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Landfill leachate, a contaminated liquid containing dissolved organic and inorganic matter, poses a significant environmental threat. This study investigated the interplay between leachate adsorption/desorption dynamics on dumpsites' soil properties and the consequent impact on environmental risk. The research focused on common cations and anions within the leachate composition and batch adsorption experiments was used to investigate the impact of leachate containing the ions on the key geotechnical soil properties like void ratio, porosity, degree of saturation, and dry density. Analysis of the leachate composition identified the presence of common cations (K+, Na+, Ca2+, Mg2+) and anions (SO42- and Cl-). The dumpsites' soil samples were characterized by low affinity or adsorption coupled with high desorption rate of these ions, which demonstrably influenced the geotechnical properties and environmental risk of the soils of the dumpsites. The increased mobility of these ions within the dumpsites' soil systems is potentially leading to contamination of surrounding soil and water resources. Therefore, this knowledge can inform strategies for mitigating environmental risks associated with leachate migration. The findings can guide approaches for leachate treatment, landfill design, and the selection of suitable cover materials to minimize contaminant movement and ensure long-term environmental protection. Hence, to maintain a balanced ecosystem, the study emphasizes the need for engineered landfills with a higher capacity for ions adsorption. [ABSTRACT FROM AUTHOR]

Calcium phosphate materials, particularly hydroxyapatite (HA), are extensively used in biomedical applications because of their prominence as primary inorganic constituents of human hard tissues. This study investigates the synthesis of HA coatings via spray pyrolysis using various precursors, including HA derived from bovine bone. The effects of pH on the formation and properties of HA coatings were systematically examined. Samples exposed to acidic conditions or left without pH adjustment led to the formation of HA, contrasting with the outcomes observed through dissolution methods. Different characterization techniques, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X‐ray diffraction (XRD), were employed to evaluate the quality and crystallinity of the coatings. Among the samples, those exhibiting superior crystallinity and nanostructured features, including bovine HA, were selected for further surface functionalization with the antibiotic enrofloxacin using spin coating. As expected, the antibiotic loading on each material's surface depended on the amount of HA deposited on the substrate. However, the desorption results indicated that, in all cases, desorption persisted beyond 38 h, implying that HA‐loaded matrices could be effective systems for controlled and prolonged drug release, which could be useful in dental or orthopedic implants for inhibiting the growth of bacterial biofilms. [ABSTRACT FROM AUTHOR]

Recently, two-dimensional systems have attracted considerable interest from scientists, due to their high H 2 storage capacity and excellent reversibility. In this context, by means of DFT computations, we predict a novel system known as boron carbide, which can be formed by replacing 50% carbon atoms with boron atoms in tetragonal-graphene. We investigate the hydrogen adsorption performance of pristine and functionalized t-B 4 C 4 sheets with the metals Li/Sc/Ti. Results indicate that metal-decorated t-B 4 C 4 exhibits significantly lower H 2 adsorption energies compared to pristine t-B 4 C 4. Moreover, the hydrogen storage capacities for Li/Sc/Ti@t-B 4 C 4 are 13.32%, 10.03% and 9.74% respectively. Furthermore, the desorption temperature exceeds the critical temperature of H 2. Based on activation energy, H 2 can migrate quickly on the t-B 4 C 4 sheet during the adsorption/desorption cycles. Our results indicate that t-B 4 C 4 functionalized with Li/Sc/Ti-metals can be an efficient material for hydrogen storage. • Based on DFT and AIMD, we predict a novel material known as t-B 4 C 4 monolayer for hydrogen storage. • Li/Sc/Ti-decoration improves the H 2 -storage performance on t-B 4 C 4 monolayer. • The wt%.H 2 for the Li/Ti/Sc-decorated t-B 4 C 4 are found to be 13.32, 10.03 and 9.74 wt%, respectively. • Desorption temperatures higher than hydrogen's critical point are found. • Hydrogen molecule can move quickly on the t-B 4 C 4 monolayer. [ABSTRACT FROM AUTHOR]

Electric potential controlled lubrication, also known as triboelectrochemistry or electrotunable tribology, is an emerging field to regulate the friction, wear, and lubrication performance under charge distribution on the solid–liquid interfaces through an applied electric potential, allowing to achieve superlubrication. Electric potential controlled lubrication is of great significance for smart tunable lubrication, micro-electro-mechanical systems (MEMS), and key components in high-end mechanical equipment such as gears and bearings, etc. However, there needs to be a more theoretical understanding of the electric potential controlled lubrication between micro- and macro-scale conditions. For example, the synergistic contribution of the adsorption/desorption process and the electrochemical reaction process has not been well understood, and there exists a significant gap between the theoretical research and applications of electric potential controlled lubrication. Here, we provide an overview of this emerging field, from introducing its theoretical background to the advantages and characteristics of different experimental configurations (including universal mechanical tribometers, atomic force microscopes, and surface force apparatus/balances) for electric potential controlled lubrication. Next, we review the main experimental achievements in the performance and mechanisms of electrotunable lubrication, especially using ionic lubricants, including electrolyte solutions, ionic liquids, and surfactants. This review aims to survey the literature on electric potential controlled lubrication and provide insights into the design of superlubricants and intelligent lubrication systems for various applications. [ABSTRACT FROM AUTHOR]

This work aims to demonstrate that the Fe2O3 nanocrystals' adsorptive and photocatalytic properties can be adjusted by exposing the crystal facets that are functionalized. To this end, cube- and disc-like structures were synthesized using a metal ion-mediated hydrothermal route. Thereafter, some of the samples were annealed at 500 °C for 3 h. Our paper combines the experimental part with theoretical calculations of the obtained materials' band edge positions. The results reveal that—aside from hematite—the as-synthesized discs also contain γ-FeOOH and β-Fe2O3 phases, which transform into α-Fe2O3 during annealing. The hydrodynamic diameter, zeta potential, and adsorption kinetics measurements show that the cube-like samples exhibit the highest affinity for cationic, whereas the discs have an affinity for anionic dye. Measurements of the wall zeta potential also reveal that annealing the discs modifies their surface state and ability to adsorb molecules. Photocatalytic tests show that the as-synthesized powders have better photocatalytic performance toward methylene blue decomposition than the annealed ones. The observed small changes in the concentration of the MO during illumination result from the energy band structure of the cube-like crystal orientation. [ABSTRACT FROM AUTHOR]

Macroporous resins are employed for the purification of polyphenolic extracts. However, the relationship between the adsorption and desorption and the textural properties remains unexplored. Thus, we evaluated the textural properties of HP-20, XAD-16 and SP-825 resins and their impact on adsorption and desorption of specific polyphenols like gallic acid, epigallocatechin, and procyanidin B2. The HP-20 resin exhibited a type II isotherm with macroporous structure, while XAD-16 and SP-825 resins displayed type IV isotherms, typically associated with mesoporous materials. The HP-20 resin demonstrated superior adsorption capacity and rupture points for epigallocatechin (2.37 mg/g, 124 min) and procyanidin B2 (1.29 mg/g, 136 min) compared to SP-825 and XAD-16. Contrary, the SP-825 resin exhibited the highest adsorption capacity (5.34 mg/g) and rupture point (68 min) for gallic acid. However, the desorption was more efficient when HP-20 resin was used for all specific polyphenols. Therefore, for an efficient purification process is necessary to consider the chemical structure of the polyphenol and the textural properties. [ABSTRACT FROM AUTHOR]

