Pore Diffusion Research Articles

Synthesis of recyclable and light-weight graphene oxide/chitosan/genipin sponges for the adsorption of diclofenac, triclosan, and microplastics

Emerging micropollutants, such as pharmaceuticals and microplastics (MPs), have become a pressing water environmental concern. The aim of this study is to synthesize chitosan sponges using graphene oxide (GO) and genipin (GP) for the removal of pharmaceuticals (diclofenac (DCF) and triclosan (TCS)) and MPs, verify their adsorption mechanisms, evaluate the effects of temperature, pH, and salinity on their adsorption capacities, and determine their reusability. The GO5/CS/GP sponge exhibited a macroporous nature (porosity = 95%, density = 32.6 mg/cm3). GO and cross-linker GP enhanced the adsorption of DCF, TCS, and polystyrene (PS) MPs onto the CS sponges. The adsorption of DCF, TCS, and PS MPs involved multiple steps: surface diffusion and pore diffusion of the sponge. The adsorption isotherms demonstrated that Langmuir model was the most fitted well model to explain adsorption of TCS (qm = 7.08 mg/g) and PS MPs (qm = 7.42 mg/g) on GO5/CS/GP sponge, while Freundlich model suited for DCF adsorption (qm = 48.58 mg/g). DCF adsorption was thermodynamically spontaneous and endothermic; however, the adsorption of TCS and PS MPs was exothermic (283–313 K). The optimal pH was 5.5–7 due to the surface charge of the GO5/CS/GP sponge (pHzpc = 5.76) and ionization of DCF, TCS, and PS MPs. As the salinity increased, DCF removal efficiency drastically decreased due to the weakening of electrostatic interactions; however, TCS removal efficiency remained stable because TCS adsorption was mainly caused by hydrophobic and π–π interactions rather than electrostatic interaction. The removal of PS MPs was enhanced by the electrostatic screening effects of high Na+ ions. PS nanoplastics (average size = 26 nm) were removed by the GO5/CS/GP sponge at a rate of 73.0%, which was better than that of PS MPs (41.5%). In addition, the GO5/CS/GP sponge could be recycled over five adsorption–desorption cycles.

Ti-substituted organosilica membranes for H2 sieving: Sol-gel and DFT insights

The fabrication of gas-sieving amorphous silica membranes exhibiting superior thermal/hydrothermal/chemical stability by the facile, scalable and controllable synthesis strategies is highly desired to bring the silica membranes a step closer to large scale deployment. Sol-gel modification of bis(triethoxylsilyl)ethane (BTESE) membrane pore network with Ti substitution resulted with a shift in the molecular level cut-off to smaller molecules establishing ideal selectivity improvement from 13 ± 2 to 20 for H2/N2 and 17 ± 4 to 28 for H2/CH4 at 200 °C. BTESE and analogous Ti-substituted BTESE membranes (BTESE-Ti) exhibited H2 permeances of (0.9–1.2)x10−6 mol/(m2sPa) and 5.8 × 10−7 mol/(m2sPa), respectively, reflecting a difference in their thickness. Decrease in the sol concentration by 2-fold led to an increase in the H2 permeance value to 8.9 × 10−7mol/(m2sPa) at 200 °C for BTESE-Ti membranes. We further theoretically designed amorphous BTESE and BTESE-Ti structures, and simulated their interactions with the gas molecules along with the pore diffusion of H2 as a model system to elucidate the membrane performance through the density functional theory (DFT) calculations. Theoretical findings suggest that the only transport mechanism is the direct transport from the gas phase to the pore entrance by excluding the surface diffusion possibility.

Behaviors and Mechanisms of Adsorption of MB and Cr(VI) by Geopolymer Microspheres under Single and Binary Systems.

