不同硅铝比ZSM-5的合成及其吸附脱除柴油中苯胺和吡啶的性能

合成了一系列不同硅铝比的ZSM-5分子筛,采用XRD、FT-IR、ICP、SEM、NH_3-TPD和N_2吸附-脱附等方法对其进行了表征,研究了不同硅铝比ZSM-5分子筛对模拟柴油中苯胺和吡啶的吸附脱除性能。结果表明,所合成的ZSM-5分子筛均具有典型MFI结构;与合成原料混合物中的硅铝比相比,实际硅铝比稍有降低。ZSM-5分子筛的酸量随硅铝比的增加而降低,硅铝比较小的ZSM-5(1)和ZSM-5(2)的吸附脱除苯胺或吡啶的效果明显优于其他样品,并且所有样品吸附脱除吡啶的效果均优于苯胺。ZSM-5(2)上苯胺和吡啶的吸附等温线符合Langmuir-Freundlich混合模型。     

改性Ｙ型分子筛的吸附脱硫性能以及苯，萘对吸附的影响

采用离子交换法制备了经金属离子改性的Y型分子筛吸附剂, 并用XRF, XRD, XPS对吸附剂的化学组成, 晶相结构等进行了表征. 以含噻吩, 苯并噻吩的辛烷溶液为模型燃料考察了吸附剂的吸附脱硫性能以及苯, 萘对脱硫的影响. 结果表明, Cu(Ⅰ)Y, CuZnY具有较大的吸附容量, 而苯对苯并噻吩吸附脱除性能几乎没有影响, 但对噻吩的吸附性能影响较大, 萘对苯并噻吩和噻吩的脱除都有较大的抑制作用. 并由此推测, 吸附剂与苯并噻吩或萘的结合比噻吩或苯更紧密, 吸附的机理是π络合.     

环己烯对噻吩在CuY分子筛上吸附的影响机制

A CuY zeolite prepared by liquid phase ion exchange was characterized by X-ray photoelectron spectroscopy, pyridine in situ Fourier transform infrared (in situ FTIR) spectroscopy, and ammonia temperature programmed desorption. The effect of cyclohexene on the adsorption of thiophene over the prepared CuY zeolite was explored by in situ FTIR. In particular, the role of the zeolite's Br?nsted acidity was investigated in the adsorption process. The results show that the percentage of Cu⁺ on the surface of the CuY zeolite can reach 77%. The surface acidity of the CuY zeolite mainly comprises medium and strong Br?nsted acidity and Lewis acidity. According to the adsorption results, cyclohexene negatively influences thiophene adsorption on the Br?nsted or Lewis acid sites in CuY by competitive adsorption. Although polymerization of thiophene and cyclohexene can occur easily on the HY or REY zeolites, the presence of Br?nsted acids in the CuY zeolite was not sufficient to polymerize either thiophene or cyclohexene. This difference may be caused by an anti-synergistic effect between the Cu ions of the CuY zeolite and neighboring Br?nsted acid sites, the result of which inhibits the polymerization of adsorbed thiophene and cyclohexene.     

Competitive adsorption of phenol and 3-chlorophenol on purified MWCNTs

A commercial multiwall carbon nanotube and its carboxylated derivate (CNTC and COOHC, respectively) was used after purification to study the competitive adsorption of phenol (P) and m-chlorophenol (CP) from 0.1 M aqueous NaCl solutions without external pH control. The adsorption takes place practically exclusively on the external surface of the nanotubes. The uptake of P is suppressed in comparison to its single solute behaviour on both nanotubes, independently of the initial pollutant concentration. The uptake of CP however is more sensitive to the concentration and the surface chemistry of the nanotube. The measured co-adsorption isotherms were compared to the isotherms calculated from the competitive Langmuir model (CLM). Preferential adsorption of CP was observed in about 95% of the relative concentration range. The total adsorption may exceed the corresponding single component sorption capacity.     