In this particular study, a hydrogel known as SAP-1 was synthesized through the grafting of acrylic acid-co-acrylamide onto pullulan, resulting in the creation of Pul-g-Poly (acrylic acid-co-acrylamide). Additionally, a sponge hydrogel named SAP-2 was prepared by incorporating the surfactant sodium dodecyl benzene sulfonate (SDBS) into the hydrogel through free radical solution polymerization. To gain further insight into the composition and properties of the hydrogels, various techniques, such as Fourier transform infrared spectroscopy, hydrogen nuclear magnetic resonance (1H NMR), atomic absorption spectroscopy, and field emission scanning electron microscopy (FE-SEM), were employed. Conversely, the absorption kinetics and the equilibrium capacities of the prepared hydrogels were investigated and analyzed. The outcomes of the investigation indicated that each of the synthesized hydrogels exhibited considerable efficacy as adsorbents for cadmium (II), copper (II), and nickel (II) ions. In particular, SAP-2 gel displayed a remarkable cadmium (II) ion absorption ability, with a rate of 190.72 mg/g. Following closely, SAP-1 gel demonstrated the ability to absorb cadmium (II) ions at a rate of 146.9 mg/g and copper (II) ions at a rate of 154 mg/g. Notably, SAP-2 hydrogel demonstrated the ability to repeat the adsorption–desorption cycles three times for cadmium (II) ions, resulting in absorption capacities of 190.72 mg/g, 100.43 mg/g, and 19.64 mg/g for the first, second, and third cycles, respectively. Thus, based on the abovementioned results, it can be concluded that all the synthesized hydrogels possess promising potential as suitable candidates for the adsorption and desorption of cadmium (II), copper (II), and nickel (II) ions. [ABSTRACT FROM AUTHOR]

Abstract Cell immobilization plays an important role in biocatalysis for high-value products. It is necessary to maintain the viability of immobilized cells for bioconversion using viable cells as biocatalysts. In this study, a novel polyester nonwoven chemostat was designed for cell immobilization to investigate biofilm formation and the dynamic balance between adsorption and desorption of cells on polyester nonwoven. The polyester nonwoven was suitable for cell immobilization, and the cell numbers on the polyester nonwoven can reach 6.5 ± 0.38 log CFU/mL. After adding the polyester nonwoven to the chemostat, the fluctuation phenomenon of free bacterial cells occurred. The reason for this phenomenon was the balance between adsorption and desorption of bacterial cells on the polyester nonwoven. Bacterial cells could adhere to the surface of polyester nonwoven via secreting extracellular polymeric substances (EPS) to form biofilms. As the maturation of biofilms, some dead cells inside the biofilms can cause the detachment of biofilms. This process of continuous adsorption and desorption of cells can ensure that the polyester nonwoven chemostat has lasting biological activity. Graphical Abstract

The use of phyllite (Phy) instead of quartz in mixtures with bentonite (B) is recommended as a buffer material for engineering barriers in a geological repository of nuclear waste. The recommendation is based on experimentally determined sorption properties of various Phy/B mixtures. The adsorption capacity of Phy/B mixtures (Phy/B: 75/25, 50/50, and 25/75), the removal efficacy of Eu(III) ions (an analog for fissiongenic lanthanides and actinides), and the rate of their binding reaction were studied using the batch adsorption equilibrium and kinetic experiments at different Eu(III) initial concentrations, solution pH, and solution to adsorbent (L/S) ratio. The adsorption capacity of the Phy/B mixtures increased with the increased bentonite content in the mixture depending on the L/S ratio and solution pH. The highest increase in the adsorption capacity of the Phy/B mixtures compared to phyllite was observed for the Phy/B proportions of 25/75 and 50/50. The rate of the Eu(III) adsorption was the best fitted by the pseudo-second-order kinetic model indicating that the adsorption rate was controlled by chemisorption. The Sips model provided the best correlation of the adsorption experimental data, indicative of more than one adsorption site. The results of this study show the advantage of the Phy/B mixtures in immobilizing Eu and certain fission products by combining adsorption properties of the materials. [ABSTRACT FROM AUTHOR]

Purpose: The three objectives are as follows: (1) to characterize phosphorus (P) adsorption/desorption with a series of representative iron/aluminum (Fe/Al) (hydr)oxides; (2) to assess the cyanobacterial availability of P adsorbed onto Fe/Al (hydr)oxides; and (3) to correlate the cyanobacterial availability of P to its adsorption/desorption onto Fe/Al (hydr)oxides and pH and discuss the related ecological implication. Materials and methods: Using five representative minerals (ferrihydrite, goethite, hematite, bayerite, and corundum), we conducted P isothermal adsorption onto Fe/Al (hydr)oxides with pH changing from 6 to 10. The cyanobacterial availability of P adsorbed onto Fe/Al (hydr)oxides (0.2 mg P g−1) was assessed by using a bioassay method with two cyanobacteria species, Microcystis aeruginosa and Dolichospermum flos-aquae, as test organisms. The 0.1 M NaOH was used to desorb P from Fe/Al (hydr)oxides that adsorbed P with different saturation degree during isothermal adsorption, to compare P desorption and its cyanobacterial availability. Results and discussion: This research verified that P adsorbed onto Fe/Al (hydr)oxides (P@Fe/Al (hydr)oxides) is a direct P source for cyanobacteria, which is available to cyanobacterial cells through desorption from mineral particles by pH regulation. The cyanobacterial availability of P@Fe/Al (hydr)oxides was dependent on mineral desorption, showing the following order: ferrihydrite < goethite < bayerite < corundum < hematite. The cyanobacterial availability of P, at an absorption amount of 0.2 mg P per gram of mineral, ranged from 66.1 to 99.4% and from 58.7 to 85.1% as assessed by Microcystis aeruginosa and Dolichospermum flos-aquae, respectively. With increasing adsorption saturation, the availability of P@Fe (hydr)oxides increased, while the availability of P@Al (hydr)oxides decreased. Conclusion: This research clarifies the relationship between the cyanobacterial availability of P and its adsorption/desorption on/from Fe/Al minerals, providing deeper insight into the ecological function of Fe/Al (hydr)oxides in water bodies. This research implies that we can characterize the buffering function of sediments/suspended particles contained Fe/Al (hydr)oxides by an adsorption–desorption equilibrium with pH regulation, greatly simplifying the complex problems in natural water bodies. [ABSTRACT FROM AUTHOR]

Abstract Inspired by biological materials, the self-shaping wood composites induced by relative humidity (RH) have been investigated over the last decade. In this study, a wood bilayer was fabricated by assembling two layers with perpendicular fiber orientation in a series of thickness ratios and initial moisture contents (iMC). The self-shaping response of the wood bilayer was explored as a function of its configuration, and the discrepancies between moisture adsorption and desorption processes were clarified. Higher iMC limited the evolution of curvature. During both the adsorption and desorption processes, a reversed bending response was observed, and there was a hysteretic bending behavior between them. Repeatable bending was achieved during the cyclic ad/desorption process, and a larger hysteresis loop was observed at a lower thickness ratio. Finite-element analysis showed that the maximum stress occurred at the interface between the active and passive layers, and larger thickness ratios had lower maximum stress. In addition, the bilayer composed of a 200 μm passive layer and a 400 μm active layer with 0.6% iMC was found to be the most sensitive to RH change. The results of this study elucidate the moisture-dependent bending response of wood bilayers and provide the possibility of precisely controlling the curvature of self-shaping wood composites in industrial applications.