Geopolymers show great potential in complex wastewater treatment to improve water quality. In this work, general geopolymers, porous geopolymers and geopolymer microspheres were prepared by the suspension curing method using three solid waste products, coal gangue, fly ash and blast furnace slag. The microstructure, morphology and surface functional groups of the geopolymers were studied by SEM, XRD, XRF, MIP, FTIR and XPS. It was found that the geopolymers possess good adsorption capacities for both organic and inorganic pollutants. With methylene blue and potassium dichromate as the representative pollutants, in order to obtain the best removal rate, the effects of the adsorbent type, dosage of adsorbent, concentration of methylene blue and potassium dichromate and pH on the adsorption process were studied in detail. The results showed that the adsorption efficiency of the geopolymers for methylene blue and potassium dichromate was in the order of general geopolymers < porous geopolymers < geopolymer microspheres, and the removal rates were up to 94.56% and 79.46%, respectively. Additionally, the competitive adsorption of methylene blue and potassium dichromate in a binary system was also studied. The mechanism study showed that the adsorption of methylene blue was mainly through pore diffusion, hydrogen bond formation and electrostatic adsorption, and the adsorption of potassium dichromate was mainly through pore diffusion and redox reaction. These findings demonstrate the potential of geopolymer microspheres in adsorbing organic and inorganic pollutants, and, through five cycles of experiments, it is demonstrated that MGP exhibits excellent recyclability.

Evaluation of biosorbent properties of Teucrium polium seeds in Rhodamine B removal; isotherm, kinetic, thermodynamic studies

Water pollution is a major environmental concern worldwide, particularly due to industrial paint waste. Therefore, treating wastewater from various industrial sources is crucial to restoring environmental quality. In this study, a batch biosorption system was used to investigate the biosorption of Rhodamine B (RhB), a highly toxic dye, on Teucrium polium seeds (TPS). The study examined the effects of different parameters such as initial dye concentration, contact time, initial pH, temperature, and biosorbent amount on RhB removal. To determine the physicochemical properties of TPS, scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET), and zero charge point (PZC) characterization analyses were performed. The maximum biosorption capacity of TPS at pH = 5.5 and 25 °C was found to be 4.18 mg g−1. The study found that the removal rate of RhB was 93.3% at an initial RhB dye concentration of 200 mg L−1. The experimental data showed that the Langmuir isotherm model (R 2 = 0.940) was the most compatible model for biosorption, while the biosorption kinetic mechanism proceeded through the pseudo-second-order (PSO) kinetic model (R 2 = 0.925). Additionally, the study found that intraparticle diffusion, pore diffusion, and film diffusion were effective in the RhB biosorption rate mechanism. Thermodynamic studies revealed that the biosorption was endothermic (ΔH0>0), spontaneous (ΔS0>0), and entropy-increasing (ΔG0 <0). As a result, TPS, which has suitable adsorbent properties for RhB, can be recommended as a new, cost-effective, abundant potential biosorbent.

Modeling competitive biosorption for methylene blue removal on rape straw powders using response surface methodology in a ternary dye aqueous solution

The improvement of biosorption efficiency for selective dye removal in a multi-dye aqueous system has become an increasingly significant research topic. However, the competitive effects of coexisting dyes and the target dye in such systems remain uncertain due to complex interactions between adsorbent and coexisting dyes. Therefore, in this research, response surface methodology (RSM) model was effectively employed to investigate the competitive effects of allura red (AR) and malachite green (MG) on methylene blue (MB) removal in a ternary dye aqueous system using three different parts of rape straw powders. In the current design of RSM, the initial concentrations of AR and MG dyes ranging from 0 mg·L−1 to 500 mg·L−1 were considered as influencing factors, while the removal rates of MB on adsorbents at an initial concentration of 500 mg·L−1 were established as response values. The RSM models exhibited high correlation coefficients with adjusted R 2 values of 0.9908 (pith core), 0.9870 (seedpods), and 0.9902 (shells), respectively, indicating a close fitted between predicted and actual values. The proposed models indicated that the perturbation effects of initial AR and MG concentrations were observed on the removal rates of MB by three types of rape straw powders in a ternary dye aqueous system, resulting in a decrease in MB removal rates, particularly at higher initial AR concentration due to stronger competitive effects compared to initial MG concentration. The structures of rape straw powders, including pith core, seedpods and shell, were analyzed using scanning eletron microscoe (SEM), energy dispersive spectroscopy (EDS), N2 physisorption isotherm, frourier transform infared spectroscopy (FTIR), Zeta potential classes and fluorescence spectrum before and after adsorption of MB in various dye aqueous systems. The characteristics of rape straw powders suggested that similar adsorption mechanisms, such as electrostatic attraction, pore diffusion, and group complex formation for MB, AR, and MG, respectively, occurred on the surfaces of adsorbents during their respective adsorption processes. This leads to significant competitive effects on the removal rates of MB in a ternary dye aqueous system, which are particularly influenced by initial AR concentrations as confirmed through fluorescence spectrum analysis.

