Aspen Adsorption在气体吸附过程模拟方面的应用

Aspen Adsorption是一款吸附模拟软件,常用于气体吸附分离过程的模拟计算,对操作条件优化、设计优化、吸附材料性能评价等方面具有一定的指导作用。简要介绍了Aspen Adsorption软件的应用、模型参数和各种衡算方程,总结了其在穿透曲线计算方面的模拟计算和应用,归纳了利用循环控制器Cycle Organizer针对各种类型的变压吸附PSA(Pressure Swing Adsorption)和变温吸附TSA(Temperature Swing Adsorption)过程进行模拟的情况。此外,针对Aspen Adsorption与其他软件结合使用的案例也进行了简要介绍。最后对Aspen Adsorption的未来发展进行了展望。

Adsorption of glycine on diamond(001): Role of bond angle of carbon atoms

The adsorption behaviors of glycine on diamond （001） are systematically investigated by first-principles calculations. We have considered all possible adsorption configurations without a surface dangling bond and give a quantitative analysis for the relationship between the deviation of carbon bond angle and adsorption energy. We found that a smaller distortion of carbon covalent bond angle results in a more stable adsorption structure, and the most stable adsorption has a benzene-ringlike structure with the highest adsorption energy of 5. 11 eV per molecule and the minimum distortion of carbon covalent bond angle.

High adsorption selectivity of activated carbon and carbon molecular sieve boosting CO_(2)/N_(2) and CH_(4)/N_(2) separation

Flue gas and coal bed methane are two important sources of greenhouse gases.Pressure swing adsorption process has a wide range of application in the field of gas separation,and the selection of adsorbent is crucial.In this regard,in order to assess the better adsorbent for separating CO_(2) from flue gas and CH_(4) from coal bed methane,adsorption isotherms of CO_(2),CH_(4) and N_(2) on activated carbon and carbon molecular sieve are measured at 303.15,318.15 and 333.15 K,and up to 250 kPa.The experimental data fit better with Langmuir 2 compared to Langmuir 3 and Langmuir-Freundlich models,and Clausius-Clapeyron equation was used to calculate the isosteric heat.Both the order of the adsorbed amount and the adsorption heat on the two adsorbents are CO_(2)>CH_(4)>N_(2).The adsorption kinetics are calculated by the pseudo-first kinetic model,and the order of adsorption rates on activated carbon is N_(2)-CH_(4)>CO_(2),while on carbon molecular sieve,it is CO_(2)-N_(2)>CH_(4).It is shown that relative molecular mass and adsorption heat are the primary effect on kinetics for activated carbon,while kinetic diameter is the main resistance factor for carbon molecular sieve.Moreover,the adsorption selectivity of CH_(4)/N_(2) and CO_(2)/N_(2) were estimated with the ideal adsorption solution theory,and carbon molecular sieve performed best at 318.15 K for both CO_(2) and CH_(4) separation.The study suggested that activated carbon is a better choice for separating flue gas and carbon molecular sieve can be a strong candidate for separating coal bed methane.

Dietary glycine supplementation enhances syntheses of creatine and glutathione by tissues of hybrid striped bass(Morone saxatilis ♀ × Morone chrysops ♂) fed soybean meal-based diets

