二氧化碳从它溶胀后的聚合物中的解吸

研究了经过４０℃,８．０￣１４．０ＭＰａ的超临界二氧化碳溶胀后的６种聚合物ＬＤＰＥ、ＰＰ、ＰＡ６、ＥＶＡ、ＰＵ中的ＣＯ２解吸情况,模拟了聚合物中ＣＯ２的解吸规律,即以时间的自然指数递减规律,并根据Ｆｉｃｋ扩散定理从理论上推导出ＣＯ２在聚合物中的解吸方程,由解吸方程计算解吸扩散系数,结果表明ＣＯ２的解吸扩散系数数量级达１０＾－７ｃｍ＾２／ｓ,解吸扩散系数与ＣＯ２在聚合物中的浓度和温度以及解吸前聚合物     

吸附/热解吸/气相色谱法测定环境空气中的丙烯酸甲酯

用ＴｅｎａｘＧＣ吸附环境空气中的丙烯酸甲酯,热解吸／气相色谱法测定,方法的回收率为８７．４％－１０８．９％,相对标准偏差为４．７％－６．３％,当采样体积２Ｌ时,最低检测质量浓度为０．０１ｍｇ／ｍ＾３。     

染料在青霉菌上的解吸特性研究

比较了有机溶剂的加入及温度变化对染料高效吸附青霉菌(BX1)解吸染料效果的影响,并对解吸过程的动力学进行了研究.结果表明,染料的解吸效果与有机溶剂的极性,以及溶剂的官能团有关,丙酮和甲醇解吸效果最好.解吸过程与吸附过程类似,可分为快速解吸和缓慢解吸两个阶段,整个过程可用二级动力学方程较好的拟合,其表观活化能约为10.64kJ/mol.△H°和△G°的计算表明,在甲醇作用下RB19染料的解吸为吸热和自发的过程.     

Positive and negative ionic desorption from condensed formic acid photoexcited around the O 1s-edge: Relevance to cometary and planetary surfaces

Photon stimulated ion desorption (PSID) studies have been performed in condensed formic acid using oxygen 1s-edge synchrotron radiation from the Brazilian synchrotron light source (LNLS), operating in a single-bunch mode. Ion formation was discussed in terms of the Auger stimulated ion desorption (ASID) and X-ray induced electron stimulated desorption (XESD) mechanisms. It is found that O 1s(C-OH) → π*(CO) and O 1s(CO) → 3s/σ*(HCO) transitions favored the production of C⁺, CH⁺, O⁺, O⁻ and H⁻ ions. The hydroxyl anion has not been observed while the hydroxyl cation showed low intensity or was absent. Some anion formation routes from dissociative reactions are suggested taking into account the positive ion yields.     

Adsorption study for removal of Congo red anionic dye using organo-attapulgite

The organo-attapulgite was prepared using hexadecyltrimethylammonium bromide (HTMAB) with equation equivalent ratio of HTMAB to CEC of attapulgite added and then used as adsorbent for the removal of Congo red (CR) anionic dye from aqueous solution. Adsorbent characterizations were investigated using infrared spectroscopy and X-ray diffraction. The effects of contact time, temperature, pH and initial dye concentration on organo-attapulgite adsorption for CR were investigated. The results show that the amount adsorbed of CR on the organo-attapulgite increase with increasing dye concentration, temperature, and by decreasing pH. The adsorption kinetics was studied with the pseudo-first-order, pseudo-second-order and intraparticle diffusion models, and the rate constants were evaluated. It was found that the adsorption mechanisms in the dye/organo-attapulgite system follow pseudo-second-order kinetics with a significant contribution of film diffusion. Equilibrium data fitted perfectly with Langmuir isotherm model compared to Freundlich isotherm model, and the maximum adsorption capacity was 189.39 mg g⁻¹ for the adsorbent. Kinetic and desorption studies both suggest that chemisorption should be the major mode of CR removal by the organo-attapulgite. The results indicate that HTMAB-modified attapulgite could be employed as low-cost material for the removal of Congo red anionic dye from wastewater.     

