Surface heterogeneity of porous polymer sorbents

The distribution function of the energy of adsorption (heterogeneity function, χ) was studied for porous polymers using inverse gas chromatography. The heterogeneity functions to-wards n-hexane, n-butanol, and ethyl acetate probes were obtained for four porous polymers prepared by polymerization of styrene and divinylbenzene. The value of c for the polar surface depends on the choice of the test sorbate. The possibility of comparing surface heterogeneity of various porous polymers using the parameter χ was shown.     

Optical isotope shifts in titanium I: new measurements

The optical isotope shifts between ⁴⁶Ti, ⁴⁸Ti and ⁵⁰Ti have been measured for eight 3d ³ 4s a ⁵F-3d ² 4s 4p y ³ F lines of titanium by use of a Doppler-free experiment. By contrast with the positive shifts previously measured for 3d ² 4s ² a ³ F-3d ² 4s 4p z ⁵ D lines, these shifts are negative and reveal the presence of large negative specific mass shifts attributed to a d-p electron jump. The interpretation of the present measurements and of former ones is made by means of Hartree-Fock calculations.     

Regulating the specificity of porous polymer sorbents used as the stationary phase in gas chromatography

Summary The main features of the retention of various homologous series on polymer sorbents with different functional groups, including typical ion-exchange resins, have been studied.Dedicated to ProfessorKiselev on the occasion of his seventieth birthday.     

Antimony phosphate nanoribbons: sorbents for uptake of uranyl ion

Antimony phosphate nanoribbons was synthesized and characterized using different techniques. Studies showed that the synthesized antimony phosphate possessed highly crystalline monoclinic SbPO₄ phase with an average crystallite size of 14 nm. TEM studies showed that antimony phosphate was present both as nano ribbons and nano particles. It is observed that the nano ribbons have length in the range of 500–700 nm and width around 100–200 nm whereas the nanoparticles size in the range of 1–5 nm. The synthesized nano phosphate was studied for its efficiency as sorbent for uptake of various metal ions including uranyl ion. The results indicated that a clean separation of uranyl ion from its various binary mixtures could be achieved at optimized pH of 4.5 and equilibration period of 1 h using 0.1 g of the sorbent.     

Evaluation of titanium and titanium oxides as chemo-affinity sorbents for the selective enrichment of organic phosphates.

Titanium (Ti) and TiO, Ti2O3, Ti3O5 and TiO(1.98) as well as TiO2 have been evaluated as chemo-affinity sorbents for the selective enrichment of organic phosphates. A column-switching high-performance liquid chromatography (HPLC) system, constructed with a precolumn (4.6 mm i.d. x 10 mm) packed with the titanium sorbents, an anion-exchange analytical column and a UV detector (215 nm) was used. When an aqueous 0.015% trifluoroacetic acid (TFA) was used as a sample-loading solution, O-phospho-L-tyrosine (P-Tyr), phenyl phosphate and phenylphosphonic acid were adsorbed onto all of the titanium sorbents with recoveries of 60.9 - 102.9%. Some acidic compounds other than phosphates, such as benzenedicarboxylic acid (BDA) isomers, were also adsorbed onto all of the titanium sorbents. To improve the selectivity to organic phosphates, various sample-loading solutions were examined using a Ti precolumn, two phosphorylated peptides [Ile-Ser(p)-Val-Arg (PP1) and Gln-Ile-Ser(p)-Val-Arg (PP2)], P-Tyr, BDA isomers and diglutamic acid (Glu-Glu) as test compounds. Among the sample-loading solutions tested, such as TFA, HClO4, organic acids, boric acid and NaCl, the use of 100 mM NaCl in 10 mM boric acid was found to be effective. The recoveries of PP1, PP2 and P-Tyr were 73.0, 88.3 and 71.5%, respectively, whereas those of Glu-Glu and BDAs were suppressed to only below 10%.     

Studies on new titanium hexacyanoferrate sorbents for radiocesium removal from primary coolant of pressurized water reactors

Recent work directed towards synthesizing and exploring new effective sorbents for radiocesium removal from primary coolants of pressurized water nuclear reactors of the WWER type is presented. Various sorbents synthesized on the basis of titanium hexacyanoferrate are compared with one another from the point of view of their sorption efficiency and stability. The uptake of¹³⁷Cs from solutions containing boric acid and millimolar quantities of ammonium and potassium ions was studied under conditions simulating the process of purification of the coolant bled from the primary circuit of the reactor. A composite-type sorbent was selected of good mechanical properties and negligible solubility, efficiently decontamining large amounts of the solution (considerably exceeding 10⁴ bed volumes) in the course of the column process.     

Mesoporous titanium phosphate molecular sieves with ion-exchange capacity.

