Adsorption Characteristics Research Articles

Sustainable biological production and innovative purification of the 1,3-propanediol from glycerol fermentation broth via resin adsorption

The study focuses on enhancing the production and purification of 1,3-Propanediol (1,3-PDO), a versatile compound used across various industries. Conventionally, 1,3-propanediol (1,3-PDO) has been derived from petroleum-based feedstocks through chemical processes, which pose significant cost and environmental concerns. This has prompted the exploration of sustainable biological production methods using microorganisms to ferment glycerol, the main by-product of palm oil transesterification in biodiesel production. However, downstream purification remains complex and inefficient. To address this, our study introduces a novel and economically viable purification strategy for 1,3-PDO derived from a semi-industrial fermentation broth. The purification process involves pre-treatment steps: centrifugation, flocculation with chitosan, decolorization with activated charcoal, and broth concentration via rotary evaporation. These steps resulted in a transparent broth with a minimal 6 % loss of 1,3-PDO. Various resin types, including Sulfonated Styrene Divinylbenzene (S-SDVB) and Styrene Divinylbenzene (SDVB) ion exchange resins in different ionic forms in addition to silica gel resin, were evaluated for their effectiveness in separating 1,3-PDO in terms of recovery and purity. A key aspect of our study is the detailed investigation of the equilibrium adsorption characteristics of SDVB and S-SDVB resins, each with different ion forms. This analysis provides insights into how resin modifications affect the separation process, aiming for higher yields and purities of 1,3-PDO. The findings revealed that the Langmuir adsorption isotherm fits experimental data. Column chromatography experiments showed SDVB resins' deficiencies in separating 1,3-PDO from other components, while silica gel resin achieved a recovery rate exceeding 96 % purity and approximately 80 % overall recovery. Notably, the Ca2+ form of S-SDVB resin achieved high recovery (95–100 %) and purity (91–93 %) in both synthetic and real fermentation broths, addressing biodiesel challenges and proposing a solution for large-scale microbial 1,3-PDO production.

Electrical and work function-based chemical gas sensors utilizing NC3 and graphene combination

Research has been conducted on the potential practical uses of heterostructures made of graphene and carbon nitride (NC3) following their successful synthesis. The remarkable gas sensing properties of these 2D nanosheets have captured significant interest, attributed to distinctive electronic characteristics and exceptional surface-to-volume ratio that are resulted from combination of NC3 and graphene. In this study, we present a detailed analysis of electronic and structural features of pristine NC3 and graphene (PG), and their in-plane heterostructures using first-principles density functional theory. Our investigation utilizes the B3LYP and dispersion-corrected van der Waals (vdW) functional WB97XD, along with 6-311G (d, p) basis set. Our findings indicate that the nanosheets we anticipated exhibit robust structural stability, characterized by a desirable cohesive energy. Furthermore, we observed a gradual increase in the bandgap as the concentration of N–C in the nanosheets increases. Additionally, we investigated the adsorption characteristics of these heterostructures towards toxic gas molecules such as SO2 and CO. Among the studied heterostructures, GNC3I demonstrated higher adsorption energy (Eads), with values of approximately −0.283 and −0.491 eV when exposed to SO2 and carbon monoxide gas molecules respectively. Electronic characteristics, including LUMO and HOMO energy values, energy gap (Eg) between HOMO and LUMO, work function, Fermi level, and conductivity, underwent notable modifications upon SO2 gas adsorption over nanosheets, except for PG. However, these parameters remained relatively unchanged following carbon monoxide adsorption. Natural bond orbital (NBO) and Mulliken charge analysis demonstrates that there is a transfer of charge from gas molecules to nanosheets. Although nanosheets exhibit slightly higher adsorption energy (Eads) values for CO gas compared to SO2 gas, various assessments, including molecular electrostatic potential (MEP) mapping, electronic properties, and charge transfer (CT) analysis, suggest that these nanosheets are superior sensors for detecting SO2 gas rather than carbon monoxide gas molecules.

