Adsorption-desorption Properties Research Articles

Ni3C/Ni3S2 Heterojunction Electrocatalyst for Efficient Methanol Oxidation via Dual Anion Co-modulation Strategy.

Enhancing active states on the catalyst surface by modulating the adsorption-desorption properties of reactant species is crucial to optimizing the electrocatalytic activity of transition metal-based nanostructured materials. In this work, an efficient optimization strategy is proposed by co-modulating the dual anions (C and S) in Ni3C/Ni3S2, the heterostructured electrocatalyst, which is prepared via a simple hot-injection method. The presence of Ni3C/Ni3S2 heterojunctions accelerates the charge carrier transfer and promotes the generation of active sites, enabling the heterostructured electrocatalyst to achieve current densities of 10/100mA cm-2 at 1.37V/1.53V. The Faradaic efficiencies for formate production coupled with hydrogen evolution approach 100%, accompanied with a stability record of 350h. Additionally, operando electrochemical impedance spectroscopy (EIS), in situ Raman spectroscopy, and density functional theory (DFT) calculations further demonstrate that the creation of Ni3C/Ni3S2 heterointerfaces originating from dual anions' (C and S) differentiation is effective in adjusting the d-band center of active Ni atoms, promoting the generation of active sites, as well as optimizing the adsorption and desorption of reaction intermediates. This dual anions co-modulation strategy to stable heterostructure provides a general route for constructing high-performance transition metal-based electrocatalysts.

Eco-recycled cement's effect on the microstructure and hygroscopic behaviour of compressed stabilised earth blocks

Recycled cement (RCP) retrieved from old cement waste aims to replace carbon-intensive ordinary Portland cement (OPC) in earth stabilisation, improving the mechanical performance and durability of earth construction, without significantly compromising its ecological character and thermophysical properties. This study analyses the microstructure and hygroscopic behaviour of compressed earth blocks (CEB) stabilised with RC. In addition, soil was partially replaced with construction and demolition waste (CDW) to further improve the CEB sustainability. To this end, the sorption-desorption isothermal behaviour of CEB with different soils, types and contents of stabiliser (0–10 % RCP or OPC), and varying percentage replacements of OPC with RCP (20, 50, 100 %) or soil with CDW (0, 15, 25 %) was analysed and related to their microstructure, which was characterised in terms of scanning electron microscopy, mercury intrusion porosimetry and nitrogen adsorption analysis. Unstabilised and OPC CEB were considered for comparison purposes. The microstructure of CEB was refined after RCP stabilisation, which influenced their hygroscopicity and adsorption-desorption hysteresis. Depending on the clay content of the soil, stabilisation reduced or increased the hygroscopic capacity of CEB. After stabilisation, the water adsorption decreased up to 25 % in CEB with clayey soil and increased up to 22 % in CEB with sandy soil. However, the hygroscopic behaviour was not significantly affected by the type of stabiliser. The substitution of OPC with RCP increased the volume of water adsorption up to 3 %, due to its slightly finer porosity. RCP has proven to be effective as an earth stabiliser, leading to CEB with adsorption-desorption properties similar to those of OPC CEB.

Enhanced ammonia adsorption-desorption properties of synthesized zeolite-carbon composite with the effect of Si/Al ratio

