Adsorption of aniline from aqueous solutions onto a nanoporous material adsorbent: isotherms, kinetics, and mass transfer mechanisms

MCM-48, which is particulate and nanoporous, was formulated to actively remove aniline (AN) (i.e., benzenamine) from wastewater. MCM-48 was characterized by several methods. It was found that the MCM-48 was highly active in adsorbing aniline from wastewater. The Langmuir, Freundlich, and Temkin isotherms were employed to evaluate the adsorption equilibrium. At 100 and 94 mg g−1, the maximum theoretical and experimental absorption of aniline, respectively, fit with a Type I Langmuir isotherm. The Langmuir model was optimal in comparison to the Freundlich model for the adsorption of AN onto the mesoporous material MCM-48. The results of these kinetics adsorption models were investigated using model kinetics that employed both pseudo-first- and pseudo-second-order models as well as models utilized intraparticle diffusion. The kinetics adsorption models demonstrated that the absorption was rapid and most closely agreed with the pseudo-first-order model. The kinetic studies and the adsorption isotherms revealed the presence of both physical adsorption and chemisorption. The potential adsorption mechanisms include the following: (1) hydrogen bonding, (2) π-π interactions, (3) electrostatic interaction, and (4) hydrophobic interactions. The solution's pH, ionic strength, and ambient temperature also played essential roles in the adsorption. HIGHLIGHTS The mesoporous silica MCM-48 was very successful to remove aniline.; A maximum aniline adsorption 94 mg/g was achieved on MCM48 adsorbent.; MCM-48 was found very active for the removal of aniline compounds from wastewater.; Aniline adsorption mechanism is a chemisorption and physical adsorption process.; The MCM-48 was regenerated and reused efficiently in a batch adsorption.

Multi-criteria/comparative analysis and multi-objective optimization of a hybrid solar/geothermal source system integrated with a carnot battery

Among the different electrical energy storage technologies, the Carnot batteries are promising options with low specific cost that do not suffer from geographical limitations and power-capacity coupling. In addition to power balancing, this approach can also be unique for multi-vector energy management. A comprehensive evaluation (thermodynamic design and exergoenvironmental and exergoeconomic evaluations), comparison, and multi-objective optimization of four Carnot battery configurations based on solar-electric energy and a geothermal source is presented. Geothermal energy can simultaneously improve the thermodynamic and environmental performances of the Carnot battery. The main structure of all configurations is based on electrical energy obtained from PV and captured thermal energy from a geothermal source. The four Brayton, heat pump, flash, and organic Rankine cycle (ORC) units are periodically integrated. The outcomes point out that the discharging process is based on an ORC unit and a flash-heat pump cycle (F-HPC)-based charging process makes more optimal heat-to-power efficiency. Moreover, the Carnot battery based on the regenerative-Brayton cycle (R-BC) unit has a higher investment cost rate compared to the ORC unit (in the discharging process). When integrating the geothermal, the third configuration (R-HPC/R-BC) experiences the greatest improvement (5.3-fold) due to the increase in thermal energy received from the geothermal source

Using different geometries on the amount of heat transfer in a shell and tube heat exchanger using the finite volume method

This research investigates the heat transfer and pressure drop characteristics of a conical spiral tube heat exchanger. The study specifically focuses on the application of Ag-HEG (Silver–Hydrogen exfoliated graphene) nanofluid and various turbulator designs. The range of Dean Numbers, specifically 2200 < Dean <4200, was studied through experiments under turbulent flow conditions. Furthermore, the finite volume method-based ANSYS Fluent commercial code was utilized for numerical simulations. Additionally, numerical simulations were performed using the ANSYS Fluent software, which utilizes the finite volume method. This research aims to perform a numerical analysis on the efficiency of a conical shell and tube heat exchanger. When compared to other models, spiral heat exchangers provide a larger contact area between the fluid and the exchanger within a specified occupied area. This advantage is one of the prominent features of this particular type of heat exchanger. The simulations were conducted in two stages. During the first stage, the thermal performance coefficients of three turbulators were evaluated. In the second stage, the four-blade turbulator with ten revolutions, which exhibited superior thermal performance, was further analyzed based on the number of circles around the center of the conical spiral coil. The numerical results showed that the four-blade turbulator with ten revolutions displayed superior thermal performance compared to the other modes, specifically the two-blade and three-blade turbulators. In the second stage, it was found that the Nusselt number achieved from 30 revolutions was higher by 4.2 %, 10 %, and 18.3 % compared to the Nusselt numbers obtained from the other two modes of 10 and 20 revolutions. Consequently, it is concluded that utilizing Ag-HEG nanofluids in conjunction with the four-blade turbulator featuring 30 revolutions is the optimal choice for improving heat transfer in conical spiral tube heat exchangers while maintaining an acceptable level of pressure drop. This combination outperforms traditional fluids and turbulators