Novel open framework molecular sieves, titanium(IV) phosphates named, i.e., TCM-7 and -8 (Toyota Composite Materials, numbers 7 and 8), with new mesoporous cationic framework topologies obtained by using both cationic and anionic surfactants are reported. The (31)P MAS NMR, UV-visible absorption, and XANES data suggest the tetrahedral state of P and Ti, and stabilization of the tetrahedral state of Ti in TCM-7/8 is due to the incorporation of phosphorus (at Ti/P = 1:1) vis-à-vis the most stable octahedral state of Ti in the pure mesoporous TiO(2). Mesoporous TCM-7 and -8 show anion exchange capacity due to the framework phosphonium cation and cation exchange capacity due to defective P-OH groups. The high catalytic activity in the liquid-phase partial oxidation of cyclohexene with a dilute H(2)O(2) oxidant supports the tetrahedral coordination of Ti in these materials.     

Interactions between C.I. Basic Blue 41 and aluminosilicate sorbents

Four aluminosilicate sorbents (montmorillonite, bentonite, raw perlite, and expanded perlite) were employed for retention of the cationic dye C.I. Basic Blue 41. Interactions between the clay and the dyestuff were investigated at several temperatures and clay:dye ratios. The mechanism behind the adsorption involves the formation of H-aggregates of the dye on both clays, followed by dye migration into the interlayer in the case of montmorillonite. Time-dependent absorbance spectra revealed the presence of various dye species in montmorillonite. Introduction of the dye molecules into the interlamellar space occurs more rapidly in bentonite than in montmorillonite. The dye molecules inserted between the clay leaves adopt different orientations and, eventually, stack in layers at increased dye loadings for both montmorillonite and bentonite. Higher dye aggregates are then present as suggested by diffuse reflectance spectroscopy. Dye sorption on both raw and expanded perlite proceeds via H-aggregate formation as well.     

一种新的有机非线性光学晶体——L-精氨酸磷酸盐

近年来,在探索新的有机非线性光学晶体的工作中,对含有给电子或受电子基团的芳香族化合物已有广泛深入的研究,并已研制出像2,4-二硝基苯丙氨酸甲酯(MAP)等具有较大倍频系数的新的非线性光学晶体。但是,由于强的共轭效应使它们大π键各能级间的距离接近而使此类晶体无法应用于紫外区。     

Ordered porous films of biomass-based polymers by breath figure: a review

Ordered porous films of polymers with uniform pore size and ordered porous structure are extensively applied in many fields such as separation, biology, photoelectric devices, templates, and other fields, which is the current research frontier in the field of porous films. Among different methods of preparing ordered porous films, the method of breath figure (BF) has attracted much attention due to its simplicity and adjustability. Many factors have been proved to influence the structure of the porous films by the BF method and the used polymer is the most important one. Recently, under the background of energy crisis and environmental pollution, polymers from biomass have received a lot of attention because of their advantages of low carbon, green, good biocompatibility, and easy modification. Up to now, a large number of porous films of biomass-based polymers including cellulose, polylactic acid, and urushiol-based polymers have been prepared by the BF method. Therefore, this article is to make a detailed review of the physicochemical modification of biomass-based polymers, the preparation of ordered porous films via BF and their applications. The method of BF is firstly introduced. The research progress of porous films of biomass-based polymers including cellulose, polylactic acid, and urushiol-based polymers prepared by the BF method is then reviewed. Finally, this review highlights the use of honeycomb films as cell culture substrates, drug delivery, wound dressings, optoelectronic devices and mimicking woody cell walls. The prospects for the development of porous films of biomass-based polymers are proposed. Future research could focus on the preparation of ordered, functional, and biocompatible porous films with smaller pore sizes for more applications in different fields, such as separation, tissue engineering, and controlled release of drugs.

Graphic abstract

Ordered porous films of biomass-based polymers via physical and chemical modification would be prepared by the breath figure method for different applications.

     

Solid phase extraction of lanthanum on modified low-polar sorbents

The preconcentration of lanthanum has been studied on low-polar sorbents modified with 1-phenyl-3-methyl-4-benzoylpyrazol-5-one, including hexadecylsilica, hyper-crosslinked polystyrene, polyvinylidene difluoride F2M, and activated carbon. The coefficients of reagent and the lanthanum distribution have been calculated under dynamic conditions. The leaching of the attached reagent from the sorbent surface has been investigated. The recovery of lanthanum with modified and nonmodified sorbents has been compared. The efficiency of lanthanum desorption with nitric acid and ethanol has been studied.     

Ag(I) solid solutions in zirconium dihydrogen phosphate. Thermal behaviour and phase changes

The thermal and redox behaviours of some Ag-low-converted zirconium phosphates have been investigated by thermoanalytical and X-ray methods: the conditions for obtaining Ag solid solutions in phases are reported.