Effective ammonia (NH3) adsorbent is crucial for removing undecomposed NH3 residue after splitting into N2 and H2 fuel. In this study, a zeolite-activated carbon (AC) hybrid was successfully synthesized with a trace AC amount and different Si/Al ratios via hydrothermal method. The NH3 adsorption–desorption properties and mechanisms were investigated through two major activity tests, employing high pressure adsorption isotherm analyzer and breakthrough set up. Incorporating AC at 1 wt%, effectively shortened the regeneration period of the pure zeolite by ∼50 % due to the AC’s pore-widening effect on zeolite network, reducing the trapping of adsorbed NH3 in the zeolite pores. Interestingly, an optimum Si/Al ratio of 1.6 led to the highest specific surface area of 977.57 m2/g by the formation of zeolite mixture with coexisting NaX (faujasite zeolite with high Al atoms per cell) and NaY (higher crystalline faujasite zeolite with low Al atoms per cell). These improved structural characteristics consequently exhibited the highest NH3 (99.9995 %) storage capacity of 15.6 mmol/g at a partial pressure of 300 kPa in isotherm analysis at 25 °C. Besides, the initial breakthrough adsorption capacity for dilute NH3 (5%/N2 balance) under atmospheric conditions reached 8.9 mmol/g, accurately equivalent to isotherm analysis result at 5 kPa. This reproducibility of consistent adsorption uptake within low pressure region in both tests was credited to the compositional presence of both acidic and alkaline surface functionalities in the optimum zeolite-AC hybrid as stable NH3 adsorption sites. These active sites also provided a uniform dynamic adsorption capacity of ∼4 mmol/g throughout 15 cycles. Conclusively, this work highlighted the importance of zeolite composition and AC-incorporated proportion for the H2 purification aspect.

A Polyzwitterionic@MOF Hydrogel with Exceptionally High Water Vapor Uptake for Efficient Atmospheric Water Harvesting.

Atmospheric water harvesting (AWH) is considered a promising strategy for sustainable freshwater production in landlocked and arid regions. Hygroscopic salt-based composite sorbents have attracted widespread attention for their water harvesting performance, but suffer from aggregation and leakage issues due to the salting-out effect. In this study, we synthesized a PML hydrogel composite by incorporating zwitterionic hydrogel (PDMAPS) and MIL-101(Cr) as a host for LiCl. The PML hydrogel was characterized using various techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR), and thermogravimetric analysis (TGA). The swelling properties and water vapor adsorption-desorption properties of the PML hydrogel were also assessed. The results demonstrate that the MIL-101(Cr) was uniformly embedded into PDMAP hydrogel, and the PML hydrogel exhibits a swelling ratio of 2.29 due to the salting-in behavior. The PML hydrogel exhibited exceptional water vapor sorption capacity of 0.614 g/g at 298 K, RH = 40% and 1.827 g/g at 298 K, RH = 90%. It reached 80% of its saturated adsorption capacity within 117 and 149 min at 298 K, RH = 30% and 90%, respectively. Additionally, the PML hydrogel showed excellent reversibility in terms of water vapor adsorption after ten consecutive cycles of adsorption-desorption. The remarkable adsorption capacity, favorable adsorption-desorption rate, and regeneration stability make the PML hydrogel a potential candidate for AWH. This polymer-MOF synergistic strategy for immobilization of LiCl in this work offers new insights into designing advanced materials for AWH.

Effects of Adsorption and Desorption of Low-Boiling-Point Total Hydrocarbon Gases on Activated Carbon.

In this study, we selected materials that efficiently adsorb total hydrocarbons (THCs) from petrochemical storage facilities and applied four types of activated carbons to adsorb THCs to evaluate their properties. Four gases with low boiling points, namely, ethylene, ethane, propylene, and propane, generated via petrochemical storage facilities, were selected and mixed to a constant concentration with four types of materials and used to investigate the adsorption capacities and desorption properties. The adsorbents comprised two raw materials and two chemically activated materials. The specific surface areas of activated palm (2085 m2/g) and coal (1752 m2/g), which are chemically activated carbons, exhibited a twofold increase compared to those of raw palm (1232 m2/g) and coal (946 m2/g). Thus, we identified the correlations between the physical properties of the activated carbon adsorption materials and their adsorption capacities for four low-boiling-point THCs generated by petrochemical storage facilities.

