表面脱羟基及再水化对硅胶表面张力的影响

表面脱羟基及再水化对硅胶表面张力的影响ＢｏｇｄａｎＢｉｌｉｎｓｋｉ著本文用气相色谱法对经热处理及再水化的硅胶表面的异辛烷和甲苯吸附等温线进行测定，还进行了表面涂氧化硼和硼砂的硅胶的相同测定。根据吸附等温线，测定了两种吸附的最大膨胀压力（Ⅱ（ｍａｘ））...     

硅藻土调湿材料的性能及调湿机理研究

通过实验测试了硅藻土调湿材料的强度、耐水性、调湿性能,并根据扫描电镜微观分析及材料的吸附/解吸理论研究了硅藻土材料的调湿机理。研究表明,通过无机改性掺合料的作用,可以使硅藻土调湿材料28和60d抗压强度分别大于5和6 MPa,软化系数分别达到0.65和0.74。硅藻土调湿材料的最大平衡含湿率近20%,且吸放湿速率高,具有优异的调湿性能。硅藻土调湿材料对空气中水分子的作用主要为毛细孔道效应和表面化学作用,其次为表面物理吸附作用。     

硅藻土基复合材料在能源与环境领域的应用进展

相比于传统的纳米颗粒材料,无机有序多孔纳米材料具有大的比表面积、高的吸附容量和许多特殊性能,在吸附、分离、催化等领域得到广泛应用。硅藻土作为一种天然的矿物材料具有多级孔道结构,是一种优良的无机多孔材料。过去对硅藻土的开发与利用的方式较为粗犷,例如用于建筑材料、过滤填料等低附加值材料。近年来,由于硅藻土具有独特的纳米和微米形态天然多孔三维分层结构、高比表面积,以及良好的热稳定性和高性价比,其研究与利用逐渐成为微纳米技术领域的热点,在微纳米尺度引出一系列理论和技术问题,其研究成果也逐步应用到工业与民生领域。得益于自身天然多孔的三维分层结构,硅藻土具有较高的比表面积,因而有潜力成为储能器件的原材料。然而,硅藻土存在高电阻率等缺点,不利于能量转换和储存等应用。为此,研究者对硅藻土的优化开展了大量的工作。具体地说,一方面将具有电化学性质的材料负载于硅藻土表面,利用硅藻土表面的硅羟基与修饰材料进行价键匹配,使复合材料具有较高的导电特性;同时,借助硅藻土高的比表面积及多孔结构,可大幅提高硅藻土基复合材料的电化学性能。另一方面,将硅藻土完全转化为另一种高导电性材料,以进一步提高复合材料的导电性能。硅藻土基复合材料在储能方面的应用已经引起广泛关注,并显示出巨大的潜力和发展空间。三维多孔材料在环境领域也具有广阔的应用空间。表面修饰可赋予硅藻土三维多孔材料优异的性能。例如,采用硅藻土表面硅羟基与纳米金属氧化物通过氢键进行结合,可显著改变纳米金属氧化物的表面价键排布,从而影响材料的性能。现阶段国内外针对硅藻土基复合材料在环境领域的应用已经开展了大量的研究工作。主要通过表面化学修饰的手段在硅藻土表面可控沉积功能材料实现功能性复合材料的构筑。这种复合材料保持着硅藻土的孔道结构,其较高的比表面积为功能材料提供了大量的活性位点,可显著提升硅藻土复合材料的性能。硅藻土基复合纳米材料是近年来出现的一个新的研究领域,它在超级电容器储能、锂电池、重金属污染物吸附、降解、催化合成等诸多领域得到了研究及应用。根据近年来国内外在硅藻土材料方面的研究现状,本文介绍了使用硅藻基复合材料在能源及环境领域应用的新进展。     

MnCl_2-NaOH改性硅藻精土吸附剂的制备及其对As(Ⅴ)的吸附机制

以硅藻精土为基体,MnCl_2和NaOH为复合改性剂制备了针对As(Ⅴ)离子的吸附剂。研究了MnCl_2-NaOH/硅藻土吸附剂用量对As(Ⅴ)去除率的影响,通过SEM、FT-IR、XRD、XPS对改性前后及吸附后的样品进行了微观分析。结果表明:随着吸附剂投量的增加,溶液中As(Ⅴ)的去除率从44.9%增加到93.9%。改性后硅藻基体未发生改变,MnCl_2-NaOH/硅藻土吸附剂平均孔径变大,比表面积增大近7倍。硅藻土经改性后红外活性羟基峰消失,表面新生成Mn—O—Si吸收峰,在XRD数据上显示新生成含有MnO_2的物相,表面Mn得到电子,通过氧化与硅藻表面形成复合接枝,吸附剂吸附溶液中含As(Ⅴ)的离子后,出现Mn_3(AsO_4)(OH)_4等物相,吸附过程中As得电子,Mn失电子,O、Si表面电子向As偏移,As在吸附剂表面的吸附方式有配位吸附、电荷吸附等。     

