Adsorption最新文献

Gas adsorption kinetics can significantly affect column size as well as the purity and recovery of products obtained from adsorption-based separation processes. Therefore, accurate adsorption kinetics are essential for designing pressure swing adsorption (PSA) processes. To obtain reliable kinetic parameters, it is crucial to employ reliable measurement methods and efficient yet accurate data evaluation procedures. In this study, we measured the equilibrium and kinetic data for CO_2, CH₄, N₂ on ZSM-5 at three temperatures at pressures up to 120 kPa using a commercial volumetric-based system to evaluate the adsorbent’s potential for natural gas upgrading. The equilibrium data were analysed by fitting them to Langmuir equations with CH₄/N₂ and CO₂/CH₄ selectivities evaluated using the ideal adsorbed solution theory (IAST). A robust and efficient procedure to extract kinetic parameters using the non-isothermal Fickian diffusion (FD) model was developed. This procedure standardises the method for determining the actual start time of the adsorption for each kinetic measurement and for estimating initial guesses for all involved parameters. The goodness of data regression was evaluated by analysing sorted residual plots of the experimental and regressed data, as well as the uncertainties of the extracted parameters. By applying the procedure, kinetic parameters for gases on ZSM-5 were assessed. Results indicate that ZSM-5 exhibits favourable adsorption kinetics and equilibrium characteristics for CH₄/N₂ separation.

When using water to cool adsorption cooling systems, it is necessary to have a permanent source of cold water or to utilize cooling towers, which consume large amounts of water due to evaporation in the process of evaporative water cooling. Therefore, many scientists focus on how to use sustainable sources of cold water, such as geothermal cooling, which is one of the most promising sources for energy system applications. The study presents a novel method for combining solar heating and geothermal cooling in Lebanon, utilizing adsorption cooling to enhance the efficient use of renewable resources. Geothermal cooling energy is primarily used to cool the condenser of the adsorption chiller, in addition to removing the heat of adsorption during the adsorption process. The effects of the diameter and length of the ground-cooling water pipes, as well as the water velocity, on the ground-cooling water temperature are investigated. Then, the impact of changes in ground-cooling water temperature on the performance of the adsorption cooling system is studied. The paper also presents theoretically the performance of the adsorption cooling system in Lebanon’s climate. The results illustrate that coupling geothermal cooling with a solar-powered adsorption cooling system increases the cooling capacity to 21.6 kW, with an improvement of about 44% compared to the traditional adsorption system with a cooling tower. The proposed combination raises the coefficient of performance (COP) to 0.52, with an enhancement of about 11.6% at a regeneration temperature of 85 °C. An additional advantage of this coupling is that the system can operate efficiently at a low hot source temperature of 50 °C with a COP of 0.55. This research demonstrates that solar energy and geothermal cooling sources can be efficiently utilized to power hybrid adsorption cooling systems. This approach not only promotes electrical power savings but also leverages renewable and environmentally friendly resources, potentially advancing these industries in the future.

Metal–organic frameworks (MOFs) are highly porous and crystalline materials synthesized from metal ions and organic ligands. They have received attention from researchers in recent years due to their enormous applications, such as separation, sensors, gas storage, and catalysis. MOFs are categorized as nanoporous, mesoporous, and microporous based on the size of the pores. Functionality of MOFs depends on their pore size and overall charge. BTEX, a subclass of volatile organic compounds found in air, is classified as a hazardous pollutant because of its toxic, carcinogenic, and mutagenic nature. One practical strategy for protecting the environment is the sequestration of multi-component BTEX using MOFs as sorbents. This review discusses the classification of MOFs and highlights the green and economical methodologies adopted for the synthesis of MOFs in order to facilitate their commercialization. This article also presents an overview of the adsorption of BTEX using various types of MOFs. More significantly, plausible processes for the adsorption or interaction of BTEX compounds with MOFs are discussed. The various kinds of interaction, including hydrophobic interactions, π–π stacking, hydrogen bonding, interaction at open metal site, and electrostatic interaction, are discussed. These processes are usually impacted by the ligands' structure and functionalization, the MOFs functionalization, the pore size, and the surface structure of the MOF.