Background We recently reported that supplementing glycine to soybean meal-based diets is necessary for the optimum growth of 5-to 40-g(Phase-I)and 110-to 240-g(Phase-II)hybrid striped bass(HSB),as well as their intestinal health.Although glycine serves as an essential substrate for syntheses of creatine and glutathione(GSH)in mammals(e.g.,pigs),little is known about these metabolic pathways or their nutritional regulation in fish.This study tested the hypothesis that glycine supplementation enhances the activities of creatine-and GSH-forming enzymes as well as creatine and GSH availabilities in tissues of hybrid striped bass(HSB;Morone saxatilis♀×Morone chrysops♂).Methods Phase-I and Phase-II HSB were fed a soybean meal-based diet supplemented with 0%,1%,or 2%glycine for 8 weeks.At the end of the 56-d feeding,tissues(liver,intestine,skeletal muscle,kidneys,and pancreas)were collected for biochemical analyses.Results In contrast to terrestrial mammals and birds,creatine synthesis occurred primarily in skeletal muscle from all HSB.The liver was most active in GSH synthesis among the HSB tissues studied.In Phase-I HSB,supplementation with 1%or 2%glycine increased(P<0.05)concentrations of intramuscular creatine(15%–19%)and hepatic GSH(8%–11%),while reducing(P<0.05)hepatic GSH sulfide(GSSG)/GSH ratios by 14%–15%,compared with the 0-glycine group;there were no differences(P>0.05)in these variables between the 1%and 2%glycine groups.In Phase-II HSB,supplementation with 1%and 2%glycine increased(P<0.05)concentrations of creatine and GSH in the muscle(15%–27%)and liver(11%–20%)in a dose-dependent manner,with reduced ratios of hepatic GSSG/GSH in the 1%or 2%glycine group.In all HSB,supplementation with 1%and 2%glycine dose-dependently increased(P<0.05)activities of intramuscular arginine:glycine amidinotransferase(22%–41%)and hepaticγ-glutamylcysteine synthetase(17%–37%),with elevated activities of intramuscular guanidinoacetate methyltransferase and hepatic GSH synthetase and GSH reductase in the 1%or 2%glycine group.Glycine supplementation also increased(P<0.05)concentrations of creatine and activities of its synthetic enzymes in tail kidneys and pancreas,and concentrations of GSH and activities of its synthetic enzymes in the proximal intestine.Conclusions Skeletal muscle and liver are the major organs for creatine and GSH syntheses in HSB,respectively.Dietary glycine intake regulates creatine and GSH syntheses by both Phase-I and Phase-II HSB in a tissue-specific manner.Based on the metabolic data,glycine is a conditionally essential amino acid for the growing fish.

Hypomethylation of glycine dehydrogenase promoter in peripheral blood mononuclear cells is a new diagnostic marker of hepatitis B virus-associated hepatocellular carcinoma

Background: Glycine dehydrogenase(GLDC) plays an important role in the initiation and proliferation of several human cancers. In this study, we aimed to detect the methylation status of GLDC promoter and its diagnostic value for hepatitis B virus-associated hepatocellular carcinoma(HBV-HCC). Methods: We enrolled 197 patients, 111 with HBV-HCC, 51 with chronic hepatitis B(CHB), and 35 healthy controls(HCs). The methylation status of GLDC promoter in peripheral mononuclear cells(PBMCs) was identified by methylation specific polymerase chain reaction(MSP). The mRNA expression was examined using real-time quantitative polymerase chain reaction(q PCR). Results: The methylation frequency of the GLDC promoter was significantly lower in HBV-HCC patients(27.0%) compared to that in CHB patients(68.6%) and HCs(74.3%)( P < 0.001). The methylated group had lower alanine aminotransferase level( P = 0.035) and lower rates of tumor node metastasis(TNM) Ⅲ/Ⅳ( P = 0.043) and T3/T4( P = 0.026). TNM stage was identified to be an independent factor for GLDC promoter methylation. GLDC mRNA levels in CHB patients and HCs were significantly lower than those in HBV-HCC patients( P = 0.022 and P < 0.001, respectively). GLDC mRNA levels were significantly higher in HBV-HCC patients with unmethylated GLDC promoters than those with methylated GLDC promoters( P = 0.003). The diagnostic accuracy of alpha-fetoprotein(AFP) combined with GLDC promoter methylation for HBV-HCC was improved compared with that of AFP alone(AUC: 0.782 vs. 0.630, P < 0.001). In addition, GLDC promoter methylation was an independent predictor for overall survival of HBV-HCC patients( P = 0.038). Conclusions: The methylation frequency of GLDC promoter was lower in PBMCs from HBV-HCC patients than that from patients with CHB and HCs. The combination of AFP and GLDC promoter hypomethylation significantly improved the diagnostic accuracy of HBV-HCC.