A solid (coal) - gas (CH4) - liquid (surfactant) three-phase interaction system model is established based on the Grand Canonical Monte Carlo (GCMC) and Molecular Dynamics (MD) methods. The effects of the nanoparticle composite cationic surfactant CTAB, anionic surfactant SDBS and nonionic surfactant VAEO8 on CH4 adsorption/desorption and diffusion in coal are investigated from the aspects of adsorption configuration, adsorption amount, interaction energy, relative concentration distribution and diffusion coefficient. The results show that the surfactants and nanoparticles are imbibed into coal pores, occupying the adsorption sites of CH4 on the coal surface under the wetting effect and electrostatic action. In the absence of nanoparticles, the anionic surfactant SDBS enhances the hydrophilicity of coal and has the best effect on promoting CH4 desorption. Whereas the cationic surfactant CTAB and nonionic surfactant VAEO8 enhance the hydrophobicity of coal, resulting in a weaker CH4 desorption capacity. Nanoparticles and surfactants act synergistically in reducing solid-liquid interfacial tension, so nanoparticle composite surfactants are better than surfactants without nanoparticles in promoting CH4 desorption. After adding nanoparticles, the electrostatic force and interaction energy of the system are all increased. The CH4 diffusion coefficient in the raw coal system > the CH4 diffusion coefficient in surfactant coal system > the CH4 diffusion coefficient in coal system with nanoparticles composite surfactant. Overall, the mechanism of the influence of nanoparticle composite different types of surfactants on CH4 adsorption and diffusion is clarified from the microscopic point of view, and the study provides a theoretical basis for optimizing fracturing fluid system to improve coalbed methane recovery.

The reduced graphene oxide aerogel modified by 4-chlorophenyl sulfoxide was obtained by a simple self-assemble process under the basic reduction-oxide condition, then freeze-dried for future using. The prepared aerogel was shortly named 4CS-rGO, which was characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscope, et al. 1 mg of 4CS-rGO composite was used as an adsorbent to adsorb Pd(II) and Pt(IV) in 1.0 mL 40 mM Britton-Robinson buffer solution with various pH. The adsorption efficiency of Pd(II) increased with the increase in pH, whereas the hydrolysis of Pd(II) happened at pH 13, and the maximum adsorption efficiency of Pd(II) was 91.82% at pH 12, which was mainly driven by electrostatic attraction. Besides, the adsorption behavior of the 4CS-rGO composite for Pt(IV) was explored to evaluate the possibility to isolate Pd(II) and Pt(IV) ions by using aerogel. We found that, quite interestingly, hydrogen bond, hydrophobic interaction and van der Waals force can strongly conquer electrostatic repulsion driven Pt(IV) ions adsorption behavior at pH 5, and Pt(IV) ions displaced by cationic surfactant. Moreover, a tighter Pt(IV) ions adsorption behavior than Pd(II) ions was observed while we adsorb them respectively with/without 4-chlorophenyl sulfoxide modified the graphene, while branched TBAB was easier and more effectively replaced the adsorbed Pt(IV) ions than strained CTAB. [ABSTRACT FROM AUTHOR]

Aluminum‐based lithium adsorbent (Li/Al‐LDH) is the only industrialized adsorbent for Li+ extraction from salt lake brines. The inherent mechanism of declined Li+ adsorption performance was revealed to explain the feebleness in sulfate‐type brines. SO42− in brines could replace interlayer Cl− by a stronger electrostatic attraction with laminates, significantly altering the stacking structure and interlayer spacing, while Cl K‐edge of XAFS showed intercalated SO42− would not obviously change the chemical environment of interlayer Cl−. Experiments as well as DFT and FEM simulations indicated the intercalated SO42− regulated Li+ adsorption of Li/Al‐LDHs at different ionic strength under a combined effect of expanded interlayers, close packing, and electrostatic repulsion. Although sufficient SO42− contents in brines might promote the single Li+ adsorption by offering ionic strength as a driving force, the long‐term usability would be severely impaired as SO42− intercalation in interlayers reduced the subsequent Li+ adsorption capacity and increased the desorption difficulty. [ABSTRACT FROM AUTHOR]

Electric potential controlled lubrication, also known as triboelectrochemistry or electrotunable tribology, is an emerging field to regulate the friction, wear, and lubrication performance under charge distribution on the solid–liquid interfaces through an applied electric potential, allowing to achieve superlubrication. Electric potential controlled lubrication is of great significance for smart tunable lubrication, micro-electro-mechanical systems (MEMS), and key components in high-end mechanical equipment such as gears and bearings, etc. However, there needs to be a more theoretical understanding of the electric potential controlled lubrication between micro- and macro-scale conditions. For example, the synergistic contribution of the adsorption/desorption process and the electrochemical reaction process has not been well understood, and there exists a significant gap between the theoretical research and applications of electric potential controlled lubrication. Here, we provide an overview of this emerging field, from introducing its theoretical background to the advantages and characteristics of different experimental configurations (including universal mechanical tribometers, atomic force microscopes, and surface force apparatus/balances) for electric potential controlled lubrication. Next, we review the main experimental achievements in the performance and mechanisms of electrotunable lubrication, especially using ionic lubricants, including electrolyte solutions, ionic liquids, and surfactants. This review aims to survey the literature on electric potential controlled lubrication and provide insights into the design of superlubricants and intelligent lubrication systems for various applications.

This work aims to demonstrate that the Fe2O3 nanocrystals’ adsorptive and photocatalytic properties can be adjusted by exposing the crystal facets that are functionalized. To this end, cube- and disc-like structures were synthesized using a metal ion-mediated hydrothermal route. Thereafter, some of the samples were annealed at 500 °C for 3 h. Our paper combines the experimental part with theoretical calculations of the obtained materials’ band edge positions. The results reveal that—aside from hematite—the as-synthesized discs also contain γ-FeOOH and β-Fe2O3 phases, which transform into α-Fe2O3 during annealing. The hydrodynamic diameter, zeta potential, and adsorption kinetics measurements show that the cube-like samples exhibit the highest affinity for cationic, whereas the discs have an affinity for anionic dye. Measurements of the wall zeta potential also reveal that annealing the discs modifies their surface state and ability to adsorb molecules. Photocatalytic tests show that the as-synthesized powders have better photocatalytic performance toward methylene blue decomposition than the annealed ones. The observed small changes in the concentration of the MO during illumination result from the energy band structure of the cube-like crystal orientation.

In this particular study, a hydrogel known as SAP-1 was synthesized through the grafting of acrylic acid-co-acrylamide onto pullulan, resulting in the creation of Pul-g-Poly (acrylic acid-co-acrylamide). Additionally, a sponge hydrogel named SAP-2 was prepared by incorporating the surfactant sodium dodecyl benzene sulfonate (SDBS) into the hydrogel through free radical solution polymerization. To gain further insight into the composition and properties of the hydrogels, various techniques, such as Fourier transform infrared spectroscopy, hydrogen nuclear magnetic resonance (1H NMR), atomic absorption spectroscopy, and field emission scanning electron microscopy (FE-SEM), were employed. Conversely, the absorption kinetics and the equilibrium capacities of the prepared hydrogels were investigated and analyzed. The outcomes of the investigation indicated that each of the synthesized hydrogels exhibited considerable efficacy as adsorbents for cadmium (II), copper (II), and nickel (II) ions. In particular, SAP-2 gel displayed a remarkable cadmium (II) ion absorption ability, with a rate of 190.72 mg/g. Following closely, SAP-1 gel demonstrated the ability to absorb cadmium (II) ions at a rate of 146.9 mg/g and copper (II) ions at a rate of 154 mg/g. Notably, SAP-2 hydrogel demonstrated the ability to repeat the adsorption–desorption cycles three times for cadmium (II) ions, resulting in absorption capacities of 190.72 mg/g, 100.43 mg/g, and 19.64 mg/g for the first, second, and third cycles, respectively. Thus, based on the abovementioned results, it can be concluded that all the synthesized hydrogels possess promising potential as suitable candidates for the adsorption and desorption of cadmium (II), copper (II), and nickel (II) ions.