Iron-lanthanum supported on graphite sheets for As(III) removal from aqueous solution: kinetics, thermodynamic and ecotoxicity assessment.

Graphene-based material is widely used to remove arsenic from water due to its layered structure with high surface area. Here, we have successfully synthesized Fe-La bimetallic modified graphite sheet materials to more efficiently remove As(III) from aqueous solution. The results showed that Fe-La-graphite sheets (FL-graphite sheets) have a larger specific surface area (194.28 m2·g-1) than graphite sheets (2.80 m2·g-1). The adsorption capacity of FL-graphite sheets for As(III) was 51.69mg·g-1, which was higher than that of graphite sheets (21.91mg·g-1), La-graphite sheets (26.06mg·g-1), and Fe-graphite sheets (40.26mg·g-1). The FL-graphite sheets conformed to the Freundlich and Dubinin-Radushkevich isotherm, and the maximum adsorption capacity was 53.62mg·g-1. The removal process obeys intra-particle diffusion and pore diffusion for As(III). The results of batch adsorption experiments and characterization analyses demonstrated that oxidation, ligand exchange, and inner sphere complexation mechanisms involved in the adsorption of FL-graphite sheets to As(III) in comparison with graphite sheets. In addition, electrostatic attraction mechanism was found vital in the adsorption. Ecotoxicity assessment revealed that FL-graphite sheets have little influence on rice germination and growth, but reduced the toxicity of As(III) to rice. Therefore, the FL-graphite sheets have good practical application value in purifying As(III) polluted water with litter ecotoxicity.

Adsorption of stable and labile emerging pollutants on activated carbon: degradation and mass transfer kinetic study

The design of adsorption processes for pharmaceuticals removal depends not only on the adsorption equilibrium but also on the mass transfer and adsorbate stability, being a problem still not solved the case of degradation products. By selecting different stable (amoxicillin, ciprofloxacin, carbamazepine and ibuprofen) and labile micropollutants (omeprazole) as case studies emerging pollutants, we have quantitatively analysed these effects on activated carbon. For stable compounds, the experimental data were fitted to equilibrium models to obtain information about the different adsorption mechanism depending on the characteristics of the molecules. Mass transfer effects were analysed for all the adsorbates, observing the control of intraparticle pore diffusion mechanism, since the effective pore diffusion coefficient is in the range from 10–8 to 10–10 cm2 h−1. As far as omeprazole is concerned, a kinetic model is proposed for predicting its degradation, identifying the reversibility of several degradation steps. The overall adsorption of OMP and derivates is calculated, observing the pore diffusion is considered as the rate-limiting step. For the first time, a combined model considering the chemical degradation and the adsorption of the degradation products is proposed and experimentally validated. This represents an important step in the modelling of processes leading to the purification of water from this type of pollutant.

Numerical Simulation of Mass Transfer in Hollow Fiber Membrane Module for Membrane-Based Artificial Organs.

The mass transfer behavior in a hollow fiber membrane module of membrane-based artificial organs (such as artificial liver or artificial kidney) were studied by numerical simulation. A new computational fluid dynamics (CFD) method coupled with K-K equation and the tortuous capillary pore diffusion model (TCPDM) was proposed for the simulations. The urea clearance rate predicted by the use of the numerical model agrees well with the experimental data, which verifies the validity of our numerical model. The distributions of concentration, pressure, and velocity in the hollow fiber membrane module were obtained to analyze the mass transfer behaviors of bilirubin and bovine serum albumin (BSA), and the effects of tube-side flow rate, shell-side flow rate, and fiber tube length on the bilirubin or BSA clearance rate were studied. The results show that the solute transport mainly occurred in the near inlet regions in the hollow fiber membrane module. Increasing the tube-side flow rate and the fiber tube length can effectively enhance the solute clearance rate, while the shell-side flow rate has less influence on the BSA clearance. The clearance of macromolecule BSA is dominated by convective solute transport, while the clearance of small molecule bilirubin is significantly affected by both convective and diffusive solute transport.

Solute Transport through Mitochondrial Porins In Vitro and In Vivo.

