Stages Of Adsorption Research Articles

Novel Method for the Classification of Shale Oil Reservoirs Associated with Mobility: Inspiration from Gas Adsorption and Multiple Isothermal Stage Pyrolysis

The characterization and description of pores in shale oil reservoirs have long been based on the classification of micropores (<2 nm), mesopores (2–50 nm), and macropores (>50 nm) in shale gas reservoirs. However, the great difference between oil and gas molecules leads to its poor applicability, which further results in the relationship between oil properties and pores being rarely understood. To establish an individual pore division method for shale oil reservoirs, N2 adsorption, Soxhlet extraction, and programmed pyrolysis were performed on the Paleogene Xin’gouzui lacustrine shale in the Jianghan Basin. With the results, a new classification method, i.e., adsorption pores (pore diameter <20 nm), restricted pores (20–100 nm), and movable pores (>100 nm), was proposed. A fractal theory and scanning electron microscopy (SEM) images confirm the rationality of this method. Hydrocarbons in movable pores determine the initial productivity of a shale oil well, while those in restricted pores are closely related to the production time of a well to some extent. Compared to the previous division methods, this novel method reveals the correlation between shale oil attributes as well as movability and pore spaces for the first time. Our work can provide more accurate evaluation results for shale oil recoverable resource potential and is of great significance for optimizing favorable areas and reducing exploration risks.

Anti-corrosion performance of dehydroacetic acid thiosemicarbazone on XC38 carbon steel in an acidic medium

Dehydroacetic acid thiosemicarbazone (DHATSC) was tested for its ability to suppress corrosion on mild steel XC38 (MS XC38) by measuring its effects by electrochemical impedance spectroscopy (EIS), weight loss (WL), and potentiodynamic polarization (PDP). Using weight loss tests and potentiodynamic polarization, the corrosion inhibiting efficiency (IE) of DHATSC for MS XC38 in 1.0 M HCl solution was calculated. The data showed that DHATSC was highly inhibitory, with increasing effectiveness as the inhibitor concentration increased. In 1 M HCl, the PDP curves showed that DHATSC was a mixed-type inhibitor. In addition to the EIS findings, the adsorption of DHATSC was also validated by analyzing the charge transfer resistance (Rct) values of the MS XC38 surface. At room temperature, the most outstanding corrosion inhibition efficiency as determined by weight loss was 78%; however, the PDP method obtained 94% at a concentration of 200 ppm. With a standard free energy (Gads) of −6.90 KJ.mol-1 for the adsorption stage, the Langmuir isotherm offered the most accurate description of DHATSC adsorption. The inhibitor has a nanocrystalline structure, measured by X-ray diffraction (XRD), with a mean crystallite size (D) of 56.11 nm. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) analyses verified the mild steel's surface analysis. The theoretical calculations generally agreed with the experimental findings to a high degree.

Gas-particle two-phase adsorption of toluene and ultrafine particles on activated carbon studied by molecular simulation

Adsorption is regarded as the most reliable technology for gaseous pollutant removal. Activated carbon is a widely used adsorbent due to its good adsorption capacity and low price. However, substantial ultrafine particles (UFPs) in the air cannot be effectively removed even if a high-efficiency particulate air filter is located before the adsorption stage. The adhesion of UFPs to the porous surface of activated carbon affects the removal of gaseous pollutants and shortens its service life. So, we adopted molecular simulation to explore the gas-particle two-phase adsorption and analyze the effects of the properties of UFPs such as concentration, shape, size and chemical composition on the toluene adsorption. The parameters of equilibrium capacity, diffusion coefficient, adsorption site, radial distribution function, adsorption heat and energy distribution were used to evaluate the gas adsorption performance. The results showed that the equilibrium capacity of toluene was decreased by 16.51 % compared to that of only toluene adsorption at the toluene concentration of 1 ppb and UFPs concentration of 1.81 × 10−5/cm3. Compared with cubic and cylindrical particles, the particles in spheres were more likely to hinder the pore channels from reducing gas capacity. Larger UFPs in the selected particle size range (1–3 nm) had a greater impact. Carbon black UFPs themselves could adsorb toluene, so the amount of toluene adsorbed was not significantly decreased.

Revealing the Combined Effect of Active Sites and Intra-Particle Diffusion on Adsorption Mechanism of Methylene Blue on Activated Red-Pulp Pomelo Peel Biochar.