Inspired by biological materials, the self-shaping wood composites induced by relative humidity (RH) have been investigated over the last decade. In this study, a wood bilayer was fabricated by assembling two layers with perpendicular fiber orientation in a series of thickness ratios and initial moisture contents (iMC). The self-shaping response of the wood bilayer was explored as a function of its configuration, and the discrepancies between moisture adsorption and desorption processes were clarified. Higher iMC limited the evolution of curvature. During both the adsorption and desorption processes, a reversed bending response was observed, and there was a hysteretic bending behavior between them. Repeatable bending was achieved during the cyclic ad/desorption process, and a larger hysteresis loop was observed at a lower thickness ratio. Finite-element analysis showed that the maximum stress occurred at the interface between the active and passive layers, and larger thickness ratios had lower maximum stress. In addition, the bilayer composed of a 200 μm passive layer and a 400 μm active layer with 0.6% iMC was found to be the most sensitive to RH change. The results of this study elucidate the moisture-dependent bending response of wood bilayers and provide the possibility of precisely controlling the curvature of self-shaping wood composites in industrial applications. [ABSTRACT FROM AUTHOR]

Small mineral particles present in soils, such as clay minerals and some oxyhydroxides, constitute important nutrient reservoirs. This behavior is due to the negative charges and high specific surface areas of these particles allowing them to adsorb cations such as calcium (Ca), a macronutrient that occupies key physiological and structural functions in plant metabolism. Although the chemical reactivity of clay minerals is rather well-known in the literature, especially toward macronutrients such as Ca, that of oxyhydroxides such as phyllomanganate minerals remains largely unexplored. To enhance our understanding of the mechanisms at the origin of the storage/release of the different isotopes of Ca in a soil solution, the possible fractionation between 40Ca and 44Ca during adsorption and desorption of Ca on a synthetic phyllomanganate, abiotically precipitated in the laboratory [synthetic analog of vernadite (δ-MnO 2)], was studied. Experiments were performed in batch (closed system), and several parameters (time, pH of the solution, Ca concentration and nature and concentration of the desorbent) were tested to cover a large range of physicochemical conditions. This study demonstrated that the light 40Ca isotope is preferentially adsorbed on δ-MnO 2 , with Δ44/40Ca (the apparent fractionation of the aqueous solution at the stationnary state of adsorption compared to the initial one) of the adsorbed Ca that can reach 1.19 ± 0.15‰. The results showed that this isotopic fractionation occurs at chemical equilibrium in a closed system and that the isotopic fractionation measured in this study during Ca adsorption on phyllomanganate is significantly higher than that reported in the literature during Ca adsorption on other soil constituents such as clay minerals. At pH below 4 Ca occupies only the interlayer/basal sites whereas above this pH Ca fills interlayer/basal sites (∼86%) and edges sites (∼14%). By combining the experimental data obtained at different pH values, initial Ca concentrations and interaction times, our results suggest that isotopic signature of the Ca adsorbed on δ-MnO 2 is dependent on the nature of the site involved in the adsorption step (i.e., enriched in 40Ca in the interlayer with Δ44/40Ca equal to −0.43‰ and enriched in 44Ca when bound to the edges with Δ44/40Ca equal to +3.5‰). As revealed by surface complexation modeling, such contrasting behavior between the two types of adsorption sites could be due to the bidendate nature of the Ca adsorption occurring on edges and to ion exchange of Ca2+ with H+ in the interlayer sites. Finally, desorption experiments point to total but not instantaneous Ca desorption, probably due to a partial collapse of the interlayer with some ions used to desorb Ca2+ (K+, NH 4 +, hexaamine-cobalt). This suggests that the amount of bioavailable Ca in soils by simple ion-exchange reactions is highly dependent on the nature of the ions which could desorb Ca present in the soil solution. [ABSTRACT FROM AUTHOR]

Goethite was modified by chitosan (CS) or poly(acrylic acid) (PAA) to improve its adsorptive abilities toward components of agrochemicals, i.e., copper ions (Cu), phosphate ions (P), and diuron. The pristine goethite effectively bound Cu (7.68 mg/g, 63.71%) and P (6.31 mg/g, 50.46%) only in their mixed systems. In the one adsorbate solutions, the adsorption levels accounted for 3.82 mg/g (30.57%) for Cu, 3.22 mg/g (25.74%) for P, and 0.15 mg/g (12.15%) for diuron. Goethite modification with CS or PAA did not yield spectacular results in adsorption. The maximum increase in adsorbed amount was noted for Cu ions (8.28%) after PAA modification as well as for P (6.02%) and diuron (24.04%) after CS modification. Both goethite modifications contributed to clear reduction in desorption of pollutants (even by 20.26% for Cu after PAA coating), which was mainly dictated by electrostatic attractive forces and hydrogen bonds formation occurring between macromolecules and impurities. The only exception in this phenomenon was Cu desorption from CS-modified solid—the polymer made it higher (to 95.00%). The Cu adsorption on PAA-modified goethite enhanced solid aggregation and thus facilitated metal cation separation from aqueous media. Consequently, the goethite modification with PAA was considered more promising for environmental remediation. [ABSTRACT FROM AUTHOR]

Pharmaceutical metabolites and their residues have been identified as major environmental pollutants in aquatic ecosystems. N-succinyl chitosan (NSCS) was studied as a potential adsorbent for a pharmaceutical residue, fluoxetine, from aqueous media. NSCS was investigated using Fourier transform infrared (FTIR) and 1H-nuclear magnetic residence (NMR) spectroscopies. Scanning electron microscopy (SEM) was used to investigate the formation of nanofibers by electrospinning of these green biomaterial polymer membranes. The mechanisms of FLX adsorption, as well as the effects of pH value in the original solution on adsorption capacities, were investigated using high-performance liquid chromatography (HPLC-UV DAD) under identical adsorption conditions. It was found that NSCS/PEO nanofibers with a diameter of 183 ± 38 nm were more effective to remove pharmaceutical residues from aqueous media than other commercial and modified adsorbents such as activated carbon (AC). FLX adsorption on NSCS/PEO nanofibers was favoured at pH 8.0. Pseudo-first order model was the more adequate to represent the kinetic data, being the maximum adsorption capacities of FLX on NSCS/PEO reached up to 70%. A study of the desorption potential and reusability of the mat was also conducted. According to the results, electrospun NSCS/PEO mats can be desorption and reused up to 4 times without significant loss in adsorption capability.