Carbon-Based Adsorbents for Microplastic Removal from Wastewater.

Plastics are widely used across various industries due to their flexibility, cost-effectiveness, and durability. This extensive use has resulted in significant plastic pollution, with microplastics (MPs) becoming pervasive contaminants in water bodies worldwide, adversely affecting aquatic ecosystems and human health. This review explores the surface characteristics of carbon-based adsorbents, including biochar, activated carbon, carbon nanotubes (CNTs), and graphene, and their influence on MP removal efficiency. Key surface characteristics such as the carbon content, surface area, pore size, and particle size of adsorbents influenced adsorption efficiency. Additionally, hydrophobic interaction, van der Waals forces, π-π interactions and electrostatic interaction were found to be mechanisms by which microplastics are trapped onto adsorbents. Modified biochar and activated carbon demonstrated high adsorption efficiencies, while CNTs and graphene, with their high carbon contents and well-defined mesopores, showed outstanding performance in MP removal. Although a high surface area was generally associated with better adsorption performance, modifications significantly enhanced efficiency regardless of the initial surface area. This review emphasizes the importance of understanding the relationship between surface characteristics and adsorption efficiency to develop optimized adsorbents for MP removal from wastewater. However, challenges such as the lack of standardized testing methods, variability in biochar performance, and the high cost of regenerating carbon adsorbents remain. Future research should focus on developing cost-effective production methods, optimizing biochar production, and exploring advanced modifications to broaden the application of carbon adsorbents. Integrating advanced adsorbents into existing water treatment systems could further enhance MP removal efficiency. Addressing these challenges can improve the effectiveness and scalability of carbon-based adsorbents, significantly contributing to the mitigation of microplastic pollution in wastewater.

Comparative Study on Ammonia Adsorption Characteristics of Various Porous Materials and Ammonia Adsorption Effect According to MgCl2 Impregnation

Comparative Study on Ammonia Adsorption Characteristics of Various Porous Materials and Ammonia Adsorption Effect According to MgCl2 Impregnation

A computational study on the detection properties of pristine, Al-, and Ga- doped Zn12O12 nanoclusters toward Deferiprone in gas and solvent phases

Electrochemical sensors have great potential in point-of-care diagnostic devices, benefiting from advancements in nanomaterials that enhance sensitivity and selectivity and reduce costs. This study theoretically investigates Deferiprone (DEF) sensing using pristine and aluminum – and gallium-doped Zn12O12 nanoclusters (AlZn11O12 and GaZn11O12) through a density functional theory (DFT) approach at the B3LYP-D level with a 6-311G (d, p) basis set. The results indicate DEF adsorption energies of −29.53 kcal mol−1 for Zn12O12, −42.19 kcal mol−1 for AlZn11O12, and −27.12 kcal mol−1 for GaZn11O12 in their most stable orientations. The adsorption of DEF significantly alters the energy gap (Eg) in the doped nanoclusters, highlighting the superior sensitivity of AlZn11O12 and GaZn11O12 for DEF detection. Transition theory calculations reveal a practical recovery time of 72.64 s for GaZn11O12, indicating favourable adsorption characteristics. Solvent effect studies show that the DEF/GaZn11O12 complex is stable in water, with a higher dipole moment reflecting increased water polarisation. UV-Vis analysis demonstrates that DEF adsorption on GaZn11O12 shifts the spectrum to higher wavelengths, indicating enhanced adsorption. Thus, GaZn11O12 is proposed as a promising candidate for DEF detection in both gas and solvent phases.

Rational Design of Two-Dimensional MA2Z4 Monolayers as Effective Anchoring Materials for Lithium-Sulfur Batteries.

