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Polyurethane rigid foam is a widely used insulation material, and the behavior characteristics and heat absorption performance of the blowing agent used in the foaming process are key factors that affect the molding performance of this material. In this work, the behavior characteristics and heat absorption of the polyurethane physical blowing agent in the foaming process were studied; this is something which has not been comprehensively studied before. This study investigated the behavior characteristics of polyurethane physical blowing agents in the same formulation system, including the efficiency, dissolution, and loss rates of the physical blowing agents during the polyurethane foaming process. The research findings indicate that both the physical blowing agent mass efficiency rate and mass dissolution rate are influenced by the vaporization and condensation process of physical blowing agent. For the same type of physical blowing agent, the amount of heat absorbed per unit mass decreases gradually as the quantity of physical blowing agent increases. The relationship between the two shows a pattern of initial rapid decrease followed by a slower decrease. Under the same physical blowing agent content, the higher the heat absorbed per unit mass of physical blowing agent, the lower the internal temperature of the foam when the foam stops expanding. The heat absorbed per unit mass of the physical blowing agents is a key factor affecting the internal temperature of the foam when it stops expanding. From the perspective of heat control of the polyurethane reaction system, the effects of physical blowing agents on the foam quality were ranked in order from good to poor as follows: HFC-245fa, HFC-365mfc, HFCO-1233zd(E), HFO-1336mzzZ, and HCFC-141b. [ABSTRACT FROM AUTHOR]

Adsorption is a potential technology that is expected to meet NOx ultra-low emission standards and achieve the recovery of NO2. In this study, the adsorption/desorption behavior of NOx with competitive gases (e.g., H2O(g) and CO2) was studied on MFI zeolites with different Si/Al ratios and under different relative humidity (0~90% RH). Sample characterization of self-synthesizing zeolites was conducted by means of X-ray diffraction, Ar adsorption-desorption, and field emission scanning electron microscopy. The results showed that low-silica HZSM-5(35) showed the highest NOx adsorption capacity of 297.8 μmol/g (RH = 0) and 35.4 μmol/g (RH = 90%) compared to that of other adsorbents, and the efficiency loss factor of NOx adsorption capacity at 90%RH ranged from 85.3% to 88.1%. A water-resistance strategy was proposed for NOx multicomponent competitive adsorption combined with dynamic breakthrough tests and static water vapor adsorption. The presence of 14% O2 and lower adsorption temperature (25 °C) favored NOx adsorption, while higher CO2 concentrations (~10.5%) had less effect. The roll-up factor (η) was positively correlated with lower Si/Al ratios and higher H2O(g) concentrations. Unlike Silicalite-1, HZSM-5(35) exhibited an acceptable industrial desorption temperature window of NO2 (255~265 °C). This paper aims to provide a theoretical guideline for the rational selection of NOx adsorbents for practical applications. [ABSTRACT FROM AUTHOR]

The effects of operating temperature on the performance of small scale oxygen concentrator were experimentally investigated using a rotary valve multi-column rapid cycle pressure swing adsorption (PSA) unit which produced a continuous stream of ≥ 90% O2 from compressed air. Simple cooling fans and air cylinder were used for controlling the temperature of compressed air. The change of column midpoint gas temperature inside adsorption column was relatively small and approximately 3–5 K with a low pressure ratio of ~ 250:101 kPa during each cycle. The oxygen recovery could be improved by increasing the operating temperature and the bed size factor (BSF) could be reduced by decreasing the operating temperature. However, the adverse thermal effects on oxygen recovery and BSF became more dominant at very low and high operating temperatures. A similar trend between unit power and BSF at different operating temperature was emerged. There was an appropriate temperature range for achieving favorable performance. [ABSTRACT FROM AUTHOR]

The rapid pressure swing adsorption (RPSA) technology has been widely used for applications including portable oxygen generators due to high O2 productivities and low bed size factors (BSF, total amount of adsorbent per ton of O2 produced per day, kg/TPDO2). The improvement of RPSA process has been a key issue for efficient O2 production in terms of its generally lower O2 recovery as compared to other processes. In this work, a dual-column RPSA oxygen production system with an intermittent purge step (intermittently switching between purge and interruption) was designed to investigate the effects of interruption frequency (the number of interruptions during a purge step) and times on the O2 recovery, purity, productivity and BSF. Experimental results show the improvement on O2 production performance using the intermittent purge step in comparison to conventional continuous purge step. Under the optimized interruption frequency of 2 and time of 0.3 s, the O2 recovery, purity and productivity were increased from 36 to 39.2%, 89.5 to 93%, and 6.24 to 6.49 mmol/kg/s, respectively, while the BSF was decreased from 57.94 to 55.75 kg/TPDO2. [ABSTRACT FROM AUTHOR]

[Display omitted] • Comparisons of NO x adsorption and desorption among series of zeolites are conducted. • Effects of zeolite structures, cations, SiO 2 /Al 2 O 3 ratios on NO x sorption are shown. • H-typed 10-membered-ring straight-channel zeolite is selected as preferred sorbent. • Importance of kinetics of NO oxidation-NO 2 physisorption process is revealed. • Accessibility of Brønsted acid sites that drives NO-NO 2 catalytic cycle is discussed. Adsorption is a promising technology for deep purification of nitrogen oxides (NO x) from flue gases and simultaneously recycling NO 2 as an economically valuable chemical. Zeolite as a robust NO x adsorbent provides the key step for success in practical applications, of which the screening remains challenging regarding the NO-NO 2 oxidation and adsorption combined process. In this work, experimental evaluations on practical NO x sorption performances on series of zeolites were conducted. Effects of the zeolite typological structure, compensating cation, and SiO 2 /Al 2 O 3 ratio on deep purification efficacy, water resistance, and regenerability at varying humidity were obtained, revealing the importance of kinetics of the NO oxidation and NO 2 physisorption consecutive process. The H-typed 10-membered-ring straight-channel zeolites (MFI and FER) were demonstrated to be the preferred NO x adsorbents qualified for industrial needs, as compared to other caged-channel, hybrid-channel, larger-sized straight-channel, or Na-typed counterparts. Deeper insights into the key role of Brønsted acid sites (BAS) in driving the NO-NO 2 catalytic cycle and promoting the adsorption competitiveness of NO x over water vapor were revealed based on in-situ diffuse reflectance Fourier transform infrared spectroscopy characterizations. The MFI zeolite with improved performance at the low-silica version could benefit from the efficient utilization of BAS within the highly accessible medium-sized straight channel, while the FAU zeolite (representative caged-channel zeolite) requiring appropriate SiO 2 /Al 2 O 3 ratio for optimal BAS utilization may suffer from the limited site accessibility. The findings clarify the relationships between NO x oxidative adsorption performances and zeolite properties, which provides a fundamental perspective and scientific screening strategy for NO x adsorbents. [ABSTRACT FROM AUTHOR]

Abstract Adsorption thermodynamics of N 2 and O 2 on two most commonly used zeolites (5A and Li-LSX) under plateau special conditions of wide ranges of temperature (238–298 K) and pressure (0–300 kPa) for pressure swing adsorption (PSA) oxygen production were studied based on molecular simulations and theoretical model fitting. Adsorption isotherms for each adsorbate-adsorbent pair at different temperatures were fitted by Langmuir, Freundlich and Sips models, obtaining equilibrium parameters including adsorption capacity, strength, heterogeneity and N 2 /O 2 selectivity. Thermodynamic parameters such as Gibb's free energy, enthalpy, and entropy changes were numerically derived, and isosteric adsorption heats and distributions of potential energy were simulated. The results suggest that the adsorption capacity and affinity follow the order of N 2 -Li-LSX > N 2 -5A > O 2 -5A > O 2 -Li-LSX, leading to higher N 2 /O 2 selectivity on Li-LSX compared to 5A. For Li-LSX, N 2 /O 2 selectivity increases significantly with temperature above 273 K due to the difference in adsorption thermodynamics of N 2 and O 2 varying with temperature in terms of different adsorption heterogeneities. For 5A, the homogeneous distributions of N 2 and O 2 as well as the wide scopes of affinities from Na+ and Ca2+ exhibit N 2 /O 2 selectivity with negligible temperature dependence, which is beneficial for stable oxygen production with a fixed PSA process under large day-and-night temperature difference. This study provides theoretical basis for obtaining an optimal balance between efficiency and stability of oxygen production by using a proper mixture of Li-LSX and 5A. Highlights • Adsorption equilibrium of N 2 and O 2 on zeolites at plateau conditions are obtained. • N 2 /O 2 selectivity is higher with greater temperature dependence on Li-LSX than on 5A. • Adsorption capacity and affinity follow the order of N 2 -Li-LSX > N 2 -5A > O 2 -5A > O 2 -Li-LSX. • Advantage of thermodynamic stability of 5A over wide temperature range is discussed. [ABSTRACT FROM AUTHOR]

