混合二甲苯吸附平衡的测定与关联

用静态法测定了液相二甲苯在三种沸石分子筛上的吸附平衡，借助汽液平衡模型将液相吸附平衡的关联转化为气相吸附平衡问题，转化后的气相吸附平衡能较好地符合Langmuir等温式。     

用气相色谱法研究C8芳烃在HZSM—5分子筛上的传质

本文利用气相色谱法测定了在１８０℃和２００℃对二甲苯、乙苯、邻二甲苯在ＨＺＳＭ—５分子筛上的微孔扩散系数及吸附平衡常数；并将不同模型的处理结果作了比较。     

超细4A分子筛的超声波低温快速合成

在低温条件下用超声波快速合成了4A分子筛.产物分别用XRD,IR,SEM和DSC等进行了表征.结果表明,用超声波法合成4A分子筛的速度是常规法的24倍.合成产物的白度为95%,钙离子交换容量为335mgCaCO₃/g4A分子筛,平均粒径为280nm.与采用常规方法合成的产物相比,超声波法合成的产物热稳定性有所下降.     

乙醇在双功能Pd-Cu/分子筛催化剂上气相氧化酯化一步合成乙酸乙酯

研究了乙醇在双功能在Ｐｄ－Ｃｕ／分子筛催化剂上一步合成乙酸乙酯的反应，发现Ｐｄ是氧化活性中心的主组分，Ｃｕ主要对Ｐｄ的氧化功能起调变作用，以减少乙醇浓度氧化副反应，提高酯化选择性，分子筛和酸性强弱对活性，特别是对酯化选择性有明显的影响，酯化要求在较强的酸中心上进行，探讨了氧化活性中心和酸中心的匹配关系以及Ｃｕ对Ｐｄ－的调变作用，提出了乙醇氧化酯化机理。     

基于压电陶瓷的A型分子筛膜合成与吸附性能

无铅压电陶瓷0.8Na_0.5Bi_0.5TiO₃-0.2K_0.5Bi_0.5TiO₃表面采用化学改性预涂晶种作为基底,分别以微乳和澄清溶液法在基底上水热晶化合成了A型分子筛膜.通过XRD、SEM和FTIR对晶种及分子筛膜进行了表征,通过压电谐振法测量甲烷吸附性能.结果表明:微乳和澄清溶液法均合成单一A型分子筛相,1次合成分子筛膜的时间分别为6、9 h,通过不同镀膜次数生成A型分子筛膜的形貌、膜厚不同.经A型分子筛膜修饰压电振子后,其对甲烷气体的灵敏度可分别达到59 Hz/1%CH₄、68 Hz/1%CH₄.     

膨润土碱熔活化合成4A分子筛的研究

以天然膨润土为原料,采用高温碱熔水热法合成4A分子筛。探讨了活化温度、SiO2/Al2O3、Na2O/SiO2、H2O/Na2O等工艺条件对4A分子筛结构与性能的影响。结果表明,最佳的活化温度为600℃;物料经此温度活化后,调节组成为SiO2/Al2O3=1.5、Na2O/SiO2=3与H2O/Na2O=50,于90℃反应6小时可以得到质量较好的4A分子筛,其产品的晶形规整,晶粒均小于2μm,钙离子交换容量可达到314mg CaCO3/g。     

吸附分离正构烃结焦失活的无粘结剂5A分子筛氧化再生研究

在固定床吸附器上模拟无粘结剂5A分子筛的失活过程,并对失活分子筛进行氧化再生研究。结果表明,焦炭会堵塞部分分子筛孔道,导致失活分子筛的比表面积和孔容减小、平均孔径增加。焦炭含量增加,分子筛的失活度增加,但增加的速率逐渐减小。氧化反应温度由582K升至787K,焦炭脱除率由64%增至100%。失活分子筛于787K下氧化处理后,其上焦炭被完全脱除,分子筛的吸附活性完全恢复。氧化再生后分子筛的比表面积和孔容增加,但难以恢复至新鲜分子筛的水平。在685K~884K,实验得到的无粘结剂5A分子筛上焦炭的氧化脱除宏观动力学方程为：ln(C₀/C) = 0.013exp(-28122.1/T) (p_O2)0.32t。     

微波辐射对乙酸乙酯皂化反应的影响

采用电导率法研究了微波辐射对乙酸乙酯皂化反应动力学常数的影响.结果表明,反应物经微波辐射后化学反应的动力学常数增大,且与辐射时间长短呈正相关.分析了微波辐射使动力学常数增大的原因.     