Investigations of methane adsorption characteristics on marine-continental transitional shales and gas storage capacity models considering pore evolution

Methane adsorption is a critical assessment of the gas storage capacity(GSC)of shales with geological conditions.Although the related research of marine shales has been well-illustrated,the methane adsorption of marine-continental transitional(MCT)shales is still ambiguous.In this study,a method of combining experimental data with analytical models was used to investigate the methane adsorption characteristics and GSC of MCT shales collected from the Qinshui Basin,China.The Ono-Kondo model was used to fit the adsorption data to obtain the adsorption parameters.Subsequently,the geological model of GSC based on pore evolution was constructed using a representative shale sample with a total organic carbon(TOC)content of 1.71%,and the effects of reservoir pressure coefficient and water saturation on GSC were explored.In experimental results,compared to the composition of the MCT shale,the pore structure dominates the methane adsorption,and meanwhile,the maturity mainly governs the pore structure.Besides,maturity in the middle-eastern region of the Qinshui Basin shows a strong positive correlation with burial depth.The two parameters,micropore pore volume and non-micropore surface area,induce a good fit for the adsorption capacity data of the shale.In simulation results,the depth,pressure coefficient,and water saturation of the shale all affect the GSC.It demonstrates a promising shale gas potential of the MCT shale in a deeper block,especially with low water saturation.Specifically,the economic feasibility of shale gas could be a major consideration for the shale with a depth of<800 m and/or water saturation>60%in the Yushe-Wuxiang area.This study provides a valuable reference for the reservoir evaluation and favorable block search of MCT shale gas.

大豆对胞囊线虫(Heterodera glycines Ichinohe)1号和4号生理小种抗性的遗传分析

大豆胞囊线虫(Heterodera glycinesIchinohe)是我国大豆的全国性主要病害之一。1号和4号生理小种是黄淮地区的优势小种。以Essex×ZDD2315、Peking×ZDD2315、PI88788×ZDD2226、Peking×ZDD2226的P1、P2、F1、BC1F2为材料,用主基因+多基因混合遗传模型分析大豆对胞囊线虫1号和4号生理小种抗性的遗传机制。结果表明,ZDD2315、ZDD2226对1号生理小种的抗性受主效基因控制,未发现多基因效应,且与Peking存在相同的抗病基因;抗性遗传表现组合特异性,Essex×ZDD2315组合为3对加性主基因遗传模型,主基因遗传率72.02%,PI88788×ZDD2226组合为2对显性上位主基因遗传模型,主基因遗传率62.33%。对4号生理小种的抗性为主基因+多基因混合遗传模型,Essex×ZDD2315、Peking×ZDD2315、PI88788×ZDD2226等3个组合为3对主基因+多基因遗传模型,主基因遗传率分别为67.76%7、2.46%和53.25%,多基因遗传率分别为24.48%、21.31%和35.77%;Peking×ZDD2226表现为2对主基因遗传模型,主基因遗传率45.40%。抗性基因表现为隐性,育种上可以在早代选择。培育多抗品种应以抗4号生理小种为主要目标进行基因聚合。

Enhanced nitrite electroreduction to ammonia via interfacial dual-site adsorption