Assessment of inhibitor protection efficiency of oilfield equipment from salt deposits

In the field development practice, the most common method for protecting oilfield equipment and pipeline surfaces from inorganic salt deposits is inhibitor protection. To enhance prevention efficiency, a salt deposit inhibitor has been developed, which contains a surfactant, acid, and anionic polymer. The aim of this development is to eliminate the need for scarce and expensive reagents, increase formation productivity by preventing the formation of inorganic deposits during the treatment of carbonate and terrigenous productive formations, and eliminate contamination of formation and downhole equipment by insoluble salts, as well as salt deposits in pipeline systems. Samples prepared at a flow rate of 10-30 g/t demonstrated a high inhibitor effect in preventing calcium sulphate and carbonate deposition. Field tests of the developed salt deposition inhibitor yielded positive results. Keywords: Salt deposition inhibitor; Adsorptiondesorption properties; Inhibition efficiency; Calcium sulfate; Calcium carbonate; Field tests.

Reversible hydrogen storage in Li-functionalized [1,1,1,1]paracyclophane: A computational insight

This study focuses on investigating the hydrogen adsorption-desorption properties and storage capacities of Li functionalized [1,1,1,1]paracyclophane (PCP1111) using dispersion-corrected density functional theory and molecular dynamics simulation. The Li atom is bound to the [1,1,1,1]paracyclophane's benzene ring via Dewar mechanism, with a binding energy of 0.32 eV without any clustering. Each Li atom is found to adsorb 5H2 molecules, causing the host material PCP1111–4Li to adsorb up to 20H2 molecules via charge polarization with an average adsorption energy of 0.156 eV/H2, indicating physisorption type adsorption. The charge polarization during hydrogen adsorption is studied using Hirshfeld charge analysis and electrostatic potential maps. PCP1111–4Li saturated with 20H2 results in gravimetric densities as high as 9.4 wt%, which is considerably higher than the US-DOE target. During the H2 adsorption process, the host material's geometry does not change significantly, indicating its chemical stability. When the temperature exceeds 180 K under 30–60 bar, the gravimetric density decreases, but it is still greater than 5.5 wt%, which is the target set by the US Department of Energy for 2025. The maximum H2desorption temperature estimated by the Vant-Hoff relation is found to be 216 K and 266 K at 1 atm and 5 atm, respectively. ADMP molecular dynamics shows the structural integrity and reversibility of host materials.

Engineering Ru–RuO2 interface with regulated hydroxyl adsorption towards efficient and CO-tolerant hydrogen oxidation reaction

Owning to the similar hydrogen binding strength and lower price, Ru is considered as a promising substitute for Pt towards hydrogen oxidation reaction (HOR). However, the unoptimized intermediate adsorption on metallic Ru site makes Ru/C inferior to Pt/C benchmark in terms of lower HOR activity as well as CO tolerance. Herein, we developed a novel competitive adsorption strategy through the construction of Ru–RuO2 interface to enhance alkaline HOR performance and CO tolerance simultaneously. Specifically, the competitive adsorption of OH* between Ru and RuO2 could alleviate the strong affinity of OH* on Ru, which would promote both alkaline HOR and CO oxidation significantly. Besides, the engineered interface structure optimized hydrogen binding energy (HBE) via electronic modulation effect as well. Benefitting from these attributes, the as-designed Ru–RuO2/C catalyst exhibits remarkable HOR performance with a mass activity of 2.50 A mg−1 @ 50 mV, which is 10 and 5 times higher than that of Ru/C and commercial Pt/C, respectively. More strikingly, Ru–RuO2/C performs unprecedented anti-poisoning capacity towards CO, with only a small decrease of 6.9 % in the limiting current density in the presence of 30,000 ppm CO, far surpassing the commercial Pt/C catalyst. This work not only provides a cost-effective and robust HOR catalyst in alkaline media, but also opens up a new avenue to tailor the adsorption-desorption properties of intermediates on heterogenous electrocatalyst.

Functionalized Ordered Mesoporous MCM-48 Silica: Synthesis, Characterization and Adsorbent for CO2 Capture.