氟化活性炭纤维对极性分子的吸附

将活性炭纤维（ACF）与氟气反应制备出氟化活性炭纤维（FACF），根据将FACF与参照试样XPS的对比，碳原子是以sp^3杂化轨道同氟原子形成共健键。αs图分析氮吸附等温线的线果表明，ACF氟化后其比表面积和微孔容积都显著降低，微孔宽度基本不变，ACF的水吸附等温线呈V型，而FACF对水的吸附量极小；FACF的微孔表面具有完美的憎水性和高稳定性，乙醇和甲醇在ACF上的吸附等温线是Ⅰ型，在FACF上接近于Ⅰ型，但吸附量显著降低。     

MnCl2-NaOH改性硅藻精土吸附剂的制备及其对As(V)的吸附机制

以硅藻精土为基体,MnCl₂和NaOH为复合改性剂制备了针对As（V）离子的吸附剂。研究了MnCl₂-NaOH/硅藻土吸附剂用量对As（V）去除率的影响,通过SEM、FT-IR、XRD、XPS对改性前后及吸附后的样品进行了微观分析。结果表明：随着吸附剂投量的增加,溶液中As（V）的去除率从44.9%增加到93.9%。改性后硅藻基体未发生改变,MnCl₂-NaOH/硅藻土吸附剂平均孔径变大,比表面积增大近7倍。硅藻土经改性后红外活性羟基峰消失,表面新生成Mn-O-Si吸收峰,在XRD数据上显示新生成含有MnO₂的物相,表面Mn得到电子,通过氧化与硅藻表面形成复合接枝,吸附剂吸附溶液中含As（V）的离子后,出现Mn₃（AsO₄）（OH）₄等物相,吸附过程中As得电子,Mn失电子,O、Si表面电子向As偏移,As在吸附剂表面的吸附方式有配位吸附、电荷吸附等。     

炭化温度对木材液化物碳纤维吸附特性及孔结构的影响

以速生杉木为原料,经过苯酚液化物后加入六次甲基四胺熔融纺丝,初纺纤维固化处理后直接炭化制备出碳纤维,并对碳纤维的比表面积、孔径分布以及吸附特性进行了研究。研究结果表明,木材液化物碳纤维样品的等温线属于典型的Ⅰ型吸附等温线,其吸附滞后回线属于H4型。木材液化物碳纤维孔径主要以微孔为主,微孔率达到73.4%。碳纤维样品的BET比表面积、微孔面积、微孔容随着炭化温度的提高呈增大趋势,其中600～800℃是其孔隙结构发生变化的关键温度区间。液化原料中木材/苯酚比对其制备的碳纤维的比表面积、孔容及孔径的影响变化不大。     

新型硅藻土调湿材料温湿度调节效果及机制

通过小室试验研究新型硅藻土调湿材料对室内温湿度的调节效果,根据X射线衍射、环境扫描电镜分析及材料的吸附/解吸理论研究材料的改性机制和调湿机制。研究表明,小室内表面涂覆0.5 mm厚硅藻土调湿材料时,密闭条件下,调湿材料对单位空间的最大吸、放湿量分别为2.51和1.76 g/m~3,能将小室内相对湿度维持在50%～60%。与外界有换气条件下,随着预留缝隙的增大,材料对小室内湿度有效调节作用逐渐减弱,但对温度仍有1～2℃的调节作用。硅藻土调湿材料具有纳米级微孔特征及微孔内壁的缔合羟基作用,在毛细孔道效应、化学吸附和表面物理吸附的共同作用下,材料具有优异的吸放湿功能。     