Advances in lithium-sulfur batteries (LSBs) are impeded by the inefficiency of anchoring materials in facilitating long-term cycling and rate performance. To address this challenge, an exploration of two-dimensional MA2Z4 monolayers as potential anchoring materials for LSBs is proposed based on density functional theory calculations and machine learning (ML) techniques. Adsorption features, sulfur reduction reaction behaviors, and solvent interactions are assessed and analyzed; and MoGe2N4 and WGe2N4 are identified as the most promising candidates because they have optimal adsorption energies for lithium polysulfides to suppress the shuttle effect and exhibit enhanced catalytic activity. Meanwhile, ML analysis highlights the critical influence of the electronegativity of element Z in MA2Z4 on anchoring properties, providing valuable insights into future anchoring material design for high-performance LSBs.

Methane Adsorption Characteristics of Marine-Continental Transitional Shales Based on the Experimental Study of Shanxi Formation of the Lower Permian in the Ordos Basin

Methane Adsorption Characteristics of Marine-Continental Transitional Shales Based on the Experimental Study of Shanxi Formation of the Lower Permian in the Ordos Basin

Adsorption of Lufenuron 50-EC Pesticide from Aqueous Solution Using Oil Palm Shell-Derived Activated Carbon.

The use of Lufenuron 50-EC pesticide in oil palm crops affects water quality and aquatic life. This study investigated the adsorption of Lufenuron 50-EC from an aqueous solution using activated carbon derived from oil palm shells (OPSs). Activated carbon (AC) was prepared through physical and chemical activation processes in carbon dioxide environments, using potassium hydroxide (KOH) as a chemical activating agent. The resulting AC was characterized using standard techniques. The most favorable operating parameters were physical activation at 900 °C for 2 h, achieving a BET surface area of 548 m2/g. For chemical activation, at 800 °C, 1 h, and an impregnation ratio (KOH/biochar) of 2:1 (w/w), a BET surface area of 90 m2/g was obtained, which was smaller than that achieved by physical activation. The use of KOH reduced the surface area but generated a high presence of functional groups on the AC surface, which is important for adsorption processes. The AC produced achieved high Lufenuron adsorption yields, reaching a maximum of 96.93%. AC produced at 900 °C with 2 h showed the best performance. Therefore, OPS is an excellent precursor for producing AC with favorable characteristics for pollutant adsorption in aqueous solutions, especially for the insecticide Lufenuron.

Improved gas sensing properties of copper-doped MoSe2 monolayers: a first-principles study on CO2 and NO2 adsorption

Abstract This paper investigates the impact of copper (Cu)-doped MoSe2 monolayer (ML) on gas sensing properties. The adsorption behaviour of CO2 and NO2 gas molecules on Cu-doped MoSe2 ML is reported and various sensing and electronic parameters such as adsorption energy, charge transfer and recovery time, are computed to delineate the adsorption characteristics and gas sensitivity. In our study, the doped Cu-atom in Se vacant MoSe2 ML shows the adsorption energies to be −1.32 eV (O-orient) and −1.72 eV (C-orient), for CO2, while for NO2, they are −0.879 eV (O-orient) and −1.06 eV (N-orient), respectively. The negative formation energy of −6.62 eV shows the electronic stability of Cu-doped MoSe2 ML and thermal stability, demonstrated by the molecular dynamics study through the Nose-Vervlet Thermostat (NVT) algorithm. Also, significant changes are observed in electronic conductivity and work function upon adsorbed Cu-MoSe2 ML. Lastly, these outcomes illustrate that Cu doping amplifies the capture ability of MoSe2 ML towards gas molecules, fostering improved electron interaction between the substrate surface and gas molecules, consequently enhancing its gas sensing ability.

Selective Adsorption of Lignin Peroxidase on Lignin for Biocatalytic Conversion of Poplar Wood Biomass to Value-Added Chemicals.