The ordered mesoporous silica MCM-48 with cubic Ia3d structure was synthesized using the cationic surfactant hexadecyltrimethylammonium bromide (CTAB) as a template agent and tetraethylorthosilicate (TEOS) as a silica source. The obtained material was first functionalized with (3-glycidyloxypropyl)trimethoxysilane (KH560); further, two types of amination reagents were used: ethylene diamine (N2) and diethylene triamine (N3). The modified amino-functionalized materials were characterized by powder X-ray diffraction (XRD) at low angles, infrared spectroscopy (FT-IR) and nitrogen adsorption-desorption experiments at 77 K. Characterization from a structural point of view reveals that the ordered MCM-48 mesoporous silica has a highly ordered structure and a large surface area (1466.059 m2/g) and pore volume (0.802 cm3/g). The amino-functionalized MCM-48 molecular sieves were tested for CO2 adsorption-desorption properties at different temperatures using thermal program desorption (TPD). Promising results for CO2 adsorption capacities were achieved for MCM-48 sil KH560-N3 at 30 °C. At 30 °C, the MCM-48 sil KH560-N3 sample has an adsorption capacity of 3.17 mmol CO2/g SiO2, and an efficiency of amino groups of 0.58 mmol CO2/mmolNH2. After nine adsorption-desorption cycles, the results suggest that the performance of the MCM-48 sil KH N2 and MCM-48 sil KH N3 adsorbents is relatively stable, presenting a low decrease in the adsorption capacity. The results reported in this paper for the investigated amino-functionalized molecular sieves as absorbents for CO2 can be considered as promising.

Experimental investigation on water vapor adsorption performance of solvent-free synthesized MIL-100(Fe) and its composite adsorbent

With high hydrothermal stability and hydrophilicity, MIL-100(Fe) has potential applications in sorption-based atmospheric water harvesting (SAWH). This paper reports the water vapor adsorption properties of MIL-100(Fe) prepared by solvent and solvent-free methods. Performance tests show that the MIL-100(Fe) prepared by solvent-free method has more advantages. To further improve the performance of the adsorbent, the composite adsorbent MgCl2@MIL-100(Fe) was obtained by impregnating MIL-100(Fe) with MgCl2 solution. The results showed that the composite adsorbent had good adsorption performance, desorption properties, and fast adsorption rate. The equilibrium adsorption capacities of the composite adsorbent with 35% salt content were 0.533 g/g and 1.062 g/g at 25 °C with the relative humidity (RH) of 35% and 80%, respectively, which were 1.51 times and 1.74 times of the adsorption capacity of MIL-100(Fe) under the same working conditions. This showed that the solvent-free synthesized MIL-100(Fe) and its composite adsorbent have the potential for application in SAWH.

Synthesis and Characterization of Biodegradable Poly(vinyl alcohol)-Chitosan/Cellulose Hydrogel Beads for Efficient Removal of Pb(II), Cd(II), Zn(II), and Co(II) from Water

Globally, water contamination by heavy metals is a serious problem that affects the environment and human health. Adsorption is the most efficient way of water treatment for eliminating heavy metals. Various hydrogels have been prepared and used as adsorbents to remove heavy metals. By taking advantage of poly(vinyl alcohol) (PVA), chitosan (CS), cellulose (CE), and the process for physical crosslinking, we propose a simple method to prepare a PVA-CS/CE composite hydrogel adsorbent for the removal of Pb(II), Cd(II), Zn(II) and Co(II) from water. Structural analyses of the adsorbent were examined by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy-energy dispersive X-ray (SEM-EDX) analysis, and X-ray diffraction (XRD). PVA-CS/CE hydrogel beads had a good spherical shape together with a robust structure and suitable functional groups for the adsorption of heavy metals. The effects of adsorption parameters such as pH, contact time, adsorbent dose, initial concentration of metal ions, and temperature on the adsorption capacity of PVA-CS/CE adsorbent were studied. The adsorption characteristics of PVA-CS/CE for heavy metals may be completely explained by pseudo-second-order adsorption and the Langmuir adsorption model. The removal efficiency of PVA-CS/CE adsorbent for Pb(II), Cd(II), Zn(II), and Co(II) was 99, 95, 92, and 84%, respectively, within 60 min. The heavy metal's hydrated ionic radius may be crucial in determining the adsorption preference. After five consecutive adsorption-desorption cycles, the removal efficiency remained over 80%. As a result, the outstanding adsorption-desorption properties of PVA-CS/CE can potentially be extended to industrial wastewater for heavy metal ion removal.

