Strong Adsorption Performance Research Articles

Two-dimensional Co(OH)2/graphene oxide composite as an efficient multifunctional interlayer for high-performance lithium–sulfur batteries

The shuttling-effect of soluble lithium-based polysulfides (LiPS) represents one of the main obstacles for practical application of lithium–sulfur (Li–S) batteries. Herein, to address this issue, a flexible Li–S interlayer consisting of a two-dimensional α-Co(OH)2 nano-plate and graphene oxide (GO) is developed using a simple vacuum filtration technique. In the interlayer, the α-Co(OH)2 and GO are assembled into a layered structure forming a physical barrier for the shuttling of LiPS. Additionally, the α-Co(OH)2 offers strong chemical adsorption and efficient catalysis performance towards LiPS conversion, further inhibiting its shuttling. Attributed to these beneficial features of the interlayer, the Li–S battery delivers an initial discharge capacity of 834 mAh g−1 at the current density of 1 C. More importantly, after 300 cycles, a high discharge capacity of 590 mAh g−1 was retained, corresponding to a low capacity fading rate of 0.1% per cycle. This work might be of great interest for the feasible and scalable preparation of multifunctional interlayers in Li–S batteries.

The adsorption enhancement of graphene for fluorine and chlorine from water

A high concentration of F (Cl) element in drinking water threatens people’s health. Hence, in this work, we systematically investigated the F and Cl atoms adsorption on pristine graphene (PG) or defective graphene (vacancy and Al, B, Si-doped) by using density functional theory calculations to explore materials with stronger adsorption performance for F and Cl elements removal from water. Based on the analysis of adsorption energy, PDOS and charge population, results indicate that F/Cl atom preferentially adsorbed on the Top site of graphene. We also find that the vacant graphene and doped graphene are good candidates for the adsorbents for F and Cl atom because the single F or Cl atom can be strongly trapped in the positions of defects. The negative adsorption energy and the diffusion barrier suggest that the F/Cl-AlG system has the most thermodynamic stability among our considered systems. In the H2O environment, the adsorption energy for the co-adsorption of F(Cl) atom and H2O molecule on Al-doped graphene is −4.2 eV(−3.77 eV), suggesting that the strong adsorption performance still presents between F(Cl) atom and Al-doped graphene in a background of H2O molecule.

Fouling and Retention Mechanisms of Selected Cationic and Anionic Dyes in a Ti3C2Tx MXene-Ultrafiltration Hybrid System.

Ti3C2Tx MXenes, a very new family of nanostructured material, were applied in combination with an ultrafiltration (UF) membrane (MXene-UF) for removal of the selected dyes including methylene blue (MB) and methyl orange (MO) as the first attempt. The normalized flux of the MXene-UF (0.90 for MB and 0.92 for MO) indicated better performance than a single UF (0.86 for MB and 0.90 for MO) and a powdered activated carbon (PAC)-UF (0.72 for MB and 0.75 for MO) for both dyes. The addition of an adsorbent decreased the irreversible fouling of the hybrid system compared to single UF, due to adsorption of dyes. The observed dominant fouling mechanism was cake layer fouling, evaluated using a resistance-in-series model, permeate flux modeling, and four conceptual blocking law models. PAC in particular acted as a foulant, leading to a severe flux decline. The average retention rate was found to be on the order of PAC-UF (57.7 and 47.9%) > MXene-UF (51.7 and 34.9%) > single UF (45.0 and 34.7%) for MB and MO, respectively. The results showed that although PAC exhibits relatively strong adsorption performance, MXene-UF also exhibited high selectivity due to electrostatic interaction between the MXene and dyes. In addition, humic acid (HA) adsorption on the membrane led to a reduction in the effective membrane area, resulting in a higher retention and lower flux for MXene-UF in the presence of HA. Furthermore, higher retention was observed for MXene-UF at pH 10.5 compared to pH 3.5 and 7, because MXene has more negative terminations at higher pH, leading to greater MB adsorption. Additionally, because of the bridging effect between the membrane and the MXene and competition between MB and cation ions for adsorption on the MXene, lower retention and flux were observed in MXene-UF with background ions.