Abstract Background C-glycosylated flavonoids are a main type of structural modification and can endow flavonoids with greater stability, bioactivity, and bioavailability. Although some C-glycosylated flavonoids have been biosynthesized in vivo or vitro, only a few C-glycosylflavonols have been prepared by these methods. Results In this study, several uridine 5’-diphosphate (UDP)-glucose biosynthesis pathways and Escherichia coli hosts were screened to reconstruct recombinant strains for producing the novel C-glycosylflavonols kaempferol 8-C-glucoside and quercetin 8-C-glucoside. To increase C-glycosylflavonol production, the timing of flavonol addition was adjusted, and glycerol was added to avoid degradation of C-glycosylflavonols. By using resting cell bioconversion, the highest kaempferol 8-C-glucoside and quercetin 8-C-glucoside production reached 16.6 g/L and 12.5 g/L, respectively. Then, ultrasound-assisted adsorption/desorption was used to prepare C-glycosylflavonols by using macroporous resins. Through screening macroporous resins and optimizing the adsorption/desorption conditions, the highest adsorption capacity and desorption capacity for kaempferol 8-C-glucoside on HPD100 reached 28.57 mg/g and 24.15 mg/g, respectively. Finally, kaempferol 8-C-glucoside (15.4 g) with a yield of 93% and quercetin 8-C-glucoside (11.3 g) with a yield of 91% were obtained from 1 L of fermentation broth. Conclusions Kaempferol 8-C-glucoside and quercetin 8-C-glucoside are novel C-glycosylflavonols, which have not been extracted from plants. This study provides an efficient method for the preparation and biocatalytic synthesis of kaempferol 8-C-glucoside and quercetin 8-C-glucoside by metabolic engineering of Escherichia coli. Graphical Abstract

This paper outlines the fabrication of zeolite humidity control material via alkaline melting and hydrothermal synthesis based on solar panel waste glass (SPWG) and sandblasting waste (SW). We assessed the effects of Si/Al molar ratio, crystallization temperature, and crystallization time on microstructure and humidity control properties. Synthesis parameters were optimized using the Box-Behnken DOE strategy. In experiments, a crystallization temperature of 120 °C and crystallization time of 48 h with a Si/Al ratio of 2.0 resulted in a highly uniform zeolite material. The resulting synthetic zeolite possessed a surface area of 100.34 m2/g, a pore volume of 0.161 cm3/g, and an optimal crystal size of 12.66 nm. Under optimal application conditions, the proposed zeolite achieved water vapor adsorption capacity of 73.17 g/m2. This study provides a feasible alternative use for recycled solar panel waste glass and sandblasting waste, which has great potential for waste recycling in the future.

This research aims to conduct a general study about the dolomite ability for the removal of heavy metals (Ag, Cu, Cd, Co, Ni, Ba, and Sr ions) in aqueous solutions. Desorption studies were performed for adsorbent recovery and reuse in adsorption processes. This research focused on the dependence of the adsorption capacity on the process parameters including pH in the range of 2–8, metal concentration in the range of 10–60 mg/L, the temperature in the range of 20–50 °C, and period of the domain of 5 min–6 hr. The dolomite powder was characterized using X-ray, scanning electron microscope (SEM), and Fourier-transform infrared spectroscopy (FTIR). The process optimization was analyzed using CCD, and RSM with three independent values of adsorbate (categoric), temperature, and concentration. The maximum adsorption of heavy metals was 60 mg/L and 293 K with a desirability of 0.976. The kinetic studies indicate that the pseudo-second-order (PSO) model for the adsorption of Ni, Ag, Co, Cu, Cd, and Ba ions indicated a better correlation with the experimental results. Thermodynamic factors implied that processes are spontaneous with heat releasing. The outcome showed that the temperature and concentration interaction in the designated range had a high effect on the maximum ability adsorption of metallic ions. Besides, the maximum adsorption for nickel-metal has occurred. The order of coefficient of mass transfer and flux of mass transfer obeys this arrangement: Cu > Sr > Cd > Ni > Ba > Ag > Co. This comparison demonstrates that the Cu ions have more tendency to migrate inside the pores, and Co ions have the least tendency to enter the pores. A comparison of the results revealed this case that Iranian dolomite has an appropriate potential in eliminating heavy metals in terms of capacity and economy.

High moisture content affecting coal bed methane (CBM) occurrence and transport is a typical feature of low-rank coal (LRC). The mechanism of the influence of moisture on methane diffusion properties of LRC is critical to improve CBM production and prevent coal and gas outburst. In this paper, a new method was designed to prepare coal samples with different moisture contents (0–16.80%). The desorption experiment at different moisture contents was conducted to study the time-varying diffusion properties of selected LRC and medium-rank coal samples. Results show that with the moisture content increase, the desorption volume and the initial desorption rate of LRC decrease obviously. Based on the negative linear relationship between the initial diffusion coefficient (D0) and moisture content (M), a mathematical model between them is established, which can be described as D0 = λM + Ddry, where λ and Ddry are the material constant and D0 of the dry coal sample, respectively. Moreover, with the increase in moisture content, the time-varying diffusion coefficient (Dt) and its decay rate decrease obviously. It indicates that moisture can significantly reduce the diffusion capacity of LRC, and the competitive adsorption between moisture and methane molecules is an important factor affecting the diffusion properties of LRC. It is worth noting that there is a critical value of moisture content, beyond which increasing moisture content has no significant effect on reducing desorption and diffusion capacity. Results can provide a theoretical basis for taking hydraulic technology to prevent outburst in LRC mining. Article Highlights: Moisture can significantly reduce methane desorption capacity of low-rank coal. Effect of moisture on the time-varying diffusion properties of methane in low-rank coal was studied. Mathematical model of methane initial diffusion coefficient and moisture was established. [ABSTRACT FROM AUTHOR]

The co-occurrence of mixtures of glyphosate (GLP) and aminomethylphosphonic acid (AMPA) in contaminated water, soil, sediment, and plants is a cause for concern due to potential threats to the ecosystem and human health. Major routes of exposure include contact with contaminated water and soil and through consumption of crops containing GLP and AMPA residues. Calcium montmorillonite (CM) and acid-processed montmorillonite (APM) clays were investigated for their ability to tightly sorb and detoxify GLP and AMPA mixtures. In vitro adsorption and desorption isotherms and thermodynamic analysis indicated saturable Langmuir binding of both chemicals with high capacities, affinities, enthalpies, and free energies of sorption and low desorption rates. In silico computational modeling indicated that both GLP and AMPA can be readily absorbed onto clay surfaces through electrostatic interactions and hydrogen bonding. The safety and efficacy of the clays were confirmed using well-established living organisms, including an aquatic cnidarian (Hydra vulgaris), a soil nematode (Caenorhabditis elegans), and a floating plant (Lemna minor). Low levels of clay inclusion (0.05% and 0.2%) in the culture medium resulted in increased growth and protection against chemical mixtures based on multiple endpoints. Results indicated that montmorillonite clays may be used to bind mixtures of GLP and AMPA in water, soil, and plants. [ABSTRACT FROM AUTHOR]

• Biochars (BCs) were produced by pyrolysis of potato or raspberry stems at 600 °C. • They are effective adsorbents in the systems containing two different impurities. • Dissolved organic carbon of BCs was composed of aromatic substances of large weight. • The examined biochars showed satisfactory potential for environmental remediation. This paper presents a method of agricultural waste management — the production of two biochars (BC) from potato and raspberry stems. It defines the potential of these materials for remediation of degraded water and soil environments. The performed study included analyses of BC physicochemistry, dissolved organic carbon (DOC) release and ability to immobilize copper (Cu), tetracycline (TC) and carboxin (CB) in one- and two-adsorbate systems. The BCs were obtained with pyrolysis at 600 °C for 30 min in a nitrogen atmosphere. Their DOC was predominantly constituted of substances with large molecular weights and high aromaticity, meaning that both BCs can be safely applied as soil additives. Potato-biochar (P-BC) had a more developed surface than raspberry-biochar (R-BC). The specific surface area (S BET) of P-BC was 122 m2/g, whilst of R-BC was 87 m2/g. As a result, the efficiency of impurity adsorption in the one-adsorbate systems was higher for P-BC (61.75% for Cu, 73.84% for TC, and 54.43% for CB). In the two-adsorbate systems, organic impurities improved the immobilization of heavy metal ions on BCs. The efficiency of Cu adsorption on P-BC when TC was present was 88.29%. Desorption of Cu from BC was highest using HCl, whilst that of TC and CB was highest using NaOH. Maximum desorption was observed in a two-adsorbate system with TC + CB (up to 63.6% for TC). These results confirmed that potato and raspberry stems can be used to produce highly effective BCs with large application potential, especially for remediation of degraded soils and polluted waters. [ABSTRACT FROM AUTHOR]

