumina content ranging from 25 to 75% (AlZ-25, AlZ-50, and AlZ-75) were prepared in the laboratory to study the optimum zeolite-alumina ratios for maximum olefin production from heavy oil. The catalysts were characterized for their chemical and physical properties using nitrogen adsorption (N2 adsorption), X-ray diffraction (XRD), inductively coupled plasma (ICP) spectrometry, Fourier transform infrared (FT-IR) spectroscopy, and NH3 temperature programmed desorption (TPD). A gradual increase in the average pore diameter (APD) of the catalysts was observed due to the alumina ratio with a distinct range of acidity that is in the range of 125 to 375°C, and also the geometry of pores is not the same for all of the supports. Catalytic performance tests were conducted in a fixed-bed reactor at 450°C, 10 bar, and liquid hourly space velocity (LHSV) of 1 h−1. The results revealed that the prepared catalysts were thermally stable and effective in heavy oil conversion to olefins. Moreover, the selectivity of propylene was higher than that of ethylene (P/E) due to the modified textural and acidic properties of the catalysts. The results showed that the catalysts prepared with moderate acidity and adequate mesopores exhibited a considerable effect on the conversion of heavy crude oil into olefins. Hence, the acidity and mesoporosity of the catalysts play a vital role in determining the catalyst performance.