Modelling dynamic adsorption of sulfur dioxide (SO 2 ) on activated carbons (ACs) is significant in guiding practical desulphurization processes and making highly efficient use of adsorbents in terms of the adsorption rate which largely depends on particle size. In this work, models derived from the Vermeulen and an improved linear driving force (LDF) rate equation were studied for the first time on SO 2 adsorption over AC particles with different sizes. For larger particles (≥3 mm), breakthrough curves predicted by the Vermeulen equation showed good agreement with experimental data, demonstrating that intraparticle diffusion resistance varied with particle size, feed concentration, adsorption time and location. For smaller particles (1 mm), a correction on the volume-averaged adsorption capacity as a function of adsorption time and saturation in the rate equation was developed to avoid the underestimation of adsorption rate due to the inappropriate parabolic concentration profile inherent in the conventional LDF model. By providing a concentration gradient and adsorption rate closer to actual values, the improved LDF equation was confirmed to provide excellent prediction results on 1-mm particles. Different modelling characteristics of the two models indicates varying effects of intraparticle diffusion on adsorption rate with particle size regarding the specificity of SO 2 physisorption on ACs. [ABSTRACT FROM AUTHOR]

Adsorption is a promising technology for simultaneously capturing nitrogen oxides (NO x) from flue gases and recycling NO 2 as a profitable chemical, for which a robust and efficient adsorbent provides the key step for success in practical applications. This work reports the enhancement of NO x adsorption performances with less cost of desorption energy on Cu-ZSM-5 zeolites prepared by a facile and rapid (690 s) modification method, the incipient-wetness impregnation coupled with microwave drying (IM). In comparisons to H-ZSM-5, Na-ZSM-5 and conventionally liquid-phase ion-exchanged counterparts under sub-1000 ppm NO x feed concentrations and room temperature, the IM sample renders a record NO x adsorption capacity (q t,NOx) of 0.878 mmol/g from dry gas stream on zeolites, and an applicable q t,NOx of 0.1 mmol/g from wet gas stream with a proper copper loading (2.1 wt%). The temperature programmed desorption of NO x on the optimal IM sample saturated with NO x from wet gas stream exhibit primary peak temperature lower than reported Cu-ZSM-5 and significant NO 2 proportion (72.6 %) in desorbed NO x. Deeper insights into advantageous NO x oxidative adsorption over the properly-loaded Cu-ZSM-5 in terms of diverse adsorbate states and competitiveness towards H 2 O were gained, showing IM method a promising sorbent improvement strategy for practical use. [Display omitted] • Cu-ZSM-5 is prepared by incipient-wetness impregnation coupled with microwave drying. • A record NO x adsorption capacity at sub-1000 ppm dry gas feed on zeolites is obtained. • Applicable NO x adsorption capacity at wet feed is gained on properly-loaded Cu-ZSM-5. • Lower NO x desorption temperature and higher NO 2 proportion in desorbed gas are shown. • Advantageous NO x oxidative adsorption competing with H 2 O on Cu-ZSM-5 is revealed. [ABSTRACT FROM AUTHOR]

Performances of mesoporous materials in removal of polycyclic aromatic hydrocarbons (PAHs) from hot gases were evaluated systematically. The adsorption and desorption natures for PAHs with different aromatic rings, naphthalene (Nap), phenanthrene (Phe) and pyrene (Pyr) on mesosilicas MCM-41 and SBA-15, and mesocarbon CMK-3, were studied. Adsorption equilibria were well described by Langmuir or Freundlich model, giving the order of adsorption capacity of CMK-3 > SBA-15 > MCM-41 and Pry > Phe > Nap. Temperature programmed desorption exhibited the order of ease of desorption of SBA-15 > MCM-41 > CMK-3, along with desorption kinetic triplet determined by combined model fitting analysis. The Johnson-Mehl-Avrami (JMA) rate equation was found to well describe PAH desorption kinetics, except for Phe/SBA-15 and Pyr/CMK-3 due to potential blockage and strong binding, respectively. MCM-41 with simple 1-D mesoporous structure provided smooth diffusion and consistent behavior but very low adsorption capacity for each PAH. SBA-15 with micropores/small mesopores as interconnectivity between primary mesopores not only showed high sorption capacities but also diffusion advantages in desorption. CMK-3 with great microporosity facilitated the adsorption at low concentrations due to micropore-filling, and with surface hydrophobicity rendered high affinities especially for the bulkier Pyr. [ABSTRACT FROM AUTHOR]

Adsorptive removal of the predominant polycyclic aromatic hydrocarbons (PAHs), represented by phenanthrene, from hot gases using mesoporous adsorbents (mesosilicas MCM-41 and SBA-15, and mesocarbon CMK-3) has been studied through tests of column adsorption and temperature programmed desorption (TPD). Adsorption equilibria on MCM-41 and CMK-3, and on SBA-15 were well described by Langmuir and Freundlich models, respectively, showing the order of adsorption capacity of CMK-3 > SBA-15 > MCM-41 originated from different geometrical structures and texture properties. Adsorption dynamics based on breakthrough fitting by the constant-pattern wave propagation model showed that mesoporosity contributed to fast overall adsorption kinetics by reducing the internal resistance as being the predominant mass-transfer step, particularly on SBA-15 with a 2-D cross-linked structure. The TPD tests revealed the order of ease of desorption of SBA-15 ≈ MCM-41 > CMK-3, where the structural advantage on SBA-15 dominated the strong site binding as indicated by the intrinsic activation energy and exponential factor obtained by TPD models. Results from different TPD models showed that re-adsorption effect during desorption increased with decreasing dimension of adsorbent structure and that the utilization of the simplified linear TPD model could be violated by the strong sorbate-sorbent binding. Comparisons with traditional adsorbents and with the removal of naphthalene by these mesoporous adsorbents were made, showing higher applicability of CMK-3 for phenanthrene regarding stronger adsorption affinity and capacity as well as decreased disadvantages in regenerability relative to mesosilicas. [ABSTRACT FROM AUTHOR]

A novel rapid vacuum pressure swing adsorption process with intermediate gas pressurization for producing oxygen is proposed to improve the performance of miniature oxygen concentrator based rapid pressure swing adsorption technology. The effects of intermediate gas pressurization and desorption pressure on the performance of the process are evaluated by experiments and simulations. Results showed that pressurization with intermediate gas from product end can effectively improve the oxygen purity of the product. The pressure and oxygen purity of intermediate gas before pressurization were key parameters that affected the oxygen purity of the product. When the adsorption pressure was 240 kPa and the desorption pressure was 60 kPa, the test unit for the process produced 0.75 L min of ~90% O with 29.45% of oxygen recovery from compressed air. The minimum bed size factor (BSF) for ~90% O product was 82.84 kg TPD. The BSF could be effectively reduced by lowering the desorption pressure. Moreover, oxygen recovery could be improved by lowering the desorption pressure. [ABSTRACT FROM AUTHOR]

Adsorption is a promising technology for capturing nitrogen oxides (NO x) from humid flue gases, for which as the preferred NO x adsorbent, zeolite with an appropriate silica to alumina (Si/Al) ratio provides the key step for success in practical applications. In this work, the effects of Si/Al ratio, temperature, relative humidity (RH), and feed gas (NO x -H 2 O(g)–CO 2 –O 2 -N 2) compositions on NO x sorption behavior on HZSM-5 zeolites were systematically investigated, based on a series of characterizations, fixed-bed adsorption and temperature programmed desorption (TPD) tests. The low-silica HZSM-5(25) showed the best performance (326.6 μmol/g and 39.2 μmol/g at dry and 90%RH) as compared to others with higher Si/Al ratios at each RH, in which the roll-up effect was positively correlated with the Si/Al ratios and humidity. O 2 enhanced NO x adsorption and reached an optimal adsorption capacity at the concentration of 14%, while CO 2 had little effect on NO x adsorption. The decrease in temperature increased NO x adsorption capacity on HZSM-5(25), benefitting from NO 2 physisorption as well as satisfactory NO oxidation within the active adsorbent structure. The facile thermal desorption of NO x and significant NO–NO 2 conversion on HZSM-5(25) was exhibited by bimodal TPD peaks at 343–353K and 533–543K respective for NO and NO 2 , in contrast to those on Silicalite-1. A potential "water-resistant" strategy via the enhancement of NO x adsorption competitiveness was revealed, providing a theoretical guideline for NO x adsorbent screening in industrial applications. [Display omitted] • Influential rules of multiple factors on NO x adsorption are systematically explored. • Low-silica HZSM-5 shows the best NO x adsorption performance at each condition. • Contributions of NO oxidation and NO 2 physisorption at varying temperatures are shown. • Greater regenerability of NO x from NO x -H 2 O(g)–CO 2 –O 2 -N 2 feed on HZSM-5 is demonstrated. • A "water-resistant" strategy for enhancing NO x adsorption competitiveness is proposed. [ABSTRACT FROM AUTHOR]

