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One of the most unique properties of two‐dimensional carbides and nitrides of transition metals (MXenes) is their excellent water dispersibility and yet possessing superior electrical conductivity but their industrial‐scale application is limited by their costly chemical synthesis methods. In this work, the niche feature of MXenes was capitalized in the packed‐bed electrochemical reactor to produce MXenes at an unprecedented reaction rate and yield with minimal chemical waste. A simple NH 4 F solution was employed as the green electrolyte, which could be used repeatedly without any loss in its efficacy. Surprisingly, both fluoride and ammonium were found to play critical roles in the electrochemical etching, functionalization, and expansion of the layered parent materials (MAXs) through which the liberation of ammonia gas was observed. The electrochemically produced MXenes with excellent conductivity, applied as supercapacitor electrodes, could deliver an ultrahigh volumetric capacity (1408 F cm −3 ) and a volumetric energy density (75.8 Wh L −1 ). This revolutionary green, energy‐efficient, and scalable electrochemical route will not only pave the way for industrial‐scale production of MXenes but also open up a myriad of versatile electrochemical modifications for improved functional MXenes.

The anaerobic treatment of raw vinasse in a combined system consisting in two methanogenic reactors, up-flow anaerobic sludge blanket (UASB) + anaerobic packed bed reactors (APBR), was evaluated. The organic loading rate (OLR) was varied, and the best condition for the combined system was 12.5 kg COD m −3 day −1 with averages of 0.289 m 3 CH 4  kg COD r −1 for the UASB reactor and 4.4 kg COD m −3 day −1 with 0.207 m 3 CH 4  kg COD r −1 for APBR. The OLR played a major role in the emission of H 2 S conducting to relatively stable quality of biogas emitted from the APBR, with H 2 S concentrations <10 mg L −1 . The importance of the sulphate to COD ratio was demonstrated as a result of the low biogas quality recorded at the lowest ratio. It was possible to develop a proper anaerobic digestion of raw vinasse through the combined system with COD removal efficiency of 86.7% and higher CH 4 and a lower H 2 S content in biogas.

The excessive strength of phenol present in industrial wastewater is a major issue of concern to be looked upon. Among the pollutant removal techniques, a novel robust device, the rotating packed bed (RPB) adsorber, offers efficient adsorption of phenol due to its ability to magnify the mass transfer rate. In the present study, support vector regression (SVR) has been applied to predict adsorption of phenol on activated carbon in RPB by taking into account the independent parameters, namely, spray density, gravity factor, concentration, and contact time. The experimental data set of phenol adsorption sample has been randomized and normalized prior to constructing the models. The predictive ability of the SVR model has been compared with other data-driven models like artificial neural network (ANN) and multiple regression (MR) models. Both the SVR-based model and the ANN model have almost similar prediction efficacy; however, the ANN model was found to predict the outputs slightly better. The coefficient of determination (R 2 ) and root mean square error (RMSE) values of test data set for the MR RPB adsorption model were found to be 0.934 and 0.149, while for the SVR and ANN-based models, these values were 0.996 and 0.045 and 0.998 and 0.027, respectively. Thus, it was concluded that the soft computing SVR and ANN models possessed tremendous potential to predict the adsorption process of RPB with remarkable accuracy and were greatly generalized.

Microreactor technology is seen as a promising approach to achieve green and sustainable synthesis in chemical fields because of the significant process intensification and fine control over reaction parameters caused by the miniaturization of reactor scale. The incorporation of solid catalysts as a packed bed in microreactors opens numerous opportunities for the efficient heterogeneous catalysis that plays a pivotal role in many industrially relevant chemical processes. In this review, the recent development in the use of packed bed microreactors as a versatile research tool and intensified production unit will be highlighted in the application areas including the synthesis of valuable chemicals and fuels, high-throughput catalyst screening, and kinetic/chemistry investigation. Selected reaction examples involving different reactant phases and catalyst categories will be particularly discussed, with an emphasis on the reactor performance in relation to the fundamental chemistry and engineering principles under microflow. In the end, future challenges and the outlook of packed bed microreactors for sustainable chemistry and process development will be provided.

This paper presents an integrated experimental and numerical study of a thermocline-based packed-bed thermal energy storage (TES) system employing nitrogen as the heat transfer fluid (HTF), designed for use in Concentrated Solar Power (CSP) applications. A full-scale laboratory setup was developed at the University of Cagliari to investigate charging behavior under various nitrogen flow rates. Axial temperature evolution was measured using an array of 16 thermocouples and compared against predictions from a three-dimensional CFD model developed in ANSYS Fluent. The CFD model incorporates a porous media approach with Ergun-based resistance parameters and was validated against experimental temperature profiles and pressure drop data. Detailed plots of temperature and velocity distributions confirm strong thermal stratification and accurate thermocline formation. The model captures the progression of the thermal front across the packed bed and agrees closely with experimental sensor data, confirming the accuracy of the simulated heat transfer dynamics. In parallel, a mathematical model was formulated to evaluate nanofluid inclusion, using CuO nitrogen mixtures at low volume fractions. The model predicts enhanced thermal conductivity and energy storage potential. Based on mathematical modeling, the inclusion of CuO nanoparticles in nitrogen is projected to increase thermal conductivity and convective heat transfer coefficient, while reducing pressure drop. These predicted enhancements indicate the potential for sharper thermocline formation, improved energy storage efficiency, and reduced hydraulic losses; paving the way for more compact and effective TES systems in solar thermal applications.