Transition from chemisorption to physisorption of H2 on Ti functionalized [2,2,2]paracyclophane: A computational search for hydrogen storage

In this work, we studied the hydrogen adsorption-desorption properties and storage capacities of Ti functionalized [2,2,2]paracyclophane (PCP222) using density functional theory and molecular dynamic simulation. The Ti atom was bonded strongly with the benzene ring of PCP222 via Dewar interaction. Subsequently, the calculation of the diffusion energy barrier revealed a significantly high energy barrier of 5.97 eV preventing the Ti clustering over PCP222 surface. On adsorption of hydrogen, the first H2 molecule was chemisorbed over PCP222 with a binding energy of 1.79 eV with the Ti metals. Further addition of H2 molecules, however, exhibited their adsorption over PCP222-Ti through the Kubas-type H2 interaction. Charge transfer mechanism during the hydrogen adsorption was explored by the Hirshfeld charge analysis and electrostatic potential map, and the PDOS, Bader's topological analysis revealed the nature of the interaction between Ti and H2. The PCP222 functionalized with three Ti atoms showed a maximum hydrogen uptake capacity of up to 7.37 wt%, which was fairly above the US-DOE criterion. The practical H2 storage estimation revealed that at ambient conditions, the gravimetric density of up to 6.06 wt% H2 molecules could be usable, and up to 1.31 wt% of adsorbed H2 molecules were retained with the host. The ADMP molecular dynamics simulations assured the reversibility by desorption of adsorbed H2 and the structural integrity of the host material at sufficiently above the desorption temperature (300 K and 500 K). Therefore, the Ti-functionalized PCP222 can be considered as a thermodynamically viable and potentially reversible H2 storage material.

Synergistic Mechanism of Ultrasonic-Chemical Effects on the CH4 Adsorption-Desorption and Physicochemical Properties of Jincheng Anthracite.

Ultrasonic is a new method to enhance coalbed methane recovery. A deeper comprehension of the synergistic mechanisms of combined ultrasonic-chemical modification on the CH4 adsorption-desorption capability and physicochemical properties of coal is necessary for potential field implementation, as the modification of coal reservoirs frequently necessitates the addition of chemical reagents. This paper evaluated the CH4 adsorption-desorption properties of anthracite modified by sodium dodecyl sulfate (SDS) solution, ultrasonic modification, and combined ultrasonic-SDS modification. Fourier transform infrared spectroscopy, low-temperature nitrogen adsorption, and micro-CT were applied to elucidate the synergistic mechanism of the combined modification. The research results show that the SDS solution reduces the saturated adsorption capacity of anthracite and increases its final desorption rate by dissolving clay minerals and the physical adsorption masking effect of SDS micelles on the coal surface. Some surface groups with low bond energy are broken or evaporated under mechanical vibration and thermal effects generated by ultrasonic. The original fractures are expanded and connected, which changes the adsorption-desorption properties of anthracite. The synergistic effect of the combined modification of ultrasonic-SDS can promote the penetration range and chemical reaction efficiency of the SDS solution, which expands the effective range of ultrasonic. After combined modification, the amount of aromatics, oxygen-containing functional groups, and aliphatic hydrocarbons on the surface of coal is reduced. The connected porosity of coal samples accounts for 91.5% of the total porosity. As a result, the saturated adsorption capacity of anthracite reduces by 26.7%, and the final desorption rate increases by 28.0%. The effect of the combined ultrasonic-chemical modification is better than that of a single modification.