Comparative study on the properties of lignin isolated from different pretreated sugarcane bagasse and its inhibitory effects on enzymatic hydrolysis

Five sugarcane bagasse lignin samples, namely, dilute sulfuric acid (DSAL), sodium hydroxide (SHL), ethanol (EL), hot liquid water (HLWL)-pretreated residual solids, and raw material (cellulolytic enzyme lignin, CEL), were extracted. Comparative studies on the physicochemical properties of isolated lignin, nonproductive adsorption of cellulase by lignin, and its effect on enzymatic hydrolysis was performed. Results showed that the molecular weight and homogeneity of lignin remarkably decreased after pretreatment compared with CEL. Lignin with low negative zeta potential, high phenolic hydroxyl group content and hydrophobicity exhibited strong nonproductive adsorption performance to cellulase. This phenomenon was positively correlated with it's inhibitory effect on enzymatic hydrolysis. Compared with the control (without lignin), the Avicel conversion rate (40 mg lignin/200 mg Avicel) decreased by 10.74%, 9.28%, 8.73%, 4.22%, and 2.80% after digestion of Avicel for 72 h with the presence of EL, SHL, CEL, HLWL, and DSAL, respectively.

Advances in research on effects of biochar on soil nitrogen and phosphorus

In the context of global research, soil non-point source pollution is becoming more and more severe. Biochar is used as a soil amendment to repair soil. Therefore, research on biochar has received extensive attention. According to relevant literature reports, biochar has strong adsorption performance, and according to its nature, it can improve the availability of nitrogen and phosphorus in crops and fix nitrogen and phosphorus in soil. Also, biochar can also improve soil structure and reduce the migration of N and P with soil media. The research mechanism of biochar is distinct. The article cites the results of the majority of researchers and explains the effects of different biochars. Biochar has a certain promoting effect on nitrogen, phosphorus adsorption, conversion and leaching. In the future, we should strengthen the prospect of biochar in the treatment of soil environment and sustainable development of the environment.

Preparation and thermal properties of n-eicosane/nano-SiO2/expanded graphite composite phase-change material for thermal energy storage

Composite phase-change materials (CPCM) were prepared using n-eicosane as phase-change material, nano-SiO2 as supporting matrix, and expanded graphite (EG) as thermal conductivity promoter. Nano-SiO2 with strong adsorption performance can prevent leakage of n-eicosane in CPCM. Adding expanded graphite significantly enhanced thermal conductivity of CPCM. Leakage tests showed that the maximum mass proportion of n-eicosane in CPCM was 70 wt%. Fourier transformation infrared spectroscopy (FT-IR), an X-ray diffractometer (XRD), and a scanning electronic microscope (SEM) were used to determine chemical structures, crystal phases, and morphologies of CPCM. The DSC results indicated that the melting latent heat of CPCM was 135.80 J/g with a melting temperature of 35.35 °C, and that the solidifying latent heat of CPCM was 125.93 J/g with a solidifying temperature of 36.23 °C. Thermal conductivity meter (TCM) test results showed that CPCM had high thermal conductivity, representing a 15%–137% increase compared to CPCM without EG. Thermal properties and chemical structures of CPCM were investigated after 100 thermal cycles. The results indicated that CPCM3 (with 7 wt% EG) had good structure and thermal stability. Thermal conductivity of CPCM3 is 2.37 times that of CPCM without EG. Therefore, CPCM3 has potential application prospects for thermal energy storage.

Adsorption behavior of Pd-doped SnS2 monolayer upon H2 and C2H2 for dissolved gas analysis in transformer oil

Dissolved gas analysis (DGA) is an effective technique to evaluate the operation status of the power transformer, and to guarantee the safe operation of the power system. Using density functional theory (DFT), we proposed the application of Pd-doped SnS2 (Pd-SnS2) monolayer as a sensing material to detect H2 and C2H2 in transformer oil. The electronic and geometric structures of Pd-doping behavior on SnS2 were also analyzed to give insight into the physicochemical property of the active surface. The adsorption configuration, density of state (DOS), frontier molecular orbital theory as well as recovery property of the adsorption systems were comprehensively studied to estimate the suitability of our proposed material for sensing application. Our calculations showed that Pd-doping exerts some deformations on the SnS2 monolayer and leads to the narrowed bandgap of such surface. Meanwhile, Pd-SnS2 monolayer has stronger adsorption performance upon C2H2 compared to H2. And the desirable interaction with C2H2 makes it possible for application of a resistance-type sensor given the good electrical response and recovery property. Our calculations are meaningful to suggest novel sensing material for application in the field of electrical engineering.