Lignin-first biorefineries aim to maximize the valorization of lignin by prioritizing its conversion over other biomass components. This study investigates the selective adsorption of lignin peroxidase (LiP) isozymes from white rot fungi Phanerochaete chrysosporium on lignin, aiming to enhance the biocatalytic conversion of poplar wood biomass into value-added chemicals. The research focuses on the adsorption characteristics of ten recombinant LiP isozymes, particularly PcLiP03, which exhibited the highest adsorption capacity on lignin and negligible adsorption on cellulose. Adsorption isotherms and structural analyses revealed that hydrophobic interactions significantly contribute to the selective adsorption of PcLiP03. Applying PcLiP03 in a continuous stirring cell system effectively converted lignin in unpretreated poplar wood to 2,6-dimethoxy-1,4-benzoquinone under ambient and mild conditions, highlighting its potential for selective lignin depolymerization in integrated biorefineries. This work underscores the importance of enzyme-substrate interactions and offers a promising approach for more efficient and sustainable biomass utilization.

Adsorption mechanism study of viscoelastic surfactants with various molecular structures on oil and gas reservoir rocks

As clean thickeners used in fracturing fluids or self-diverting acids, viscoelastic surfactants (VESs) have garnered increased attention for their unique properties. While VESs leave little residue, their adsorption on rocks can lead to adverse effects on oil and gas seepage. Herein, sandstone and limestone were utilized as adsorbents to examine a series of VESs with diverse molecular structures. The relationship between adsorption capacity and molecular structure was investigated, along with the impact of salinity and temperature on adsorption capacity through static and dynamic adsorption tests. Experiments were conducted at various temperatures (25 °C–100 °C) and different salinity levels (0–4 wt%) using sandstone and limestone as adsorbents. The wettability alteration caused by each VES solution was assessed to confirm the adsorption capacity of these VESs on sandstone and limestone. Scanning electron microscopy was employed to visually study the microscopic morphologies of rock surfaces after adsorption in VES solutions to investigate the adsorption characteristics. Owing to the differing charges between sandstone and limestone, the adsorption capacity of each VES varied. Cationic VESs tend to be absorbed by sandstone, while zwitterionic VESs are easily adsorbed by limestone. The increase in salinity considerably enhances the adsorption capacity of rocks, with a greater amplification on sandstone compared to limestone. Additionally, the adsorption capacity of cationic VESs on sandstone is highly sensitive to salinity owing to the ease with which their head groups are disrupted by ions. Rising temperatures can weaken adsorption capacity due to the breakdown of hydrogen bonding or van der Waals forces. The wettability changes caused by VES solutions on sandstone are more pronounced than on limestone. By combining experimental results, the mineral content of rocks, molecular structure characteristics of VESs, and adsorption-free energy, the adsorption mechanisms of various VESs with different molecular structures on rocks were examined. This research lays a theoretical foundation for optimizing VES molecular structures for the preparation of fracturing fluids or self-diverting acid.

Fabrication and adsorption characteristics of cuprammonium cellulose-based membranes for removing anionic and cationic dyes

A cotton linter-based source was used to form conjugate electrospun membranes composed of cuprammonium cellulose, polyethylene oxide, and polyacrylonitrile for the removal of the anionic and cationic dyes from aqueous media. The highest removal efficiencies of 94 %, 89.9 %, 87.4 % were achieved for the anionic dyes Congo red (CR), Metanil yellow (MY), and Methyl orange (MO), respectively, and less so on the cationic dyes Crystal violet (CV), and Rhodamine B (RB) were 55.8 % and 15.1 %, respectively. The pseudo-second-order model effectively described the adsorption kinetics for both types of dyes. The composite membrane exhibited adsorption behaviors following the Dubinin-Radushkevich (D-R) isothermal model. Thermodynamics study suggests that the adsorption process was spontaneous except for the RB dye. The activation energy values of CR, MY, MO, CV, and RB dyes were 27.65, 21.17, 11.50, 10.47, and 71.12 kJ/mol, respectively, confirming the physisorption phenomenon for CR, MY, MO, and CV dyes, while chemisorption occurs for RB dyes. This study investigates the potential of a conjugate electrospun membranes as a reusable adsorbent for dye removal. The effects of solution pH, temperature, and dye concentration on adsorption performance were systematically evaluated. The conjugate electrospun membrane efficiency declined by only 10 % after undergoing five adsorption/desorption cycles.