氯化钙改性硅藻土的调湿性能

利用CaCl2对硅藻土进行改性,以改善硅藻土的调湿性能。制备不同CaCl2浓度改性的硅藻土样品,通过测定在不同相对湿度下的最大平衡含湿量和吸放湿动力学曲线,研究CaCl2对硅藻土调湿性能的影响规律,并通过SEM、BET等测试方法,表征改性硅藻土的微观形貌和孔结构,探讨改性作用的机制。结果表明,随着CaCl2浓度提高,改性硅藻土在不同相对湿度下的最大平衡湿含量和吸放湿速率均明显增大。改性后硅藻土表面包覆了一层均匀的颗粒,比表面积和孔容积下降,平均孔径增大。硅藻土多孔结构增大了CaCl2与水蒸气的接触面积,促进了水合反应,而CaCl2吸附的水会被及时地输送到孔隙中,促进了硅藻土的物理吸附。CaCl2改性是提高硅藻土调湿性能的有效途径。     

硅藻土基无机抗菌材料的制备与性能

选择硅藻土原土和煅烧硅藻土为载体,通过吸附方法将浓度为20×10-6的cpf抗菌剂负载到硅藻土上获得硅藻土基无机抗菌材料。采用扫描电镜、氮吸附测比表面积等手段进行表征,考察不同硅藻土的吸附性能,并对无机抗菌材料的抗菌性能进行了大肠杆菌抑菌圈实验研究。结果表明:硅藻土可以很好地吸附抗菌剂,硅藻土原土的最大负载率可达60.79%,煅烧硅藻土的负载率为24.78%,硅藻土原土的吸附效果明显优于煅烧硅藻土,这主要是由硅藻土不同的孔结构所导致。所制备新型硅藻土基无机抗菌材料具有较强的抗菌性能且持久长效,其抑菌圈尺寸均在20mm以上。     

The dynamic water vapour sorption behaviour of natural fibres and kinetic analysis using the parallel exponential kinetics model

Hygroscopic behaviour is an inherent characteristic of natural fibres which can influence their applications as textile fabrics and composite reinforcements. In this study, the water vapour sorption kinetic properties of cotton, filter paper, flax, hemp, jute, and sisal fibres were determined using a dynamic vapour sorption apparatus and the results were analyzed by use of a parallel exponential kinetics (PEK) model. With all of the fibres tested, the magnitude of the sorption hysteresis observed varied, but it was always greatest at the higher end of the hygroscopic range. Flax and sisal fibres displayed the lowest and highest total hysteresis, respectively. The PEK model, which is comprised of fast and slow sorption components, exhibited hysteresis in terms of mass for both processes between the adsorption and desorption isotherm. The hysteresis derived from the slow sorption process was less than from the fast process for all tested fibres. The fast processes for cotton and filter paper dominated the isotherm process; however, the hemp and sisal fibres displayed a dominant slow process in the isotherm run. The characteristic time for the fast sorption process did not vary between adsorption and desorption, except at the top end of the hygroscopic range. The characteristic time for the slow process was invariably larger for the desorption process. The physical interpretation of the PEK model is discussed.     

Heterogeneity of the adsorption mechanism of low molecular weight compounds in reversed-phase liquid chromatography

The retention mechanism in RPLC mode was investigated based on the acquisition of adsorption isotherm data by frontal analysis measurements and their modeling. This work is a review of the results of four years of adsorption data measurements. The data were acquired on a wide variety of brands of C18-silica columns (from Akzo Nobel, Bishoff, Hypersil, Merck, Phenomenex, Supelco, Vydac, and Waters) with several low molecular weight compounds such as phenol (94 g/mol), caffeine (194 g/mol), tryptophan (204 g/mol), sodium 2-naphthalenesulfonate (235 g/mol), and propranololium chloride (295 g/mol). The mobile phase was a mixture of methanol and water at variable composition. The adsorption isotherms were all convex upward (langmuirian), and the degree of heterogeneity of the adsorption system was determined from the calculation of the adsorption energy distribution using the expectation-maximization method. The adsorption isotherm parameters (number of types of adsorption sites, surface concentration of each type of site, and difference between the adsorption energies E(i) - E(j) on sites i and j), obtained from the mathematical fit of the adsorption data to the appropriate multi-Langmuir adsorption isotherm model, were analyzed and compared. The results allow the drawing of general conclusions regarding the relationships between the size of the analyte and the adsorption properties (saturation capacities, adsorption energies) characterizing the retention mechanism in RPLC mode for neutral, anionic, and cationic compounds.     