Mitochondria are most likely descendants of strictly aerobic prokaryotes from the class Alphaproteobacteria. The mitochondrial matrix is surrounded by two membranes according to its relationship with Gram-negative bacteria. Similar to the bacterial outer membrane, the mitochondrial outer membrane acts as a molecular sieve because it also contains diffusion pores. However, it is more actively involved in mitochondrial metabolism because it plays a functional role, whereas the bacterial outer membrane has only passive sieving properties. Mitochondrial porins, also known as eukaryotic porins or voltage-dependent anion-selective channels (VDACs) control the permeability properties of the mitochondrial outer membrane. They contrast with most bacterial porins because they are voltage-dependent. They switch at relatively small transmembrane potentials of 20 to 30 mV in closed states that exhibit different permeability properties than the open state. Whereas the open state is preferentially permeable to anionic metabolites of mitochondrial metabolism, the closed states prefer cationic solutes, in particular, calcium ions. Mitochondrial porins are encoded in the nucleus, synthesized at cytoplasmatic ribosomes, and post-translationally imported through special transport systems into mitochondria. Nineteen beta strands form the beta-barrel cylinders of mitochondrial and related porins. The pores contain in addition an α-helical structure at the N-terminal end of the protein that serves as a gate for the voltage-dependence. Similarly, they bind peripheral proteins that are involved in mitochondrial function and compartment formation. This means that mitochondrial porins are localized in a strategic position to control mitochondrial metabolism. The special features of the role of mitochondrial porins in apoptosis and cancer will also be discussed in this article.

Giant mud crab shell biochar: A promising adsorbent for methyl violet removal in wastewater treatment

Giant mud crab (Scylla serrata sp.) shell prepared through pyrolysis at various temperatures without any modification were characterized for physicochemical properties and methyl violet (MV) removal potential. Hence, this paper investigated the performance and mechanism of biochar derived from giant mud crab shell as adsorbent in the removal of methyl violet as well as the potential for regenerating adsorbents via hot water regeneration. The results show that CSB500 (produced through pyrolysis at 500 °C) exhibits a surface area of 59.73 m2/g and mesopore size of 31.3 nm, favorable for methyl violet removal at 3139 mg/g. The equilibrium adsorption data agreed well with Langmuir and Redlich-Peterson isotherm models, indicating a monolayer adsorption of MV. The kinetics data fitted better with both pseudo-first-order and pseudo-second-order models. The intraparticle diffusion and Boyd's models revealed that both film and pore diffusion may be involved in the adsorption process. In hot water regeneration studies, CSB500 shown superior regeneration performance when using water with temperature of 70 °C rather than 30 °C for 9th regeneration cycles, with retained to achieve >90 % MV removal for 6th regeneration cycles. Biochar derived from giant mud crab shell has shown significant promise as a low-cost, effective, and ecologically friendly with reasonably good adsorption capacity and reusability for dye removal, and it can be considered as an environmental sustainability strategy in wastewater treatment.

Synthesis of granulated Li1.33Mn1.67O4via two antisolvent methods for lithium adsorption from gas-produced water

Gas produced water is an accompanying wastewater in the natural gas extraction process, and it’s a potential liquid lithium resource contains a considerable amount of lithium. This paper investigated the feasibility of using manganese-based ion sieves to adsorb and extract lithium from gas produced water. And we focused on the applicability of two different granulation methods and extrusion and droplet in gas produced water systems. Two types of H1.33Mn1.67O4 particles were prepared by extrusion method (EHMO), and by droplet method (DHMO). The porosity of DHMO was much higher than that of EHMO, and the adsorption performance of DHMO increased with the decrease of binder concentration. DHMO prepared with binder concentration of 0.14 g·ml−1 exhibited the best adsorption performance in gas produced water, and the Li+ adsorption capacity could reach 25.14 mg·g−1. In gas produced water, the adsorption equilibrium of DHMO only took 9 hours, and the adsorption process conformed to the Langmuir model and pseudo-second-order kinetic model. The pore diffusion model (PDM) could well describe its adsorption process. Besides, DHMO showed a great selectivity to Li+, and the selectivity order of DHMO in gas produced water was Li+>Ba2+>>Mg2+, Ca2+, Sr2+>>Na+>>K+, and after 20 cycles, the Li+ adsorption capacity was still higher than 17.30 mg·g−1, and the rate of manganese dissolution was less than 1%.

