Using density functional theory, noncovalent interactions and two mechanisms of covalent functionalization of drug carmustine with functionalized carbon nanotube（CNT） have been investigated. Quantum molecular descri...Using density functional theory, noncovalent interactions and two mechanisms of covalent functionalization of drug carmustine with functionalized carbon nanotube（CNT） have been investigated. Quantum molecular descriptors of noncovalent configurations were studied. It was specified that binding of drug carmustine with functionalized CNT is thermodynamically suitable. NTCOOH and NTCOCl can bond to the NH group of carmustine through OH（COOH mechanism） and Cl（COCl mechanism） groups, respectively. The activation energies, activation enthalpies and activation Gibbs free energies of two pathways were calculated and compared with each other. The activation parameters related to COOH mechanism are higher than those related to COCl mechanism, and therefore COCl mechanism is suitable for covalent functionalization. COOH functionalized CNT（NTCOOH） has more binding energy than COCl functionalized CNT（NTCOCl） and can act as a favorable system for carmustine drug delivery within biological and chemical systems（noncovalent）. These results could be generalized to other similar drugs.展开更多
Amorphous carbon materials play a vital role in adsorbed natural gas(ANG) storage. One of the key issues in the more prevalent use of ANG is the limited adsorption capacity, which is primarily determined by the porosi...Amorphous carbon materials play a vital role in adsorbed natural gas(ANG) storage. One of the key issues in the more prevalent use of ANG is the limited adsorption capacity, which is primarily determined by the porosity and surface characteristics of porous materials. To identify suitable adsorbents, we need a reliable computational tool for pore characterization and, subsequently, quantitative prediction of the adsorption behavior. Within the framework of adsorption integral equation(AIE), the pore-size distribution(PSD) is sensitive to the adopted theoretical models and numerical algorithms through isotherm fitting. In recent years, the classical density functional theory(DFT) has emerged as a common choice to describe adsorption isotherms for AIE kernel construction. However,rarely considered is the accuracy of the mean-field approximation(MFA) commonly used in commercial software. In this work, we calibrate four versions of DFT methods with grand canonical Monte Carlo(GCMC) molecular simulation for the adsorption of CH_4 and CO_2 gas in slit pores at 298 K with the pore width varying from 0.65 to 5.00 nm and pressure from 0.2 to 2.0 MPa. It is found that a weighted-density approximation proposed by Yu(WDA-Yu) is more accurate than MFA and other non-local DFT methods. In combination with the trapezoid discretization of AIE, the WDA-Yu method provides a faithful representation of experimental data, with the accuracy and stability improved by 90.0% and 91.2%, respectively, in comparison with the corresponding results from MFA for fitting CO_2 isotherms. In particular, those distributions in the feature pore width range(FPWR)are proved more representative for the pore-size analysis. The new theoretical procedure for pore characterization has also been tested with the methane adsorption capacity in seven activated carbon samples.展开更多
This study was designed to explore the dietary fiber potential of Lycium Barbarum residue,aiming to ascertain its viability as a sustainable dietary fiber source.The study examined the extraction of water-insoluble di...This study was designed to explore the dietary fiber potential of Lycium Barbarum residue,aiming to ascertain its viability as a sustainable dietary fiber source.The study examined the extraction of water-insoluble dietary fiber(LBIDF)from Lycium barbarum residue(LBR)using the enzymatic method.The comparison involved analyzing the monosaccharide composition,microstructure,physicochemical properties,and adsorption properties of LBR and LBIDF.The results indicated that LBIDF possesses the ideal physicochemical properties compared to LBR.Through instrumental analysis,it has been demonstrated that LBIDF possesses a specific structure and functional group of fibers,making it suitable for processing below 300℃.Furthermore,LBIDF exhibited an optimal functional capacity for cholesterol(41.749 mg/g vs.31.464 mg/g in LBR),bile acid(30.623 mg/g vs.19.875 mg/g in LBR),nitrite ion(1159.394μmol/g vs.783.261μmol/g in LBR),glucose(3.552 mmol/g vs.2.664 mmol/g in LBR),and glucose dialysis retardation index(6.43%vs.13.52%in LBR).LBIDF can inhibit the digestion of fat and starch in vitro.These findings implied that dietary fiber samples from LBR may offer potential as functional food components.展开更多