真空原位水热合成法快速合成A型分子筛膜

采用真空原位水热法在管状αAl2O3基膜上快速合成了A型分子筛膜;采用XRD和SEM方法表征了膜的性质;研究了真空度对A型分子筛膜性能的影响。在外加真空作用下,分子筛晶粒可以均匀、快速地迁移到基膜表面形成分子筛膜,从而可以在较短时间里合成均匀、连续的分子筛膜。     

微波快速合成4A分子筛过程中镧复盐的作用

微波快速合成4A分子筛过程中镧复盐的作用;4A分子筛;硫酸镧硫酸钠复盐;微波合成     

Adsorption of uranium from crude phosphoric acid using activated carbon

The adsorption of uranium from crude phosphoric acid has been investigated using conventional activated carbons. It was found that treatment with nitric acid oxidized the surface of activated carbon and significantly increased the adsorption capacity for uranium in acidic solutions. The parameters that affect the uranium(VI) adsorption, such as contact time, solution pH, initial uranium(VI) concentration, and temperature, have been investigated. Equilibrium data were fitted to a simplified Langmuir and Freundlich isotherms for the oxidized samples which indicate that the uranium adsorption onto the activated carbon fitted well with Langmuir isotherm than Freundlich isotherm. Equilibrium studies evaluate the theoretical capacity of activated carbon to be 45.24 g kg^?1.     

The significance of a second adsorption phase with weakly adsorbed species for the calculation of the surface concentrations of a mixture: methanol–DME and methanol–ethene adsorption in SAPO-34

With the calorimetric (adsorption heat versus coverage) curve also measured together with the adsorption isotherm, the simultaneous use of both curves showed that there were two phases of adsorption in the adsorption of methanol, dimethyl ether, ethene and propane in SAPO-34. The dual-site Langmuir equation gave good fits to the adsorption data to support the interpretation that a second (type 2) adsorption phase occurred in the high-pressure region in addition to a first (type 1) adsorption phase on the acid sites at lower pressures. Adsorption experiments and calculations using binary gas mixtures showed that due to the existence of two types of adsorption, the multicomponent Langmuir isotherm equation (Langmuir competitive adsorption model) calculated incorrect surface concentrations when the concentrations were high. In contrast, the ideal adsorbed solution theory (IAST) calculated correct surface concentrations in the adsorption of mixtures.     

Adsorption of zinc(II) and copper(II) to Shirasu (pyroclastic flow)

A fundamental study on the adsorption of metal elements on Shirasu, a pyroclastic flow deposit distributed in southern Kyushu, Japan, has been conducted. The adsorption experiment was carried out by a batch method, and by using Zn(II) and Cu(II) under several conditions; the effects of the initial concentration of metal ions, grain size, and pH were investigated. At smaller grain sizes, the amount of Zn(II) and Cu(II) adsorbed increased. At higher pH values, the amount of Zn(II) and Cu(II) adsorbed increased. Plots of the adsorption isotherm indicated that the adsorption of Zn(II) and Cu(II) on Shirasu followed the Langmuir isotherm model, and the Langmuir isotherm constants, W(0) and b, were obtained. W(0) at pH 5.0 was approximately two-times larger than that at pH 3.0. This may reflect an increase in the number of anionic binding sites on the surface of Shirasu with an increase in the pH. The b value for Zn hardly changed with an increase in the pH, and for Cu the value decreased with an increase in the pH. These observations suggest that anionic binding sites have a low stability constant, since the apparent stability constant, b, is obtained as the average of stability constant of all sites on the Shirasu surface.     

Adsorption and inhibition performance of the novel cationic Gemini surfactant as a safe corrosion inhibitor for carbon steel in hydrochloric acid

The new synthesized cationic Gemini surfactant (CGS) was tested as a corrosion inhibitor for carbon steel (CS) in 1.0?M hydrochloric acid using weight loss, electrochemical spectroscopy and potentiodynamic polarization. The inhibition efficiency is increased by increasing the CGS concentration and is almost constant within the temperature range studied. The inhibition was explained by adsorption of the CGS molecule on the CS surface. A mixed-type inhibitor is suggested for the inhibitory effects of CGS as revealed by the potentiodynamic polarization technique. The changes in impedance parameters suggested that the adsorption of the inhibitor on the CGS surface led to the formation of protective films. The adsorption of the CGS on the surface of CS obeys Langmuir adsorption isotherm. Thermodynamic and kinetic parameters were calculated and discussed.     

ZnO/C纳米球的亚甲基蓝单吸附特性:平衡、动力学及机理

采用电弧放电法制备了ZnO/C纳米球,利用FESEM、XRD和N₂吸附/脱附测试进行了表征。在避光条件下研究了复合材料对亚甲基蓝的吸附性能。研究结果表明,随着亚甲基蓝的浓度及接触时间的增长吸附量明显上升,在吸附时间为150 min时达到吸附平衡。采用Langmuir、Freundlich及Temkin等温吸附模式对吸附平衡进行了研究。结果表明,吸附等温线符合Langmuir等温吸附模式,单层吸附饱和容量可达188.68 mg·g^-1。利用动力学模型、内扩散模型和外扩散速率控制模型拟合实验数据,拟合数据表明其动力学符合伪二级动力学模型;内扩散机理不是吸附速率的唯一限制机理,亚甲基蓝的总吸附速率受膜扩散控制。     