Pharmaceutical metabolites and their residues have been identified as major environmental pollutants in aquatic ecosystems. N-succinyl chitosan (NSCS) was studied as a potential adsorbent for a pharmaceutical residue, fluoxetine, from aqueous media. NSCS was investigated using Fourier transform infrared (FTIR) and 1H-nuclear magnetic residence (NMR) spectroscopies. Scanning electron microscopy (SEM) was used to investigate the formation of nanofibers by electrospinning of these green biomaterial polymer membranes. The mechanisms of FLX adsorption, as well as the effects of pH value in the original solution on adsorption capacities, were investigated using highperformance liquid chromatography (HPLC-UV DAD) under identical adsorption conditions. It was found that NSCS/PEO nanofibers with a diameter of 183 ± 38 nm were more effective to remove pharmaceutical residues from aqueous media than other commercial and modified adsorbents such as activated carbon (AC). FLX adsorption on NSCS/PEO nanofibers was favoured at pH 8.0. Pseudo-first order model was the more adequate to represent the kinetic data, being the maximum adsorption capacities of FLX on NSCS/PEO reached up to 70%. A study of the desorption potential and reusability of the mat was also conducted. According to the results, electrospun NSCS/PEO mats can be desorption and reused up to 4 times without significant loss in adsorption capability. [ABSTRACT FROM AUTHOR]

Copyright of Coal Geology & Exploration is the property of Xian Research Institute of China Coal Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

[Display omitted] • High-carbon fly ash (HiC FA) was managed effectively through zeolite synthesis. • Immobilization potential of zeolite Na-X and its precursor was compared. • Na-X was a good adsorbent of metal cations (cadmium and copper ones). • Na-X modified with anionic polyacrylamide adsorbed Se(IV) more effeciently. • Herbicides were bound more strongly by Na-X after cationic polyacrylamide addition. Immobilization of toxic compounds on the solids limits their bioavailability in natural ecosystems. The use of waste-derived adsorbents for this purpose has additional benefit – the possibility of managing undesirable and dangerous by-products. Thus, the main aim of the study was to explore immobilization mechanism of metals (Cd, Cu), metalloids (As, Se), and herbicides (diuron, glyphosate) on zeolite Na-X free of ash residue, coming from waste solution after high carbon fly ash (HiC FA) conversion, under specific conditions – in multicomponent solutions as well as after solid modification with polymers. Immobilization strength was assessed based on adsorption/desorption studies, whereas the solid surface was investigated by XPS, FTIR, SEM-EDS, etc. The results obtained for Na-X was compared with those measured for its precursor, HiC FA. It was found that Na-X was a good adsorbent of Cu(II) and Cd(II) cations – it bound 195.8 mg/g (58.7 %) of Cd(II) and 126.9 mg/g (38.1 %) of Cu(II) mainly in the form of hydroxides. The Na-X modification with polymers made its adsorption capacity towards metalloid anions and herbicides higher. Anionic polyacrylamide increased the Se(IV) adsorption from 0.2 to 67.5 mg/g. Cationic polyacrylamide contributed to higher immobilization of glyphosate and diuron by 43.9 % and 46.4 %, respectively. [ABSTRACT FROM AUTHOR]

Concentrated photovoltaic (PV) is a suitable solution for reducing the cost of a PV system by focusing solar radiation on the panel with cheap collectors. However, increasing the radiation on the PV panel resulted in a higher operating temperature. The elevated temperature harms the panel's efficiency, which results in a reduced output of the generated power and PV's short life span. Considering these concerns, researchers introduced many cooling methods for more efficient and prolonged PV life. The adsorption/desorption cooling method is a new trend in PV cooling that utilizes atmospheric water harvesters to capture water from the atmosphere at night and release part of the PV heat in the daytime by evaporation of the adsorbed water. This article uses silica gel as the atmospheric water harvester to cool low-concentrated PV in the presence/absence of metal heat sinks. Three configuration designs are investigated for PV cooling: (i) cooling the concentrated PV with silica gel bed, (ii) cooling the concentrated PV with a combination of aluminum heat sink and silica gel bed, and (iii) cooling the concentrated PV with aluminum heat sink only. The work was conducted experimentally over 3 consecutive days, and the three configurations were tested at the same period and compared. It was found that the configuration, which uses a combination of a heat sink and silica gel bed, performs best with an average PV temperature reduction of 9.8 °C and enhanced generated power of 29.8 %. • A full day adsorption/desorption cycle is used to cool PV. • Three configurations of adsorption/desorptions and metal heat sinks for CPV cooling are investigated. • Temperature reduction and generated power are compared for three configurations. • A configuration of metal heat sink integrated with adsorption/desoption was the best. [ABSTRACT FROM AUTHOR]

At present, many studies have come to the conclusion that the coal seam contains primary CO gas, but the possibility of CO being adsorbed by coal after CO generated in drilling construction is not considered. In order to explore whether there is primary CO in spontaneous combustion coal seam in Northwest China, the original coal seam in-situ drilling detection method is used to detect primary CO. Three test boreholes are arranged in a row along the roadway side in the solid coal area not affected by mining. After the boreholes are sealed, high-purity N2 is used to replace the gas in the closed gas chamber, and the gas in the boreholes is extracted by a special air pump, so as to eliminate the impact of CO generated by coal oxidation on the test results during the construction of in-situ detection boreholes. On the basis of analyzing the source possibility of primary CO in coal seam and its emission theory, the variation characteristics of gas concentration in closed borehole with time are discussed. The results show that volume fraction of O2 and CO in the sealed borehole decrease rapidly with the extension of sealing time, and the volume fraction of O2 is stable below 2% after 12 days. After 12 days, the CO volume fraction is lower than 10−12, and no CO gas is detected by gas chromatograp. The gas in the borehole is mainly N2. It is concluded that there is no primary CO gas in the tested coal seam. The results of coal breaking test in N2 environment and coal sample oxidation test at normal temperature and constant temperature show that CO gas detected at the initial stage of borehole sealing comes from coal breaking operation in drilling construction.

Background: C-glycosylated flavonoids are a main type of structural modification and can endow flavonoids with greater stability, bioactivity, and bioavailability. Although some C-glycosylated flavonoids have been biosynthesized in vivo or vitro, only a few C-glycosylflavonols have been prepared by these methods. Results: In this study, several uridine 5'-diphosphate (UDP)-glucose biosynthesis pathways and Escherichia coli hosts were screened to reconstruct recombinant strains for producing the novel C-glycosylflavonols kaempferol 8-C-glucoside and quercetin 8-C-glucoside. To increase C-glycosylflavonol production, the timing of flavonol addition was adjusted, and glycerol was added to avoid degradation of C-glycosylflavonols. By using resting cell bioconversion, the highest kaempferol 8-C-glucoside and quercetin 8-C-glucoside production reached 16.6 g/L and 12.5 g/L, respectively. Then, ultrasound-assisted adsorption/desorption was used to prepare C-glycosylflavonols by using macroporous resins. Through screening macroporous resins and optimizing the adsorption/desorption conditions, the highest adsorption capacity and desorption capacity for kaempferol 8-C-glucoside on HPD100 reached 28.57 mg/g and 24.15 mg/g, respectively. Finally, kaempferol 8-C-glucoside (15.4 g) with a yield of 93% and quercetin 8-C-glucoside (11.3 g) with a yield of 91% were obtained from 1 L of fermentation broth. Conclusions: Kaempferol 8-C-glucoside and quercetin 8-C-glucoside are novel C-glycosylflavonols, which have not been extracted from plants. This study provides an efficient method for the preparation and biocatalytic synthesis of kaempferol 8-C-glucoside and quercetin 8-C-glucoside by metabolic engineering of Escherichia coli. [ABSTRACT FROM AUTHOR]