To decrease the operating cost of flue gas purification technologies based on carbon-based materials, the adsorption and regeneration performance of low-price semi-coke and activated coke were compared for SO2 and NO ...To decrease the operating cost of flue gas purification technologies based on carbon-based materials, the adsorption and regeneration performance of low-price semi-coke and activated coke were compared for SO2 and NO removal in a simulated flue gas. The functional groups of the two adsorbents before and after regeneration were characterized by a Fourier transform infrared（FTIR） spectrometer, and were quantitatively assessed using temperature programmed desorption（TPD） coupled with FTIR and acid–base titration. The results show that semi-coke had higher adsorption capacity（16.2% for SO2 and 38.6% for NO） than activated coke because of its higher content of basic functional groups and lactones. After regeneration, the adsorption performance of semi-coke decreased because the number of active functional groups decreased and the micropores increased. Semi-coke had better regeneration performance than activated coke. Semi-coke had a larger SO2 recovery of 7.2% and smaller carbon consumption of 12% compared to activated coke. The semi-coke carbon-based adsorbent could be regenerated at lower temperatures to depress the carbon consumption, because the SO2 recovery was only reduced a small amount.展开更多
Residue biochar can be utilized as an adsorbent for ammonium nitrogen(NH_(4)^(+)-N)to prevent non-point source pollution.However,the limited adsorption capacity has restricted its extensive application.In this study,b...Residue biochar can be utilized as an adsorbent for ammonium nitrogen(NH_(4)^(+)-N)to prevent non-point source pollution.However,the limited adsorption capacity has restricted its extensive application.In this study,biochar was modified with hydrogen peroxide(H_(2)O_(2)),potassium permanganate(KMnO_(4)),and sodium hydroxide(NaOH)to enhance its adsorption performance.A comparative analysis of the biochar surface characteristics was used to investigate the adsorption systems.The results indicated that the adsorption capacities of the modified biochar(MB)were significantly enhanced compared with the raw biochar(RB).At the highest NH_(4)^(+)-N concentration of 150 mg L^(−1),the adsorption capacities of RB-H_(2)O_(2),RB-NaOH,and RB-KMnO_(4)increased to 3.0,3.2,and 4.0 times that of RB,respectively.As predicted by the Langmuir isotherm model,the maximum adsorption capacities of these three MB were 13.93,41.00,and 68.15 mg g^(−1),respectively.Ammonium adsorption on the MB surfaces was affected by surface adsorption,liquid membrane diffusion,and intra-particle diffusion.The specific surface area and pore volume of RBKMnO_(4)were significantly enhanced,with an increase in active sites on the pore surfaces,thereby strengthening its adsorption capacity for NH_(4)^(+)-N.In contrast,the adsorption of NH_(4)^(+)-N by RB-H_(2)O_(2)and RB-NaOH primarily relied on the substantial increase in-C-O functional groups,with additional contributions from other oxygen-containing functional(e.g.-OH,-COOH,and Fe-O).In conclusion,RB-KMnO_(4)exhibited the highest adsorption efficiency,with pore-based adsorption playing a dominant role over functional group-based adsorption.These findings highlight the critical role of pore structure optimization in enhancing the biochar adsorption capacity for NH_(4)^(+)-N.展开更多
Here we present a combined DFF and molecular dynamics study of uranyl （U（VI）） interaction mecha- nisms with the calcite （104） surface in aqueous solution. The roles of three anion ligands （CO2 , HCO3, OH ） and...Here we present a combined DFF and molecular dynamics study of uranyl （U（VI）） interaction mecha- nisms with the calcite （104） surface in aqueous solution. The roles of three anion ligands （CO2 , HCO3, OH ） and solvation effect in U（VI） interaction with calcite have been evaluated. According to our calculations, water adsorbed on the calcite （104） surface prefers to exist in molecular state rather than dis- sociative state. Energy analysis indicate that the positively charged uranyl species prefers to form surface complexes on the surface, while neutral uranyl species may bind with the surface via both surface complexing and ion exchange reactions of U（VI） → Ca（II）. In contrast, the negatively charged uranyl species prefer to interact with the surface via ion exchange reactions of U（VI）→ Ca（II）, and the one with UO2（CO3）2（H2O）^2- as the reactant becomes the most favorable one in energy. We also found that uranyl adsorption increases the hydrophilicability of the （104） surface to different extents, where the UO2（CO3）3Ca2 species contributes to the largest degree of energy changes （ 53 kcal/mol）. Our calcula- tions proved that the （104） surface also has the ability to immobilize U（VI） via either surface complexing or ion exchange mechanisms under different pH values.展开更多
文摘Using density functional theory, noncovalent interactions and two mechanisms of covalent functionalization of drug carmustine with functionalized carbon nanotube（CNT） have been investigated. Quantum molecular descriptors of noncovalent configurations were studied. It was specified that binding of drug carmustine with functionalized CNT is thermodynamically suitable. NTCOOH and NTCOCl can bond to the NH group of carmustine through OH（COOH mechanism） and Cl（COCl mechanism） groups, respectively. The activation energies, activation enthalpies and activation Gibbs free energies of two pathways were calculated and compared with each other. The activation parameters related to COOH mechanism are higher than those related to COCl mechanism, and therefore COCl mechanism is suitable for covalent functionalization. COOH functionalized CNT（NTCOOH） has more binding energy than COCl functionalized CNT（NTCOCl） and can act as a favorable system for carmustine drug delivery within biological and chemical systems（noncovalent）. These results could be generalized to other similar drugs.