Facile construction of a fascinating dual Z-scheme Bi2S3/tg-C3N4/α-Ag2WO4 photocatalyst for effective removal of organic pollutants: Influence factors, mechanism insight and degradation pathway

Inefficient utilization of sunlight response, low separation of photoinduced charge carriers, narrow redox potential and inferior recycling capacity significantly affects the functionalities of catalyst to get access in the practical wastewater treatment. A novel dual Z-scheme Bi2S3/tg-C3N4/α-Ag2WO4 ternary nanocomposite was designed and fabricated successfully to improve the absorption range of sunlight. The structural, optical, morphological, compositional and nitrogen adsorption-desorption properties of as-prepared pristine, binary and ternary photocatalysts were examined comprehensively. The 15 % Bi2S3/tg-C3N4/α-Ag2WO4 ternary nanocomposite demonstrated the highest degradation efficiency for toxic pollutants such as TC antibiotic (η = 95.02 %), MB (η = 98.94 %), RhB (η = 99.26 %) and MO (η = 77.35 %) under sunlight irradiation. The optimized 15 % Bi2S3/tg-C3N4/α-Ag2WO4 photocatalyst exhibits the reaction rate constant of TC antibiotic (k = 0.0209 min−1) was 3.6, 6.7 and 1.8 folds higher than that of pristine 1D-α-Ag2WO4, 1D-Bi2S3 and 2D-tg-C3N4. The favorable photocatalytic performance of dual Z-scheme heterojunction is attributed to a tight contact interface, good redox potential capacity, higher separation of photogenerated electron-hole pairs and inferior charge carriers recombination rate. The recycling tests reveal the attractive reusability and photostability of 15 % Bi2S3/tg-C3N4/α-Ag2WO4 photocatalyst. Moreover, the quenching experiment suggested that the holes (h+) radical play a dominant role in the photocatalytic activity process of toxic contaminants over 15 % Bi2S3/tg-C3N4/α-Ag2WO4 ternary nanocomposite. The possible reaction mechanism and degradation pathways of TC antibiotic were speculated with several characteristic intermediates identified. This present work deals with new understanding of the design and construction of dual Z-scheme heterojunction photocatalysts for wastewater remediation in an environmental application.

Dye recovery with photoresponsive citric acid-modified BiOCOOH smart material: Simple synthesis, adsorption-desorption properties, and mechanisms

Dye recovery is of great significance for a circular economy and sustainable development. However, green recovery strategies without secondary pollution remain a significant challenge. To resolve this issue, a light-responsive smart material (citric acid-modified BiOCOOH (m-BOCH)) was synthesized and applied for dye recovery through adsorption in the dark, and desorption under visible light. With the modification of citric acid, the adsorption level of methylene blue (MB) on m-BOCH (43.4%) was more than six times that of pure BiOCOOH (7.1%). The desorption rate was ∼90% in 120 min under 420 nm light irradiation (there was no desorption for pure BOCH). Further, the adsorption rate was improved to 83.9% and the desorption rate remained stable at an optimal pH of 10.09. Characterization results indicated that carboxyl groups were modified onto the surface of BiOCOOH and served as adsorption sites for MB. Under visible light exposure, the connections between the carboxyl groups and BiOCOOH were damaged, which led to the desorption of MB from the surface of the m-BOCH. The recovered MB exhibited a good staining effect on hepatic stellate cells (HSC) as a fresh dye. The regeneration of m-BOCH was achieved through a moderate hydrothermal process, and the adsorption and desorption capacities were restored to 80.8% and 85.7%, respectively. This research provides a novel environmentally compatible strategy for dye recovery without secondary pollution. This is a very promising treatment technique for dye effluents, which highlights the application of smart materials resource recycling for environmental remediation.