AXAFS技术在Ni/ZnO吸附剂上模型油反应吸附脱硫机理研究中的应用

原子X射线吸收精细结构（AXAFS）由吸收原子的外围束缚电子对出射光电子波的背散射引起,AXAFS信号与嵌入原子势能、原子间隙势能和吸收原子电子密度的分布密切相关,可以作为精确的探针来探测原子的电子化学结构。研究利用AXAFS技术,以Ni/ZnO脱硫吸附剂为研究对象,探讨了模型油在不同气体气氛下的脱硫反应机理。结果表明,在氢气气氛下、350 ℃和3.0 MPa的条件下,从Zn元素的原位AXAFS谱图中可观察到脱硫过程中Zn元素的化学态变化。根据这些结果,揭示了氢气在脱硫过程中的重要作用,阐述了原位反应条件下吸附剂中Zn元素的化学态变化。     

Interaction between congo red and copper in a binary adsorption system: Spectroscopic and kinetic studies

This study focused on the competitive adsorption of congo red (CR) and copper by chitosan hydrogel beads in a binary adsorption system. Spectroscopic analysis, including Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) were integrated with kinetic studies to elucidate the interaction. It was determined that chitosan hydrogel beads show better adsorption performance towards congo red and copper in single adsorption systems. The addition of copper caused a 25% reduction in congo red adsorption capacity, while copper adsorption was enhanced slightly by the presence of congo red. The adsorption results for binary adsorption systems seem due to competition for the present amine and hydroxyl groups that may occur between congo red and copper. A congo red–copper complex was formed in binary adsorption systems. Copper attached to chitosan hydrogel beads individually or was bound by the congo red–copper complex, which resulted in an increase in adsorption capacity. Chitosan exhibited higher adsorption selectivity to the free Cu²⁺ ion than the congo red–copper complex in the binary adsorption system. Adsorption of the congo red–copper complex indicated an inhibition in the attachment of the free Cu²⁺ ion in the form of Cu(II).     

活性炭液相吸附去除噻吩硫化物的研究

迄今为止,国内外降低汽油硫含量的方法主要有原料加氢脱硫、汽油加氢脱硫、溶剂抽提脱硫、催化裂化脱硫、氧化脱硫、生物脱硫、吸附脱硫及组合技术,同时一些非常规技术如膜过程脱硫、等离子体和光脱硫也在积极探索之中。     

Protein adsorption and transport in dextran-modified ion-exchange media. I: Adsorption

Adsorption behavior is compared on a traditional agarose-based ion-exchange resin and on two dextran-modified resins, using three proteins to examine the effect of protein size. The latter resins typically exhibit higher static capacities at low ionic strengths and electron microscopy provides direct visual evidence supporting the view that the higher static capacities are due to the larger available binding volume afforded by the dextran. However, isocratic retention experiments reveal that the larger proteins can be almost completely excluded from the dextran layer at high ionic strengths, potentially leading to significant losses in static capacity at relevant column loading conditions. Knowledge of resin and protein properties is used to estimate physical limits on the static capacities of the resins in order to provide a meaningful interpretation of the observed static capacities. Results of such estimates are consistent with the expectation that available surface area is limiting for traditional resins. In dextran-modified media, however, the volume of the dextran layer appears to limit adsorption when the protein charge is low relative to the resin charge, but the protein–resin electroneutrality may be limiting when the protein charge is relatively high. Such analyses may prove useful for semiquantitative prediction of maximum static capacities and selection of operating conditions when combined with protein transport information.     

Kinetic and equilibrium studies of urea adsorption onto activated carbon: Adsorption mechanism

We found that activated carbon effectively removed urea from solution and that urea adsorption onto activated carbon followed a pseudo-second-order kinetic model. We classified the urea adsorption on activated carbon as physical adsorption and found that it was best described by the Halsey adsorption isotherm, suggesting that the multilayer adsorption of urea molecules on the adsorption sites of activated carbon best characterized the adsorption system. The mechanism of adsorption of urea by activated carbon involved two steps. First, an amino (–NH₂) group of urea interacted with a carbonyl (–C?O) group and a hydroxyl (?OH) group on the surface of activated carbon via dipole–dipole interactions. Next, the –C?O group of the urea molecule adsorbed to the activated carbon interacted with another –NH₂ group from a second urea molecule, leading to multilayer adsorption.     