Phosphoric acid-activated biochar has been proven to be a promising adsorbent for pollutant removal in an aqueous solution. It is urgent to understand how surface adsorption and intra-particle diffusion synergistically contribute to the adsorption kinetic process of dyes. In this work, we prepared a series of PPC adsorbents (PPCs) from red-pulp pomelo peel under different pyrolysis temperatures (150-350 °C), which have a broad specific surface area range from 3.065 m2/g to 1274.577 m2/g. The active sites on the surface of PPCs have shown specific change laws of decreasing hydroxyl groups and increasing phosphate ester groups occurring as the pyrolysis temperature rises. Both reaction models (PFO and PSO models) and diffusion models (intra-particle diffusion models) have been applied to simulate the adsorption experimental data to verify the hypothesis deduced from the Elovich model. PPC-300 exhibits the highest adsorption capacity of MB (423 mg/g) under given conditions. Due to its large quantities of active sites on the external and internal surfaces (1274.577 m2/g), a fast adsorption equilibrium can be achieved within 60 min (with an initial MB concentration of 100 ppm). PPC-300 and PPC-350 also exhibit an intra-particle-diffusion-controlled adsorption kinetic process with a low initial MB concentration (100 ppm) or at the very beginning and final stage of adsorption with a high initial MB concentration (300 ppm) at 40 °C, considering that the diffusion is likely hindered by adsorbate molecules through internal pore channels at the middle stage of adsorption in these cases.

Natural Products and Derivatives as Potential Zika virus Inhibitors: A Comprehensive Review.

Zika virus (ZIKV) is an arbovirus whose infection in humans can lead to severe outcomes. This article reviews studies reporting the anti-ZIKV activity of natural products (NPs) and derivatives published from 1997 to 2022, which were carried out with NPs obtained from plants (82.4%) or semisynthetic/synthetic derivatives, fungi (3.1%), bacteria (7.6%), animals (1.2%) and marine organisms (1.9%) along with miscellaneous compounds (3.8%). Classes of NPs reported to present anti-ZIKV activity include polyphenols, triterpenes, alkaloids, and steroids, among others. The highest values of the selectivity index, the ratio between cytotoxicity and antiviral activity (SI = CC50/EC50), were reported for epigallocatechin gallate (SI ≥ 25,000) and anisomycin (SI ≥ 11,900) obtained from Streptomyces bacteria, dolastane (SI = 1246) isolated from the marine seaweed Canistrocarpus cervicorni, and the flavonol myricetin (SI ≥ 862). NPs mostly act at the stages of viral adsorption and internalization in addition to presenting virucidal effect. The data demonstrate the potential of NPs for developing new anti-ZIKV agents and highlight the lack of studies addressing their molecular mechanisms of action and pre-clinical studies of efficacy and safety in animal models. To the best of our knowledge, none of the active compounds has been submitted to clinical studies.

Theoretical insights into the effect of CO on the heterogeneous reduction of N2O on char

AbstractBACKGROUNDThe role of CO and adsorption sequence of CO and N2O in the adsorption and reduction of N2O on char was investigated based on density functional theory at the M06‐2X/6‐311G(d) theoretical level. This study lays a foundation for reaction mechanisms of the influence of CO on heterogeneous N2O reduction on char.RESULTSZigzag and armchair models were used as char models. The first adsorption of CO increases the limiting‐step energy barrier of the reaction by 44.5 kJ⋅mol−1 compared with the first adsorption of N2O for zigzag char. However, the adsorption sequence does not have an effect for armchair char. The rate‐limiting steps of the overall reaction for zigzag and armchair char models occur in the stages of N2O adsorption and N2O reduction, respectively. The introduction of CO has little effect on the N2O adsorption stage but increases the energy barrier of the N2O reduction stage. During the reduction of N2O on coal char, zigzag char releases greater heat than armchair char; moreover, zigzag char has a much lower activation energy than armchair char.CONCLUSIONIn the simultaneous presence of CO and N2O, the char model prefers to adsorb N2O. The rate‐limiting step of the two char models are located in different reaction stages, and CO mainly affects the N2O reduction stage. The presence of CO hinders the reduction of N2O on the surface of both zigzag and armchair char models. A rise of temperature can promote the reduction of N2O by char. Zigzag char is superior to armchair char in both thermodynamics and kinetics. © 2023 Society of Chemical Industry (SCI).