Inferring the favorable adsorption level and the concurrent multi-stage process with the Freundlich constant

This paper proposes a method for inferring a favorable level for the adsorption isotherm curve with the Freundlich constant (1/n), explains that a favorable level is only a function of 1/n, and then, five favorable levels are classified according to 1/n value. The adsorbent consumption ratio of the concurrent multi-stage to single-stage system was deduced in order to investigate the relationship between favorable level and the most suitable number of stages. Activated carbon (TGBAC) was prepared from Taiwan Giant Bamboo with steam activation. The isotherm equilibrium of the adsorption of three phenols (phenol, 3-CP, and 4-CP), two dyes (MB and BB 69), and tannic acid on TGBAC was obtained. According to the Freundlich constant (1/n), the adsorption of MB was inferred in a strongly favorable zone. The favorable zone for BB69, phenol, 3-CP, and 4-CP was determined. The tannic acid, the pseudo-linear zone and their most suitable number of stages were also determined. The 1/n values and favorable levels summarized from more than a hundred sources/studies indicate that the favorable levels of the adsorption of dyes and phenols on TGBAC are excellent. This paper proposes a simple method for inferring the favorable level and the most suitable number of stages for the concurrent multi-stage adsorption system.     

Mathematical modeling for the evaluation of zinc removal efficiency on clay sorbent

The adsorption characteristics of zinc ion from aqueous solution on the lateritic clay were investigated through batch and column mode of operation. The system variables were optimized to evaluate the maximum extent of zinc adsorption as well as for the purpose of modeling. A model equation correlating zinc adsorption with input concentration was described. The adsorption behavior can well be described by Freundlich isotherm model rather than Langmuir isotherm model. The favorable and spontaneous nature of adsorption was indicated from the thermodynamical parameters. The capacity was determined from isotherm parameters in batch mode and breakthrough parameters in column mode. The bed depth service time (BDST) model was utilized to predict column efficiency corresponding to different bed heights. Elution performance of retained zinc, using HNO(3) of definite composition, was examined from elution profile. Efficiency of the process was determined through repetitive operation cycles of retention and elution. Effectiveness of the process was judged through estimation of efficiency versus the cost of operation.     

Fe3O4/高岭土磁性复合材料对Cu2+的吸附性能

为实现高岭土（Kaolin）在Cu²⁺废水处理中的实际应用,采用球磨方法制备了剥离Kaolin,并通过氧化沉淀法制备了Fe₃O₄/Kaolin磁性复合材料。通过激光粒度分析仪、SEM、XRD对Fe₃O₄/Kaolin磁性复合材料的形貌及组成进行表征,并通过测试Fe₃O₄/Kaolin磁性复合材料对Cu²⁺的饱和吸附量和磁分离回收率,确定了当Kaolin球磨4.0 h、掺量为3.0 g时所制备的Fe₃O₄/Kaolin磁性复合材料对Cu²⁺的吸附性能最佳,平衡吸附量为17.98 mg/g。磁滞回线结果表明,Fe₃O₄/Kaolin磁性复合材料具有较好的磁响应性,饱和磁化强度约为16.19 emu/g。此外,采用Langmuir和Freundlich吸附等温式对Fe₃O₄/Kaolin磁性复合材料的吸附数据进行拟合,结果表明,Fe₃O₄/Kaolin磁性复合材料对Cu²⁺的吸附行为基本符合Langmuir吸附等温模型和Freundlich吸附等温模型,既存在单分子层吸附,也存在多分子层吸附。     

Determination of kinetic and equilibrium parameters of the batch adsorption of Mn(II), Co(II), Ni(II) and Cu(II) from aqueous solution by black carrot (Daucus carota L.) residues

In this study, the effect of temperature on the adsorption of Mn(II), Ni(II), Co(II) and Cu(II) from aqueous solution by modified carrot residues (MCR) was investigated. The equilibrium contact times of adsorption process for each heavy metals-MCR systems were determined. Kinetic data obtained for each heavy metal by MCR at different temperatures were applied to the Lagergren equation, and adsorption rate constants (kads) at these temperatures were determined. These rate constants related to the adsorption of heavy metal by MCR were applied to the Arrhenius equation, and activation energies (Ea) were determined. In addition, the isotherms for adsorption of each heavy metal by MCR at different temperatures were also determined. These isothermal data were applied to linear forms of isotherm equations that they fit the Langmuir adsorption isotherm, and the Langmuir constants (qm and b) were calculated. b constants determined at different temperatures were applied to thermodynamic equations, and thermodynamic parameters such as enthalpy (Delta H), free energy (Delta G), and entropy (Delta S) were calculated and these values show that adsorption of heavy metal on MCR was an endothermic process and process of adsorption was favoured at high temperatures.     