The nitrite(NO_(2)^(−))to ammonia(NH3)electroreduction reaction(NO_(2)^(−)RR)would be impeded by sluggish proton-coupled electron transfer kinetics and competitive hydrogen evolution reaction(HER).A key to improving the NH_(3) selectivity is to facilitate adsorption and activation of NO_(2)^(−),which is generally undesirable in unitary species.In this work,an efficient NO_(2)^(−)RR catalyst is constructed by cooperating Pd with In2O3,in which NO_(2)^(−)could adsorb on interfacial dual-site through“Pd–N–O–In”linkage,leading to strengthened NO_(2)^(−)adsorption and easier N=O bond cleavage than that on unitary Pd or In2O3.Moreover,the Pd/In_(2)O_(3)composite exhibits moderate H^(*)adsorption,which may facilitate protonation kinetics while inhibiting competitive HER.As a result,it exhibits a fairly high NH_(3)yield rate of 622.76 mmol h^(−1)g^(−1)cat with a Faradaic efficiency(FE)of 95.72%,good selectivity of 91.96%,and cycling stability towards the NO_(2)^(−)RR,surpassing unitary In_(2)O_(3)and Pd/C electrocatalysts.Besides,computed results indicate that NH_(3)production on Pd/In_(2)O_(3)follows the deoxidation to hydrogenation pathway.This work highlights the significance of H^(*)and NO_(2)^(−)adsorption modulation and N=O activation in NO_(2)^(−)RR electrochemistry by creating synergy between a mediocre catalyst with an appropriate cooperator.

Ultra-high specific surface area activated carbon from Taihu cyanobacteria via KOH activation for enhanced methylene blue adsorption

Cyanobacteria-based activated carbon(CBAC)was successfully prepared by pyrolysis-activation of Taihu cyanobacteria.When the impregnation ratio and activated temperature were 2 and 800-C,respectively,the optimal CBACs possessed an ultra-high specific surface(2178.90 m^(2)·g^(-1))and plenty of micro-and meso-pores,as well as a high pore volume(1.01 cm^(3)·g^(-1)).Ascribed to ultra-high surface area,π-π interaction,electrostatic interaction,as well as hydrogen-bonding interactions,the CBACs displayed huge superiority in efficient dye removal.The saturated methylene blue adsorption capacity by CBACs could be as high as 1143.4 mg·g^(-1),superior to that of other reported biomass-activated carbons.The adsorption was endothermic and modeled well by the pseudo-second-order kinetic,intra-particle diffusion,and Langmuir models.This work presented the effectiveness of Taihu cyanobacteria adsorbent ascribed to its super large specific surface area and high adsorption ability.

Development and performance evaluation of high temperature resistant strong adsorption rigid blocking agent

As drilling wells continue to move into deep ultra-deep layers,the requirements for temperature resistance of drilling fluid treatments are getting higher and higher.Among them,blocking agent,as one of the key treatment agents,has also become a hot spot of research.In this study,a high temperature resistant strong adsorption rigid blocking agent(QW-1)was prepared using KH570 modified silica,acrylamide(AM)and allyltrimethylammonium chloride(TMAAC).QW-1 has good thermal stability,average particle size of 1.46μm,water contact angle of 10.5.,has a strong hydrophilicity,can be well dispersed in water.The experimental results showed that when 2 wt%QW-1 was added to recipe A(4 wt%bentonite slurry+0.5 wt%DSP-1(filtration loss depressant)),the API filtration loss decreased from 7.8to 6.4 m L.After aging at 240.C,the API loss of filtration was reduced from 21 to 14 m L,which has certain performance of high temperature loss of filtration.At the same time,it is effective in sealing 80-100mesh and 100-120 mesh sand beds as well as 3 and 5μm ceramic sand discs.Under the same conditions,the blocking performance was superior to silica(5μm)and calcium carbonate(2.6μm).In addition,the mechanism of action of QW-1 was further investigated.The results show that QW-1 with amide and quaternary ammonium groups on the molecular chain can be adsorbed onto the surface of clay particles through hydrogen bonding and electrostatic interaction to form a dense blocking layer,thus preventing further intrusion of drilling fluid into the formation.