Influence of reduction conditions on the structure-activity relationships of NaNO3-promoted Ni/MgO dual function materials for integrated CO2 capture and methanation

Integrated CO2 capture and utilization (ICCU) represents an innovative concept and technique for reducing industrial carbon emissions. Ni-MgO dual function materials (DFMs) promoted by alkali metal salt (AMS) for integrated CO2 capture and methanation (ICCU-M) is gaining increasing interest. The in-situ methanation performance depends heavily on the high-temperature NiO reduction process, while this might adversely affect CO2 adsorption due to loss of AMS. Herein, we investigated the effects of H2 concentration and reduction temperature on structure–activity relationships of AMS-promoted Ni-MgO DFMs for ICCU-M. The increase in H2 concentration and reduction temperature favors NiO reduction to metallic Ni0 and boosts oxygen vacancy concentration in the DFMs. Both CO2 uptakes and CH4 yield increase with the elevating H2 concentration, and CH4 yield also increases with the increasing reduction temperature, considering the increased metallic Ni0 content and oxygen vacancy concentration. CO2 uptakes of the DFMs decline with the increase in reduction temperature, due to the obvious loss in AMS. The bulk diffusion kinetics in CO2 adsorption stage will be improved under higher H2 concentration and reduction temperature, while the chemisorption kinetics will be weakened at elevating reduction temperature. The methanation kinetics will be enhanced when the DFMs are reduced under higher H2 concentration and temperature. The AMS-NM-100-450 DFMs reduced in 100 %H2 and 450 °C exhibit good ICCU-M performance with high CO2 adsorption capacity and CH4 yield of 6.46 mmol CO2/g and 0.85 mmol CH4/g. The results in this work enlighten that the ICCU-M performance of AMS promoted Ni-MgO DFMs can be tuned by regulating the operating parameters for catalyst reduction.

Investigation of the activity of baicalein towards Zika virus

BackgroundZika virus (ZIKV) is a mosquito transmitted virus spread primarily by Aedes species mosquitoes that can cause disease in humans, particularly when infection occurs in pregnancy where the virus can have a significant impact on the developing fetus. Despite this, there remains no prophylactic agent or therapeutic treatment for infection. Baicalein is a trihydroxyflavone, that is found in some traditional medicines commonly used in Asia, and has been shown to have several activities including antiviral properties. Importantly, studies have shown baicalein to be safe and well tolerated in humans, increasing its potential utilization.MethodsThis study sought to determine the anti-ZIKV activity of baicalein using a human cell line (A549). Cytotoxicity of baicalein was determined by the MTT assay, and the effect on ZIKV infection determined by treating A549 cells with baicalien at different time points in the infection process. Parameters including level of infection, virus production, viral protein expression and genome copy number were assessed by flow cytometry, plaque assay, western blot and quantitative RT-PCR, respectively.ResultsThe results showed that baicalein had a half-maximal cytotoxic concentration (CC50) of > 800 µM, and a half-maximal effective concentration (EC50) of 124.88 µM. Time-of-addition analysis showed that baicalein had an inhibitory effect on ZIKV infection at the adsorption and post-adsorption stages. Moreover, baicalein also exerted a significant viral inactivation activity on ZIKV (as well as on dengue virus and Japanese encephalitis virus) virions.ConclusionBaicalein has now been shown to possess anti-ZIKV activity in a human cell line.

Highly efficiently selective separation of zirconium from scandium by TRPO modified adsorbent

Scandium (Sc) and zirconium (Zr) often co-exists with each other and are difficult to separate effectively due to their similar behavior during separation. Herein, a series of adsorbents were synthesized by vacuum impregnation method for the separation of Sc and Zr. The results show that the Trialkylphosphine oxide silica-based modified adsorbent (TRPO/SiO2-P) has excellent adsorption selectivity (SFSc/Zr = 3694). It has fast adsorption and elution kinetics with equilibrium obtained within 30 min, and the adsorption matches the pseudo-second-order kinetic model and Langmuir isotherm model. Fourier transform infrared spectrometer (FT-IR), x-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) analysis showed that Sc and Zr was successfully adsorbed mainly through binding with P = O in Trialkylphosphine oxide (TRPO). Stoichiometry of Sc or Zr extraction by TRPO shows that one Sc or Zr combines with two TRPO molecules. In addition, the results of column experiments show that the separation and recovery of Sc and Zr can be achieved in the adsorption and elution stages, respectively, where the purity of Sc reaches 99.3 %. It shows the great potential of TRPO modified adsorbent for practical application in Sc and Zr dynamic separation process.