Effect of Aggregation and Adsorption Behavior on the Flow Resistance of Surfactant Fluid on Smooth and Rough Surfaces: A Many-Body Dissipative Particle Dynamics Study.

To study the effect of surfactant on the resistance of wall-bound flow, the adsorption and aggregation behaviors of surfactant fluid on both smooth and groove-patterned rough surface are investigated through many-body dissipative particle dynamics (MDPD) simulation. The MDPD models of surfactants were carefully parametrized and have been validated to be able to simulate the aggregation and adsorption behavior of surfactants. The simulation results show that the surfactant in laminar flow can only increase the flow resistance on the smooth surface. On the rough surface, surfactant with strong adsorption performance on the channel wall shows a drag reduction effect at moderate concentration. The surfactant with weak adsorption properties can enhance the flow resistance, which is even more significant than that of those surfactants with no adsorption capacity. Although heating (high temperature) can generally reduce the viscosity and flow resistance of surfactant fluid, it would cause a poor drag reduction efficiency. It may arise from the destruction of the adsorption layer and the interruption of the fluid/boundary interface. Surfactant adsorption can tune the roughness of the fluid boundary on either the smooth or rough surface in a different manner, which turns out to be highly correlated to the change in flow resistance. Compared with the adsorption layer, surfactant in the bulk fluid makes a greater contribution to enhancing the flow resistance as the concentration rises. This study is expected to be helpful in guiding the application of surfactants on the micro- and nanoscale such as lab-on-a-chip nanodevices and EOR in a low-permeability porous medium.

Dissolved gas analysis in transformer oil using Pd catalyst decorated MoSe2 monolayer: A first-principles theory

Dissolved gas analysis (DGA) by high-sensitive gas sensors is an effective manner to estimate the operation status of electrical transformers. In this paper, based on first-principles calculations, a novel 2D material, Pd-doped MoSe2 (Pd-MoSe2) monolayer, is explored as gas sensor or scavenger for detection or removal of typical gases in transformer oil, including H2, CO and C2H2, to guarantee the safety operation for the transformers. Adsorption configuration, density of state (DOS), recovery property, band structure and frontier molecular orbital theory are used to fully investigate the adsorption and desorption behaviors for Pd-MoSe2/gas systems. It is found that Pd-MoSe2 monolayer possesses strong adsorption performance towards CO molecule, thus allowing the removal of such pollutant to guarantee the safety operation of transformers. Besides, Pd-MoSe2 monolayer would be a promising candidate for C2H2 sensing due to the desirable adsorption and desorption behaviors. However, the poor adsorption behavior of Pd-MoSe2 monolayer upon H2 molecule even at ambient temperature reveals its unsuitability for H2 detector. Our results not only expound the transition metal doping effect on pure MoSe2 monolayer, but also provide a first insight into the potential application of Pd-MoSe2 monolayer in the field of electrical engineering.

Chitosan–silica nanoparticles catalyst (M@CS–SiO2) for the degradation of 1,1-dimethylhydrazine

Hybrid materials of chitosan–silica (CS–SiO2) with nonprecious-metallic ions (Cu) immobilized on (Cu–M@CS–SiO2) were developed as green catalysts for degrading 1,1-dimethyl hydrazine (UDMH) wastewater. SEM, XRD, EDX, and FT-IR were employed for characterizing the catalysts. Results indicated that metal ions were chelated with N or N and O atoms of CS–SiO2. The efficiency of UDMH degradation, chemical oxygen demand (COD) removal and the concentration of N-nitrosodimethylamine (NDMA) were used to evaluate the catalytic activity. The catalysts were firstly combined into the process of catalytic wet peroxide oxidation (CWPO) for the degradation of UDMH wastewater with H2O2. Based on the study of the effects of different metallic ions, anions and reaction factors on the catalyst activity, the optimal conditions for CWPO with M@CS–SiO2 were determined, the H2O2 dosage and temperature were 3.0 mL and 65 °C, respectively. Under these conditions, the treatable UDMH concentration was 500 mg L−1, obtaining the high efficiency of UDMH degradation and COD removal (100% in 10 min and 87.38% in 30 min, respectively) and the low concentration of NDMA (0.31 mg L−1). The catalyst activity was less affected within six reaction cycles. Meanwhile, owning a huge surface area and strong adsorption performance, this kind of hybrid material can rapidly degrade, adsorb, and separate pollution.