As an element relevant to human health, iodine is highly worthy of researchers' attention, especially the mechanism of iodine migration and enrichment in groundwater systems. A total of 43 groundwater, 1 seawater, 107 sediment, and 111 pore water samples from two boreholes (toward to Bohai Sea: BT, HH) were collected along a groundwater flow path at the North China Plain to investigate hydro-geochemical processes controlling groundwater iodine. High iodine groundwater (> 100 μg/L) was characterized by Na-Cl type, with high TDS values (827–2,400 mg/L) and high Cl (110–705 mg/L) and Br (416–1,180 μg/L) concentrations, which may be related to marine influence. Borehole BT and HH had pore water I concentration ranges of 1.4–132 μg/L and 3.6–830 μg/L, with high level that occurred near to coastline and corresponded to ancient transgression events. The results of sequential extraction of borehole sediments indicate that the fractions of sediment inorganic iodine mainly consisted of exchangeable, carbonate, and Fe-oxides associated fractions. Fe-oxides associated iodine was the main occurrence state in borehole BT far from the coastline, but high exchangeable iodine fractions (up to 92% of total extracted iodine) were observed in a high salinity borehole HH located near Bohai Bay, corresponding to the occurrence of high iodine pore water and groundwater. The analysis of iodine species indicates that iodide with strong migration ability dominated high iodine groundwater, pore water, and exchangeable sediment iodine, reflecting the occurrence of adsorption/desorption processes of iodine in groundwater system. High iodine groundwater and pore water exhibited iodine enrichment relative to Cl and Br, which suggests that iodine adsorbed on sediment desorbed under suitable pH and high solution ionic strength and subsequently released to pore water and aquifers. Inverse geochemical modeling stressed that ion exchange plays an important role in iodine enrichment of groundwater system. [ABSTRACT FROM AUTHOR]

Due to the extensive application of pesticides and their hazardous effects on organisms, there is an urgent need to remove them effectively from wastewater. Metal-incorporated carbon-mineral composites (Ni/Mn-CMC and Ni/Fe-CMC) described in this paper can certainly be applied for this purpose. They were synthesized by combining mechanochemical and pyrolytic processes and their physicochemical properties were investigated using numerous methods (SEM-EDS, N 2 adsorption/desorption, XRD, surface charge, FTIR). Adsorption capacity towards diuron and carboxin with and without impurities commonly detected in natural ecosystems, cadmium ions or arsenite, was measured. The obtained results indicated that Ni/Fe-CMC is more efficient adsorbent of pesticides due to its well-developed surface. It was able to bind 158.34 mg g−1 of diuron and 133.58 mg g−1 of carboxin in the solutions, where only one pesticide was present. In turn, these values for the Ni/Mn-CMC sample were 126.49 mg g−1 and 102.08 mg g−1, respectively. It should be noted that the composites maintained their high adsorption capacity in the multicomponent solutions, i.e., containing both pesticide and metal ions. Then, the maximum reduction in pesticide adsorption was only 8.36. Ni/Mn-CMC and Ni/Fe-CMC were successfully regenerated with ethanol without changing their structure and adsorption capacity. Also, the extracts from investigated materials did not have negative impact on plant growth. This confirmed suitability of carbon-mineral composites for repeated multiple use without toxic effects to organisms. [Display omitted] • Mechanochemistry was applied to synthesize new adsorbents of diuron and carboxin. • Carbon-mineral composite with Ni and Fe bound even 82.30% of diuron. • The materials retained their abilites in the presence of metals and metalloids. • In the system with both pesticides, their efficiency was reduced by max. 25.78%. • After regeneration with alcohol, they can be reused in pesticide removal. [ABSTRACT FROM AUTHOR]

In this study, zeolite clay was modified with Fe-Al LDH (layered double hydroxide or hydrotalcite) under ultrasonic process and was then used to remove methyl violet (MV) and Nile blue (NB) dyes from aqueous media. Various analyses such as FT-IR, EDX, SEM, and XRD were done to evaluate the adsorbent properties. The highest sorption efficiency of MV and NB dyes was 99.15% and 98.16%, respectively, which indicate significant adsorption efficiencies. The highest adsorption efficiency of MV dye was obtained at pH 8, adsorbent dosage of 1 g/L, contact time of 40 min, dye concentration of 20 mg/L and temperature of 25 °C. Also, the highest adsorption efficiency of NB dye was obtained at pH 9, adsorbent dosage of 1.25 g/L, contact time of 40 min, dye concentration of 20 mg/L and temperature of 25 °C. In addition, the maximum adsorption capacity of MV and NB dyes was found to be 81.98 and 60.61 mg/g, respectively, which are significant values. Moreover, the maximum desorption efficiencies of MV and NB were achieved 99.14% and 98.67%, respectively. Furthermore, the sorption mechanism showed that the intraparticle and film diffusion processes are important in the adsorption process. The aforementioned adsorbent can be effectively reused for five consecutive cycles. Equilibrium and kinetic studies indicated that the Freundlich isotherm model and pseudo-second-order kinetic model fit the experimental data well. [ABSTRACT FROM AUTHOR]

Riparian buffer zones adjacent to reservoirs and lakes protect aquatic ecosystems from polluted surface runoff. Sediments, collected from the buffer zones of Danjiangkou Reservoir (SR) and Honghu Lake (SL) in an ecologically fragile region in central China, were evaluated to reveal their phosphorus-adsorbing/desorbing properties and storage capacities. A nonlinear regression method was used to fit the pseudo-second-order kinetic and the modified crossover-type Langmuir isotherm models to the experimental data. It is shown that the adsorption of phosphorus onto the studied sediments followed the pseudo-second-order kinetic expression. The modified crossover-type Langmuir isotherm model was found to be a suitable method for describing adsorption/desorption processes in the experimental sediments. The maximum adsorption capacities (Q m), partitioning coefficients (K p), native adsorbed exchangeable phosphorus (NAP), and equilibrium phosphorus concentration (EPC0) were subsequently obtained for the experimental sediments. The effects of sediment concentration and pH were also investigated by batch experiments and Fourier transformation infrared and scanning electron microscopy analyses. The adsorption/desorption characteristics of different phosphate species on the sediments from reservoir and lake buffer zones were identified.

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Sedimentologica Sinica is the property of Acta Sedimentologica Sinica Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The adsorption and desorption characteristics of CH4 on coal with different depths are significant of development effect and productivity distribution of coalbed methane in Gujiao Mining Area, Xishan Coalfield. Thus, as the No.2 coal seam from Shanxi Formation and the No.8 coal seam from Taiyuan Formation were sampled, the change of adsorption and desorption characteristics of CH4 on dry coal under the conditions of temperature of 40 ℃ and pressure of 8 MPa with the increasing buried depth was analyzed. The control mechanisms of buried depth on CH4 adsorption and desorption were discussed based on the characteristics of nano-pores distribution. The results show that, with the increase of burial depth, both the coal rank and micropores increase, resulting in the increase of CH4 adsorption capacity. However, the influence of mesopores and macropores on the adsorption of CH4 in coal reservoirs with different depths is weak. The buried depth dependent high pressure is another reason favoring for CH4 adsorption. The deeper the coal seam is buried, the higher the degree of hysteresis of CH4 adsorption and desorption. The increasing in ultra-pore with size less than 0.7 nm and the induced enhancement of micropore heterogeneity are reasons for the significant CH4 adsorption hysteresis with the increasing burial depth.