Kinetic and adsorption isotherm studies of Malachite Green dye onto surfactant-tailored alginate hydrogel beads: An influence of surfactant hydrophobicity

This study details the synthesis and characterization of surfactant-modified sodium alginate hydrogel beads crosslinked with Ba2+ ions through ionotropic gelation. Cationic surfactants such as, dodecyltrimethylammonium bromide (DTAB), didodecyldimethylammonium bromide (DDAB), and butanediyl-α,ω-bis-(dimethyldodecylammonium bromide) (GEM), were employed in the modification process. The surfactant-modified ALG-DTAB, ALG-DDAB, and ALG-GEM beads were investigated for the removal of cationic dye Malachite Green (MG) to elucidate the impact of hydrophobicity of amphiphiles on the adsorption process. The characterizations were carried out using Rheometry, Field Emission Scanning Electron Microscopy (FESEM), Infrared Spectroscopy (IR), and Energy Dispersive X-ray Spectroscopy (EDX). Under optimized conditions, ALG-GEM and ALG-DDAB demonstrated highest maximum adsorption capacity (Qmax > 700 mgg−1). The adsorption data fitted well to pseudo-second order kinetic and Langmuir adsorption models, suggesting the involvement of chemisorption phenomena with notable contributions from pore diffusion. The effects of pH, initial dye concentration, adsorbent dose, temperature, and competing ions on the removal of MG were investigated. Interestingly, ALG-GEM beads exhibited an increase in adsorption capacity with rising pH and a subsequent decrease with increasing temperature, showcasing optimal adsorption at pH 7.0 and 25 °C. The study proposes that ALG beads modified with cationic surfactants with higher hydrophobicity could offer a promising avenue in wastewater treatment processes.

Entrained-flow pyrolysis and (co-)gasification characteristics of Indian high-ash coals

Co-utilization in entrained-flow gasifiers is a potential solution to address the high ash-related problems persistent in fluidized-bed gasifiers. This work presents the hitherto unreported high-temperature (1000–1400 °C) entrained-flow pyrolysis and (co-) gasification characteristics of Indian high-ash coals and two candidate fuels (indigenous bituminous coal and petcoke) for possible co-utilization. Char analyses – TGA, FTIR, Raman, and SEM − are also performed to characterize the pyrolysis-induced structural changes. Volatile yields of candidate fuels matched with proximate values while those of high-ash coal exceeded by ∼12 wt%. Thermal deactivation was more pronounced for coal chars. High-ash coals achieved 100% carbon conversion at conditions exceeding 1300 °C and 20 vol% CO2. Bituminous coal showed comparable conversions, 70−90%, at identical conditions; further increase in conversion potential may be possible through steam addition due to enhanced char deactivation and pore diffusion effects at higher temperatures. Petcoke achieved lowest conversion of ∼30% even at the severest conditions; decreasing the average particle size by half showed an improvement of only ∼15%. Co-gasification of high-ash coal and petcoke blends showed no synergy. Considering closely matching carbon conversion, volatile release potential, and industry-standard slag tapping temperatures (1300−1500 °C), indigenous bituminous coals are more promising for co-utilization with high-ash coals in autothermal entrained-flow gasifiers.

Biomimetic hybrid porous microspheres with plant membrane-wall structure for evaluating multiscale mechanisms of ultrasound-assisted mass transfer

Determination of mass transfer during ultrasound-assisted extraction (UAE) has always been a challenge, not to mention the novel breakthrough of mechanisms for its positive effects. Herein, versatile porous microspheres (PM) with membrane-wall structure like plant tissues, which were made from sodium alginate/polyacrylamide dual crosslinking gels loaded with liposomes, were prepared to reveal the micro mass transfer effects during UAE. Results showed that prepared PM kept stable microstructure during extraction and ultrasound significantly accelerated the pore diffusion rather than surface diffusion. This effect resulted in higher UAE efficiency of PM with 60 % porosity than solid microspheres (143.72 to 155.47 mg/L), and the finding can be further explained as the accelerated internal diffusion (14.25 %) under ultrasound treatment. Moreover, multi-physics coupling simulations were performed to elucidate the enhanced pore flow and UAE efficiency. Acoustic streaming induced by cavitation effect increased the seepage velocity within the PM, and the pore structure would undergo compression and expansion deformation with alternated acoustic pressure due to its elastic characteristic. Both microscale effects improved the mass transfer and increase the UAE efficiency without structural damage from cavitation. This study fills the UAE mechanisms from micro view and provides a novel method for the study of vital micro processes.