New design and fabrication of Cu3SnS4@C nanostructure for high efficient removal of anionic dye

A new type of strong adsorbent nanostructure Cu3SnS4@C has been first designed and fabricated by two-step hydrothermal synthesis. For removal of anionic dye methyl orange (MO), in striking contrast to the weak adsorption of bare C nanospheres (0.7 mg/g), the Cu3SnS4@C nanostructures exhibit a very strong pH-sensitive adsorption performance with a maximum adsorbability of 65.99 mg/g at pH 5.0 and a minimum value of 8.11 mg/g at pH 11.0, in initial concentrationof 70 mg/L MO. The samples’ adsorption mechanism could be well explained by pseudo-second-order kinetic model. Such significantly enhanced adsorbability of Cu3SnS4@C could be ascribed to the synergistic adsorption effect of Cu3SnS4 nanoparticles at C nanospheres, which can induce holes transfer and thus lead tomassive positive active sites generation on Cu3SnS4@C available for synergistic adsorption anion dye.

Novel Fabrication and Enhanced Photocatalytic MB Degradation of Hierarchical Porous Monoliths of MoO3 Nanoplates

Porous monoliths of MoO3 nanoplates were synthesized from ammonium molybdate (AHM) by freeze-casting and subsequent thermal treatment from 300 to 600 °C. Pure orthorhombic MoO3 phase was obtained at thermal treatment temperature of 400 °C and above. MoO3 monoliths thermally treated at 400 °C displayed bimodal pore structure, including large pore channels replicating the ice crystals and small pores from MoO3 sheets stacking. Transmission electron microscopy (TEM) images revealed that the average thicknesses of MoO3 sheet were 50 and 300 nm in porous monoliths thermally treated at 400 °C. The photocatalytic performance of MoO3 was evaluated through degradation of methylene blue (MB) under visible light radiation and MoO3 synthesized at 400 °C exhibited strong adsorption performance and best photocatalytic activity for photodegradation of MB of 99.7% under visible illumination for 60 min. MoO3 photocatalyst displayed promising cyclic performance, and the decolorization efficiency of MB solution was 98.1% after four cycles.

Interactions of nitric oxide with various rank coals: Implications for oxy-coal combustion flue gas sequestration in deep coal seams with enhanced coalbed methane recovery

Oxy-coal combustion is a promising option for capturing CO2 emitted from coal-fired power plant. Meanwhile, CO2 sequestration in deep coal seams with enhanced coal-bed methane (CH4) recovery (CO2-ECBM) can store the captured CO2 in geologic period. Thus, if the oxy-coal combustion flue gas directly sequestrated in deep coal seams is successfully implemented, the emissions of greenhouse gas (CO2) and the main gaseous pollutants (NOx, SO2) contained in flue gas will be simultaneously mitigated and CH4 as a by-product can also be recovered. It is acknowledged that the fluid sequestration in the deep coal seams is mainly attributed to the strong adsorption performance of coal matrix, thus the interactions of NO with various rank coals including adsorption behaviors and the possible interaction mechanism were primarily addressed in this work. Adsorption equilibrium study shows that the Sips isotherm model can well describe NO adsorption behavior on various rank coals, which is probably related to the high heterogeneity of coals. The Elovich equation can fit NO adsorption kinetics on coals successfully, indicating that the chemisorption probably plays a dominant role between NO and coals. Both Fourier Transform Infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) characterization results further confirm that the interactions with NO can change the nitrogen speciation compositions of all the test coals, and chemisorption is the main interaction mechanism between NO and coals. The chemisorption mechanism between NO and coals will contribute to the steady storage of NO in the target coal seams.