Adsorption studies of methylene blue using mangosteen shell porous biochar as adsorbent

The biomass of mangosteen shells was utilized as a raw material to prepare activated carbon based on mangosteen shells through a two-step process of mixed alkali carbonization and activation. This study aimed to investigate the efficacy of the activated carbon in removing methylene blue. The optimum preparation conditions for the study are KOH : NaOH : MSC = 1 : 1 : 1 with a particle size of 80 mesh. The activated carbon exhibits a BET specific surface area of 1432.699 m2/g and a Langmuir maximum specific surface area of 2066.130 m2/g. It demonstrates excellent adsorption performance for methylene blue, with a maximum adsorption amount of 985.5 mg/g. Characterization of the activated carbon is conducted using various techniques including Scanning Electron Microscope, X-ray Diffraction Instrument (XRD), Raman Spectrometry (RMS), Fourier IR Spectrometry (FT-IR), XPS, and BET theory. The adsorption results were consistent with the Freundlich model and the pseudo-first-order kinetic model, indicating that the carbon material exhibits multilayer physical adsorption characteristics for methylene blue. The prepared material offers a large specific surface area, good environmental economics, and excellent adsorption performance, making it a promising choice for adsorption material preparation compared to other biomass activated carbons.

Progress in development of characterization capabilities to evaluate candidate materials for direct air capture applications

As part of U.S. national efforts to combat the detrimental effect of global climate change, the National Institute of Standards and Technology (NIST) was recently tasked to support efforts in direct air capture (DAC) of carbon dioxide research and deployment. In order to develop test procedures, materials, and documentary standards, key characterization methods relevant to DAC materials have been investigated and used to identify desirable properties for a potential Standard Reference Material (SRM). Select amine-supported materials that previously showed potential for DAC applications have been characterized using commonly available laboratory methods. Further insights into the adsorption characteristics have been gained from developing and applying more specialized characterization tools ideal for probing low concentrations of carbon dioxide. A broad suite of capabilities that examine relevant properties under appropriate conditions gives the most profound insights into a material’s specific performance. We advocate for even more specialized capabilities to be developed and standardized to quantitatively monitor the interactions of CO2 with molecular species in complex and often disordered systems to advance DAC and support carbon dioxide reduction (CDR) in general.

Sustainable soil rehabilitation with multifunctional mandarin orange peel/tobermorite composite hydrogels: Water retention, immobilization of heavy metals, fertilizer release and bacterial community composition

Traditional hydrogel applied in soil tends to be unacceptable due to the high cost of synthesis raw materials and difficulty in degradation. To enhance water holding, adsorption of heavy metals and substrate fertility, this work developed a novel composite hydrogel (MxTy-CH) prepared from mandarin orange peel (MOP) and tobermorite (TOB). By arranging the enhancement of MOP and TOB, the water absorbency (from 171.23 g/g to 204.29 g/g), water holding (66.77 %, 144 h), adsorption characteristics (Cd2+ 339.93 mg/g; Pb2+ 1743.44 mg/g) and fertilizer slow-release performance (0.938 % released in 6 days) were significantly enhanced. The results indicated that the addition of MOP and TOB contributed to an enrichment in the number of –COOH and –OH groups contained in the system. Additionally, the adsorption behavior of cadmium/lead on MxTy-CH was more consistent with the pseudo-second-order kinetics and Langmuir isotherm models. The regeneration test results suggested that the adsorption removal rate of cadmium/lead by MxTy-CH remained stable after 5 cycles. Fish toxicity tests indicated that MxTy-CH was biocompatible and would not cause obvious physiological toxicity to fish organisms. The MxTy-CH treatment group performed better than control group in Cd(II) and Pb(II) passivation performance in soil with mung beans. Changes in the microbial community composition and structure after MxTy-CH treatment in soil provided demonstration for stimulated C and N cycling in soil, suggestive of enhanced soil quality. The abovementioned further proves the considerable application potential of MxTy-CH in plant growth and rehabilitation of cadmium and lead contaminated soil.