Exploration of cephalexin adsorption mechanisms onto bauxite and palygorskite and regeneration of spent adsorbents with cold plasma bubbling

The aim of the present study was the direct comparison of two popular minerals, bauxite and palygorskite, as adsorbents for the removal of cephalexin (CPX) from aqueous solutions and the regeneration of the spent adsorbents through cold atmospheric plasma. Batch kinetics and isotherm studies were carried out to evaluate the effect of contact time, initial CPX concentration, adsorbent dosage, pH and temperature. The adsorbents were characterized by ATR-FTIR, N2 sorption, SEM and XRD, while several isotherm, kinetic and thermodynamic models were evaluated attempting to shed light on the adsorption mechanisms. CPX adsorption on both adsorbents was better described by Langmuir model, with an adsorption capacity of 112.36 mg/g for palygorskite and 11.79 mg/g for bauxite. Thermodynamics revealed the endothermic and the spontaneous character of the process, indicating chemisorption as the main adsorption mechanism for both adsorbents. The pseudo-second-order and the Elovich models fitted satisfactorily the adsorption onto bauxite, while adsorption onto palygorskite was well presented by Weber–Morris model, indicating that pore diffusion is also involved in the process. The adsorption capacity of both minerals decreased significantly after being used for several adsorption cycles and then almost completely recovered (regeneration efficiency was 99.6% and 98% for palygorskite and bauxite, respectively) inside a novel cold plasma microbubble reactor energized by high-voltage nanopulses, revealing the potential of these adsorbents to be reused. In addition to the regeneration of the adsorbents, the cold plasma completely eliminated the CPX transferred from the solid to the aqueous phase during the regeneration process.

Acidification-Induced Micronano Mechanical Properties and Microscopic Permeability Enhancement Mechanism of Coal.

An acid solution improves the pore-plugging problem in hydraulic fracturing, which in turn improves the permeability of the coal seam. The study aimed to investigate the effect of mixed acid on the micronano mechanical properties and permeability of the coal seam. The surface morphology of acidified coal was analyzed from the micronano scale using atomic force microscopy (AFM) and scanning electron microscopy. Additionally, the micronano scale mechanical characteristics of acidified coal were examined using the mechanical mode in an atomic force microscope. Furthermore, the complexity and connectivity of the micronano pores of samples were investigated using the low-temperature nitrogen adsorption and mercury intrusion porosimetry methods and the fractal theory. The results indicated that the surface minerals of acidified coal were dissolved, loosening the coal and increasing the complexity of the pore structure. Mineral deformation and pore deformation weakened the mechanical properties of coal at the micronano scale, and the mean elastic modulus of acidified coal (B# and E#) decreased by 28.78 and 25.66% compared to that of raw coal. The acid solution effectively enlarged the pore diameter, transitioning from micropores to mesopores and macropores, and the total pore volume of acidified coal increased by 1.88 times and 1.25 times, Kn increased from 0.064 to 0.581 and 0.37, respectively. The type of methane diffusion in the diffusion pores changed from Knudsen diffusion to transition-type diffusion. The tortuosity of the pore structure of acidified coal decreased, the fractal dimension of the tortuosity of the pore structure decreased, and the permeability increased by nearly three times. The research results indicate that the mechanical properties of coal decrease after acidification and that the microstructural changes can promote methane migration (diffusion-seepage), which can provide theoretical guidance for coalbed methane extraction in low-permeability coal reservoirs.

Permeability Modeling of Pore Shapes, Compaction, Sorption, and Molecular Diffusivity in Unconventional Reservoirs

Summary Shale and ultratight gas reservoirs are multiscale, containing organic matter (OM) and inorganic minerals in multiple pore compartments of different pore shapes and scales. Selecting a suitable model to describe the multiscale transport mechanisms requires a minimum understanding of the inherent pore shape, OM content, typical pore size, and inherent flow regime. Interestingly, during gas production and associated pressure depletion, some mechanisms, such as pore compressibility, pore diffusion, and diffusion of sorbed gas molecules, become significant at lower pressure. In this study, multiscale and multiphysics permeability models are introduced that couple the effects of poroelasticity (especially in slit-shaped pores with &amp;lt;1.0 aspect ratio) and sorbed gas diffusion, Fick diffusion, transition diffusion, or Knudsen diffusion, depending on the pore structural properties at multiscale for shale and ultratight gas applications. Shale here refers to organic-rich low-permeability rock with &amp;gt;1–2 wt% OM, while ultratight gas has negligible organic content with &amp;lt;1.0 wt%. These experimentally and computationally validated models could be combined with Gaussian pressure transient solutions to effectively understand the uncertainty in multiphysics gas permeability in addition to the hydraulic and natural fracture parameters for large-scale flow simulation of hydraulically fractured unconventional reservoirs.