Molybdenum carbide phase effects in heterogeneous catalytic ammonia synthesis

The design of an efficient catalyst utilizing non-precious metals is a top priority in ammonia synthesis, and Mo is found to be inferior in ammonia synthesis due to strong nitrogen adsorption. The carburization of Mo species might be an ideal strategy for optimizing nitrogen adsorption energy and ammonia synthesis activity. In this work, we prepare two molybdenum carbides with different crystal structures (α-MoC and β-Mo2C). The result shows that there is a larger number of Mo-C bonds and lower Mo/C ratio in α-MoC, leading to the strong adsorption of hydrogen and ammonia species on α-MoC. In contrast, the desorption energies of hydrogen and ammonia are lower for β-Mo2C, and the spillover and migration of hydrogen species are boosted. The facile desorption of hydrogen and ammonia species also limits the accumulation of H adatoms and ammonia on the surface of β-Mo2C, releasing of active sites available for the subsequent activation of hydrogen and nitrogen as well as ammonia synthesis reaction. As a result, the ammonia synthesis activity of β-Mo2C catalyst is 2.5-fold higher than that of α-MoC, and a small negative value of NH3 reaction order also would be obtained for β-Mo2C. This work not only reports the effect of molybdenum carbide phases on the adsorption–desorption properties of reactants and catalytic activities for ammonia synthesis, but also opens a perspective for the design and development of efficient metal based heterogeneous catalysts by tuning the adsorption and desorption properties of the reactant gases. Keywords: Molybdenum Carbide; Phase effect; Adsorption–desorption property; Mo catalyst; Ammonia synthesis

New Isolated Shrimp (Litopenaeus setiferus) Chitosan-Based Films Loaded with Fly Ash for Antibacterial Evaluation.

New three fabricated chitosan (CS) loaded with fly ash (FA) films were developed in this study. The shell waste of white shrimp was used as a precursor for the isolation of chitin and converted into chitosan by carrying out a deacetylation process. The formation of chitosan was conducted by various preparation steps deproteinization, demineralization, and deacetylation. The degree of deacetylation was found to be 95.2%. The obtained chitosan was used to prepare three different chitosan loaded-fly ash films. The prepared films contained various fly ash: chitosan ratios (2:1, FA-CSF1), (1:1, FA-CSF2), and (1:2, FA-CSF3). The obtained films were characterized using FTIR, XRD, and SEM. The micrograph images of the formed films showed spherical particles with an average size of 10 µm. The surface area, adsorption-desorption properties, thermal stability, and water/fat binding features of the fabricated chitosan films were studied. The results revealed that the prepared films displayed typical BET graphs with surface areas ranging from 2.436 m2 g−1 to 8.490 m2 g−1. The fabricated FA-CSF films also showed high thermal stability at temperatures up to 284.9 °C and excellent water/fat binding capacities. The antibacterial potential of the designed films was screened against E. coli (Gram-negative) and B. cereus (Gram-positive) bacterial strains. The tested solution of CS (1%) exhibited inhibition zones for E. coli and B. cereus as 18.51 mm and 14.81 mm, respectively, while in FA solution (1%), the inhibition zones were found to be 10.16 mm, and 13.57 mm, respectively. The results encourage and open up the new and promising areas of research for applying chitosan extracted from waste materials in biological applications.

Inorganic Phosphorus Transformation and Phosphorus Adsorption–Desorption Properties of Soil in a Cotton Field Under Mulched Drip Irrigation in Xinjiang: A Four-Year Field Assessment