Recyclable Carbon-Based Hybrid Adsorbents Functionalized with Alumina Nanoparticles for Water Remediation

Developing and improving adsorbent materials for wastewater treatment have become crucial for achieving recyclable water and keeping the environment safe. Carbon materials are modified with alumina (Al2O3) using various doping ratios and a solvothermal treatment. The process aims to combine the advantages of stable carbon and alumina materials with an efficient adsorbent for methylene blue removal. Fabricated materials including carbon and carbon/alumina derivatives were characterized with TEM, SEM, EDS, XRD, and FTIR, revealing successful surface modifications. The carbon materials exhibited pore diameters between 23 and 39 µm, while the modified ones showed pore diameters between 1.68 and 6.08 µm. The alumina nanoparticles were formed on a carbon surface with a particle size between 174 nm and 179 nm. Fabricated adsorbents were applied for the removal of methylene blue by adsorption at pH 4. The equilibrium and steady state adsorption stage was achieved after 2 h of reporting fast adsorption behavior. Low ratio carbon doping with alumina improved the adsorption capacity for methylene blue removal, while the excessive doping of carbon materials with alumina led to a reduction in adsorption efficiency. The application of pseudo-first-order and pseudo-second-order kinetic models indicated a fast adsorption mechanism, which agreed with the second-order model. The adsorption capacity for methylene blue was found to be 234 mg/g. Adsorption-isotherms including the Langmuir and Freundlich models were applied to investigate the adsorption mechanism. The results indicate that the Langmuir model fits with the adsorption data, which suggests a monolayer adsorption process.

Mechanisms of dyes adsorption on titanium oxide– graphene oxide nanocomposites

Graphene oxides (GOs), synthesized with different oxidation degrees and associated with Titanium dioxide (TiO2) nanoparticles show efficient adsorption processes for dye molecules in solution. The structural, morphology, electronic and optical features of the nanocomposites were investigated by dedicated methods. Water remediation was investigated through the adsorption efficiency of methylene blue (MB) dye as a function of the nanocomposites concentration from 1 to 5 g/L in solutions. While pristine TiO2 showed a maximum removal of ∼44%, the incorporation of the GO ensures the fast and complete elimination of MB within 9 min. The ball milling process contributed to the increase in the number of defects and surface area in the nanocomposites, which was demonstrated by ID/IG ratios by Raman spectroscopy and surface areas by BET. Pseudo-second-order and mechanistic kinetic models were considered, and the performed analysis points out the relevance of the pseudo-second-order model to account for the adsorption kinetics. The Langmuir and Freundlich isotherm models were applied to the experimental data to find an adequate model to describe the adsorption equilibrium, as well as the intra-particle diffusion model during the different adsorption stages involved in the TiO2/GO nanocomposites. The role of the oxidation degree of GO was clarified through their respective efficiency in the removal of the dyes.

Nitrogen Removal for Low Concentration Ammonium Wastewater by Adsorption, Shortcut Simultaneous Nitrification and Denitrification Process in MBBR

Excessive discharge of ammonia nitrogen wastewater from intensive aquaculture has worsened in recent years. Therefore, there is an urgent need to develop an effective and energy-saving denitrification technology. This study intends to adopt a moving bed biofilm reactor (MBBR) to remove ammonia nitrogen through the combination of adsorption and shortcut simultaneous nitrification and denitrification (SND). The research focuses on the operational parameters and regeneration mechanism of the MBBR adsorption-shortcut SND process. The optimal operating parameters in the adsorption stage were a hydraulic retention time of 8 h and an agitation rate of 120 r/min. For the shortcut SND stage, the ideal optimal parameters were two times alkalinity and dissolved oxygen (DO) 1.0 mg/L. Under optimal operating parameters conditions, the SND rate, TN removal rate, NH4+-N removal rate and nitrite accumulation rate were 89.1%, 84.0%, 94.3%, and 86.4%, respectively. The synergetic actions of ion exchange and microorganisms were the main driving force for regenerating ceramsite zeolite components. The synergistic inhibitory effect of high-concentration free ammonia and low-level DO on nitrite-oxidizing bacteria was the key to achieving stable and efficient NO2−-N accumulation. NO2−-N produced in shortcut nitrification entered the ceramsite through complex mass transfer, and denitrifying bacteria can reduce these NO2−-N to N2.