Adsorption of chlorhexidine onto cellulosic fibers

Comparative investigations of adsorption properties of chlorhexidine (CHX) on two cellulose fibers, bleached cotton and viscose, were studied in order to obtain dry gauzes covered with known amount of this antiseptic. Adsorption isotherm results carried out at 293 and 323 K can be described by Langmuir isotherm model, nevertheless, at high concentration correlation is better to Freundlich isotherm. Electrokinetic potential evolution with CHX concentration, shows that initial negative zeta potential of cotton and viscose diminish its absolute value as the concentration of the treatment increases; both fibers present an isoelectric point at high concentration of CHX that is 0.3 mM for viscose and 0.8 mM for cotton. Electrostatic interactions between cationic groups of CHX and carboxylic acid groups of the fibers could explain adsorption at low concentration, but when it is higher than these values, possible hydrogen bonding between the amine groups of CHX and hydroxyl groups of cellulose could explain increasing adsorption when it is hindered by electrostatic repulsion as it is predicted by Freundlich model, that describes heterogeneous surface and multilayer adsorption. Adsorption kinetics isotherms reveal that the process is quick with t _1/2 values of 5.4 min for cotton and 2.8 min for viscose. Differences in adsorption behaviour between the two fibers could be attributed to structural differences as we have observed from estimation of CI index based on FTIR spectra. Values obtained 1.6 for viscose and 2.2 for cotton could explain that the amount of CHX adsorbed on viscose is higher than it is on cotton. Finally desorption experiments performed with 0.01 M of NaCl solution at room temperature and pH 6 reveals the possibility of therapeutical application of these fibers although further investigations must be done to optimize the process.     

Investigation of ionene adsorption on quartz surfaces by thermal-lens spectrometry

Thermal-lens spectrometry was used for the investigation of the adsorption of ionene to quartz surfaces. The thermooptical analysis of the surface makes it possible to distinguish the modified surface from a clean quartz surface and to provide sensitive direct concentration measurements of the light absorbing co-adsorbed substance. The co-adsorption of chromate ions and 2,10-ionene from aqueous solutions to quartz surfaces was investigated and the desorption procedure proposed.     

密度泛函理论研究纯的及不同掺杂原子石墨烯和CaH_2分子相互作用

本研究采用密度泛函理论研究了纯的及V,Fe,Ni,Pd,Si,P,S和Cl掺杂原子的石墨烯和CaH_2分子之间相互作用.研究结果发现CaH_2分子与所有石墨烯表面均具有较大的相互作用,而CaH_2分子与掺杂石墨烯相互作用都大于与纯石墨烯的相互作用,在所有掺杂原子中,其中与Pd掺杂石墨烯具有最大的相互作用,S次之,其它掺杂石墨烯与CaH_2分子相互作用能力相差不大.这些结果表明虽然所有石墨烯均有助于CaH_2中H原子的脱附,但掺杂石墨烯脱附能力仍然大于纯的石墨烯.在掺杂原子中,Pd和S掺杂石墨烯对CaH_2中H原子的脱附效果最好,其它的掺杂原子脱附效果相差不明显.此研究结果将有望为CaH_2分子在石墨烯基材料中吸氢-脱氢行为提供有用的理论参考价值.     

Review of recent advances in the preparation of organic polymer monoliths for liquid chromatography of large molecules

In recent years the use of monolithic polymers in separation science has greatly increased due to the advantages these materials present over particle-based stationary phases, such as their relative ease of preparation and good permeability. For these reasons, these materials present high potential as stationary phases for the separation and purification of large molecules such as proteins, peptides, nucleic acids and cells. An example of this is the wide range of commercial available polymer-based monolithic columns now present in the market.     

Tuning properties of silver particle monolayers via controlled adsorption-desorption processes

Nanoparticle self-assembly at fluid-fluid interfaces has been traditionally exploited in emulsification, encapsulation and oil recovery, and more recently in emerging applications including functional nanomaterials and biphasic catalysis. We provide a review of the literature focusing on the open challenges that still hamper the broader applicability of this potentially transformative technology, and we outline strategies to achieve improved control over interfacial self-assembly of nanoparticles. First, we discuss means to promote spontaneous adsorption by tuning the interfacial energies of the nanoparticles with the fluids using capping ligands, and the occurrence of energy barriers. We then examine the interactions between interfacial nanoparticles and how they affect the formation of equilibrium interfacial suspensions versus non-equilibrium two-dimensional phases, such as weakly attractive glasses and gels. Important differences with colloidal interactions in a bulk suspension arise due to the discontinuity in solvent properties at the interface. For instance, ligand brushes rearrange in asymmetric configurations, and thus play a significant role in determining interparticle interactions. Finally, we briefly discuss the link between interfacial microstructure and the dynamic response of particle-laden interfaces, including interfacial rheology and the fate of nanoparticle monolayers upon out-of-plane deformation.