Graphene oxide coated quartz sand as a high performance adsorption material in the application of water treatment

GO firmly planted on the surface of quartz sand, will not fall off and cause secondary pollution. A series of experiments show that the GO coated sand (GOS) granules have a strong adsorption performance for organic matter and heavy metal ions.

Microstructure Analysis of Xanthoceras Sorbifolia Shell Activated Carbon

The Xanthoceras sorbifolia shell activated carbon which was prepared by using zinc chloride as activating agent has a strong adsorption performance of cationic adsorbate (methylene blue) 845.275mg/g and anionic adsorbate (iodine) 1584.96mg/g. Specific surface area study showed that: the adsorption isotherms of activated carbonsamples are type I isotherm adsorption, BET specific surface area was 1455.233m2/g. Displayed by pore specific surface analyzer's measurement results that the pore radius ratio of activated carbon in the range of 3.2-3.4Å is the largest. This proves that these holes are mainly micropores. Meanwhile, the conclusions obtained by the SEM further proof.

The preparation of nitrogen-doped TiO2 nanocrystals with exposed {001} facets and their visible-light photocatalytic performances

Anatase TiO2 with exposed {001} facets has been deepgoingly studied for optimizing its photocatalytic activity. In this study, we synthesized N-doped TiO2 nanocrystals with exposed {001} facets by sol–gel method and solvothermal method, respectively. The physical and chemical properties of as-synthesized samples, such as morphology, crystal phase, surface elements composition, porous structure, specific surface area, and optical response, were characterized in detail. The photocatalytic performances of all samples were evaluated by photocatalytic decoloration of methylene blue under visible-light irradiation (λ > 420 nm). The results showed that the as-prepared samples present high visible-light photocatalytic performances, which can be ascribed to the excellent crystallization, the enhancement of absorbance in the visible-light region, and the strong adsorption performance, and calcination treatment is helpful to further improve the visible-light photocatalytic performance of N-doped TiO2 nanocrystals with exposed {001} facets.

A kinetics study of multi-stage counter-current circulation acid leaching of vanadium from stone coal

The multi-stage counter-current circulation acid leaching of vanadium from stone coal was presented to decrease sulfuric acid consumption and enhance the leaching efficiency. The main factors on multi-stage counter-current circulation acid leaching were investigated. The factors were analyzed in terms of kinetics using the shrinking core model (SCM). The results show that the vanadium recovery could reach 86% under the conditions of sulfuric acid concentration of 4M, liquid to solid ratio of 2mL/g, temperature of 95°C, reaction time of 60min, mean particle size of 125μm and circulation acid leaching stage of three. During the four-stage acid leaching process, the KAl(SO4)2(H2O)12 could form and lead to the losses of vanadium in acid leaching solution due to the strong adsorption performance. The acid leaching process was controlled by chemical reaction with the sulfuric acid concentration under 4M, but controlled by internal diffusion with the sulfuric acid concentration above 4M. However, the acid leaching process was always controlled by internal diffusion at different temperatures.

Exceptional arsenic adsorption performance of hydrous cerium oxide nanoparticles: Part B. Integration with silica monoliths and dynamic treatment

A novel composite adsorbent (SCO) was synthesized by integrating CeO2 nanoparticles into silica monoliths for the removal of arsenic from water in a dynamic flow through reactor. The silica monoliths provided 3-dimensional interconnected macropores for the effective transportation of water while a large amount of mesopores on the silica skeleton served as the sites for attachment of CeO2 nanoparticles. After impregnation and calcinations, CeO2 nanoparticles were firmly fixed on the walls of silica monoliths. The SCO composite demonstrated a superior arsenic removal performance on both lab-prepared and natural water samples. At a fast empty bed contact time of 4min, a high breakthrough bed volume of 20,000bv was achieved for the treatment of arsenic-contaminated natural water of ∼80μg/L to meet the maximum contaminant level of arsenic at 10μg/L for drinking water. Even after desorption/regeneration, the composite still maintained a strong arsenic adsorption performance, which is beneficial for their potential industrial applications.