Removal of phenol from wastewater using Luffa cylindrica fibers in a packed bed column: Optimization, isotherm and kinetic studies

This research entails a comparison of the effectiveness of unmodified Luffa cylindrica fiber in a fully packed bed (RLCF) and NaOH-modified Luffa cylindrica fiber in another fully packed bed (MLCF) in the context of phenol removal from wastewater. Experimental data obtained through batch adsorption experiments were utilized to determine the most suitable model. It was observed that as the initial concentration of phenol increased from 100 to 500 mg/l, the maximum percentage removal increased from 63.5 to 83.1% for RLCF-PB and from 89.9 to 99.5% for MLCF-PB. The correlation coefficient (R2) was calculated for the Langmuir, Freundlich, Temkin, Harkin-Jura, Halsey, and Flory-Huggins models for both materials. The analysis revealed that the pseudo-second-order model was the most suitable, followed by the Elovich model, with the pseudo-first-order model being the least suitable. The Weber-Morris diffusion model suggested that pore diffusion was the rate-determining step, and diffusion at the border layer was determined to be endothermic, feasible, heterogeneous, and spontaneous. In summary, this study indicates that MLCF-PB is a promising material for the efficient removal of phenol from aqueous solutions.

A Fixed Bed Adsorption Column Study for Synthetic Dye Wastewater using Magnetic Biochar

The study aimed to investigate the performance of a fixed bed column using magnetic biochar as an adsorbent for synthetic dye wastewater treatment. The magnetic biochar was synthesized by pyrolyzing paper mill sludge at 350 ℃ and modified with iron oxide nanoparticles to enhance its magnetic properties. The adsorption capacity of the magnetic biochar was evaluated using methylene blue (MB) dye in wastewater. In present study the fixed bed column adsorption was conducted using MBC to treat MB wastewater. A fixed bed column setup was utilized in the experiments, maintaining a continuous flow rate of 15 mL/min at various bed height (i.e. 2.5, 5 &amp; 7cm). Breakthrough &amp; exhaustion capacity for each three different bed height at constant flow rate was also carried out. The Yoon-Nelson and Thomas kinetics models were also used in order to understand the dynamic performance of the fixed bed column. the respectively. The results shows that Yoon-Nelson model fitted best for the experimental data approximately R2 value of 0.96 against Thomas model R2 value of 0.95. Hence, it can be concluded that fixed bed column with MBC performed best with higher bed height &amp; adsorption process is limited by film &amp; pore diffusion

Performance and mechanism of benzene adsorption on ZnCl2 one-step modified corn cob biochar.

Utilizing cost-effective corn cob, zinc chloride-modified biochar was synthesized through one-step method for benzene adsorption from air. Study on impregnation ratio impact showed optimal benzene adsorption at ZnCl2:CC ratio of 1.5:1, with capacity reaching 170.53mgg-1. Characterization using BET, SEM, FTIR, and XPS was conducted. BET results indicated specific surface area of Zn1.5BC at 1260.63 m2g-1 and maximum pore volume of 0.546 m3g-1. SEM analysis revealed microporous-mesoporous structure in Zn1.5BC, marking significant improvement over original biomass. DFT pore size distribution and FTIR analysis suggested post-modification dehydration and elimination reactions, leading to volatile compound release, functional group reduction, and pore widening. XPS analysis showed decrease in O = C-OH content with increased impregnation ratio, enhancing biochar's π-π electron diffusion for benzene. Langmuir isotherm and pseudo-second-order kinetic models effectively described experimental data, indicating multilayer benzene adsorption on biochar controlled by complex physicochemical adsorption and pore diffusion. Adsorption condition assessment, including adsorption temperature (20-120℃) and benzene concentration in inlet phase (159.73-383.36 mg L-1), was performed. Yoon-Nelson model fitting indicated adsorption site loss at higher temperatures and reduced capture ability due to increased adsorbate molecule kinetic energy. Higher adsorbate concentrations aided adsorption molecule diffusion to biochar surface and internal pores, increasing adsorption rate and shortening equilibrium time. Overall, zinc chloride-modified biochar facilitates benzene adsorption through pore filling and π-π interactions, with pore filling as primary mechanism. Produced biochar shows excellent regeneration properties and reusability.