Managing wastewater in industrial laundries poses a significant challenge, particularly in the removal of emerging contaminants such as phenolic compounds. The performance of a two-stage process combining ultrafiltration followed by adsorption using modified activated carbon was studied for the removal of nonylphenol ethoxylate (NPEO_3-17) from real laundry wastewater. The use of ultrafiltration as a pretreatment allowed removing solids and colloids before adsorption. Ultrafiltration led to a reduction in total suspended solids from 14.0 ± 2.1 to 3.0 ± 1.3 mg.L⁻¹ and turbidity from 110 ± 1.4 to 1.8 ± 0.9 NTU. Additionally, NPEO_3-17 concentration decreased from 1095 ± 50 µg.L⁻¹ to 534 ± 78 µg.L⁻¹, whereas the chemical oxygen demand (COD) concentration passed from 585 ± 14 mg.L⁻¹ to 281 ± 9 mg.L⁻¹ in the permeate. The ultrafiltration permeate was subsequently treated by dynamic adsorption. The adsorption process was designed and optimized considering parameters such as hydraulic retention time (HRT), initial feed temperature, and column height-to-diameter (H/D) ratio. HRT was found to be the most important parameter contributing significantly to NPEO_3-17 and COD removal. Under the optimal conditions (HRT of 9.6 min, a temperature of 20 °C, and an H/D ratio of 6.9) using Box-Behnken Design methodology, 99% and 82% of NPEO_3-17 and COD were removed, respectively. The breakthrough behavior of the adsorption column was further analyzed using six classical models including Bohart–Adams, Yoon–Nelson, Thomas, Wolborska, Yan, and Clark, to interpret the dynamic adsorption kinetics and predict column performance. The Bohart-Adams and Wolborska models described very well the adsorption process for NPEO_3-17. Results demonstrated that the modified activated carbon maintained NPEO_3-17 levels below the reuse threshold (< 200 µg.L⁻¹) for water reuse, even after treating nearly 100 L of ultrafiltered water, confirming the efficiency and long-term stability of the hybrid ultrafiltration–adsorption system.

Graphical abstract

The pressure swing adsorption (PSA) process has a wide range of applications for CO₂ capture from flue gas, due to the advantages of simple operation, low investment and energy consumption. However, existing research results have shown that conventional single-stage PSA typically cannot achieve 95% purity CO₂ with 90% recovery using most commercial adsorbents. Dual reflux pressure swing adsorption (DR-PSA) is a special process that combines stripping and enriching PSA, where light and heavy products with high purity and high recovery can be obtained simultaneously. However, its industrial applications are limited by the problems of discontinuous feeding and high energy consumption. To overcome these limitations, a 4-bed continuous DR-PSA was developed and simulated using a model validated against published experimental data, with simulated flue gas (CO₂/N₂ = 15%/85%) as the feed and silica gel as the adsorbent. After comparing internal state variables, four key parameters, including feed flow rate, step duration, light reflux-to-feed ratio, and feed position, were studied in detail. The results indicate that the proposed process can achieve CO₂ purity of 96.42% with 96.52% recovery, N₂ purity of 99.40% with 99.40% recovery, a productivity of 0.4607 mol CO₂/kg/h, and a specific energy consumption of 1.172 GJ/t CO₂. The process demonstrates significantly superior specific energy consumption compared to prior studies.

This work reports a comparative analysis of Carbon dioxide (CO₂) adsorption in three different pore-sized Metal organic frameworks (MOFs) named MOF-5, ZIF-8 and UiO-66. The Grand Canonical Monte Carlo (GCMC) simulations have been performed between temperature ranges 258–323 K under 0–30 bar pressure to examine the CO₂ adsorption capacity of the three MOFs.The adsorption isotherms and isosteric heat of adsorption across the three MOFs have been studied to understand their gas storage capacities and adsorption mechanisms. It is observed that MOF-5 outperforms UiO-66 and ZIF-8 in CO₂ adsorption under high pressure at all temperatures. At ambient conditions (298 K and 1 bar), UiO-66 is found to be the best adsorber among the studied MOFs. This study establishes a structure adsorption analysis, linking pore architecture and chemistry with CO₂ uptake behaviour.