Effectiveness of Artificially Synthesized Granitic Residual Soil-Supported Nano Zero-Valent Iron (Gr-nZVI) as Effective Heavy Metal Contaminant Adsorbent

Supported nano zero-valent iron is receiving great attention nowadays due to its effectiveness in treating heavy metal pollutants. Therefore, this study aimed to investigate the effectiveness of granitic residual soil-supported nano zero-valent iron (Gr-nZVI) for the removal of the heavy metals Pb2+, Cu2+, Co2+, Cd2+ Ni2+ and Zn2+ in mixture solutions under different experimental conditions of batch equilibrium tests. In this study, Gr-nZVI was successfully synthesized by using the chemical reduction of Ferric Chloride Hexahydrate (FeCl3.6H2O) and Sodium Borohydride (NaBH4). The physical and chemical properties, morphology and mineralogy of all adsorbents were characterized by the Braeuer–Emmett–Teller (BET) method, cation exchange capacity (CEC), X-ray fluorescence (XRF), scanning electron microscopy (SEM), field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Isotherm, kinetic and diffusion model analyses were conducted to fit the experimental data. The results show rapid adsorption within 5 min in the initial adsorption stage for Pb2+ on nZVI (qe.Pb = 17.89 mg/g) and Gr-nZVI (qe.Pb = 15.29 mg/g). nZVI and Gr-nZVI also showed no significant effects on pH and temperature, serving as a good example of an energy-efficient process. The isotherm data fitted better to the Langmuir model and the pseudo-second-order kinetic model for the adsorption of all of the heavy metals. The diffusion models revealed that adsorption was not the only rate-limiting step. In this study, nZVI compared to Gr-nZVI and Gr demonstrated superior adsorption capacity for the heavy metal adsorption selectivity. Hence, these materials can be utilized as alternative energy-efficient adsorbents for the adsorption of metal ions from wastewater.

Protective and Therapeutic Capacities of Lactic Acid Bacteria Postmetabolites against Koi Herpesvirus Infection In Vitro.

The accumulation of data on beneficial biological effects of probiotics and their metabolic products favors their potential use in the prevention and treatment of various malaises. Nine postmetabolites from Lactic acid bacteria (LAB) of human or dairy origin and their antiviral activity were studied using the cytopathic effect inhibition test. The virucidal capacity, their influence on the adsorption stage of Koi herpes virus (KHV) and their preventive role against subsequent viral challenge on intact Common carp brain (CCB) cells were also determined by titration assay. Residual viral infectivity in postmetabolites-treated samples was compared to mock-treated controls and Δlgs were calculated. When administered during KHV replication, the microbial products isolated from Lactiplantibacillus plantarum showed remarkable activity with a selectivity index (SI) between 26.5 and 221.4, as those effects were dependent on the sample-virus incubation time. Postmetabolites from Lactobacillus gasseri and Lactiplantibacillus plantarum also demonstrated significant inhibition of KHV replication with SI of 24 and 16, respectively. The bioactive metabolites isolated from Limosilactobacillus fermentum had a minor effect on the viral replicative cycle. Compounds, produced during the fermentation by lactobacilli, grown on different nutritive media and collected at different time points, significantly inhibited extracellular KHV virions. All investigated postmetabolites remarkably blocked KHV attachment to the host cell (CCB), leading to a drop in viral titers by Δlg = 4.25-5.25, and exerted protective effects on CCB cells before they were subjected to viral infection. Our results open new horizons and promote LAB and their postbiotic products to be used in the prophylaxis and therapy of viral infections.

First-principles study of the initial stage of Pentacene adsorption on the twofold surface of the Ag-In-Yb quasicrystal

The adsorption of the pentacene (Pn) molecule on the twofold surface of icosahedral (i)-Ag-In-Yb Quasicrystal (QC) have been studied by means of density functional theory (DFT) calculations. We calculate the adsorption energy of Pn at various positions with the molecular axis parallel to the surface and aligned along the fivefold or twofold symmetry axes directions. Pn is stabilised on a Yb trapezoid site from the acute rhombohedron units located between the rhombic triacontahedral clusters. The calculated adsorption energies for different molecular orientations can explain a recent experimental observation.