Removal of cationic dyes by modified waste biosorbent under continuous model: Competitive adsorption and kinetics

Modified waste sugarcane bagasse (SCB) was prepared to remove cationic dyes: methylene blue and rhodamine B from aqueous solution by using a continuous mode. Effects of flow rate on adsorption of the two dyes in fixed bed column were studied. Competitive adsorption kinetics of the two dyes in binary system was investigated in detail. Results showed that the adsorption capacities of the modified sorbent for methylene blue and rhodamine B in one component system were 1.7 and 0.4 mmol g^?1, respectively. Competitive adsorption process in the binary system could be divided into three phases: free adsorption, substitution adsorption and adsorption equilibrium. 0.19 mmol of rhodamine B absorbed was replaced by 0.35 mmol of methylene blue in the second phase. Simple modified Yoon–Nelson model was used to predict the adsorption kinetics for the first time. The obtained adsorption rate constants for the two dyes in the three phases both followed the order: phase I > phase III > phase II, demonstrating that substitution adsorption phase is the rate determining step. Desorption experiment showed that the loaded two dyes could be separated and recycled by using the mixture solution of HCl (0.1 mol L^?1) and ethanol as eluent. The prepared fixed bed column had great potential in industrial wastewater treatment.     

Single and binary adsorption of proteins on ion-exchange adsorbent: The effectiveness of isothermal models

Simultaneous and sequential adsorption equilibria of single and binary adsorption of bovine serum albumin and bovine hemoglobin on Q Sepharose FF were investigated in different buffer constituents and initial conditions. The results in simultaneous adsorption showed that both proteins underwent competitive adsorption onto the adsorbent following greatly by protein-surface interaction. Preferentially adsorbed albumin complied with the universal rule of ion-exchange adsorption whereas buffer had no marked influence on hemoglobin adsorption. Moreover, an increase in initial ratios of proteins was benefit to a growth of adsorption density. In sequential adsorption, hemoglobin had the same adsorption densities as single-component adsorption. It was attributed to the displacement of preadsorbed albumin and multiple layer adsorption of hemoglobin. Three isothermal models (i.e. extended Langmuir, steric mass-action, and statistical thermodynamic (ST) models) were introduced to describe the ion-exchange adsorption of albumin and hemoglobin mixtures. The results suggested that extended Langmuir model gave the lowest deviation in describing preferential adsorption of albumin at a given salt concentration while steric mass-action model could very well describe the salt effect in albumin adsorption. For weaker adsorbed hemoglobin, ST model was the preferred choice. In concert with breakthrough data, the research further revealed the complexity in ion-exchange adsorption of proteins.     

Biomimetic oxidative transformations of pericine: partial synthesis of apparicine and valparicine, a new pentacyclic indole alkaloid from Kopsia

A new pentacyclic indole alkaloid of the pericine-type, valparicine, representing the first member of this sub-group, was obtained from a Malayan Kopsia species and the structure was established by spectroscopic analysis. A partial synthesis of valparicine and apparicine from pericine was carried out via the Potier-Polonovski reaction and the biogenetic implications are discussed.     

Competitive adsorption and desorption of a bi-solute mixture: effect of activated carbon type

This study aims to clarify the effects of carbon activation type and physical form on the extent of adsorption capacity and desorption capacity of a bi-solute mixture of phenol and 2-chlorophenol (2-CP). For this purpose, two different PACs; thermally activated Norit SA4 and chemically activated Norit CA1, and their granular countertypes with similar physical characteristics, thermally activated Norit PKDA and chemically activated Norit CAgran, were used. The thermally activated carbons were better adsorbers for phenol and 2-CP compared with chemically activated carbons, but adsorption was more reversible in the latter case. 2-CP was adsorbed preferentially by each type of activated carbon, but adsorption of phenol was strongly suppressed in the presence of 2-CP. The simplified ideal adsorbed solution (SIAS) model underestimated the 2-CP loadings and overestimated the phenol loadings. However, the improved and modified forms of the SIAS model could better predict the competitive adsorption. The type of carbon activation was decisive in the application of these models. For each activated carbon type, phenol was desorbed more readily in the bi-solute case, but desorption of 2-CP was less compared with single-solute. This was attributed to higher energies of 2-CP adsorption.     