Simulation of fixed-bed adsorption process considering particle size distribution

The distribution of adsorbent particle sizes typically has a significant impact on adsorption performance.Most fixed-bed adsorption studies adopt the assumption of average particle size to simplify the adsorption model,but this does not eliminate the deviation between experiments and simulations caused by particle size distribution in practice.In this study,the population balance equation(PBE)and fixed-bed adsorption kinetics model were combined to simulate the adsorption process in a fixed-bed reactor,modeling the distribution of adsorbate uptake over time on adsorbent particles of different sizes.We integrated and optimized the PBE and fixed-bed mass transfer model in the algorithm,and the resulting combined model adopts a variable time step size,which can achieve a balance between computational efficiency and error while ensuring computational convergence.By slicing the model in the spatial dimension,multiple sets of PBE can be calculated in parallel,improving computational efficiency.The adsorption process of single-component and multi-component CO_(2)/CH_(4)/N_(2)on 4A zeolite without binder was simulated,and the influence of adsorbent particle size distribution was analyzed.Simulation results show that the assumption of average adsorbent particle size,which was commonly made in published work,will underestimate the time required for adsorbates to break through the fixed bed compared with the assumption of uniform adsorbent particle size.This model helps to consider the impact of adsorbent particle size distribution on the adsorption process,thereby improving the prediction accuracy of adsorbent performance.

Coverage Dependent Dissociative Adsorption of HCl on Au(111)

Dissociative adsorption of HCl on Au(111)has become one of unsolved puzzles in surface chemistry.Despite tremendous efforts in the past years,varioustheoretical models still greatly overestimate the zero-coverage initial sticking probabilities(So).To find the origin of the large experiment-theory discrepancy,we have revisited the dissociative adsorption of HCl on Au(111)with a newly designed molecular beam-surface apparatus.The zero-coverage So derived from Cl-coverage measurements with varying HCl doses agree well with previous ones.However,we notice a sharp change of the coverage/dose slope with the HCl dosage at the low coverage regime,which may result in some uncertainties to the fitted So value.This seems consistent with a coverage-dependence of the dissociation barrier predicted by density functional theory at low Cl-coverages.Our results reveal the potential inconsistency of utilizing simulations with finite coverage to compare against experimental data with zero coverage in this system,and provide guidance for improving both experiment and theory in this regard.

Effective removal of chromium,copper,and nickel heavy metal ions from industrial electroplating wastewater by in situ oxidative adsorption using sodium hypochlorite as oxidant and sodium trititanate nanorod as adsorbent

Sodium hypochlorite and synthesized sodium trititanate nanorods(Na_(2)Ti_(3)O_(7),186 nm×1270 nm)were used as the oxidant and adsorbents for in situ oxidative adsorption treatment of actual electroplating wastewater containing Cr(Ⅵ)(2.6-5.2 mg·L^(-1)),Cu^(2+)(2.7-5.4 mg·L^(-1)),and Ni^(2+)(0.2705-0.541 mg·L^(-1))ions at pH of 8.8-9.1 and 20-60℃.The as-synthesized sodium trititanate nanorods were characterized by XRD,HRTEM,N2 adsorption/desorption,SEM,EDX,and zeta potential techniques.The concentrations of heavy metal ions in wastewater were analyzed by ICP technique.After in situ oxidative adsorption treatment under the concentrations of 25 g·L^(-1) for sodium hypochlorite and 125 mg·L^(-1) for sodium trititanate nanorods at 60℃ for 5 h,the heavy metal ion concentrations could be reduced from initial value of 2.6 to final value of 1.92 mg·L^(-1) for Cr(Ⅵ),3.6 to 0.17 mg·L^(-1) for Cu^(2+),and from 0.2705 to 0.097 mg·L^(-1) for Ni^(2+),respectively.Cr(Ⅵ),Cu^(2+) and Ni^(2+) ions could be effectively removed by the in situ oxidative adsorption method.The in situ oxidative adsorption processes of Cr(Ⅵ),Cu^(2+) and Ni^(2+) ions are satisfactorily simulated by the pseudo-second order adsorption kinetics and Langmuir adsorption isotherm,respectively.Adsorption thermodynamics analyses reveal that the oxidative adsorption processes of Cr(Ⅵ),Cu^(2+) and Ni^(2+) ions are spontaneous and endothermic.The oxidation degree of metalcontained complexes influences the values of thermodynamics functions.