Optimum tilt and azimuth angles of heat pipe solar collector, an experimental approach

The application of solar energy as the widest, clean and free source of thermal energy requires the solar collector. As one of the common types of solar collector, heat pipe solar collector has been investigated. The thermal performance of a solar heat pipe collector was simulated using the anisotropic sky radiation model in eight different tilt angles and thirteen azimuth angles at the location of Isfahan City, Iran. The obtained theoretical results were compared with experimental ones and an average discrepancy of 5 % was obtained. After approving the chosen model, the optimum seasonal and yearly tilt angles were calculated and the correlations also were drawn from a written subroutine. The results show that through spring and summer, the optimum tilt angle is somewhat less and through autumn and winter the optimum tilt angle is beyond the latitude angle with the largest difference in spring and autumn. For the whole year and under the conditions of the present study, the optimum tilt angle is nearly the same as the latitude angle of the location

The effect of initial pressure on the thermal behavior of the silica aerogel/PCM/CuO nanostructure inside a cylindrical duct using molecular dynamics simulation

Amidst escalating fuel expenses and growing concerns over greenhouse gas pollution, the adoption of renewable alternative energy sources has become increasingly imperative. In response, scientists are fervently dedicated to identifying energy-saving solutions that are readily adaptable. Notably, silica aerogels have demonstrated remarkable efficacy in temperature management under both hot and cold conditions, while phase change materials are renowned for their capacity to store thermal energy. The study examines the effect of initial pressure on the thermal performance of silica aerogel/PCM/CuO nanostructure in a cylindrical duct. This was investigated using MD simulations and the LAMMPS software. The study will investigate several elements, such as density, velocity, temperature patterns, heat flux, thermal conductivity, and charge time or discharge time of the simulated structure. According to the results, with an increase in the initial pressure, the maximum density increases from 0.0838 atom/Å3 to 0.0852 atom/Å3, and the maximum velocity decreases from 0.0091 Å/fs to 0.0081 Å/fs. Also, the findings show that, by increasing the initial pressure, the temperature decreases from 931.42 K to 895.63 K, and thermal conductivity and heat flux decrease to 1.56 W/m.K and 56.66 W/m2 with increasing the initial pressure to 5 bar. Finally, the results show that charging time increases to 6.34 ns at 5 bar. The increase in charging time with increasing initial pressure may be attributed to the reduced mobility of particles within the structure as a result of the higher pressure. The findings of this study can help for a better understanding of energy-saving solutions, advanced thermal management systems, and the design of efficient energy storage technologies tailored to specific pressure-related operating conditions

A new model for viscosity prediction for silica-alumina-MWCNT/Water hybrid nanofluid using nonlinear curve fitting

One of the most crucial concerns is improving industrial equipment's ability to transmit heat at a faster rate, hence minimizing energy loss. Viscosity is one of the key elements determining heat transmission in fluids. Therefore, it is crucial to research the viscosity of nanofluids (NF). In this study, the effect of temperature (T) and the volume fraction of nanoparticles (φ) on the viscosity of the silica-alumina-MWCNT/Water hybrid nanofluid (HNF) is examined. In this study, a nonlinear curve fitting is accurately fitted using MATLAB software and is used to identify the main effect, extracting the residuals and viscosity deviation of these two input variables, i.e., temperature (T = 20 to 60 °C) and volume fraction of nanoparticles (φ = 0.1 to 0.5 %). The findings demonstrate that the viscosity of silica-alumina-MWCNT/ Water hybrid nanofluid increases as the φ increases. In terms of numbers, the μnf rises from 1.55 to 3.26 cP when the φ grows from 0.1 to 0.5 % (at T = 40 °C). On the other hand, the μnf decreases as the temperature was increases. The μnf of silica-alumina-MWCNT/ Water hybrid nanofluid reduces from 3.3 to 1.73 cP when the temperature rises from 20 to 60 °C (at φ = 0.3 %). The findings demonstrate that the μnf exhibits greater variance for lower temperatures and higher φ

Numerical investigation of the heat flux frequency effect on the doxorubicin absorption by Bio MOF11 carrier: A molecular dynamics approach

The present study investigated the effect of heat flux frequency on doxorubicin adsorption by bio MOF11 biocarrier using molecular dynamics simulation. This simulation examined the effect of several heat flux frequencies (0.001, 0.002, 0.005, and 0.010 1/fs) on the quantity of drug particles absorbed, mean square displacement (MSD), diffusion coefficient, and interaction energy. The present outputs of simulations predicted the structural stability of the modeled MOF-drug system in 300 K. Also, simulation outputs predicted by frequency optimization, the adsorption of target drug inside MOF11 maximized, and efficiency of this sample in actual clinical applications, such as drug delivery process increased. Numerically, the optimum value of frequency was estimated to be 0.005 1/fs. Using this heat setting, the interaction energy between MOF 11 and the doxorubicin drug increased to −929.05 kcal/mol, and the number of penetrated drug particles inside MOF11 converged to 207 atoms. The results reveal that the MSD parameter reached 64.82 Å2 after 100000-time steps. By increasing frequency to 0.005 fs−1, this increased to 78.05 Å2. By increasing MSD parameter, the drug diffusion process effectively occurred, and the diffusion coefficient increased from 67.29 to 82.47 nm2/ns. It is expected that the findings of present investigation guide the design of more efficient drug delivery platforms, enhance drug-carrier interactions, improve manufacturing processes, and aid in developing novel nanomaterials with enhanced adsorption properties for various applications