Isolation of indole alkaloid and anthranilic acid derivatives from Indigo Pulverata Levis

A new indole alkaloid, pulveratinol (1), and two new anthranilic acid derivatives (2 and 3) were isolated from Indigo Pulverata Levis, together with 12 known compounds (4–15). The structures of the new compounds (1–3) were determined through spectroscopic methods. The absolute configuration of 1 was confirmed further by electronic circular dichroism (ECD) data analysis and computational method with advanced statistics (DP4). All isolated compounds (1–15) were evaluated for their potential neuroprotective effects through induction of nerve growth factor (NGF) in C6 glioma cells.     

基于光波导分光光谱技术研究蛋白质与亚甲基蓝的竞争吸附行为

通过利用时间分辨光波导分光光谱技术原位测量从蛋白质-亚甲基蓝(MB)混合水溶液吸附到亲水玻璃光波导表面的MB可见光吸收谱,观测到在溶液pH值低于蛋白质等电点时MB与牛血清蛋白(BSA)以及MB与血红蛋白(Hb)存在竞争吸附行为,进一步测得这种竞争吸附行为对蛋白质浓度十分敏感,可以用于简单测定溶液中的蛋白质含量.基于Langmuir等温吸附理论推导出了两种分子竞争吸附的动力学方程,并利用该动力学方程对实验测得的吸光度随时间变化曲线进行了最佳拟合,揭示了玻璃表面吸附的MB分子个数在达到最大值后随时间呈指数衰减,同时得出拟合参数与蛋白质浓度呈准线性关系.     

Adsorption of cadmium and lead from palm oil mill effluent using bone-composite: optimisation and isotherm studies

The adsorption of Cd and Pb ions from palm oil mill effluent on a mesoporous-activated cow bone composite powder has been investigated. Adsorbent was developed from cow bones, coconut shells and zeolite. The composite examined in the present work has a BET surface area of 248.398 m²/g. The optimisation of the removal efficiency of the heavy metals was investigated using central composite design and analysed using response surface methodology. The analysis of variance of the quadratic model signified that the model suitably predicted the uptake of the heavy metal ions at a 95% confidence level. The optimal operating condition was recorded at pH 4, 50 rpm, within 24 h and 1 mm of particle size and 12.5 gL^?1 of adsorbent dosage. The characteristics of the composite were investigated using the Fourier transform irradiation. The morphology and chemical composition of composite was examined using the scanning electron microscopy equipped with energy dispersive x-ray. Characterisation study was conducted before and after the adsorption process. The results obtained illustrated that the removal of cadmium and lead from POME was influenced by the functional groups available on the surface of the composite. The carboxyl and hydroxyl groups are mainly responsible for the removal of cadmium and lead through chelating process. The point of zero charge (pH_pzc) revealed that the adsorbent contained acidic sites with negatively charge surface which influenced the adsorption process. The experimental data of the heavy metals of Cd and Pb investigated were fitted to the Langmuir and Freundlich models. The result revealed that the adsorption equilibrium data fitted better to the Langmuir model for the adsorption Cd and to the Freundlich model for the adsorption of Pb.     

Adsorption of Toluene and Water over Cationic-Exchanged Y Zeolites: A DFT Exploration

