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181.
The interfacial interactions between methylene diphenyl di-isocyanate (MDI) and polymeric MDI (PMDI) with 316L stainless steel have been studied in order to understand the adhesion properties of polyurethane based adhesives (containing free isocyanate groups) on metal surfaces. A thin (<5 nm) layer of MDI and PMDI was deposited on the surface of clean 316L stainless steel and then analysed by X-ray photoelectron spectroscopy (XPS) and time of flight secondary ion mass spectrometry (ToF-SIMS). By using density functional theory (DFT) methods for the interpretation of XPS data, the presence of specific interactions between the adsorbate and the substrate was established. The reaction between isocyanate and metal hydroxyl groups with the formation of urethane-like bonding with the metal was observed. The formation of hydrogen bonds between the isocyanate nitrogen and the hydroxyl groups and the formation of a nitrogen-metal double bond, as a consequence of the cycloaddition reaction between isocyanate and metal oxide, are also proposed. 相似文献
182.
Long Lin Longbin Yan Chaozheng He Linwei Yao Kun Xie Ruixin Chen Linghao Zhu Jingtao Huang Jingwen Sun Junwu Zhu Zhanying Zhang 《International Journal of Hydrogen Energy》2021,46(21):11711-11720
The adsorption and activation of gas molecules are investigated substantially in solid-gas heterogeneous catalysis. Here we investigated the interaction between gas molecules and unique two-dimensional monolayer Au (111) structure using density functional theory. It is found that CO2, H2O, N2 and CH4 molecules are weakly adsorbed on the surface with the adsorption energies between ?0.150 and ?0.250 eV due to van der Waals interaction. While CO, NO, NO2, and NH3 molecules are adsorbed more stably with the adsorption energies between ?0.300 and ?0.470 eV. Especially, the bond length of CO is stretched by 0.038 Å and the bond angle of NO2 is obviously enlarged by 10.460°. The activation originates from the rearrangement of molecule orbitals and the orbitals hybridization between the partial orbitals of gas molecules and Au-5d orbitals. The fundamental analyses of adsorption mechanism and electronic properties may provide guidance for the applications of two-dimensional monolayer metal catalysis.PACSnumbers 73.22.-f, 73.61.-r 相似文献
183.
《Journal of Industrial and Engineering Chemistry》2014,20(3):787-795
In this study a green approach described for the synthesis of copper sulfide nanoparticles loaded on activated carbon (CuS-NP-AC) and usability of it for the removal of reactive orange 12 (RO-12). This material was characterized using instruments such as scanning electron microscopy (SEM) and X-ray diffraction (XRD). The effects of variables were optimized using Principal component analysis-artificial neural network (PCA-ANN). Fitting the experimental equilibrium data shows the suitability of the Langmuir isotherm. The small amount of proposed adsorbent (0.017 g) is applicable for successful removal of RO-12 (RE > 95%) in short time (31.09 min) with high adsorption capacity (96.9 mg g−1) 相似文献
184.
The storage of molecular hydrogen into ZSM-5 zeolite in the ambient atmosphere was examined by hydrogen filling into the micropore and the following sealing of the micropore outlet to prevent the release of hydrogen to the outside. The surface grafting of 1,4-bis(hydroxydimethylsilyl)benzene onto ZSM-5 zeolite was applied to the sealing of the micropore outlet. Pressurized hydrogen (10 MPa) was filled into the micropore of ZSM-5 at liquid nitrogen temperature (−196 °C), and then the sample was heated at 150 °C for forming strong binding between the zeolite surface and the disilane compound under the hydrogen pressure. The hydrogen sorption isotherm at −196 °C showed that the adsorption of hydrogen onto the disilane-grafted ZSM-5 thus obtained was reduced to less than 20% from the original ZSM-5. The remarkable hysteresis between the adsorption and desorption branches of the isotherm indicated that the kinetic trap of hydrogen occurred by the narrowed outlets of the micropores of ZSM-5 with the disilane compound. Even after exposing the disilane-grafted ZSM-5 to the atmosphere over a few months, hydrogen could be discharged by heating over 150 °C. This result demonstrated that molecular hydrogen was successfully stored into ZSM-5 zeolite in the ambient atmosphere for a long time. 相似文献
185.
《International Journal of Hydrogen Energy》2019,44(5):2960-2975
The hydrogen adsorption capacity of dual-Ti-doped (7, 7) single-walled carbon nanotube (Ti-SWCNTs) has been studied by the first principles calculations. Ti atoms show different characters at different locations due to local doping environment and patterns. The dual-Ti-doped SWCNTs can stably adsorb up to six H2 molecules through Kubas interaction at the Ti2 active center. The intrinsic curvature and the different doping pattern of Ti-SWCNTs induce charge discrepancy between these two Ti atoms, and result in different hydrogen adsorption capacity. Particularly, eight H2 molecules can be adsorbed on both sides of the dual-Ti decorated SWCNT with ideal adsorption energy of 0.198 eV/H2, and the physisorption H2 on the inside Ti atom has desirable adsorption energy of 0.107 eV/H2, ideal for efficient reversible storage of hydrogen. The synergistic effect of Ti atoms with different doping patterns enhances the hydrogen adsorption capacity 4.5H2s/Ti of the Ti-doped SWCNT (VIII), and this awaits experimental trial. 相似文献
186.
