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We use coarse-grained molecular dynamics simulations to study adsorption on ligand-tethered particles. Nanoparticles with attached flexible and stiff ligands are considered. We discuss how the excess adsorption isotherm, the thickness of the polymer corona, and its morphology depend on the number of ligands, their length, the size of the core, and the interaction parameters. We investigate the adsorption-induced structural transitions of polymer coatings. The behavior of systems involving curved and flat “brushes” is compared. 相似文献
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采用水热法制备粉末状N-Cd共掺杂TiO2催化剂,研究了催化剂对水体中菲的光催化降解反应,讨论了菲初始浓度、催化剂的投加量、H2O2的浓度、异丙醇以及呋喃甲醇对菲光降解反应的影响。结果表明:菲的光催化降解符合一级反应动力学,水体中菲初始浓度越高,其光降解率越低;催化剂和H2O2在一定范围内随投入量的增加,菲的光催化降解速率也增加,但当投入量较多时又降低了降解速率;异丙醇以及呋喃甲醇的加入可以推断出菲的光催化降解过程.OH是的主要活性物种,而1O2的作用较小。 相似文献
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A simple correction to the infinite dilution activity coefficient computed via molecular simulation for a nonelectrolyte solid solute in solution is proposed. The methodology adopts the concept that the activity coefficient may be fundamentally interpreted as a product of a residual and combinatorial term. The residual contribution is assumed to be insensitive to concentration, and the combinatorial term is modeled using the athermal Flory–Huggins theory. The proposed method uses only properties for the solute computed at infinite dilution to estimate solution‐phase properties at finite concentrations. Properties of the pure solid solute are estimated using the group contribution method of Gani and coworkers, allowing for efficient blind solubility predictions to be made. The method is applied to predict the solubility of solid phenanthrene in 17 different solvents. For all cases, the combinatorial correction lowers the predicted solubility relative to the infinite dilution approximation, and in general, improves agreement with experiment. © 2013 American Institute of Chemical Engineers AIChE J, 59: 2647–2661, 2013 相似文献
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研究了聚锑酸离子交换剂吸附0.01 mol/L HNO_3溶液中锶的热力学特征,通过吸附动力学实验,初步探讨了温度对吸附过程的影响.结果表明,聚锑酸对0.01mol/L HNO_3溶液中锶的吸附符合Freundlich 经验公式,表现为吸热的化学吸附过程.根据毛细孔扩散模型,由平衡数据和动力学曲线计算了锶在聚锑酸离子交换剂颗粒内液相有效扩散系数为8.18×10~(-9)cm~2/s(20℃)和1.33×10~(-8)cm~2/s(30℃). 相似文献
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G. Grimmer H. Brune G. Dettbarn J. Jacob E. Mohtashamipur K. Norpoth 《Polycyclic Aromatic Compounds》2013,33(1):39-47
Excretion of phenanthrene and its metabolites, 1–; 2–; 3–; 4– and 9–OH–phenanthrene after alkaline and acidic saponification of urine and faeces, has been studied in rats following oral, intraperitoneal and intrapulmonary application of phenanthrene. GC and GC/MS methods have been used as analytical techniques. In all cases 1,2-oxidation of phenanthrene was found to be the predominant pathway. Total excretion of 11–18% of the phenanthrene administered by the above routes was observed indicating the presence of water-soluble metabolites other than sulfates and glucuronides. Phenanthrene apparently is suitable for biologically monitoring polycyclic aromatic hydrocarbons. The reasons are: a) the large amounts of phenanthrene and its metabolites excreted in the urine within a period of 3 days following intrapulmonary (1.3%), intraperitoneal (2.9%), or oral (4.1%) administration of phenanthrene, respectively; b) varied metabolites are formed which can reflect qualitatively the regiospecific monooxygenase activities of the organism and; c) the high concentration of phenanthrene in the environment. 相似文献
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《分离科学与技术》2012,47(17):2649-2658
Carbon aerogel (CA) and xerogel (CX) are proposed for pesticide adsorption as new carbon adsorbent materials. These materials are prepared by polycondensation of resorcinol and formaldehyde in Na2CO3 catalysis, followed by a drying step, in CO2 supercritical or normal conditions to obtain organic aerogel or xerogel, and a pyrolytic step to obtain CA or CX. Adsorption experiments were carried out in batch conditions under magnetic stirring. Adsorbent quantity and grain size, pH, and temperature, and alpha-cypermethrin concentration influence on the adsorption efficiency were considered. The optimum parameters were established to be as follows: 0.01 g adsorbent, d < 0.025 mm, and 318 K. In all cases, CA proved to be more efficient than CX for alpha-cypermethrin removal from water samples. Equilibrium (Langmuir and Freundlich isotherms), kinetics (pseudo-first- and pseudo-second-order, intra-particle diffusion, and liquid film diffusion models) and thermodynamics of the considered adsorption process were discussed in detail. Equilibrium was best described by the Langmuir isotherm, while the kinetic of the process was best described by the pseudo-second-order model. Thermodynamic parameters showed that alpha-cypermethrin adsorption is an endothermic process. 相似文献
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Peter T. Cummings Clare McCabe Christopher R. Iacovella Akos Ledeczi Eric Jankowski Arthi Jayaraman Jeremy C. Palmer Edward J. Maginn Sharon C. Glotzer Joshua A. Anderson J. Ilja Siepmann Jeffrey Potoff Ray A. Matsumoto Justin B. Gilmer Ryan S. DeFever Ramanish Singh Brad Crawford 《American Institute of Chemical Engineers》2021,67(3):e17206
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通过对b-环糊精(b-CD)改性制备了阴离子b-环糊精/Fe3O4磁性微球(b-CDM),并研究了b-CDM对Cu2+吸附的热力学、动力学及循环使用性能,借助数学拟合的方法得到了吸附热力学和动力学参数,探讨其吸附机理。研究表明,b-CDM对Cu2+的吸附是一个自发的放热过程,Langmuir与Freundlich等温吸附模型均适用于b-CDM对Cu2+的吸附研究,b-CDM对Cu2+的吸附经历颗粒外部扩散-孔隙扩散-吸附反应3个阶段,该吸附过程既存在物理吸附,又有化学吸附,在吸附温度298、308、318 K下得到的吸附速率常数分别为0.0906、0.1161、0.1674 g·mmol-1·min-1,吸附表观活化能为24.12 kJ·mol-1,且随着介质中Cu2+平衡吸附量的增大,b-CDM对Cu2+的吸附驱动力由焓变转变为熵变。b-CDM重复利用8次后,对Cu2+的除去率由首次使用时的95.20%下降至88.21%。 相似文献
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铝粉氧化对端羟基聚丁二烯界面吸附影响的分子模拟 总被引:1,自引:0,他引:1
为研究铝粉氧化对丁羟推进剂黏合剂界面吸附的影响,采用分子动力学方法和COMPASS力场,分别对端羟基聚丁二烯(HTPB)在Al和Al_2O_3不同晶面吸附进行了模拟计算,求得界面吸附能和静态力学性能(弹性系数、模量和泊松比),结合吸附能和径向分布函数揭示了界面相互作用本质.模拟结果表明,采用HTPB包覆后的Al和Al_2O_3刚度降低,弹性增强;HTPB在Al_2O_3的晶面吸附能远高于在Al晶面,HTPB与Al晶面只存在范德华力作用,而在Al_2O_3的界面吸附主要由静电作用引起. 相似文献