In this study, density functional theory (DFT) calculations have been performed to investigate the adsorption mechanisms of toluene and water onto various cationic forms of Y zeolite (LiY, NaY, KY, CsY, CuY and AgY). Our computational investigation revealed that toluene is mainly adsorbed via π–interactions on alkalis exchanged Y zeolites, where the adsorbed toluene moiety interacts with a single cation for all cases with the exception of CsY, where two cations can simultaneously contribute to the adsorption of the toluene, hence leading to the highest interaction observed among the series. Furthermore, we find that the interaction energies of toluene increase while moving down in the alkaline series where interaction energies are 87.8, 105.5, 97.8, and 114.4 kJ/mol for LiY, NaY, KY and CsY, respectively. For zeolites based on transition metals (CuY and AgY), our calculations reveal a different adsorption mode where only one cation interacts with toluene through two carbon atoms of the aromatic ring with interaction energies of 147.0 and 131.5 kJ/mol for CuY and AgY, respectively. More importantly, we show that water presents no inhibitory effect on the adsorption of toluene, where interaction energies of this latter were 10 kJ/mol (LiY) to 47 kJ/mol (CsY) higher than those of water. Our results point out that LiY would be less efficient for the toluene/water separation while CuY, AgY and CsY would be the ideal candidates for this application.     

Adsorption affinity of certain biomolecules onto polymeric resins: Interpretation from molecular orbital theory

Molecular interactions have been studied for adsorption of certain biomolecules in aqueous solutions using two different types of polymeric resins as adsorbents. Molecular modeling study is based on molecular orbital theory. Adsorption affinity expresses as the slope of the linear region of the isotherm for a solute is found to be different for different adsorbents, and this difference can be interpreted from the differences in sorbent surface chemistry and morphological structure. The adsorptive interaction on the polymeric resins computed on the basis of frontier orbital theory seems to correlate well with the experimentally measured adsorption affinity. Electronic states of adsorbent and adsorbate were calculated using the semiempirical molecular orbital (MO) method from which energy of adsorption in aqueous solution was estimated. It was found that charge transfer interaction plays an important role in the adsorption of certain biomolecules on aqueous solution. The experimentally measured enthalpy of adsorption seems to correlate well with the adsorptive interaction energy computed from molecular orbital theory.     

Liquid-phase hydrogenation of methyl oleate on a Ni/α-Al2O3 catalyst: A study based on kinetic models describing extreme and intermediate adsorption regimes

The kinetics of the hydrogenation of methyl oleate on a Ni/α-Al₂O₃ catalyst was studied in the absence of mass-transport limitation, at 398 ≤ T ≤ 443 K and 3.7 ≤ P_H2 ≤ 6.5 bar. The kinetic modeling was performed on the basis of elementary step mechanisms involving different regimes of competition between hydrogen and methyl oleate. Admitting a distinction between occupied-sites and covered-sites by the large molecule of methyl oleate, a rigorous proposal was made to link the seemingly separate kinetic models corresponding to the extreme modes of competitive and non-competitive adsorption, without having to draw the common distinction between two types of surface sites. General rate equations were formulated without expressing opinion a priori on whether the adsorption regime is competitive or non-competitive. Then, typical LHHW rate equations for both extreme adsorption regimes were straightforwardly derived as special cases. Statistical results demonstrated the inadequacy of the models approaching non-competitive adsorption to describe the experimental data but results did not allow a definite discrimination between rival models with competitive and semi-competitive adsorption. A mechanistic model featuring dissociative adsorption of hydrogen, molecule of methyl oleate interacting with a single atom of Ni, and second insertion of hydrogen as RDS, proved to be the best candidate to describe the experimental data satisfactorily with physically reasonable parameters. As a distinctive feature, the model considering semi-competitive adsorption gave additional indication that the adsorbed molecule of methyl oleate could cover up to seven surface sites. From this finding, the semi-competitive model seems to be more realistic than the competitive one.     

[Amim]Cl/ZnCl_2离子液体脱除燃料油中碱性氮化物

合成了金属基离子液体[Amim]Cl/Zn Cl2,采用红外光谱对其结构和酸性进行表征,并以碱性氮含量高达0.52%(质量分数)的抚顺页岩油柴油馏分为原料考察其脱氮性能。结果表明,在反应温度30℃、剂油质量比1∶7、反应时间20 min、静置时间2 h的条件下,[Amim]Cl/Zn Cl2对柴油馏分中碱性氮化物的脱除率可达83.78%,且该离子液体经回收重复使用四次后,碱氮脱除率仍能达到52%。