Adsorption of phthalic acid and its esters onto high-area activated carbon-cloth studied by in situ UV-spectroscopy

The adsorption behavior of phthalic acid and its three esters dimethyl phthalate, diethyl phthalate and diallyl phthalate onto high-area activated carbon-cloth was studied by in situ UV-spectroscopic technique. The effect of ionization of phthalic acid on its adsorption was examined by carrying out the adsorption process in three media; water, 1 M H(2)SO(4) and 0.005 M NaOH. Maximum adsorption was observed in 1 M H(2)SO(4) and almost no adsorption in 0.005 M NaOH. These results were discussed in terms of electrostatic and dispersion interactions between the adsorbate species and the carbon-cloth surface taking the point of zero charge (pH(pzc)) of the carbon-cloth into account. The adsorption process for the phthalate species studied was found to follow the first-order rate law, and the rate constants were determined. The isotherm data for the adsorption of phthalic acid and its esters were derived experimentally and fitted to Langmuir and Freundlich isotherm equations. Both equations were found to represent the experimental isotherm data almost equally well.     

Adsorption of boron from aqueous solutions using fly ash: batch and column studies

In the present paper, boron removal from aqueous solutions by adsorption was investigated. Fly ash particle size used in adsorption experiments was between 250 and 400 microm. During the experimental part of this study, the effect of parameters such as pH, agitation time, initial boron concentration, temperature, adsorbent dosage and foreign ion on boron removal were observed. In addition, adsorption kinetics, adsorption isotherm studies and column studies were made. Maximum boron removal was obtained at pH 2 and 25 degrees C. Thermodynamic parameters such as change in free energy (DeltaG degrees), enthalpy (DeltaH degrees), entropy (DeltaS degrees) were also determined. As a result of the kinetic studies, it was observed that the adsorption data conforms to the second degree kinetics model. In the isotherm studies, Langmuir and Freundlich isotherm models were applied and it was determined that the experimental data conformed to Langmuir isotherm model. Batch adsorbent capacity (q(o)) was calculated as 20.9 mg/g. The capacity value for column study was obtained by graphical integration as 46.2 mg/g. The Thomas and the Yoon-Nelson models were applied to experimental data to predict the breakthrough curves and to determine the characteristics parameters of the column useful for process design.     

A partially interpenetrated metal-organic framework for selective hysteretic sorption of carbon dioxide

The selective capture of carbon dioxide in porous materials has potential for the storage and purification of fuel and flue gases. However, adsorption capacities under dynamic conditions are often insufficient for practical applications, and strategies to enhance CO(2)-host selectivity are required. The unique partially interpenetrated metal-organic framework NOTT-202 represents a new class of dynamic material that undergoes pronounced framework phase transition on desolvation. We report temperature-dependent adsorption/desorption hysteresis in desolvated NOTT-202a that responds selectively to CO(2). The CO(2) isotherm shows three steps in the adsorption profile at 195?K, and stepwise filling of pores generated within the observed partially interpenetrated structure has been modelled by grand canonical Monte Carlo simulations. Adsorption of N(2), CH(4), O(2), Ar and H(2) exhibits reversible isotherms without hysteresis under the same conditions, and this allows capture of gases at high pressure, but selectively leaves CO(2) trapped in the nanopores at low pressure.     

Characterizations of strontium(II) and barium(II) adsorption from aqueous solutions using dolomite powder

In this research, adsorption technique was applied for strontium and barium removal from aqueous solution using dolomite powder. The process has been investigated as a function of pH, contact time, temperature and adsorbate concentration. The experimental data was analyzed using equilibrium isotherm, kinetic and thermodynamic models. The isotherm data was well described by Langmuir isotherm model. The maximum adsorption capacity was found to be 1.172 and 3.958 mg/g for Sr(II) and Ba(II) from the Langmuir isotherm model at 293 K, respectively. The kinetic data was tested using first and pseudo-second order models. The results indicated that adsorption fitted well with the pseudo-second order kinetic model. The thermodynamic parameters (ΔG°, ΔH°, and ΔS°) were also determined using the equilibrium constant value obtained at different temperatures. The results showed that the adsorption for both ions was feasible and exothermic.