A novel copper(II)-based metal-organic framework (MOF), hexakis(4-acetamidobenzoato)dicopper(II), was synthesized via a solution-based reaction using 4-acetamidobenzoic acid and copper(II) chloride. Structural elucidation through single-crystal X-ray diffraction revealed a classical paddle-wheel dicopper(II) core with bidentate bridging by six acetamidobenzoate ligands, forming a distorted square-pyramidal coordination geometry. Spectroscopic analyses (FT-IR, Raman, UV-Vis) confirmed successful metal–ligand coordination, while thermal analysis highlighted multi-step decomposition with stable CuO residue. SEM–EDS and XRF affirmed high crystallinity and homogenous elemental distribution. Hirshfeld surface and DFT-based frontier molecular orbital (FMO) analyses underscored strong intermolecular interactions and semiconducting behavior with a narrow band gap (0.36 eV), indicating potential in catalytic and optoelectronic applications. Adsorption studies demonstrated significant dye uptake capacities, with preferential chemisorption of methyl orange due to favorable structural and electronic properties. Furthermore, the MOF exhibited promising CO₂ and C₂H₂ gas adsorption behavior, with stronger van der Waals interaction and higher uptake for acetylene. These findings demonstrate the multifunctional potential of this copper MOF in environmental remediation, separation technologies, and sensor development.

The hybrid adsorption cooling desalination system presents a dual solution, offering reliable water production and cooling effects, and reducing electricity consumption and greenhouse gas emissions. This study introduces a novel utilization of two promising adsorbent materials (Bentonite/CaCl₂ (Bent/CaCl₂) and Max/CaCl₂) in the adsorption cooling desalination system driven by low-temperature heat, such as solar energy (SE) or waste heat (WH). The proposed system expresses the potential of integrating two types of ejectors, a vapor-vapor ejector and a liquid-vapor ejector, to increase its performance and reduce the cost of freshwater production. This study presents comprehensive mathematical models to investigate the energetic performance and the economic feasibility of the proposed hybrid systems, operating under real meteorological conditions for three distinct locations: Arish (Egypt), Riyadh (Saudi Arabia), and Dubai (United Arab Emirates). Different configurations of the hybrid systems used in cooling and desalination modes (ADCS) were examined, with and without internal evaporator condenser heat recovery and ejectors integration. The numerical results showed that the adsorbent Max/CaCl₂ exhibits the best performance among the tested adsorbents in the cooling and desalination mode. Arish City achieved the highest daily freshwater production and cooling effect with 84.2 m³/ton and 801.3 W/kg in June using Max/CaCl₂, while Dubai exhibited the lowest SCP at 356.5 W/kg in December. Arish exhibited the highest daily freshwater production for evaporator condenser heat recovery mode with ejectors integration, reaching a promising value of 129.9 m³/ton in June. Among the tested adsorbents, the most cost-effective operation was observed in Arish in June, where Max/CaCl₂ achieved the lowest water production cost of $0.385/m³ utilizing a waste heat source. Overall, this study expresses the effectiveness and potential of integrating an adsorption system with ejectors and heat recovery in improving system performance and cost efficiency across different climatic conditions.

Understanding hydrogen adsorption mechanisms on nanostructured materials is essential for advancing safe and efficient hydrogen-based energy technologies. In this study, we performed a Density Functional Theory (DFT) investigation to evaluate the interaction of H₂ molecules with B₁₂N₁₂ nanocages decorated with Y, Zr, and Nb. The most stable configurations, Y@b64, Zr@r4e, and Nb@b66—adsorbed up to 5, 4, and 3 H₂ molecules, respectively. The first H₂ molecule was dissociatively adsorbed with strong interaction energies (− 1.71 to − 1.85 eV), while the remaining were molecularly adsorbed with average energies between − 0.29 and − 0.38 eV/H₂. Desorption temperature calculations (T_D = 370–490 K) indicated favorable retention at ambient conditions and potential for controlled release. Molecular dynamics (MD) simulations (500 ps) revealed partial desorption, with 3, 2, and 1 H₂ molecules retained in Y@b64, Zr@r4e, and Nb@b66, respectively. The corresponding gravimetric hydrogen content values were below the DOE. Nevertheless, the systems exhibit adsorption behavior comparable to Ti- and Nb-decorated fullerenes and graphene-based materials. These results highlight the potential of B₁₂N₁₂ nanocages as model platforms for selective H₂ interaction and pave the way for future structural optimizations aiming at practical solid-state hydrogen storage.