基金Supported by the National Sci-Tech Support Plan(2015BAD21B05)China Scholarship Council(201408320127)
文摘Amorphous carbon materials play a vital role in adsorbed natural gas(ANG) storage. One of the key issues in the more prevalent use of ANG is the limited adsorption capacity, which is primarily determined by the porosity and surface characteristics of porous materials. To identify suitable adsorbents, we need a reliable computational tool for pore characterization and, subsequently, quantitative prediction of the adsorption behavior. Within the framework of adsorption integral equation(AIE), the pore-size distribution(PSD) is sensitive to the adopted theoretical models and numerical algorithms through isotherm fitting. In recent years, the classical density functional theory(DFT) has emerged as a common choice to describe adsorption isotherms for AIE kernel construction. However,rarely considered is the accuracy of the mean-field approximation(MFA) commonly used in commercial software. In this work, we calibrate four versions of DFT methods with grand canonical Monte Carlo(GCMC) molecular simulation for the adsorption of CH_4 and CO_2 gas in slit pores at 298 K with the pore width varying from 0.65 to 5.00 nm and pressure from 0.2 to 2.0 MPa. It is found that a weighted-density approximation proposed by Yu(WDA-Yu) is more accurate than MFA and other non-local DFT methods. In combination with the trapezoid discretization of AIE, the WDA-Yu method provides a faithful representation of experimental data, with the accuracy and stability improved by 90.0% and 91.2%, respectively, in comparison with the corresponding results from MFA for fitting CO_2 isotherms. In particular, those distributions in the feature pore width range(FPWR)are proved more representative for the pore-size analysis. The new theoretical procedure for pore characterization has also been tested with the methane adsorption capacity in seven activated carbon samples.
文摘This study was designed to explore the dietary fiber potential of Lycium Barbarum residue,aiming to ascertain its viability as a sustainable dietary fiber source.The study examined the extraction of water-insoluble dietary fiber(LBIDF)from Lycium barbarum residue(LBR)using the enzymatic method.The comparison involved analyzing the monosaccharide composition,microstructure,physicochemical properties,and adsorption properties of LBR and LBIDF.The results indicated that LBIDF possesses the ideal physicochemical properties compared to LBR.Through instrumental analysis,it has been demonstrated that LBIDF possesses a specific structure and functional group of fibers,making it suitable for processing below 300℃.Furthermore,LBIDF exhibited an optimal functional capacity for cholesterol(41.749 mg/g vs.31.464 mg/g in LBR),bile acid(30.623 mg/g vs.19.875 mg/g in LBR),nitrite ion(1159.394μmol/g vs.783.261μmol/g in LBR),glucose(3.552 mmol/g vs.2.664 mmol/g in LBR),and glucose dialysis retardation index(6.43%vs.13.52%in LBR).LBIDF can inhibit the digestion of fat and starch in vitro.These findings implied that dietary fiber samples from LBR may offer potential as functional food components.