Defect-induced synthesis of nanoscale hierarchically porous metal-organic frameworks with tunable porosity for enhanced volatile organic compound adsorption

Nanoscale hierarchically porous metal-organic frameworks(NH-MOFs)synergistically combine the advantages of nanoscale MOFs and hierarchically porous MOFs,resulting in remarkable characteristics such as increased specific surface area,greater porosity,and enhanced exposure of active sites.Herein,nanoscale hierarchically porous UIO-66(UIO-66_X)was synthesized using a defect-induced strategy that employed ethylene diamine tetraacetic acid(EDTA)as a modulator.The introduced EDTA occupies the coordination sites of organic ligands,promoting the formation and growth of UIO-66 crystal nuclei and inducing defects during synthesis.The as-synthesized UIO-66_X crystals exhibit a uniform distribution with an average size of approximately 100 nm.In addition,the total pore volume attains a remarkable value of 0.95 cm^(3)g^(-1),with mesopores constituting 36.8% of the structure.Furthermore,the porosities of UIO-66_X can be easily tuned by controlling the molar ratio of EDTA/Zr^(4+).In addition,the as-synthesized UIO-66_X exhibits excellent adsorption capacities for n-hexane(344 mg g^(-1))and pxylene(218 mg g^(-1)),which are 44.5% and 27.5% higher than those of conventional UIO-66,respectively.Finally,the adsorption behavior of n-hexane and p-xylene molecules in UIO-66_X was investigated using density functional theory simulations.

Enhanced Oxygen Evolution Reaction Performance by Dynamic Adsorption of Intermediates on C2N-Supported Single Atom Catalysts

The dynamic adsorption of possible intermediates on single-atom catalysts(SACs)under working condition plays a key role in the electrocatalytic performance by the oxygen evolution reaction(OER),and therefore the performance of the dynamic adsorption should be fully considered in the theoretical screening of potential SACs.Based on density functional theory calculations,the OER performance of 27 types of C_(2)N-supported single transition metal atoms(TM@C_(2)N)is systematically investigated without and with considering the dynamic adsorption of possible intermediates.Without considering dynamic adsorption,only Rh@C_(2)N and Ni@C_(2)N are screened out as good catalysts.However,by further considering the dynamic adsorption configurations of possible intermediates,more promising TM@C_(2)N SACs including Fe(Co,Ni,Ru,Rh,Ir)@C_(2)N toward the OER are screened out.The presence of the intermediates(*HO,*O)on SACs could shift their d band center toward lower energy level,which makes the interaction between the adsorbate and SACs moderate and thus enhances their OER performance.The present work is instructive for further screening and designing of efficient single-atom catalysts for the oxygen evolution reaction.

Dual-functional poly(2-methyl-2-oxazoline)/poly(2-(dimethylamine)ethyl methacrylate)mixed brushes with switchable protein adsorption and antibacterial properties