Abstract Wettability modification of coal rock may cause serious change in the methane adsorption/desorption behaviors. Thus, the contact angle measurement and isothermal adsorption/desorption experiment of raw coal and samples treated with surfactants (STS) were conducted to investigate the wetting properties and methane adsorption/desorption characteristics. The results indicated that the long‐flame coal (LFC) has the good hydrophilicity itself, and there was no evident sign of saturated adsorption for different samples at relatively low‐pressure (

Heavy metal-containing waste has become one of heavy environmental problems. Processing of such waste accumulated at waste dumps to extract valuable components is commercially beneficial activity and, in addition, decreases environmental impact. In this study, Lewatit MonoPlus TP 207 (TP 207) ion exchange resin was evaluated for its suitability for selective removal of cobalt (Co) and copper (Cu) from mine waste waters, generated by heap leaching waste materials at a Chilean copper mine. In series of laboratory scale fixed-bed ion exchange column tests, the effects of process parameters, such as waste water flow rate and regenerant (sulfuric acid) concentration, were studied in both waste water treatment by the ion exchange resin process and the resin regeneration (metals eluting) process. The regeneration process tests were performed using 1 % and 10 % sulfuric acid. The best separation of the metals (in the eluting process) was achieved with regeneration of TP 207 resin using 1 % sulfuric acid at flow rate of 1 bed volume per hour (BV/h).

Coal reservoirs are highly heterogeneous, and different macrolithotypes of coal have differences in material composition and pore structure, resulting in different coalbed methane (CBM) adsorption/desorption performance and gas-water migration characteristics. In order to explore the pore development characteristics of different macrolithotypes in low-rank coal and their influence on adsorption and desorption, the low-rank coal of the Yan'an Formation in the Huanglong coalfield is taken as the sample of the research object. Vitrain and durain are collected and then separated. The results show that the porosity of coal is 2.92%–11.81%, and the total porosity is relatively developed. The porosity of durain is slightly higher than that of vitrain, the pore throat of durain is thicker, and the macropores are more developed. The Brunauer-Emmett-Teller (BET) specific surface area (SSA) and Barrett-Joyner-Halenda (BJH) total pore volume (TPV) of vitrain is slightly larger than durain, the micropores are more developed, and most of them are semiclosed and ink-bottle-shaped pores. The pore-fracture connectivity of the durain is better than vitrain via nuclear magnetic resonance (NMR). Vitrain has more developed micropores than durain, with larger specific surface area and stronger adsorption capacity. In the process of methane adsorption/desorption, the phenomenon of desorption hysteresis generally exists. Moreover, the pore connectivity of durain is relatively good, the degree of desorption hysteresis is weaker than vitrain, and the theoretical desorption efficiency is higher than vitrain. Temperature has a significant influence on adsorption and desorption of methane. The increase in temperature is beneficial to desorption and weakens the hysteresis effect of desorption. At the same temperature, the isosteric adsorption heat in the desorption process is greater than the adsorption process, which further explains the incomplete reversibility of the adsorption and desorption process. Under the same conditions, the isosteric adsorption heat of vitrain in the adsorption process is greater than durain, and adsorption capacity of vitrain is stronger than durain. Similarly, the isosteric adsorption heat of vitrain in the desorption process is greater than durain, and desorption needs to absorb more heat. The desorption capacity is weaker than durain. [ABSTRACT FROM AUTHOR]

During the production and application of Bacillus thuringiensis (Bt) transgenic crops, large doses of insecticidal Bt toxic proteins are expressed continuously. The multi-interfacial behaviors of Bt proteins entering the environment in multi-media affects their states of existence transformation, transport and fate as well as biological and ecological impacts. Because both soil matrix and organisms will be exposed to Bt proteins to a certain extent, knowledge of the multi-interfacial behaviors and affecting factors of Bt proteins are vital not only for understanding the source-sink distribution mechanisms, predicting their bio-availability, but also for exploring the soil safety and environmental problems caused by the interaction between Bt proteins and soil matrix. This review summarized and analyzed various internal and external factors that affect the adsorption/ desorption and degradation of Bt proteins in the environment, so as to understand the multi-interfacial behaviors of Bt proteins. In addition, the reasons of concentration changes of Bt proteins in soil are discussed. This review will also discuss the existing knowledge of the combined effects of Bt proteins and other pollutants in environment. Finally, discussing the factors that should be considered when assessing the environmental risk of Bt proteins, thus to further improve the understanding of the environmental fate of Bt proteins.

[Display omitted] • The synthesized OPHS zwitterionic surfactant exhibits wetting reversal and competitive adsorption effects. • The wetting reversal mechanism of OPHS has a time-dependent effect. • OPHS can remove the adsorbed oil film on the shale surface and desorb methane. • Contact angle testing proved effective wettability alteration by OPHS zwitterionic surfactant. Shale reservoirs have the characteristics of low permeability and low porosity. In order to enhance the recovery of shale oil and gas, surfactant flooding is a mature reservoir oil recovery method. However, the adsorption of different surfactants on the reservoir rock surface is restricted, depending on the type of surfactant. Therefore, a zwitterionic surfactant (OPHS) was synthesized from oleic acid, 3-dimethylaminopropylamine and sodium 3-chloro-2hydroxypropanesulfonate, and characterized by FTIR, 1H NMR, and TGA, and the mechanism of the OPHS for enhancing oil and gas recovery on shale surfaces was investigated. The results showed that the critical micelle concentration (CMC) of OPHS surfactant solution is 7.9 × 10-4 mol/L and the γ CMC is 27.5 mN/m; the concentration of 0.1 % OPHS surfactant solution could reduce the contact angle of the cores from 127.2° to 38.8°, which resulted in spontaneous imbibition; The absolute Zeta potential of shale particles in the OPHS surfactant solution was measured at 39 mV, whereas in deionized water at 15.3 mV. This difference can be attributed to the formation of a stable hydration film on the surface of shale particles induced by the wetting reversal effect. Spontaneous imbibition experiments showed that a 0.1 % solution of OPHS surfactant was able to increase the recovery rate by more than four times compared to the imbibition solution without added surfactant; In high-pressure gas adsorption/desorption experiments, the OPHS surfactant solution demonstrated a higher affinity for adsorption onto the shale surface. It effectively occupied adsorption sites, ultimately facilitating methane gas desorption from the shale. In summary, OPHS zwitterionic surfactants exhibit the capability to desorb hydrocarbons from shale pores through mechanisms such as wetting reversal and competitive adsorption. This research holds significant potential for advancing the field of shale oil and gas recovery, providing valuable insights for enhancing recovery processes. [ABSTRACT FROM AUTHOR]

In order to detect coal and gas outburst disasters by means of electric exploration technology, the characteristics of gas adsorption/desorption electrical response were studied. The law of resistivity variation of different coal samples was investigated under different gas pressures with the aid of a self-built real-time test system of coal resistivity during gas adsorption/desorption. In addition, the mechanism of coal resistivity variation was studied. The research results indicate that coal resistivity decreases during gas adsorption and increases during gas desorption, but generally it cannot return to the initial value. Gas influences coal resistivity through a variety of mechanisms. In the gas adsorption process, coal resistivity decreases under the combined effect of surface energy decline, skeleton expansion, free gas pressure and adsorption swelling stress. In addition, as the gas pressure rises, the resistivity varies in a wider range. The coal resistivity shares the relation of y = a + b ln(x + c) with gas pressure and the relation of y = ax + b with the content of adsorbed gas. This study lays a foundation for the application of electrical prospecting technology to gas hazard prediction and provides technical support for safe production in coal mines.