Huge numbers of residential energy prosumers (EPs) will be widely deployed in the next generation power system which is dominated by renewable energies. The intermittent and non-dispatchable natures of the renewable energies will inevitably bring sporadic and unpredictable disturbances to the power system, making "grid friendliness" an essential requirement for the EPs. To tackle this problem, this paper focuses on the hardware implementation of the energy router (ER) and corresponsive coordinated energy management strategy for grid friendly EPs. The coordinated energy management strategy, combined with a fuzzy logic controller (FLC) for energy storage (ES) unit control and an improved discrete binary particle swarm optimization (DBPSO) algorithm for load scheduling, is elaborated for embedded control of the ER by maintaining balance of the accuracy, efficiency and cost considerations. Built as the energy interface between the EP and the power system, the ER is facilitated with plug-and-play source/load/ES connections, intelligent monitor and control interfaces as well as a load switching module, enabling the functionalities of the coordinated energy management strategy to be implemented. Experimental verification shows that, the developed ER enhances the energy management flexibilities for the EP, and the presented FLC + DBPSO algorithm enables coordinated operation of the EP and potential benefits in renewable DG utilization by improving the performances of PV self-use ratio, load rate and energy cost of the EP system by about 20 %, 50 % and 20 %, respectively, while at the same time maintaining the EP system reliability and consumer comfort, as well as meeting the grid friendly requirements. [ABSTRACT FROM AUTHOR]

Flow maldistribution and local high velocity in an axial adsorber is numerically studied to investigate the potential occurrence of sorbent pulverization and uneven utility. A considerable maldistribution induced by the entrance effect and local high velocity caused by rapid gas discharge during depressurization is observed. Three types of gas distributors and different depressurization strategies are then proposed and studied to determine their capabilities to create uniform velocity profiles. Results show that locating the predistributor in the dead zone is critical to flow distribution. The maldistribution factor ( Mf) can decrease to a minimum of 0.055 when a perforated inlet plenum is used with a conventional distributor. In addition, the internal ring can effectively reduce wall effects. Moreover, both gas expansion and desorption have a significant influence on the evolution of local velocity during depressurization. In this step, local high velocity can possibly exceed incipient fluidization velocity and cause attrition and pulverization of the sorbent. To a certain extent, employing methods to control the depressurization rate is necessary. Applying linear depressurization ( $$p = 101,325 - p_{AD} /t_{DP} \times t + p_{AD}$$ ) or downward convex conic depressurization ( $$p = p_{AD} - \sqrt {\left( {p_{AD} - 101,325} \right)^{2} /t_{DP} \times t}$$ ) can reduce local high velocity, and thus, improve flow conditions. [ABSTRACT FROM AUTHOR]

Pressure swing adsorption (PSA) is a suitable method to enrich the concentration of methane in coal mine methane (CMM) separation processes. However, traditional PSA processes for low-concentration CMM can easily increase the concentration of methane to explosive limits, which subsequently increases the risk of explosion. In this paper, a novel PSA process for low-concentration CMM was studied. Using a mixture of activated carbon (AC) and carbon molecular sieve (CMS) as the adsorbent, this method ensures that the gaseous mixture adsorbed does not reach the explosive limits by adsorbing methane and part of the oxygen simultaneously. Using a two-bed vacuum PSA experimental apparatus, the low-concentration CMM was safely enriched from 20% to more than 30%, with CMS and AC mass ratio of 3.4. The results of experimental studies indicate that the mixture adsorbent (AC and CMS) has explosion-suppression and flameproof characteristics. The igniting resource (methane) will not explode even if it appears in the adsorbent layer and, in addition, the explosion will not propagate through the adsorbent layer if it happens in other areas. [ABSTRACT FROM AUTHOR]

• A visualization experimental system for NO 2 gas condensation is designed. • Fog, droplet-streamlet-film (DSF), and freezing condensation modes are revealed. • Formations of DSF mode divided into 4 periods at varying conditions are quantified. • Relationship between mode evolution and heat transfer performance is demonstrated. • Insight into evolution of each mode regarding NO 2 -N 2 O 4 dimerization effect is gained. Pure nitrogen dioxide (NO 2) is a profitable feedstock for production of various chemicals. The condensation technology plays an essential role in NO 2 enrichment during production or resource recovery from industrial exhausts, which, however, remains challenging in process optimization due to the lack of thorough comprehension on NO 2 condensation behavior. In this work, the visualization experiments of NO 2 condensation on the vertical SS316 surface at varying temperatures, NO 2 mole fractions and volume flow rates in the absence and presence of non-condensable gas (NCG) were conducted. Three major NO 2 condensation modes, the fog mode, the droplet-streamlet-film (DSF) coexistence mode, and the freezing mode, have been identified. The formation process of NO 2 gas-fog-droplet-DSF mode as well as the occurrence frequency of streamlets (OFS) was quantified under different conditions. The higher OFS was found to contribute to greater overall heat transfer coefficient and condensate amount, showing the optimal parameters at each condition. Deeper insights into gas-fog, gas-liquid, and gas-ice phase transformations for NO 2 were gained, revealing the unique effects of dimerization of NO 2 to N 2 O 4 on condensation. The dimerization triggers the facile formation (< 10 s) of N 2 O 4 fog with increased intermolecular forces, the heterogeneity of heat and mass transfer in DSF mode with complex heat resistance network and condensate states, and the melting-thickening cycle of ice layer in the freezing process along with the release of dimerization reaction heat. The findings render a microscopic view of favorable heat and mass transfer towards optimal NO 2 condensation strategies in practical uses. [Display omitted]. [ABSTRACT FROM AUTHOR]

This work developed a novel method for measuring the effective rate of a PBA (physical blowing agent) and solved the problem that the effective rate of a PBA could not be directly measured or calculated in previous studies. The results show that the effectiveness of different PBAs under the same experimental conditions varied widely, from approximately 50% to almost 90%. In this study, the overall average effective rates of the PBAs HFC-245fa, HFO-1336mzzZ, HFC-365mfc, HFCO-1233zd(E), and HCFC-141b are in descending order. In all experimental groups, the relationship between the effective rate of the PBA, r e P B A , and the initial mass ratio of the PBA to other blending materials in the polyurethane rigid foam, w , demonstrated a trend of first decreasing and then gradually stabilizing or slightly increasing. This trend is caused by the interaction of PBA molecules among themselves and with other component molecules in the foamed material and the temperature of the foaming system. In general, the influence of system temperature dominated when w was less than 9.05 wt%, and the interaction of PBA molecules among themselves and with other component molecules in the foamed material dominated when w was greater than 9.05 wt%. The effective rate of the PBA is also related to the states of gasification and condensation when they reach equilibrium. The properties of the PBA itself determine the overall efficiency, while the balance between the gasification and condensation processes of the PBA further leads to a regular change in efficiency with respect to w around the overall average level. [ABSTRACT FROM AUTHOR]

[Display omitted] • Flexible improvement on PSA O 2 production at wide product flow rate range is studied. • Individual effects of process parameters on O 2 production performance are obtained. • Adjusted/unadjusted PSA experiments using appropriate valve settings are conducted. • Process improvement strategies for different product flow rate ranges are proposed. • Higher O 2 purity, recovery and productivity with lower energy consumption are gained. Improvement on oxygen (O 2) concentrator using pressure swing adsorption (PSA) technology according to variable product demands is of great significance, which, for instance, provides the key step for success in practical O 2 therapy for COVID-19 patients who need to be delivered with a wide product flow rate range (1–15 standard liter per minute (SLPM)) of medical O 2 (purity > 82%). This work studied the individual effects of major PSA process parameters on O 2 production performance at the product flow rate of 3.46–19.88 SLPM (0.64–3.68 SLPM per kilogram of adsorbent (SLPM/kg)), based on a self-designed two-bed PSA unit with a modified Skarstom cycle using Li-LSX zeolite adsorbents. The improvement strategies were accordingly proposed based upon influential mechanisms of each parameter: 1) at lower product flow rates (≤2.00 SLPM/kg), increasing the purge flow rate and decreasing the adsorption pressure to suppress excess O 2 adsorption, and decreasing the feed flow rate to ensure low energy consumption; 2) at higher product flow rates (≥2.00 SLPM/kg), decreasing the purge flow rate and increasing the adsorption pressure to eliminate N 2 breakthrough and O 2 -rich product waste, and appropriately increasing the feed flow rate to enhance cost-effectiveness. An improved set of parameters rendered O 2 purity (95.67–74.86%), recovery (11.28–49.05%), productivity (0.47–2.04 mmol/kg/s) increased by up to 3.52–20.08%, 0.36–20.47%, 6.82–19.61%, and energy consumption (4.07–0.95 kWh/kgO 2) decreased by up to 10.56–18.10%, in comparison to two conventional sets, respectively. The results are beneficial for developing intellectualized and flexibly-controlled O 2 concentrators for practical applications. [ABSTRACT FROM AUTHOR]