Herein,binary mixed brushes consisting of poly(2-methyl-2-oxazoline)(PMOXA)and poly(2-(dimethylamine)ethyl methacrylate)(PDMAEMA)with different chain lengths were fabricated by successive grafting of NH_(2)-terminated PMOXA and SH-terminated PDMAEMA onto polydopamine-anchored substrates.The mixed-brush coating was characterized by variable-angle spectroscopic ellipsometry,X-ray photoelectron spectroscopy,Fourier transform infrared spectroscopy,zeta potential measurements,water contact angle,and atomic force microscopy.The mixed brushes showed tunable surface charge,wettability,and surface roughness,depending on the degree of PDMAEMA swelling under varying pH and ionic strength(Ⅰ).Then the adsorption behaviors of pepsin,bovine serum albumin(BSA),γ-globulin,and lysozyme,four very different proteins with regard to isoelectric point,on the mixed brushes coating were studied by using fluorescence microscopy and surface plasmon resonance.When the chain length of PDMAEMA was about twice as long as PMOXA,the mixed brushes not only had high adsorption capacity for pepsin,BSA,and y-globulin but also had a desorption efficiency of 86.9%,87.1%,and 93.5%,respectively.It is explained that electrostatic attraction between the protonated PDMAEMA and positively charged acidic proteins(pepsin and BSA,whose isoelectric points were below the pK_(a) of PDMAEMA)would drive the intensive adsorption(at pH 3,I=10^(-3)mol·L^(-1)for pepsin,and pH 5,I=10^(-5)mol·L^(-1)for BSA),while desorption was dominated by the hydrophilic PMOXA when PDMAEMA was shrinking(at pH 7,I=10^(-1)mol·L^(-1)for pepsin,and pH 9,I=10^(-1)mol·L^(-1)for BSA).Furthermore,the isoelectric precipitation led to the adsorption of neutral protein(γ-globulin,whose isoelectric point was near the pK_a of PDMAEMA)at pH 7,I=10^(-5)mol·L^(-1),while electrostatic repulsion and antifouling PMOXA triggered the desorption of y-globulin at pH 3,I-10^(-1)mol·L^(-1).However,alkaline protein(lysozyme,whose isoelectric point was higher than the pK_(a) of PDMAEMA)exhibited slight adsorption on PMOXA/PDMAEMA mixed brushes under test conditions,regardless of whether PMOXA or PDMAEMA occupied the outermost layer.The antibacterial property of the mixed brushes against Escherichia coli was investigated.PMOXA/PDMAEMA mixed brushes showed significant bactericidal activity at pH 3,I=10^(-3)mol·L^(-1),while the rinse of pH 9,I=10^(-1)mol·L^(-1)solution could remove most of the residual bacteria.This work not only enables controlled adsorption of proteins with different isoelectric points but also ensures that the surface of the coating is minimized from bacterial contamination.

Integrated adsorption and photocatalytic removal of methylene blue dye from aqueous solution by hierarchical Nb_(2)O_(5)@PAN/PVDF/ANO composite nanofibers

This work presents the development of hierarchical niobium pentoxide(Nb_(2)O_(5))-based composite nanofiber membranes for integrated adsorption and photocatalytic degradation of methylene blue(MB)pollutants from aqueous solutions.The Nb_(2)O_(5) nanorods were vertically grown using a hydrothermal process on a base electrospun nanofibrous membrane made of polyacrylonitrile/polyvinylidene fluoride/ammonium niobate(V)oxalate hydrate(Nb_(2)O_(5)@PAN/PVDF/ANO).They were characterized using field-emission scanning electron microscopy(FE-SEM),X-ray diffraction(XRD)analysis,and Fourier transform infrared(FTIR)spectroscopy.These composite nanofibers possessed a narrow optical bandgap energy of 3.31 eV and demonstrated an MB degradation efficiency of 96%after 480 min contact time.The pseudo-first-order kinetic study was also conducted,in which Nb_(2)O_(5)@PAN/PVDF/ANO nanofibers have kinetic constant values of 1.29×10^(-2) min^(-1) and 0.30×10^(-2) min^(-1) for adsorption and photocatalytic degradation of MB aqueous solutions,respectively.These values are 17.7 and 7.8 times greater than those of PAN/PVDF/ANO nanofibers without Nb_(2)O_(5) nanostructures.Besides their outstanding photocatalytic performance,the developed membrane materials exhibit advantageous characteristics in recycling,which subsequently widen their practical use in environmental remediation applications.

Selective adsorption of tetracycline by β-CD-immobilized sodium alginate aerogel coupled with ultrafiltration for reclaimed water