Fixed-bed columns mathematical modeling for selective nickel and copper recovery from industrial spent acids by chelating resins

Spent acid streams generated in industry containing high concentrations of heavy metals are potential secondary sources of raw materials. Chelating resins are excellent candidates to recover valuable metals from complex mixtures at very low pH conditions. In particular, previous works reported high recoveries of nickel and copper from real industrial acids (3400 mg Cu2+ L−1, 8700 mg Ni2+ L−1 and 24000 mg Fe L−1) using commercial bis-picolyamine (BPA)-based resins. In this work, adsorption and desorption using two in-series fixed-bed columns with BPA resins have been proposed to carry out the selective and independent separation and recovery of nickel and copper. Under the selected operating conditions, it was possible to recover 90% of the copper and 80% of the nickel present in the problem solution. A mathematical model based on mass transfer was developed in order to describe the adsorption and desorption stages. Adsorption chemical reactions were modeled as equilibrium reactions, fitting to Langmuir’s and Freundlich’s isotherms for copper and nickel respectively. The chemical reactions for both metals in desorption fitted into first order reactions. Finally, the kinetic constants kde=0.81 kgdryresin L−1 h−1 for copper and kde=1.10 kgdryresin L−1 h−1 for nickel were estimated using the software Aspen Custom modeler. The predicted values agreed with the experimental data.

N-Butanol Extract of Glycyrrhizae Radix et Rhizoma Inhibits Dengue Virus through Targeting Envelope Protein.

At present, about half of the world's population is at risk of being infected with dengue virus (DENV). However, there are no specific drugs to prevent or treat DENV infection. Glycyrrhizae Radix et Rhizome, a well-known traditional Chinese medicine, performs multiple pharmacological activities, including exerting antiviral effects. The aim of this study was to investigate the anti-DENV effects of n-butanol extract from Glycyrrhizae Radix et Rhizome (GRE). Compounds analysis of GRE was conducted via ultra-performance liquid chromatography/tandem mass spectrometry (UHPLC-MS/MS). The antiviral activities of GRE were determined by the CCK-8 assay, plaque assay, qRT-PCR, Western blotting, and the immunofluorescence assay. The DENV-infected suckling mice model was constructed to explore the antiviral effects of GRE in vivo. Four components in GRE were analyzed by UHPLC-MS/MS, including glycyrrhizic acid, glycyrrhetnic acid, liquiritigenin, and isoliquiritigenin. GRE inhibited the attachment process of the virus replication cycle and reduced the expression of the E protein in cell models. In the in vivo study, GRE significantly relieved clinical symptoms and prolong survival duration. GRE also significantly decreased viremia, reduced the viral load in multiple organs, and inhibited the release of pro-inflammatory cytokines in DENV-infected suckling mice. GRE exhibited significant inhibitory activities in the adsorption stage of the DENV-2 replication cycle by targeting the envelope protein. Thus, GRE might be a promising candidate for the treatment of DENV infection.

Highly efficient Cu2O@CuxFeyO4 nanohybrid catalyst for the degradation of emerging pollutants

Cu2O@CuxFeyO4 nanohybrids (NHs) have been electrosynthesized by a simple and environmentally safe method to be used as catalysts for tetracycline degradation. NHs shown an average diameter of 14(5) nm and exhibit high crystallinity with spherical morphology. XPS results demonstrate a cuprite-enriched surface; meanwhile, the inner layer is composed by a nonstoichiometric copper spinel structure. The degradation has been monitored by UV–Visible spectroscopy, TOC analysis, and HPLC. The electrochemical characterization demonstrates the synergetic effect of Fe3+/Fe2+ and Cu2+/Cu+ coupling to enhance the activation of persulfate. This effect results in a greater degradation efficiency of NHs than other catalysts, namely, CuxOy, Fe3O4, and a mixture of both and Cu2O.It has been found that a previous adsorption stage before degradation does not improve the elimination of the pollutant and its length in time, with a TOC reduction of 72.6 % in 2 h. Conversely, conducting the oxidative process in a direct step resulted in a more rapid and efficient process, 82.3 % of reduction in 1 h. Through this method, the catalyst reutilization resulting in a decrease of 50 % in TOC degradation from the third use, while the TCY concentration degraded remains almost constant. This reduced catalytic activity with use might be a consequence of 1) the absence of the single Cu-oxide layer due to the leaching of mainly Cu ions but also Fe ions during the degradation tests, and, 2) the passivation of the outermost layer, mainly covered by CO species and OH groups, which hinders access to active catalyst sites.