A small scale (~270 Nm3·h−1) vacuum pressure swing adsorption (VPSA) air separation system was established in Qinghai Province (in China) with an altitude of 3800 m, which was used to supply oxygen for relieving the hypoxia. The effects of adsorption and desorption time, purge and pressure equalization step and feed temperature on the performance of the process were investigated by performing experiments under plateau special conditions. Results showed that pressure equalization and intermittent purge steps could effectively improve the performance of the VPSA process. The system could produce 270 Nm3·h−1 of 90% O2 with 62.6% oxygen recovery from compressed air. The maximum productivity and minimum energy consumption with pressure ratio of 160:42 for ~90% O2 were 121.7 L·h−1·kg−1 and 0.55 kWh·Nm−3, respectively. [ABSTRACT FROM AUTHOR]

A novel adsorbent of CO2 from biogas was prepared by synthesizing and modifying the mesoporous molecular silica of SBA-15 with methyl-diethyl-amine (MDEA) and piperazine (PZ). The adsorbent showed good performance in separating CO2 from biogas. The loaded amines did not change the ordered structure of SBA-15, but enhanced its adsorption of CO2. The adsorbents were characterized by X-ray powder diffraction (XRD) and N2 adsorption/desorption. With the increase in MDEA loading, the surface area, pore size, and pore volume of the MDEA-loaded SBA-15 decreased. The modification of amines enlarged the difference between the equilibrium adsorption of CO2 and CH4. Quantitatively evaluated on the basis of the breakthrough curves, the separation factors between CO2 and CH4, was increased more than seven fold due to the MDEA modification. With mixed-amine (MDEA + PZ) modification, the separation factors between CO2 and CH4 was further improved. In addition, not only the adsorbent was regenerable by purging with the purified gas, but also the adsorption performance is stable in adsorption cycles. Effect of moisture on adsorption of CO2 is investigated and the results show the increase in the adsorption performance. [ABSTRACT FROM AUTHOR]

Capturing and recovering naphthalene as a profitable chemical from hot flue gas are of significance in terms of environmental protection with economic benefits, for which the adsorption technology using high-performance sorbents provides the key step for success in practical applications. Carbonaceous materials with hydrophobic natures have been shown to render high affinities with non-polar naphthalene, but remain challenging due to difficulties in tackling the trade-off between adsorption and desorption. This work reports a systematic investigation with deeper insights into adsorption equilibria, kinetics and regenerabilities of gaseous naphthalene on typical carbonaceous sorbents originated from different texture properties, including ordered mesoporous carbons (CMK-3, CMK-5 and FDU-15), carbon nanotubes (SWCNT and MWCNT) and a coconut-shell-based activated carbon (AC). The adsorption isotherm and breakthrough curves at wide feed concentration ranges and temperature programmed desorption curves for each sorbent were obtained along with series of theoretical model fitting. FDU-15 and CMK-5 were demonstrated as superior sorbents with high maximum adsorption capacities (1.13 and 1.735 mmol/g) and low desorption activation energy (62.66 and 72.68 kJ/mol), respectively exhibiting advantages of the 3-dimensional diffusion-controlled desorption upon a hexagonal pore arrangement and the efficient adsorption upon a reasonable mesopore-micropore hierarchical structure, in contrast to poor kinetics on pure microporosity (AC) and 1-dimensional topologies (CNTs). Deeper insights into the morphology-affinity relationship revealed advantageous naphthalene transport behaviors over 3-dimensional ordered mesoporosities with appropriate coexisting microporosities and narrower primary size (2–5 nm) or diverse forms of mesopore, which contribute toward reaching comprehensive balances of sorption performances. [Display omitted] • Adsorption equilibria of gaseous naphthalene on carbonaceous sorbents are obtained. • Regenerability with desorption kinetic triplet for each sorbent is quantified. • Ordered mesoporous carbons, FDU-15 and CMK-5, are demonstrated as superior sorbents. • 3-dimensional ordered mesoporosities with narrower primary size (2–5 nm) are favored. • Micropore-mesopore hierarchical structure gives high adsorption/desorption kinetics. [ABSTRACT FROM AUTHOR]

[Display omitted] • Distillation separation process is proposed to recover NO 2 and SO 2 from flue gases. • The feasibility of NO 2 /SO 2 distillation separation is theoretically verified. • A distillation process with advantageous dual-column liquid-phase feeding is designed. • Process optimization based on robust sensitivity analysis are demonstrated. • Significant economic benefits from the recovered NO 2 and SO 2 products are estimated. High-purity NO 2 and SO 2 have significant economic values and are widely used in many fields. The large amounts of NO 2 and SO 2 in industrial flue gases are worthy of recovery for environmental protection and economic benefits. In this work, a dual-column distillation separation process was proposed to further separate and upgrade NO 2 and SO 2 following a flue gas adsorption capture process. The feasibility of distillation separation of NO 2 /SO 2 from the desorbed gas, and the advantage of liquid-phase feeding way over gas-phase counterpart in terms of lower energy consumption (1286.39 kW) were demonstrated. Key process parameters such as the number of total stages, the feed stage number, the mole flow rate at bottom of column, the reflux ratio and operating pressure for the two columns (15, 6, 16.66 kmol/h, 0.16, 4 bar; 21, 10, 4.43 kmol/h, 0.50, 1 bar) were determined. Heat and mass transfers along the column height as well as the process robustness against feed composition fluctuation indicate its applicability for practical operation and adaptation to industrial needs. An economic analysis shows a significant annual revenue of 14,333.52 thousand USD based on high-purity (>99.5%) SO 2 and NO 2 products recovered from a typical scale (~1000,000 m3/h) of iron-ore sintering flue gas, not only offsetting the total operating cost of the entire adsorption capture-distillation recovery process but also generating net profit. [ABSTRACT FROM AUTHOR]

Conventional flue gas nitrogen oxides (NO x) abatement technologies commonly convert NO x into harmless compounds, while less effort has been made to recycle NO 2 as a profitable chemical in many industries. Towards this end, adsorption is a promising technology for which an advanced technique for NO 2 desorption and efficient sorbent regeneration provides the key step for success in practical applications. This work reports a novel cyclic adsorption process for NO x removal with recycling of NO 2 from iron-ore sintering flue gas of a steel plant. This process using self-prepared and validated pelletized Na-ZSM-5 zeolites as low-cost sorbents involves NO x catalytic adsorption and reversible desorption using multiple hot gas circulations (GC) within the enclosed fixed bed followed by scavenging and purge at mild conditions. In comparison to conventional cyclic processes, greater amount of recyclable NO 2 was obtained, rendering the NO x recovery of >92% and the mean NO 2 concentration of >2% significantly enriched from original 20 ppm in feed gas. A robust adsorption-desorption performance with appreciable NO x working capacity was achieved for up to 16 cycles. The key role of the segmentation of GC in boosting NO x regenerability was addressed, providing an economical three-tower strategy for continuous NO 2 production for practical use. ga1 • NO x removal and with recycling of NO 2 from flue gas was studied through field tests. • Comparisons among different adsorption cycles in NO x removal and recycling were made. • A novel technique for efficient NO 2 desorption and sorbent regeneration was proposed. • NO x recovery of 92% and recyclable desorbed NO 2 concentration of >2% were obtained. • Robust cyclic performance with NO x working capacity of >0.1 mmol/g was demonstrated. [ABSTRACT FROM AUTHOR]