ZnO/C纳米球的亚甲基蓝单吸附特性:平衡、动力学及机理

采用电弧放电法制备了ZnO/C纳米球,利用FESEM、XRD和N₂吸附/脱附测试进行了表征。在避光条件下研究了复合材料对亚甲基蓝的吸附性能。研究结果表明,随着亚甲基蓝的浓度及接触时间的增长吸附量明显上升,在吸附时间为150 min时达到吸附平衡。采用Langmuir、Freundlich及Temkin等温吸附模式对吸附平衡进行了研究。结果表明,吸附等温线符合Langmuir等温吸附模式,单层吸附饱和容量可达188.68 mg·g^-1。利用动力学模型、内扩散模型和外扩散速率控制模型拟合实验数据,拟合数据表明其动力学符合伪二级动力学模型;内扩散机理不是吸附速率的唯一限制机理,亚甲基蓝的总吸附速率受膜扩散控制。     

Equilibrium, kinetics, mechanism, and process design for the sorption of methylene blue onto rice husk

Batch experiments were carried out for the sorption of methylene blue onto rice husk particles. The operating variables studied were initial solution pH, initial dye concentration, adsorbent concentration, and contact time. Equilibrium data were fitted to the Freundlich and Langmuir isotherm equations and the equilibrium data were found to be well represented by the Langmuir isotherm equation. The monolayer sorption capacity of rice husks for methylene blue sorption was found to be 40.5833 mg/g at room temperature (32 degrees C). The sorption was analyzed using pseudo-first-order and pseudo-second-order kinetic models and the sorption kinetics was found to follow a pseudo-second-order kinetic model. Also the applicability of pseudo second order in modeling the kinetic data was also discussed. The sorption process was found to be controlled by both surface and pore diffusion with surface diffusion at the earlier stages followed by pore diffusion at the later stages. The average external mass transfer coefficient and intraparticle diffusion coefficient was found to be 0.01133 min(-1) and 0.695358 mg/g min0.5. Analysis of sorption data using a Boyd plot confirms that external mass transfer is the rate limiting step in the sorption process. The effective diffusion coefficient, Di was calculated using the Boyd constant and was found to be 5.05 x 10(-04) cm2/s for an initial dye concentration of 50 mg/L. A single-stage batch-adsorber design of the adsorption of methylene blue onto rice husk has been studied based on the Langmuir isotherm equation.     

一个与吸附剂浓度有关的Langmuir等温式

实验测定了不同吸附剂浓度下, 高岭土对Pb(II)和Cu(II)的吸附作用, 结果表明存在明显的吸附剂浓度效应, 即吸附等温线随吸附剂浓度升高而降低. 采用传统的Langmuir 吸附等温式对实验数据进行拟合表明, 此等温式可准确地描述给定吸附剂浓度下的吸附结果, 但不能预测其吸附剂浓度效应. 根据表面组分活度(SCA)模型, 假设吸附剂颗粒间存在相互作用, 吸附剂表面吸附位的活度系数不等于1, 而应为吸附剂浓度的函数, 推导出了一个与吸附剂浓度有关的Langmuir (Langmuir-SCA)方程. 运用高岭土吸附Pb(II)和Cu(II)以及文献中蛭石吸附Zn(II)和Cd(II)、咖啡吸附Pb(II)的实验数据检验方程的适用性, 结果表明Langmuir-SCA方程可准确地描述所观察到的吸附剂浓度效应. 方程的两个内禀参数, 热力学平衡常数(K_eq)和特征饱和吸附量(Γ_m⁰), 与吸附剂浓度无关, 并可由吸附实验数据拟合求得.     

Impact of an error in the column hold-up time for correct adsorption isotherm determination in chromatography I. Even a small error can lead to a misunderstanding of the retention mechanism

The impact of a realistic error in the column hold-up time on the determination of the adsorption isotherm model was systematically investigated. Frontal analysis and the inverse method were used for the accurate determination of the adsorption isotherm. The true retention times of the breakthrough curves were used with a known hold-up time as reference. The adsorption isotherms were calculated using the same procedure that is used for real experimental adsorption isotherms, where the true hold-up time is unknown. The raw data were analyzed with calculations of adsorption energy distributions (AEDs), Scatchard plots, fitting to different rival adsorption models and finally their ability to predict true profiles. The results show that for a true Langmuir and bi-Langmuir model with an underestimated hold-up time the error may lead to a more heterogeneous model and for overestimated cases false adsorption processes like multi-layer adsorption or solute-solute interaction are assumed. The Scatchard plots for data obtained using a Langmuir adsorption isotherm are nonlinear and the AEDs show clear deviations from Langmuir behavior already at small deviations from the true hold-up time at a moderate surface coverage. The inverse method confirms the result that was obtained from the frontal analysis procedure.