Influence of flue gas components on SO2 adsorption by activated carbon at low temperature

Activated carbon can adsorb SO2 in flue gas, whose performance is significantly enhanced when lowering the adsorption temperature; however, the characteristics and mechanism of SO2 adsorption under the action of complex flue gas components at low temperatures remain unclear. In this study, adsorption experiments were conducted to investigate the characteristics of SO2 adsorption on activated carbon and the impact of O2, H2O, and NO within −20 to 20 °C. The saturated adsorption of SO2 showed a 2.21-fold increase when the temperature was lowered from 20 °C to −20 °C. Within this temperature range, physical adsorption was dominant, accounting for 73.7–91.0 %. O2 and H2O inhibited the physical adsorption of SO2 and promoted its chemical adsorption. As the temperature was lowered, the promoting effect of O2 increased, while the influence of H2O shifted from promotion to inhibition. NO affects SO2 adsorption only when co-existing with O2. As the temperature decreased, the promoting effect of NO on both physical and chemical adsorption strengthened and was significantly higher than that of O2 and H2O. Based on desorption experiments and quantum chemical calculations, the mechanisms by which H2O and NO affect SO2 adsorption were proposed·H2O and SO2 share the same physical adsorption sites, with H2O being more strongly adsorbed, thus significantly inhibiting the SO2 physical adsorption. When NO coexists with O2, gaseous SO2 reacts with the NOx adsorption configurations to form C-SO3 and C-HSO3. Active atoms near C-SO3 and C-HSO3 can adsorb NO2, forming a co-adsorption configuration, which in turn enhances the nearby physical adsorption of SO2. Enhancing the catalytic oxidation and adsorption of NO through surface modification of activated carbon can improve the low-temperature adsorption performance of SO2.

How do polyhydroxyalkanoates aged by aerobic compost interact with steroidal estrogens to alter their adsorption and transport characteristics? Kinetics, isotherms, and influencing factors

Despite evidence indicating a substantial presence of microplastics (MPs) in organic fertilizers, research exploring the differences of MPs among various types of organic fertilizers remains limited. Additionally, MPs can act as carriers for organic pollutants, influencing their environmental behaviors. This study investigated the presence of MPs in organic fertilizers and their effects on the environmental behaviors of steroidal estrogens. We compared the adsorption of estrone (E1) and estrone sulfate sodium (E1-3S) by original PHA and PHA aged through cattle manure-straw compost (CS) and vermicompost (VC). PHA-CS exhibited the highest adsorption capacities for E1 (47.97 ± 2.20μgg-1) and E1-3S (64.32 ± 2.09μgg-1). Dissolved organic matter (DOM) from CS and VC profoundly affected estrogen adsorption onto PHA, with VC-derived DOM inhibiting and CS-derived DOM promoting adsorption. In simulated avian digestive fluid, the desorption efficiency of E1 was 72.46% to -93.43% higher than that of E1-3S, indicating increased toxicity and bioavailability of E1 upon bird ingestion. Transport experiments strongly suggested that estrogens could be more easily retained in porous media containing aged PHA. This study advances our understanding of the adsorption mechanisms of aerobic compost-derived PHA on estrogens and their desorption behaviors under different environmental conditions.