• Binary adsorption of N 2 and O 2 on FAU zeolites at plateau conditions is obtained. • Water interacting with zeolites via hydrogen bond competes with N 2 and O 2 adsorption. • Effect of water content is greater than that of temperature change on air separation. • Trade-off between N 2 /O 2 selectivity and performance stability is addressed. • X zeolite with Si/Al close to 1.5 is recommended for PSA O 2 production in plateau. Adsorption thermodynamics of N 2 and O 2 on faujasite (FAU) zeolites with different Si/Al molar ratios under plateau conditions of wide ranges of temperature and humidity for pressure swing adsorption (PSA) oxygen production were studied based on validated molecular simulations. Binary adsorption isotherms and N 2 /O 2 selectivity on each adsorbent were obtained. The results suggest that dehydrated feed air with very low dew point of 213 K could still lead to ~10 wt% water adsorption capacity in FAU zeolites. The effect of water content was larger than that of temperature change on N 2 /O 2 separation performance, causing reductions in N 2 /O 2 selectivity of 50.9% and affinities of 15.6% and 10.6% for N 2 and O 2 at 238 K, and those of 45.7%, 13.7% and 11.1% at 298 K on FAU-1.1, respectively. The strong interaction of water with zeolites via hydrogen bond was shown to decrease the pore volume by 25.61%, occupy the cationic sites, and thermodynamically form competitive adsorption over N 2 and O 2. The increase in Si/Al molar ratio suppressed the negative impact of water and temperature change but sacrificed the N 2 /O 2 selectivity. To reach an optimal balance between the air separation performance and the adsorbent robustness, X zeolites with Si/Al molar ratio close to 1.5 would be recommended for PSA O 2 production under the plateau special condition. [ABSTRACT FROM AUTHOR]

Recovery and treatment of methane from coal mine ventilation air methane (VAM) with cost-effective technologies have been an ongoing challenge due to low methane concentrations. In this study, a type of coconut shell-based active carbon was employed to enrich VAM with a three-bed vacuum pressure swing adsorption unit. A new vacuum exhaust step for the VPSA process was introduced. The results show that the vacuum exhaust step can increase the methane concentration of the product without changing adsorption and desorption pressure. Under laboratory conditions, the concentration of product increased from 0.4% to 0.69% as the vacuum exhaust ratio increased from 0 to 3.1 when the feed gas concentration was 0.2%. A 500 m³/h pilot-scale test system for VAM enrichment was built rendering good correlation with the laboratory results in terms of the vacuum exhaust step. By using a two-stage three-bed separation unit, the VAM was enriched from 0.2% to over 1.2%. [ABSTRACT FROM AUTHOR]

The kinetics of the thermal desorption of CO2 adsorbed on zeolite 13X were obtained using a differential thermogravimetric analyser under two different carrier gas conditions. The varying heating rates were set as 8, 12, 16, and 20 K min−1, respectively. The desorption activation energy of the physisorption sites for this experiment evaluated by an integral method without prediction of the reaction order ranged from 12.15 to 14.12 kJ mol−1 (CO2 as the carrier gas) and 43.32 to 50.42 kJ mol−1 (Ar as the carrier gas), respectively. The desorption activation energy of the chemisorption sites ranged from 57.95 to 58.53 kJ mol−1 (CO2 as the carrier gas) and 74.02 to 79.92 kJ mol−1 (Ar as the carrier gas), respectively. [ABSTRACT FROM AUTHOR]

Li-LSX (low silica type-X) zeolite is the sorbent of choice for air separation by adsorption today. Li-LSX is obtained by ion exchange of Na-LSX. The occupancy of Site III (SIII, which is the open site in the supercage) by Li + is crucially important for N 2 adsorption. In this work, mixed-cation LiNa-LSX zeolites were prepared and N 2 adsorption isotherms were measured. The isosteric heats of adsorption of N 2 were obtained from the temperature dependence. The heats of adsorption remained at approximately 17.7 kJ/mol (i.e., that for pure Na-LSX) at Li + exchange below approximately 70%, and increased upon further increase in Li + exchange, to 22.6 kJ/mol (i.e., that for pure Li-LSX). The increase was not linear (i.e., concave shaped), however, which indicated that one N 2 molecule could likely adsorb on two adjacent cation sites. The relationship between heat of adsorption and Li ion occupancy on site SIII was obtained. It is suggested that this relationship may be used to estimate the occupancy by Li + on SIII of faujasite type of zeolites. [ABSTRACT FROM AUTHOR]

High-volume production of oxygen and nitrogen from atmospheric air is accomplished by cryogenic distillation. Prior to feeding to the air separation unit, the ambient air must be pre-purified by the removal of trace impurities such as CO 2, H 2 O vapor, and light hydrocarbons (e.g., CH 4 ) to their tolerable limits of 1.0 ppm, 0.1 ppm, and to a few ppb, respectively. In this study, the adsorption characteristics of a synthetic zeolite, Li-LSX (where LSX denotes low-silica type-X zeolite where Si/Al=1), for the removal of trace amounts of CO 2 , CH 4 , and H 2 O vapor impurities were analyzed and compared with the conventional synthetic 13X zeolite that has been used for air prepurification as well as the ion-exchanged K-LSX and Ca-LSX zeolites. Isotherms to very low partial pressures (to a few ppm of 1 atm) were measured. The Tὸth, Langmuir–Freundlich (L–F), and the Dubinin–Astakhov (D–A) isotherm models were used to correlate the low pressure experimental data and the Tὸth model was found to be the better fit especially in the low pressure range. The superior adsorption properties of Li-LSX for air prepurification are demonstrated in this work. [ABSTRACT FROM AUTHOR]

• The properties of ECSCs are controllable by adjusting the fuel in SCS process. • The superb S bet , V P, and V meso of ECSCs are beneficial to improve the naphthalene adsorption capacity. • ECSCs exhibit unprecedented high capacity, fast kinetics, and low desorption energy. Sorptive capture and recycling of gaseous naphthalene from industrial emissions are of both environmental significance and economic benefit. Constructing carbonaceous sorbents with matchable pore size and adequate active sites is significant towards the trade-off between adsorption and desorption for naphthalene. In this study, we developed a series of porous carbonaceous sorbents (ECSCs) using facile, inexpensive, and effective solution combustion synthesis (SCS) with subsequent calcination and pickling. The MgO@C precursors were fabricated via a fast and self-exothermic combustion reaction, and after calcination and MgO removal by pickling, the tailored pore structure was created. The morphology, porous structure, and surface chemical properties of ECSCs are precisely controlled by adjusting the type and content of fuel in combustion. For the optimized ECSC-G14 prepared on fuel-balanced condition, its layer-by-layer network facilitates adsorption mass transfer, and its high specific surface area (1987 m2·g−1) and abundant 3–6 nm mesoporosity promotes the accessibility of active sites. Consequently, an unprecedented high naphthalene uptake (3.075 mmol·g−1 at 398 K) and fast kinetics (∼1.43 × 10−2 s−1 at 2.82 × 10−3 mol·m−3 feed concentration) were achieved. Combined characterization and molecular calculation revealed the synergistic contribution of O and N to reversible adsorption with superb regenerability (E a of 42.71 kJ·mol−1) and cyclic properties. This study provides an effective strategy and theoretical support to customize the properties of porous carbons, overcoming the adsorption–desorption dilemma for gas purification. [ABSTRACT FROM AUTHOR]

Background: Studies have demonstrated the relationship between the fatty liver index (FLI) and metabolism, while few research reported its relationship with hyperuricemia (HUA). This study aimed to predict HUA by determining the relationship between the baseline FLI and HUA events and by validating the FLI–HUA correlation through follow-up. Methods: This study was a community-based cohort study involving 8851 adults in China. We performed anthropometric assessments and analyzed baseline and follow-up blood samples. HUA was defined as a uric acid level of > 420 µmol/L (7 mg/dL). Results: Patients with HUA had a higher prevalence of diabetes mellitus, lipid metabolism disorders, and hypertension and higher FLI values than those with normal uric acid levels (P < 0.001). Serum uric acid was positively correlated with the FLI (r = 0.41, P < 0.001); the diagnostic cut-off value of FLI for the diagnosis of HUA was 27.15, with a specificity of 70.9% and sensitivity of 79.6%. FLI was an independent risk factor for HUA, with a 1.72-, 2.74-, and 4.80-fold increase in the risk of developing HUA with increasing FLI quartile levels compared with the FLI at quartile level 1 (P < 0.001). After a mean follow-up of 4 years, as the FLI values increased compared with the FLI at quartile level 1, the risk of new-onset HUA increased by 3.10-, 4.89-, and 6.97-fold (P < 0.001). Conclusion: There is a higher incidence of metabolic abnormalities in HUA populations, and FLI is an independent factor that may contribute to HUA development. Therefore, FLI is a potential tool to predict the risk of developing HUA. [ABSTRACT FROM AUTHOR]