Displacement Characteristics of CO2 to CH4 in Heterogeneous Surface Slit Pores

Studying the CO2–CH4 displacement process is of great importance to understand the CO2-enhanced shale gas recovery technology. However, most studies have focused on the gas behavior in the reservoir during the dominant stage of competitive adsorption after CO2 injection, as well as the shale gas recovery, displacement efficiency, and gas separation after displacement, while less attention has been paid to the gas behavior during the initial period of displacement. A CO2–CH4 displacement model that can provide a continuous pressure gradient in the displacement direction and a stable back-pressure at the pore outlet was developed based on a heterogeneous surface pore. The model was divided into three areas: CO2 injection area, pore area, and back-pressure area. Molecular dynamics simulations were used to study the effects of depressurization exploitation and injection pressure on the displacement behavior at the initial period of the displacement process under different reservoir conditions. It was found that the displacement process always starts from the CH4 reverse flow stage and then experiences the injection pressure action stage and positive displacement stage in sequence. Moreover, the extent of CH4 reverse flow directly affects the system development process and the final displacement efficiency. A small system presorption pressure and a large injection pressure are beneficial to the displacement. It is believed that the reservoir pressure should be dropped to the lowest possible level during depressurization exploitation, and the CO2 injection pressure needs to be selected by considering displacement efficiency, reservoir safety, and economic cost. The CO2 occupies the adsorption sites near graphene faster than that near montmorillonite (MMT) in the direction of displacement, while the CH4 desorption is faster near MMT. Therefore, it cannot be concluded that the displacement process near graphene is ahead of MMT. It is considered that the gas desorption/adsorption behavior near the graphene dominates the displacement process in terms of gas amount, while the fluctuation near MMT with time and injection pressure directly affects the gas adsorption variation in the pore space from the trend.

Biochar Derived from Chinese Herb Medicine Residues for Rhodamine B Dye Adsorption.

In this study, one well-known CHM residue (Atropa belladonna L., ABL) was used to prepare biochar capable of adsorbing rhodamine B (RhB) with an ultrahigh surface area for the first time. Three micropore-rich ABL biochars including ABL@ZnCl2 (1866 m2/g), ABL@H3PO4 (1488 m2/g), and ABL@KOH (590 m2/g) were obtained using the one-step carbonization method with activation agents (ZnCl2, H3PO4, and KOH) via chemical activation and carbonization at 500 °C, and their adsorption performance for RhB was systematically studied with adsorption kinetics, isotherms, and thermodynamics. Through pore diffusion, π-π interaction, and hydrogen bonding, ABL biochar had excellent adsorption performance for RhB. Moreover, when C 0 was 200 mg/L, biochar dosage was 1 g/L, and the contact time was 120 min; the maximum RhB adsorption capacity and removal efficiency on ABL@ZnCl2 and ABL@H3PO4 were 190.63 mg/g, 95% and 184.70 mg/g, 92%, respectively, indicating that it was feasible to prepare biochar from the ABL residue for RhB adsorption. The theoretical maximum adsorption capacities of ABL@ZnCl2 and ABL@H3PO4 for RhB were 263.19 mg/g and 309.11 mg/g at 25 °C, respectively. Furthermore, the prepared biochar showed good economic applicability, with pay back of USD 972/t (ABL@ZnCl2) and USD 987/t (ABL@H3PO4), respectively. More importantly, even after five cycles, ABL@H3PO4 biochar still showed great RhB removal efficiency, suggesting that it had a good application prospect and provided a new method for the resource utilization of traditional CHM residues. Additionally, pore diffusion, π-π interactions, and hydrogen bonding all play roles in the physical adsorption of RhB on ABL biochar. π-π interactions dominated in the early stage of RhB adsorption on ABL@H3PO4, while pore diffusion played a crucial role in the whole adsorption process on both adsorbents.