Assessment of interfering/synergistic effects in the adsorption between polar and non-polar VOCs on a commercial biomass-based microporous carbon

This research has been carried out to investigate unique relationships in adsorption behavior between polar and non-polar volatile organic compounds (VOCs: formaldehyde (FA) versus toluene) using commercial macadamia nutshell (MNS)-based microporous activated carbon (i.e., Procarb-900: namely, P900). The breakthrough (BT) volume, adsorption capacity, and partition coefficient of P900 are estimated for 100 ppm FA as a single component and as a binary phase with 100 ppm toluene. The contrasting features of adsorption (such as interfering/synergistic relationships) for VOC mixtures with different polarities are accounted for in terms of interaction between the key variables (e.g., pore size distribution, adsorbent particle size, surface element compositions, and sorbent bed mass). Accordingly, the powdered P900 (0.212–0.6 mm: 150 mg) exhibits an adsorption capacity of 5.7 mg g−1 and a partition coefficient of 0.19 mol kg−1 Pa−1 for single-phase FA at the 10% BT level. Interestingly, its FA adsorption performance is synergistically improved in the presence of toluene (e.g., > 150%) in the early stage of adsorption (e.g., 10% BT), although their competition reduced its performance at 99% BT. The apparent synergistic trend in the early BT stage may possibly reflect diffusion resistance of the adsorbent (e.g., small particle size and developed ultra-micropore structure) and natural attributes of FA (e.g., low affinity and smaller kinetic diameter). The overall results of this study are expected to offer a better understanding of the mechanisms underlying the interactions between the mixed VOC system and microporous adsorbents.

Differential adsorption of H2S/CH4 by bituminous coal and its competitive adsorption properties

To investigate the adsorption characteristics and competitive adsorption patterns of H2S and CH4 in coal seams, we conducted a combined experimental and molecular simulation study using Ningxia Shuangma bituminous coal as the research subject. The experiments examined the adsorption of single-component H2S and CH4 gases at different temperatures and pressures, while the molecular model of bituminous coal was used to analyze the adsorption patterns of binary gas mixtures under competing conditions. Our experimental results demonstrate that both H2S and CH4 follow Langmuir’s model, with their saturated adsorption positively correlated with pressure but negatively correlated with temperature. Moreover, under identical conditions, H2S exhibits 2.43 times higher saturated adsorption than CH4. Molecular simulations reveal that temperature has a greater impact on H2S compared to CH4; both gases undergo reversible physisorption, where isosteric heat of adsorption decreases linearly with increasing amount of adsorbate molecules; interaction energy for H2S is larger in absolute value than that for CH4, indicating its stronger affinity towards coal surfaces; regarding binary component adsorption, an increase in proportion of H2S within the gas mixture leads to higher saturation adsorptions for both the mixture itself and individual H2S molecules while decreasing saturation adsorption for CH4; Coal adsorption selectivity factor for H2S/CH4 > 1. The preferential occupation of high-energy adsorption sites is more likely to be observed for H2S. The adsorption capacity and competitive adsorption capacity of H2S were greater than that of CH4.

Machine Learning-Based Prediction of the Adsorption Characteristics of Biochar from Waste Wood by Chemical Activation.

This study employs machine learning models to predict the adsorption characteristics of biochar-activated carbon derived from waste wood. Activated carbon is a high-performance adsorbent utilized in various fields such as air purification, water treatment, energy production, and storage. However, its characteristics vary depending on the activation conditions or raw materials, making explaining or predicting them challenging using physicochemical or mathematical methods. Therefore, using machine learning techniques to determine the adsorption characteristics of activated carbon in advance will provide economic and time benefits for activated carbon production. Datasets, consisting of 108 points, were used to predict the adsorption characteristics of biochar-activated carbon derived from waste wood. The input variables were the activation conditions, and the iodine number of activated carbon was used as the output variable. The datasets were randomly split into 75% for training and 25% for model validation and normalized by the min-max function. Four models, including artificial neural networks, random forests, extreme gradient boosting, and support vector machines, were used to predict the adsorption properties of biochar-activated carbon. After optimization, the artificial neural network model was identified as the best model, with the highest coefficient determination (0.96) and the lowest mean squared error (0.004017). As a result of the SHAP analysis, activation time was the most crucial variable influencing the adsorption properties. The machine learning model precisely predicts the adsorption characteristics of biochar-activated carbon and can optimize the activated carbon production process.