[Display omitted] • Development of oxygen generation from air over zeolite by PSA was reviewed in this work. • Mechanisms of O 2 separation from N 2 over zeolite by adsorption were discussed. • Requirements for zeolite adsorbents to improve the O 2 purity were analyzed. • Effect of impurities in air on the nitrogen–oxygen separation was concluded. The adsorptive generation of oxygen from air has become increasingly important in the chemical and medical industries due to the growing demand for O 2 with high purity. Among the commonly used three methods of cryogenic distillation, pressure swing adsorption (PSA) and membrane separation for N 2 /O 2 separation, PSA has received much attention due to the advantages of small volume, low management cost, and short start-up time, etc. Zeolites, with their unique pore structure, highly polarized pore environment, and abundant ion exchange sites, are widely employed as an efficient adsorbent in N 2 /O 2 separation. Hence, in this work, a review about the application of zeolites in O 2 generation via PSA was performed. In detail, the common PSA techniques applied for O 2 generation were summarized and compared from both the characteristics and application scenarios firstly. Then, the main mechanisms of O 2 separated from N 2 in air over zeolite by adsorption were summarized from three aspects of the steric effect, kinetic effect and equilibrium effect. Based on above, the requirements for silica-alumina zeolite adsorbents to improve the O 2 purity clarified from skeleton topology, extra-framework cations as well as physical & chemical properties. Moreover, the operation conditions and impurities having a significant effect on the product O 2 quality were discussed. Finally, both the challenges and prospects of air separation and O 2 generation are proposed based on existing research results. [ABSTRACT FROM AUTHOR]

An eruptive solution combustion synthesized carbonaceous sorbent (ECSC) with unprecedented naphthalene adsorption and desorption performances is generated by introducing rational mesoporosity and nitrogen groups into a layer-by-layer porous carbon network. The integration of all key elements via careful tuning of morphological, porous, and chemical properties during the synthesis of ECSC opens up vast possibilities to overcome the adsorption–desorption dilemma for low-volatile or large-molecular gases, which offers great opportunities for gas separation and purification applications. [Display omitted] • Carbon sorbent was derived with an facile eruptive solution combustion strategy. • Layer-by-layer network, rational mesoporosity, and reversible sites were integrated. • Unprecedented high adsorption capacity and kinetics for naphthalene were achieved. • Good regenerability with low naphthalene desorption activation energy was obtained. • Moderate sorption affinity of naphthalene-pyridinic N π–π bonding was proposed. Capturing naphthalene as a valuable chemical from waste gases via adsorption on porous sorbent materials is a promising approach to tackle such an environmental health issue with additional economic benefits. However, very few sorbents have simultaneously high adsorption capacity and good regenerability for the large-molecular and low-volatile naphthalene. Here we attempt to address this challenge by integrating key fabrication elements of a layer-by-layer network, rational mesoporosity, and highly reversible sites into a carbonaceous adsorbent (ECSC) using a facile and fast eruptive solution combustion synthesis method. Adsorption breakthrough and temperature-programmed desorption experiments show that the ECSC achieves all-round superior naphthalene capture performance with unprecedented high capacity, fast kinetics, and low desorption energy. The combination of in situ DRIFTS, XPS, and DFT calculations reveals the moderate adsorption affinity of mitigated π–π stacking bonding between tilted naphthalene molecule and surface pyridinic N. This work affords new insights for designing next-generation adsorbents for naphthalene removal and presents a way of overcoming the adsorption–desorption dilemma for gas purification. [ABSTRACT FROM AUTHOR]

Adsorption as an air purification method is widely employed to remove volatile organic compounds with low concentration using zeolites. In this study, ZSM-5 and LSX zeolites modified by alkali metal cations (Li+, Na+ and K+) were used as adsorbents for the abatement of toluene. The adsorption behaviors of toluene onto adsorbents with different pore sizes and cation contents were evaluated systematically based on the experiments of adsorption equilibrium, kinetic diffusion and desorption. Besides, Langmuir and Freundlich model, constant-pattern wave propagation model and Kissinger method were applied to fit with the above experimental data. The adsorption amount followed the sequence of Li-LSX > Na-LSX > K-LSX > Li-ZSM-5 > Na-ZSM-5 > K-ZSM-5 obtained from equilibrium isotherms. LSX zeolites showed twice adsorption capacity on unit volume compared to ZSM-5. The mechanisms of steric hindrances and electrostatic interactions controlling the diffusion rate under high and low concentrations were proposed, respectively. At relatively low loadings of toluene, the diffusion resistances were primarily affected by electrostatic interaction due to preferential adsorption of toluene on cationic sites. While at relatively high loadings, the diffusion resistance was mainly restricted by steric effect because of saturated cationic sites. The strength of adsorbate-adsorbent interactions was assessed by temperature programmed desorption experiments. It showed that both adsorption sites and microporous walls contributed to the desorption energy. [ABSTRACT FROM AUTHOR]

Highlights • Adsorption of CH 4 , N 2 and O 2 on carbon molecular sieves (CMSs) were studied. • CH 4 /N 2 /O 2 separation performances on CMSs were evaluated in equilibrium and kinetics. • A selectivity for practical selection of kinetic separation adsorbent was developed. • A proper existence of microporosity of CMS would benefit practical methane upgrading. Abstract Upgrading coal mine methane (CMM) with adsorption method is an effective way to enhance the energy utilizing efficiency and reduce greenhouse gas emissions. In this work, adsorption equilibrium and kinetics of CH 4 , N 2 and O 2 , as typical components in CMM, on three carbon molecular sieves (CMSs) and the corresponding separation performances were studied. The equilibrium and kinetic selectivity were obtained from adsorption isotherms fitted with the Langmuir model and uptake curves fitted with the micropore-diffusion model, respectively. O 2 with the highest diffusion time constant among three gases suggests the advantage of CMS-based kinetic separation in deoxygenation of CMM and the critical role that N 2 /CH 4 kinetic separation plays in CH 4 enrichment. CMS-1 with the highest microporosity has the largest adsorption capacities, and CMS-3 with a proper average pore size has the greatest N 2 /CH 4 kinetic selectivity. The actual separation performances shown by CH 4 /N 2 /O 2 breakthrough curves according to the principle for practical CMM upgrading processes exhibit the order of CMS-1 > CMS-3 > CMS-2 which is inconsistent with that of the conventional N 2 /CH 4 selectivity highly due to the underestimation of effects of N 2 equilibrium adsorption relative to N 2 kinetic selection without covering specific adsorption range corresponding to practical working capacity region. A modified selectivity with consideration of actual N 2 amount adsorbed was therefore developed, showing the correct performance order and the potential to be used as a practical adsorbent selection parameter. An advanced CMS materials design with proper existence of microporosity would benefit practical CMM upgrading in terms of reaching an optimal balance between adsorption equilibrium and kinetics. [ABSTRACT FROM AUTHOR]

Multiple myeloma (MM) patients are immunodeficient. Complement C1q is an important cofactor of both nonspecific and humoral immunity, and it participates in the immunomodulation of multiple tumors. Thus, this study aimed to determine the risk factors and clinical significance of C1q expression in MM patients. In total, 193 MM patients were examined. The mean value of C1q in the patient group (130.46 ± 36.17 mg/L), was lower than that in the control group (anemia and nonmalignant hematologic disease). C1q dynamically changed with different MM stages and was recovered to normal levels when the disease was in remission; however, it decreased again after disease progression. The risk factors of C1q reduction included Durie-Salmon stage and the immunoglobulin type of the disease. In conclusion, C1q appears to be a useful biomarker of tumor burden and a prognostic factor of disease relapse. C1q is a potential marker of the immunodeficiency status in MM patients. [ABSTRACT FROM AUTHOR]

Highlights • LSX containing minimum Li and Ag were prepared and evaluated for air separation. • ion exchange procedures were designed to miniemize Li+ on inaccessible sites. • The mixed-cation LSX were compared against pure Li-LSX for air separation by PSA. • The mixed cation zeolites show promising performance for replacing Li-LSX. Abstract Mixed-cation LiSr-LSX, AgCa-LSX and AgSr-LSX containing minimum lithium and silver were prepared by exchanging small fractions of Li+ into Sr-LSX and Ag+ into Sr-LSX and Ca-LSX. To avoid diffusion of the Li+ into the inaccessible sites, the LiSr-LSX sample was exposed to a specifically derived dehydration condition. Similarly, the mixed-silver cation samples were treated to the selected condition post-ion-exchange to allow the Ag+ to migrate into SII*. Strong evidences were provided that significant fractions of the exchanged Li+ and Ag+ remained in SIII and SII* respectively after comparisons of the N 2 /O 2 adsorption isotherms and isosteric heats of adsorption of the mixed-cation and single-cation samples. Furthermore, the mixed-cation LiSr-LSX, AgCa-LSX and AgSr-LSX samples were compared against the single-cation Li-LSX sample based on their O 2 productivity performance via a PSA simulation model. [ABSTRACT FROM AUTHOR]