基金financial support from the National Natural Science Foundation of China (No.21207132)the Strategic Priority Research Program of the Chinese Academy of Sciences (No.XDB05050502)the Special Research Funding for Public Benefit Industries from National Ministry of Environmental Protection (No.201209005)
文摘To decrease the operating cost of flue gas purification technologies based on carbon-based materials, the adsorption and regeneration performance of low-price semi-coke and activated coke were compared for SO2 and NO removal in a simulated flue gas. The functional groups of the two adsorbents before and after regeneration were characterized by a Fourier transform infrared（FTIR） spectrometer, and were quantitatively assessed using temperature programmed desorption（TPD） coupled with FTIR and acid–base titration. The results show that semi-coke had higher adsorption capacity（16.2% for SO2 and 38.6% for NO） than activated coke because of its higher content of basic functional groups and lactones. After regeneration, the adsorption performance of semi-coke decreased because the number of active functional groups decreased and the micropores increased. Semi-coke had better regeneration performance than activated coke. Semi-coke had a larger SO2 recovery of 7.2% and smaller carbon consumption of 12% compared to activated coke. The semi-coke carbon-based adsorbent could be regenerated at lower temperatures to depress the carbon consumption, because the SO2 recovery was only reduced a small amount.
基金supported by the National Natural Science Foundation of China(3230196931901195)+2 种基金Shandong Provincial Natural Science Foundation(ZR2024MC159)the Agricultural Science and Technology Innovation Program of the Chinese Academy of Agricultural Sciences(ASTIP-TRIC03)Yunnan Branch of China National Tobacco Corporation(2024530000241031).
文摘Residue biochar can be utilized as an adsorbent for ammonium nitrogen(NH_(4)^(+)-N)to prevent non-point source pollution.However,the limited adsorption capacity has restricted its extensive application.In this study,biochar was modified with hydrogen peroxide(H_(2)O_(2)),potassium permanganate(KMnO_(4)),and sodium hydroxide(NaOH)to enhance its adsorption performance.A comparative analysis of the biochar surface characteristics was used to investigate the adsorption systems.The results indicated that the adsorption capacities of the modified biochar(MB)were significantly enhanced compared with the raw biochar(RB).At the highest NH_(4)^(+)-N concentration of 150 mg L^(−1),the adsorption capacities of RB-H_(2)O_(2),RB-NaOH,and RB-KMnO_(4)increased to 3.0,3.2,and 4.0 times that of RB,respectively.As predicted by the Langmuir isotherm model,the maximum adsorption capacities of these three MB were 13.93,41.00,and 68.15 mg g^(−1),respectively.Ammonium adsorption on the MB surfaces was affected by surface adsorption,liquid membrane diffusion,and intra-particle diffusion.The specific surface area and pore volume of RBKMnO_(4)were significantly enhanced,with an increase in active sites on the pore surfaces,thereby strengthening its adsorption capacity for NH_(4)^(+)-N.In contrast,the adsorption of NH_(4)^(+)-N by RB-H_(2)O_(2)and RB-NaOH primarily relied on the substantial increase in-C-O functional groups,with additional contributions from other oxygen-containing functional(e.g.-OH,-COOH,and Fe-O).In conclusion,RB-KMnO_(4)exhibited the highest adsorption efficiency,with pore-based adsorption playing a dominant role over functional group-based adsorption.These findings highlight the critical role of pore structure optimization in enhancing the biochar adsorption capacity for NH_(4)^(+)-N.
基金supported by the National Natural Science Foundation of China (U1507116, 21471152, and 21477130)the Major Research Plan of Natural Science Foundation of China (91326202)The Science Challenge Project of China (JCKY2016212A504) is also acknowledged
文摘Here we present a combined DFF and molecular dynamics study of uranyl （U（VI）） interaction mecha- nisms with the calcite （104） surface in aqueous solution. The roles of three anion ligands （CO2 , HCO3, OH ） and solvation effect in U（VI） interaction with calcite have been evaluated. According to our calculations, water adsorbed on the calcite （104） surface prefers to exist in molecular state rather than dis- sociative state. Energy analysis indicate that the positively charged uranyl species prefers to form surface complexes on the surface, while neutral uranyl species may bind with the surface via both surface complexing and ion exchange reactions of U（VI） → Ca（II）. In contrast, the negatively charged uranyl species prefer to interact with the surface via ion exchange reactions of U（VI）→ Ca（II）, and the one with UO2（CO3）2（H2O）^2- as the reactant becomes the most favorable one in energy. We also found that uranyl adsorption increases the hydrophilicability of the （104） surface to different extents, where the UO2（CO3）3Ca2 species contributes to the largest degree of energy changes （ 53 kcal/mol）. Our calcula- tions proved that the （104） surface also has the ability to immobilize U（VI） via either surface complexing or ion exchange mechanisms under different pH values.