The effect of different variables and using of the internal adiabatic wall in the construction and performance of thermosiphon heat pipes: Experimental investigation

Heat pipes are a practical and powerful tool for recovering thermal energy and conserving energy sources. Thermosiphon is one of the most widely used devices that can transfer large amounts of heat at high rates between hot and cold sources without the use of external energy. The amount of vacuum in the pipe, the percentage of fluid filling, the type of operating fluid, the pipe’s length and the quantity of heat flux are the factors affecting the efficiency and effectiveness of the thermosiphon heat pipe. In this paper, the effects of different variables in the construction of heat pipes such as working fluid, pipe length, the use of mesh screen wick structure and the use of internal adiabatic wall on the thermosiphon heat pipes performance are investigated. The results show that using of an internal adiabatic wall eliminates and reduces limitations such as boiling, evaporator drying, thermosiphon flooding and vapor pressure and significantly improves the heat pipe’s performance. So that, the effective thermal conductivity (K) is increased up to 350% using the internal adiabatic wall. However, in some nanofluids, such as water/multi-walled carbon nanotubes (MWCNT), with increasing the nanofluid’s mass fraction, the startup speed in heat pipes with internal adiabatic wall is reduced by up to 20%

The effect of initial temperature and oxygen ratio on air-methane catalytic combustion in a helical microchannel using molecular dynamics approach

In industrial environments where combustion (Com.) is widely carried out, such as steam power plants, gas turbines, etc., the most common way to express the amount of oxygen consumption is its excess percentage in addition to the stoichiometric ratio, and the nearness of a catalyst causes combustion to happen at a high ratio. There are different influential factors in catalytic combustion, such as initial temperature (IT). The current study uses the molecular dynamics (MD) method to examine how the IT and oxygen ratio affect air-methane catalytic combustion in a helical microchannel. The LAMMPS package was used to conduct this investigation. This study examines how simulated structures function during burning in excess oxygen (EO) and oxygen deficiency (OD). Furthermore, palladium was used as a catalyst with an atomic ratio of 4 %. The findings show that raising the IT may enhance its atomic behavior (AB) and thermal performance (TP). The maximum velocity (MV) and maximum temperature (MT) increased from 0.26 Å/ps and 1617 K to 0.45 Å/ps and 1891 K in EO as IT increased from 300 to 700 K. By accelerating the particle velocity, it is anticipated that the catalytic combustion process would proceed more quickly. As a result, after increasing the IT to 700 K, the heat flux (HF), thermal conductivity (TC), and combustion efficiency (CE) increase to 2101 W/m2, 1.23 W/m. K, and 93 %, respectively. On the other hand, the results show that increasing IT affects combustion performance in the presence of OD. In the presence of OD, the MV and CE converge to 0.38 Å/ps and 94 % at 700 K. Therefore. It can be concluded that the atomic ratio of oxygen and the IT can significantly affect combustion process

Tribological characterization of laminated hybrid AA1050/TiC/Graphite composite bars

Hybrid composites (HC) refer to a type of material that combines aluminum (Al), titanium carbide (TiC), and graphite (Gr) at the nano level. These HC have shown promise in applications requiring high strength, wear resistance (WR), and tribological performance, such as automotive, aerospace, and industrial sectors. In this study, these HC are made using a combination of Powder metallurgy (PM) and accumulative press bonding (APB) processes have been developed. This is the first time that the wear resistance of a hybrid metal matrix composite fabricated with Gr as a solid lubricant has been done and thid is the novelty of this study. In fact, the presence of TiC nanoparticles (NP) provides improved mechanical properties, such as hardness (Hr), strength, and WR for HC. On the other hand, Gr acts as a solid nano-lubricant (NLU) in HC, reducing friction and WR during sliding contact. The presence of Gr-NP also helps to form a durable Gr-nanolayer on tribo surfaces and further improves the WR of HC. This study used a scanning electron microscope (SEM). The results demonstrated that incorporating TiC- NP reduced the WR rate and promoted NL development at extended sliding distances, creating a durable TiC/Gr HC on the TS. Finally, the improved WR of Al/TiC/Gr-HC can be attributed to the stability of the Gr-NL on the TS