Highlights • Sr-LSX zeolite shows comparable or higher N 2 adsorption capacity than Li-LSX depending on pretreatment. • Sr-LSX matches the O 2 productivity performance with Li-LSX from PSA simulation. • Sr-LSX zeolite is a promising replacement for Li-LSX. Abstract Due to the surging demand of lithium for lithium-ion batteries, the price of lithium has seen a steep rise and is projected to maintain the trend for the foreseeable future. With Li-LSX being the sorbent of choice in pressure swing adsorption systems for air separation, it is imperative to develop efficient adsorbents with significantly lower lithium content (mixed-cations zeolites) or completely replace it with abundant and low-cost alkali-earth metal cations such as Sr2+. This article presents promising results for pure Sr-LSX zeolite for O 2 productivity performance via PSA and the possibility of completely replacing Li-LSX with Sr-LSX. [ABSTRACT FROM AUTHOR]

Abstract The removal characteristics of sub-25 nm ultrafine particles (UFPs) by different porous nanomaterials with different morphologies were studied based on efficiency curves obtained with specially designed filtration system. The material morphological effects on UFPs collection were investigated. The results demonstrate a complex and synergic mechanism of material structural framework, pore size distribution, and porosity order in terms of diffusion and interception dependent on flow velocity. Both porosity and fiber-like tubular structures promoted the UFPs removal. Microporosity and disordered mesoporosity could enhance the roughness of the internal surface and intensify the interaction with UFPs. Specifically, the large and ordered mesoporosity was able to render selectivity for UFPs at certain sizes and exhibited the best particle collection performance which can be largely associated with significant pore size and volume. The dependence of the ratio of diffusion to interception on flow velocity and the comparison of different pores in terms of the matching sizes with particles derived from single sphere efficiency model fitting results were also discussed. This work is significant to deeper understanding of interactions between airborne nanoparticles and porous surfaces. Graphical abstract Unlabelled Image Highlights • UFPs removal by porous materials with different morphologies was explored. • Effects of structure, pore size and order on particle collection was studied. • Relationship between diffusional collection and mesoporsity was addressed in theory. [ABSTRACT FROM AUTHOR]

Airborne ultrafine nanoparticle (UFNP) is a key factor causing heavy haze pollution in Beijing-Tianjin-Hebei, which is very harmful to human health and the environment. Removal of environmental UFNPs by porous material is an important method of air purification treatment. However, the specific mechanism by which porous material filters UFNPs is not clear. In this study, UFNPs with 2–10 nm diameter were removed by SBA-15 mesoporous silica molecular sieves with different pore sizes, and the filtration mechanism was analyzed using transmission electron microscopy (TEM), specific surface area tests (BET), and X-ray photoelectron spectroscopy (XPS). The analyses showed a distinctive filtration of UFNPs over the interior mesopore channels. The removal efficiencies of SBA-15 with different pore sizes were also compared, demonstrating the influence of the pore size and structure on most penetrating particle size (MPPS). The UFNP filtration efficiency of SBA-15 increased with the increase of pore size. Moreover, SBA-15-14.6 could effectively purify UFNPs, and it had the highest fractional diffusive filtration efficiency of 98.79% and a total efficiency of 92.58% for UFNPs. This study provides a technical basis for the filtration of UFNPs using mesoporous materials. [ABSTRACT FROM AUTHOR]

In this study we report on a vacuum swing adsorption process and adsorbent which allows simultaneous production of high purity methane and high purity carbon dioxide from a biogas feedstock. This is a departure from conventional biogas purification processes which focus on production of high purity methane while venting the lower purity methane/carbon dioxide stream. Using NaUSY as the adsorbent, and based on experimental and simulation data, we are able to produce product purities of 98% CH 4 and 95% CO 2 in the two product streams, respectively, for an energy consumption of 0.23 GJ/tCO 2 from a feed containing 50/50% CH 4 /CO 2 . [ABSTRACT FROM AUTHOR]

[Display omitted] • Separation mechanisms for CO2/CO mixture were studied systematically by experiments and simulations. • The NaX zeolites showed low adsorption heat and high separation coefficients on CO2/CO. • The CaA zeolites showed excellent separation stability under different ratios for CO2/CO mixture. • The above separation performances were revealed by the number, distribution and charge of cations and characteristics of gas adsorption complexes. Adsorption and recovery of CO 2 from industrial gases are of great environmental significance in the field of environmental protection with reducing greenhouse gas emissions and increasing CO concentration. A comprehensive investigation with thermodynamics and kinetics experiments of CO 2 and CO on NaX and CaA zeolites were studied and the separation mechanism explained by molecular simulation methods. The experiments show that the NaX zeolites have significant differences on CO 2 and CO adsorption amounts leading the high CO 2 /CO selectivity, while the CaA zeolites exhibit separation stability under various partial pressures of mixed gas, which is supported by the standard deviation results. The theoretical simulations verify the above-mentioned experimental phenomena and provide a visual mechanism explanation for adsorption selectivity from the aspect of systematic interaction between cations and gas molecules. Compared with NaX, the same number and homogeneous distributions of Ca2+ and Na+ in the CaA provide stable separation performance. The strong electrostatic interactions between divalent Ca2+ and gas molecules especially CO make differences in the order of adsorption capacity and adsorption heat. Deeper insights into the cations-gas adsorption complexes revealed that the significant differences in the types of adsorption complexes for CO and CO 2 in NaX contribute to the improvement of the adsorption selectivity. [ABSTRACT FROM AUTHOR]

Adsorptive removal of gas phase low concentration macromolecular organic component, represented by naphthalene, from the enclosed space using ordered mesoporous carbon (OMC) has been studied by molecular simulation and experimental investigation. The simulation results indicated that both adsorption capacity and adsorption stability of the OMCs for naphthalene decreased with the increase of pore sizes from 2 nm to 8 nm. Characterizations showed that the prepared OMCs had the pore structure similar to the simulated OMCs except for the rough surface. In particular, the adsorption performance of the prepared OMCs was significantly lower than that of the simulated OMCs when pore size was 2 nm and 3 nm, which was attributed to the rough inner surface of these adsorbents, blocking the narrow pore channels and significantly reducing the pore volume. OMC with pore size of 4 nm had the highest adsorption amount for naphthalene. The co-adsorption experiments in the presence of both naphthalene and toluene, acetone or water showed the adsorption performance of OMCs for naphthalene were almost unaffected by the presence of low concentration toluene and acetone, as well as high relative humidity. [Display omitted] • Adsorption of naphthalene by OMCs were investigated by simulation and experiment. • Realistic molecular models for OMCs were constructed by "delete atom" method. • The impact of pore structure on the adsorption of naphthalene was revealed. • OMC with pore size of 4 nm has the highest adsorption capacity for naphthalene. • OMCs show excellent adsorption selectivity and good moisture resistance. [ABSTRACT FROM AUTHOR]

[Display omitted] • Adsorption of toluene and naphthalene by OMS were investigated by simulation. • The adsorption selectivity of toluene and naphthalene was predicted by IAST. • The mechanism of selective adsorption was elucidated at molecular level. • Adsorbents with the desired pore size were prepared by template synthesis method. • The experimental results are in good agreement with the simulation results. In order to ensure regeneration property of adsorption materials in the air pollution purification system of the airtight cabin, such as submarine and space station, it is necessary to selectively separate semi-volatile organic compounds whose desorption is difficult. For this reason, the effects of pore size on the adsorption capacity and adsorption selectivity of toluene and naphthalene were investigated by both molecular simulation and experimental investigation. The ordered porous silica-based adsorbents with pore sizes ranging from 1.0 nm to 2.8 nm were constructed by simulation and were prepared by template synthesis method in this study. Both simulation and experiment show that the adsorption capacity of toluene and naphthalene firstly increased and then decreased with the increase of the pore size of adsorbents from 1.0 nm to 2.8 nm, and the pore diameter (1.3 nm) corresponding to the maximum adsorption amount of toluene was smaller than that (2.3 nm) of naphthalene. Simulation results show that the adsorption energy and adsorption stability of naphthalene are higher than those of toluene, and binary-component co-adsorption experiments also testified that toluene molecules could be replaced by naphthalene molecules. The optimum pore size for selective adsorption of naphthalene is 2.3 nm. [ABSTRACT FROM AUTHOR]