Experimental studies were performed on the kinetics of the three‐phase contact formation and bubble attachment to a quartz surface in solutions of a cationic surfactant of various concentrations. By tuning the distance between the single‐bubble formation point and the quartz surface immersed in the solution, the influence of the state of the dynamic adsorption layer over a rising bubble on the mechanism of rupture of a wetting film formed was elucidated. Based on the unique methodology, allowing precise control over the initial degree of adsorption coverage at the detaching bubble, new evidence was found confirming the electrostatic character of the wetting film rupture in cationic surfactant solutions of low concentrations. 相似文献
187.
Coal fly ash(CFA)is composed of minerals containing some oxides in crystalline phase(i.e.,quartz and mullite),as well as unburned carbon as mesoporous material,thus enabling CFA to act as a dual-sites adsorbent with unique properties.This work focused on the adsorption of Pb(Ⅱ)and Zn(Ⅱ)from binary system,a mixture containing two metal ion solutions present simultaneously,onto NaOH-modified CFA(MCFA).Several adsorption tests were conducted to evaluate the effect of several parameters,includ-ing pH and contact times.The experiment results indicated that chemical treatment of CFA with NaOH increased pore volume from 0.021 to 0.223 cm3 g-1.In addition,it could also enhance the availability of functional groups on both minerals and unburned carbon,resulting in almost 100%Pb(Ⅱ)and 97%Zn(Ⅱ)adsorbed.The optimum pH for adsorption system was pH=3 and quasi-equilibrium occurred in 240 minutes.Equilibrium data from the experimental results were analyzed using Modified Extended Langmuir(MEL)and Competitive Adsorption Langmuir-Langmuir(CALL)isotherm models.The analysis results showed that the CALL isotherm model could better describe the Pb(Ⅱ)and Zn(Ⅱ)adsorption pro-cess onto MCFA in binary system compared with MEL isotherm model. 相似文献
188.
Interfacial tension of drugs with hydrophilic polymer (A) embedded gold resulting into selective drug adsorption, which also affected the drug adsorption kinetics. Two-dimensional crosslinked polymer embedded gold was synthesized for drug loading application in an acidic buffer. Lower interfacial tension of pantoprazole sodium (B) revealed the exponential loading inversely loading was gradual for chloroquine (C) having more interfacial tension with adsorbent. Initial 2 h was the exponential adsorption period for a pantoprazole sodium whereas exponential adsorption begins after 12 h for a chloroquine. Monolayer drug adsorption was obtained because Langmuir adsorption isotherm was obeyed by both drugs. Moreover, pseudo first- and pseudo second-order kinetics was also evaluated which demonstrated that reactive sites of the adsorbent are homogeneous and drug adsorption mechanism is chemisorption and not the physisorption. Thermal analysis was evaluated to confirm the polymer thermostability and glass transition temperature during catalytic applications in thermal reactions. 相似文献
189.
Green tea is a rich source of catechins, which when purified have a high economic value as they can be used as a supplement in several products, to increase their health benefits. Catechins are regarded as desired components with several applications in a variety of areas such as foods, cosmetics and pharmaceuticals. A multicomponent sorption model has been developed for the separation of catechins from liquid tea streams, with macroporous resins in a packed bed column. Two commercially available food grade resins were considered: Amberlite XADHP and Diaion HP20. For the desorption step, two food grade solvents are used: water and ethanol. The adsorption and desorption behaviour is subsequently mathematically described with one-dimensional axial dispersed plug flow model that can accurately simulate the dynamics of the solvent swing sorption columns. The model parameters were regressed from experimental data. Five components are modelled in the competitive sorption: the main four catechins present in green tea and caffeine. The model was used for the process design and optimization for the recovery of catechins from green tea. 相似文献
190.
Mohammad Mohammadian Maryam Ahmadi Mohammad Reza Khosravi-Nikou 《Petroleum Science and Technology》2017,35(6):608-614
Adsorption of heterocyclic sulfur- and nitrogen-containing compounds by mesostructure adsorbent (MSU-S) and its modified form with cobalt oxide is studied using model fuel. The results of characteristic tests (XRD, N2 adsorption–desorption, FTIR, and SEM) indicate that CoO impregnation causes a negative impact on mesoporous structure, crystalline phase, and particle shape along with a positive effect on surface ion exchange. CoO modification increased the adsorption loadings of DBT and BT to about 33.6% and 45.7%, respectively. For nitrogen compounds adsorption with the model fuel, adsorption loadings of quinoline and carbazole increase by 6.7% and 8.6%, respectively. Data fitting for carbazole, DBT, and BT is achieved better by the Langmuir model than the Freundlich model, and the data of quinoline fitted very well to the Freundlich model for CoO-MSU-S. 相似文献