In this work,a novel composite material based on β-cyclodextrin-immobilized sodium alginate aerogel(β-CD/NaAlg) was developed utilizing cross-linker of epichlorohydrin and applied as an adsorbent to remove tetracycline antibiotics from reclaimed wastewater.A series of characterizations were utilized to confirm the successful synthesis of the adsorbent and this β-CD/NaAlg presented a three-dimensional network at the nanoscale or microscale.Under optimal conditions(pH=4,t=8 h,β-CD:NaAlg=9,adsorbent dosage = 1.5 g·L-1),the maximum removal rate of β-CD/NaAlg to tetracycline was 70%.The adsorption behavior of tetracycline on β-CD/NaAlg conformed to the Freundlich isotherm model(R2=0.9977) and the pseudo-second-order kinetic model(R^(2)=0.9993).Moreover,the adsorbent still removed 55.3% of tetracycline after five cycles.Specially,the adsorbent was integrated with ultrafiltration to adsorb tetracycline antibiotics from simulated reclaimed wastewater,and the removal rate of tetracycline reached 78.9% within 2 h.The existence of Cr(Ⅵ) had a negligible impact on tetracycline removal,while the presence of humic acid exhibited a promoting effect.The possible adsorption mechanisms were also elucidated through X-ray photoelectron spectroscopy and density functional theory analysis.In summary,β-CD/NaAlg represents an environmentally friendly,efficient,and sustainable adsorbent for removing tetracycline antibiotics from reclaimed water.

Molecular Dynamics Numerical Simulation of Adsorption Characteristics and Exploitation Limits in Shale Oil Microscopic Pore Spaces

Microscopic pore structure in continental shale oil reservoirs is characterized by small pore throats and complex micro-structures.The adsorption behavior of hydrocarbons on the pore walls exhibits unique physical and chemical properties.Therefore,studying the adsorption morphology of hydrocarbon components in nanometer-sized pores and clarifying the exploitation limits of shale oil at the microscopic level are of great practical significance for the efficient development of continental shale oil.In this study,molecular dynamics simulations were employed to investigate the adsorption characteristics of various single-component shale oils in inorganic quartz fissures,and the influence of pore size and shale oil hydrocarbon composition on the adsorption properties in the pores was analyzed.The results show that different molecules have different adsorption capacities in shale oil pores,with lighter hydrocarbon components(C6H14)exhibiting stronger adsorption abilities.For the same adsorbed molecule,the adsorption amount linearly increases with the increase in pore diameter,but larger pores contribute more to shale oil adsorption.In shale pores,the thickness of the adsorption layer formed by shale oil molecules ranges from 0.4 to 0.5 nm,which is similar to the width of alkane molecules.Shale oil in the adsorbed state that is difficult to be exploited is mainly concentrated in the first adsorption layer.Among them,the volume fraction of adsorbed shale oil in 6 nm shale pores is 40.8%,while the volume fraction of shale oil that is difficult to be exploited is 16.2%.

Factors resisting protein adsorption on hydrophilic/hydrophobic self-assembled monolayers terminated with hydrophilic hydroxyl groups

The hydroxyl-terminated self-assembled monolayer(OH-SAM),as a surface resistant to protein adsorption,exhibits substantial potential in applications such as ship navigation and medical implants,and the appropriate strategies for designing anti-fouling surfaces are crucial.Here,we employ molecular dynamics simulations and alchemical free energy calculations to systematically analyze the factors influencing resistance to protein adsorption on the SAMs terminated with single or double OH groups at three packing densities(∑=2.0 nm^(-2),4.5 nm^(-2),and 6.5 nm^(-2)),respectively.For the first time,we observed that the compactness and order of interfacial water enhance its physical barrier effect,subsequently enhancing the resistance of SAM to protein adsorption.Notably,the spatial hindrance effect of SAM leads to the embedding of protein into SAM,resulting in a lack of resistance of SAM towards protein.Furthermore,the number of hydroxyl groups per unit area of double OH-terminated SAM at ∑=6.5 nm^(-2) is approximately 2 to 3 times that of single OH-terminated SAM at ∑=6.5 nm^(-2) and 4.5 nm^(-2),consequently yielding a weaker resistance of double OH-terminated SAM towards protein.Meanwhile,due to the structure of SAM itself,i.e.,the formation of a nearly perfect ice-like hydrogen bond structure,the SAM exhibits the weakest resistance towards protein.This study will complement and improve the mechanism of OH-SAM resistance to protein adsorption,especially the traditional barrier effect of interfacial water.