Three acute hepatic injury models (a CCl 4 -induced model, APAP-induced model and ethanol-induced model) in mice were used to study the importance of GSTA1 in acute hepatic injury by comparison with a standard enzyme marker, alanine aminotransferase (ALT). GSTA1 release was demonstrated to be an earlier and more sensitive indicator of hepatotoxicity than was ALT. Significant increases in GSTA1 were detected at 2 h after CCl 4 exposure, while ALT was undetected at this time. GSTA1 was also a more sensitive indicator of hepatotoxicity than ALT after 6 h. In the APAP and ethanol models, GSTA1 was markedly increased earlier than ALT, at 2 h post exposure. The release of GSTA1 was significantly increased at a dose of 12.5 mg/kg (CCl 4 model), 100 mg/kg (APAP model) and 10 ml/kg (ethanol model), the lowest exposure concentration for each model. In contrast, AST release was not statistically significant. These results suggest that GSTA1 can be detected at low concentrations during the early stages of acute hepatic injury and that GSTA1 is a more sensitive and more accurate indicator than ALT. [ABSTRACT FROM AUTHOR]

• Influence of coexisting nanoparticles on toluene adsorption was studied. • Competition between gas and particles in interaction with zeolites was addressed. • Reduction of toluene adsorption capacity by particles was up to 16.0 % on K-ZSM-5. • Reduction of toluene adsorption rate by particles was up to 20.3 % on Li-ZSM-5. • Adsorption site occupation and steric hindrance could be caused by nanoparticles. Adsorption as one of the most important air cleaning methods has been extensively applied during which the coexisting airborne nanoparticles (NPs) with sizes close to adsorbent pore sizes could inevitably influence gas adsorption processes. In this work, the influence of sub-20 nm NPs on toluene adsorption on ZSM-5 zeolites exchanged with different cations (Li+, Na+ and K+) were studied based on gas-and-particle coexisting adsorption/filtration tests. Affinities for both toluene and NPs on adsorbents follow Li-ZSM-5 > Na-ZSM-5 > K-ZSM-5 regarding the orders of charge density, pore size, and internal and external specific surface areas. The toluene adsorption was shown to be impaired by coexisting NPs from perspectives of thermodynamics and kinetics. For Li-ZSM-5, Na-ZSM-5 and K-ZSM-5, significant relative reductions of 10.4 %, 10.5 % and 16.0 % in toluene adsorption capacity at the lower feed concentration, and of 20.3 %, 15.2 % and 2.3 % in mass transfer coefficient at the higher feed concentration were observed, respectively. The influential mechanisms regarding competitiveness between toluene and NPs in interaction with cationic and porous surfaces were accordingly proposed, which are of practical significance for selecting robust adsorbents under realistic harsh air conditions. [ABSTRACT FROM AUTHOR]

The adsorption of three typical polycyclic aromatic hydrocarbons (PAHs), naphthalene, phenanthrene, and pyrene with different ring numbers, on a common mesoporous material (MCM-41) was simulated based on a well-validated model. The adsorption equilibriums (isotherms), states (angle distributions and density profiles), and interactions (radial distribution functions) of three PAHs within the mesopores were studied in detail. The results show that the simulated isotherms agreed with previous experimental results. Each of the PAHs with flat molecules showed an adsorption configuration that was parallel to the surface of the pore, in the following order according to the degree of arrangement: pyrene (Pyr) > phenanthrene (Phe) > naphthalene (Nap). In terms of the interaction forces, there were no hydrogen bonds or other strong polar forces between the PAHs and MCM-41, and the O–H bond on the adsorbent surface had a unique angle in relation to the PAH molecular plane. The polarities of different H atoms on the PAHs were roughly the same, while those of the C atoms on the PAHs decreased from the molecular centers to the edges. The increasing area of the π-electron plane on the PAHs with the increasing ring number could lead to stronger adsorption interactions, and thus a shorter distance between the adsorbate and the adsorbent. [ABSTRACT FROM AUTHOR]

Background: Hyperlipidemia is a well-established risk factor for cardiac damage, which can lead to cardiovascular diseases. Many studies have shown that Coenzyme Q10(CoQ10) protects against cardiac damage in vivo. The aim of this study was to investigate the possible protective effects of CoQ10 against cardiac damage in apolipoprotein E-deficient (ApoE−/−) mice. Methods: Eight-week-old male C57BL/6 and ApoE−/− mice were randomly divided into four groups: C57BL/6 mice fed a normal diet (C57BL/6 group); C57BL/6 mice fed a normal diet + CoQ10 (C57BL/6 + CoQ10 group); ApoE−/− mice fed a high-fat diet (ApoE−/− HD group), and ApoE−/− mice fed a high-fat diet + CoQ10 (ApoE−/− HD + CoQ10 group). All groups were fed the different diets for 16 weeks. Blood samples were obtained from the inferior vena cava and collected in serum tubes. The samples were then stored at − 80 °C until used. Coronal sections of heart tissues were fixed in 10% formalin and then embedded in paraffin for histological evaluation. The remainder of the heart tissues was snap-frozen in liquid nitrogen for mRNA or immunohistochemical analysis. Results: The metabolic parameters such as total cholesterol (TC), low-density lipoprotein-cholesterol (LDL-c), and triglycerides (TG) levels were lower in ApoE−/−HD + CoQ10 mice than in ApoE−/− HD mice. There were significant pathophysiological changes (H&E, PAS, Masson and CD68 staining) in ApoE−/− mice in the HD group compared with those in the HD + CoQ10 group. CoQ10 reduced HD-induced cardiac tissue damage via autophagy (p62 and LC3), as evidenced by immunoblotting, immunohistochemistry, and RT-qPCR. CoQ10 also inhibited inflammation (IL-6 and TNF-α) gene expression in ApoE−/− mice. Conclusions: These results indicate that CoQ10 is a potential therapeutic target for cardiac damage caused by hyperlipidemia. [ABSTRACT FROM AUTHOR]

Background: Hypercholesterolemia is a well-established risk factor for cardiac damage, which can lead to cardiovascular diseases. Many studies have shown that thymoquinone protected rats from doxorubicin-induced cardiotoxicity and cardiac damage. The aim of this study was to investigate the possible protective effects of thymoquinone against cardiac damage in apolipoprotein E knockout (ApoE−/−) mice. Methods: Eight-week-old male ApoE−/− mice were randomly divided into three groups: control group fed a normal diet (ND group), a high cholesterol diet (HD group) or HD mixed with thymoquinone (HD + TQ group). All groups were fed the different diets for 8 weeks. Blood samples were obtained from the inferior vena cava and collected in serum tubes. The samples were then stored at − 80 °C until used. Coronal sections of heart tissues were fixed in 10% formalin and then embedded in paraffin for histological evaluation. The remainder of the heart tissues was snap-frozen in liquid nitrogen for mRNA or immunohistochemical analysis. Results: The metabolic characteristics of total cholesterol (TC), low-density lipoprotein-cholesterol (LDL-c), and high-sensitivity C-reactive protein (hs-CRP) were lower in ApoE−/−HD + TQ mice than in ApoE−/− HD mice. Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) gene and protein expression was lower in the heart tissue of ApoE−/−HD + TQ mice than in those of ApoE−/−HD mice. Furthermore, the levels of macrophages and pro-inflammatory cytokines were lower in the cardiac tissues of ApoE−/−HD + TQ mice than in those of ApoE−/−HD mice. Conclusions: These results indicate that thymoquinone may provide a potential therapeutic target for cardiac damage caused by hypercholesterolemia. [ABSTRACT FROM AUTHOR]

This study characterized the process by-product particles (mostly nanoparticles) released during the preventive maintenance of semiconductor fabrication facilities, such as chemical mechanical planarization (CMP), plasma-enhanced chemical vapor deposition (PECVD), and ion implantation. Manual sampling and real-time measurements with direct reading instruments were conducted to assess the exposure levels of nanoparticles and their physical and chemical properties. Significant amount of nanoparticles were observed in the breathing zone of the workers during the maintenance of the PECVD and ion implanters with the peak number concentrations as high as 6,470,000 and 65,444 #/cm3, respectively, indicating that the deposited residual chemicals in the reaction chambers were released as airborne nanoparticles by the maintenance activities. In contrast, nanoparticles released during the maintenance of the local scrubber, CMP, and replacing CMP slurry drums were insignificant. Causes of the particle release were discussed and suggestions were made to mitigate the nanoparticle release and reduce the exposure levels. [ABSTRACT FROM AUTHOR]