Non thermal plasma (NTP) reactors packed with non-catalytic or catalytic packing material have been widely used for the abatement of volatile organic compounds such as toluene, benzene, etc. Packed bed reactors are single stage reactors where the packing material is placed directly in the plasma discharge region. The presence of packing material can alter the physical (such as discharge characteristics, power consumption, etc.) and chemical characteristics (oxidation and destruction pathway, formation of by-products, etc.) of the reactor. Thus, packed bed reactors can overcome the disadvantages of NTP reactors for abatement of volatile organic compounds (VOCs) such as lower energy efficiency and formation of unwanted toxic by-products. This paper aims at reviewing the effect of different packing materials on the abatement of different aliphatic, aromatic and chlorinated volatile organic compounds.

In the present study, a two-dimensional CFD approach has been chosen to investigate heat transfer in a packed bed filled with phase change materials (PCM) capsules. In this research, four different geometries, circular, hexagonal, elliptical, and square, are considered PCM packages made of KNO 3 covered with a copper layer and NaK as heat transfer fluid (HTF). The CFD results showed that in the charging mode, the circular geometry performed better and reached the final temperature of 660 K earlier than other geometries. Also, the effect of adding two different types of fins, namely flat and sharp fins to PCM packages, was evaluated and it was found that sharp fins improve heat transfer surface and increase system efficiency. Finally, the effect of HTF inlet velocity and packed bed porosity on the optimum geometry which consists of circular PCM capsules with sharp fins was investigated. The results showed that by increasing the HTF velocity and packed bed porosity, convection and conduction heat transfer improved, and at a velocity of 0.016 and porosity of 0.686, the energy storage system has the highest performance.

Plasma science has attracted the interest of researchers in various disciplines since the 1990s. This continuously evolving field has spawned investigations into several applications, including industrial sterilization, pollution control, polymer science, food safety and biomedicine. nonthermal plasma (NTP) can promote the occurrence of chemical reactions in a lower operating temperature range, condition in which, in a conventional process, a catalyst is generally not active. The aim, when using NTP, is to selectively transfer electrical energy to the electrons, generating free radicals through collisions and promoting the desired chemical changes without spending energy in heating the system. Therefore, NTP can be used in various fields, such as NOx removal from exhaust gases, soot removal from diesel engine exhaust, volatile organic compound (VOC) decomposition, industrial applications, such as ammonia production or methanation reaction (Sabatier reaction). The combination of NTP technology with catalysts is a promising option to improve selectivity and efficiency in some chemical processes. In this review, recent advances in selected nonthermal plasma assisted solid–gas processes are introduced, and the attention was mainly focused on the use of the dielectric barrier discharge (DBD) reactors.

Replacing the conventionally used steam reforming of methane (SRM) with a process that has a smaller carbon footprint, such as dry reforming of methane (DRM), has been found to greatly improve the industry’s utilization of greenhouse gases (GHGs). In this study, we numerically modeled a DRM process in lab-scale packed and fluidized beds using the Eulerian–Lagrangian approach. The simulation results agree well with the available experimental data. Based on these validated models, we investigated the effects of temperature, inlet composition, and contact spatial time on DRM in packed beds. The impacts of the side effects on the DRM process were also examined, particularly the role the methane decomposition reaction plays in coke formation at high temperatures. It was found that the coking amount reached thermodynamic equilibrium after 900 K. Additionally, the conversion rate in the fluidized bed was found to be slightly greater than that in the packed bed under the initial fluidization regime, and less coking was observed in the fluidized bed. The simulation results show that the adopted CFD approach was reliable for modeling complex flow and reaction phenomena at different scales and regimes.

The plasma behavior in a parallel-plate dielectric barrier discharge (DBD) is simulated by a two-dimensional particle-in-cell/Monte Carlo collision model, comparing for the first time an unpacked (empty) DBD with a packed bed DBD, i.e., a DBD filled with dielectric spheres in the gas gap. The calculations are performed in air, at atmospheric pressure. The discharge is powered by a pulse with a voltage amplitude of −20 kV. When comparing the packed and unpacked DBD reactors with the same dielectric barriers, it is clear that the presence of the dielectric packing leads to a transition in discharge behavior from a combination of negative streamers and unlimited surface streamers on the bottom dielectric surface to a combination of predominant positive streamers and limited surface discharges on the dielectric surfaces of the beads and plates. Furthermore, in the packed bed DBD, the electric field is locally enhanced inside the dielectric material, near the contact points between the beads and the plates, and therefore also in the plasma between the packing beads and between a bead and the dielectric wall, leading to values of V m−1, which is much higher than the electric field in the empty DBD reactor, i.e., in the order of V m−1, thus resulting in stronger and faster development of the plasma, and also in a higher electron density. The locally enhanced electric field and the electron density in the case of a packed bed DBD are also examined and discussed for three different dielectric constants, i.e., (ZrO2), (Al2O3) and (SiO2). The enhanced electric field is stronger and the electron density is higher for a larger dielectric constant, because the dielectric material is more effectively polarized. These simulations are very important, because of the increasing interest in packed bed DBDs for environmental applications.