Phosphorus (P) fertilizer is generally applied to enhance the soil P pool and meet crop demand, but most of the added P is absorbed by soil. This study aimed to explore the importance of P fractions and adsorption–desorption characteristics on the demand for P fertilizer to determine the optimum P fertilizer amount for a cotton field under mulched drip irrigation in Xinjiang, China. A 4-year experiment (2016–2019) was conducted in a cotton field to evaluate the effects of five P fertilizer addition levels (0, 75, 150, 300, and 450 kg P2O5 ha−1 year−1) on inorganic P fractions and P adsorption–desorption properties at different soil depths and explore the effects of soil properties on P adsorption. The 4-year continuous P fertilization enhanced the inorganic P content and altered the proportions of various P forms. A large proportion of P accumulated in soil was transformed into Ca8-P, followed by Ca2-P, mainly in the surface layer. The accumulation and transformation of P in fertilized soil reduced P adsorption and enhanced P desorption. Soils with higher P application levels had higher inorganic P accumulation with lower adsorption and higher desorption. The total P and Olsen-P in a 0- to 5-cm soil layer; Ca8-P and calcium carbonate (CaCO3) in a 5- to 10-cm soil layer; Olsen-P, Ca10-P, clay, and cation exchange capacity in a 10- to 20-cm soil layer; and Olsen-P in a 20- to 40-cm soil layer significantly affected the P adsorption–desorption (p < 0.05). The application rate of 75–150 kg P2O5 ha−1 year−1 produced lower inorganic P accumulation, favorable adsorption–desorption properties, and high cotton yield, and thus could be considered the optimal P fertilizer application level.

Selection of Characteristic Particle Size of Drilling Cuttings Based on Adsorption-Desorption Properties: Experiment and Simulation

The direct method for measuring gas content based on image processing, that is, comparing the desorption curves of drilling cuttings with the characteristic particle size with the desorption image in the database to determine the gas content of coal seams, can solve the problems of long measurement time and larger measurement errors of the traditional direct method. However, the precondition to realize this method is to define the characteristic particle size of drilling cuttings. Therefore, this paper performed adsorption and desorption experiments under different particle size ranges and dissimilar adsorption equilibrium pressures, solved the gas migration control equation in coal particles, and determined the characteristic particle size from experimental results and simulation effect. The results showed that gas desorption quantity was positively correlated with adsorption equilibrium pressure, while negatively correlated with the size of a particle size range. The greater the adsorption equilibrium pressure, the better the linear fitting relationship with the maximum desorption quantity, and the maximum correlation coefficient could reach 0.9658. Based on Darcy’s law, Langmuir adsorption equation, and mass conservation law, the theoretical control equation of gas migration in coal particles was derived and solved by Open source Field Operation and Manipulation (OpenFOAM). The accuracy of the calculation results of the solver was verified by the derived analytical solution of the gas pressure change of coal particles without considering the adsorption. From the experimental results and simulation results, the characteristic particle size of drilling cuttings was determined to be 0.5-1 mm. The research can provide help for the subsequent development of direct gas content measurement technology based on image processing.

Green Synthesis of Reusable Adsorbents for the Removal of Heavy Metal Ions.

Industrial wastewater often contains heavy metals, like lead, copper, nickel, cadmium, zinc, mercury, arsenic, and chromium. Overdoses of heavy metals will impose a severe threat to human health. Adsorption is the most efficient way of wastewater treatment for eliminating heavy metals. A novel material-reusable hydrogel-based adsorbent was developed in overcoming the regeneration issue. The polyethylene glycol diacrylate-3-sulfopropyl methacrylate potassium salt (PEGDA-SMP) hydrogel performed an ion-exchange rate to remove heavy metals from wastewater in 30–120 min. The adsorption capacity of PEGDA-SMP increases the increasing pH of a solution, in which pH 5 reaches the maximum. Pseudo-second-order adsorption and the Langmuir adsorption model can fully describe the adsorption properties of PEGDA-SMP for heavy metals. PEGDA-SMP prefers to exchange Pb2+ through K+, and its adsorption capacity can achieve 263.158 mg/g. Ag+, Zn2+, Ni2+, and Cu2+ were 227.27, 117.647, 102.041, and 99.010 mg/g, respectively. The hydrated ionic radius of the heavy metal might play an essential role to affect the adsorption preference. The removal efficiency of heavy metals can approach over 95% for each heavy metal. PEGDA-SMP performs rapid desorption and reaches desorption equilibrium in 15 min. After 10 consecutive adsorption–desorption cycles, the adsorption capacity remained over 90%. The hydrogel developed in this study showed reversible heavy metal absorption. Therefore, excellent adsorption–desorption properties of PEGDA-SMP can be potentially extended to industrial wastewater for removing heavy metals.