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Zusammenfassung Das thermische und Redoxverhalten einiger Zirkoniumphosphate niedriger Ag-Konversion wurde durch thermoanalytische und Röntgenmethoden studiert; über die Bedingungen zum Erhalten von Ag-Festphasenlösungen in HH-Phasen wird berichtet

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Résumé On a étudié le comportement thermique et oxydo-réducteur de quelques phosphates de zirconium faiblement converti par Ag, en se servant des méthodes d'analyse thermique et des rayons X: on communique les conditions permettant d'obtenir des solutions solides d'Ag dans les phases .

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- Ag- . HH.

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Paper in part presented at the 6th ICTA, in Bayreuth (Germany), July 1980.

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We thank Dr. M. A. Massucci, of our Institute, for helpful discussions and suggestions.     

Photo-oxidation of phenol over titania pillared zirconium phosphate and titanium phosphate

The photodegradation of phenol was studied in the aqueous solutions over titania pillared zirconium phosphate and titanium phosphate under solar radiation and compared with that of the UV-radiation (6 W low pressure Hg vapor lamp). This reaction was studied by varying different parameters such as catalyst dose, initial phenol concentration, pH of solution and irradiation time. The degradation rate of phenol was favourable under neutral pH condition. The degradation process approximately obeyed first-order kinetics with apparent rate of degradation constant increasing with decreasing the initial phenol concentration.     

Effect of yttrium oxide on the formation of the phase composition and porous structure of titanium dioxide

The formation of the structure of TiO₂ (anatase) doped with 1–5 mol % Y₂O₃ is reported. The dopant changes the anatase structure from regular to nanocrystalline. The nanocruystalline structure consists of incoherently intergrown 5- to 7-nm anatase crystallites (500°C) separated by interblock boundaries accommodating yttrium ions. The formation of the nanocrystalline anatase structure stabilizes small anatase crystallites and raises the anatase-to-rutile phase transition temperature above 900°C. Owing to this structure, the developed specific surface area and fine porous texture of yttrium oxide-doped titanium dioxide survive up to higher temperatures than those of undoped titanium dioxide.     

Modification of titanium phosphate precipitated from titanylsulfate

The titanium phosphate-synthesized sol–gel method was subjected to the mechanochemical treatment in a planetary ball mill Pulverisette 6 in air or water environment or the hydrothermal treatment at 873 K or 1073 K. The properties of such modified/treated samples were examined using the XRF, XRD, TGA, static light scattering, FTIR Raman and adsorption/desorption of N₂ methods. The mechanochemical treatment of xerogel samples leads to a small decrease in water contents in the sample, but the structure remains amorphous. Additionally, during milling of the sample aggregation of titanium phosphate particles and a decrease in specific surface area were observed. The hydrothermal treatment of the xerogel sample leads to a crystal product composed of titanium oxide phosphate hydrate, titanium oxide phosphate and titanium dioxide. The TGA analysis confirms the presence of titanium oxide phosphate hydrate. The hydrothermally treated titanium phosphate samples are monodispersed and have a larger specific surface area than the initial sample.

     

Tailoring the porous hierarchy of titanium phosphates

First hierarchical titanium phosphate (TiPO) materials with multiple porosities of different lengths (meso-macroporous and meso-macro-macroporous) were synthesized by the self-formation process. The further tuning of the porous hierarchy by using the poly(ethylene oxide) surfactant technique was demonstrated. The macroporous structure (50-160 nm in size) of TiPO with mesoporous walls could be self-formed in the absence of any templatable agents, including surfactant molecules. On the basis of spontaneous structurization, the addition of a small quantity of nonionic poly(ethylene oxide) surfactant (e.g., 5%) led to an improvement in macroporosity in abundance and in regularity with a slight enlargement in macropore sizes to 80-250 nm. Interestingly, a secondary, larger macropore system with parallel channels 500-1000 nm in size was generated when the synthesis was performed with moderately increasing the content of surfactant (10%), giving rise to an unprecedented trimodal meso-macro-macroporous structure. A uniform three-dimensional co-continuous macroporous structure with accessible wormhole-like mesoporous walls was synthesized by using the higher content of surfactants. This is a direct demonstration of tailoring the porous hierarchy of different lengths integrated in one solid body by fine-tuning the self-formation process and the participation of surfactant. The synthesized hierarchical titanium phosphates possess interesting optical and acidic properties, which should be significant for large application potential from catalysis and separation to electrochromic devices, fuel cells, and bioactive materials.     

Nascent phase of porous silicon

Porous silicon and its luminescent properties are well known for more than a decade. The origin of the nanoporosity evolution, however, is still obscure. We address this topic by investigating the earliest detectable stages of silicon dissolution using atomic force microscopy and synchrotron radiation photoelectron spectroscopy. The electrolyte composition and the electrode potential are chosen as to resolve the dissolution, beginning from the submonolayer regime. We find extremely local formation of nanopits due to electrolyte countercharge immobilisation at specific surface sites of the ideally hydrogen terminated (1 1 1) surface. In conjunction with density functional theory calculations on dissolution reaction intermediates and photoelectron spectroscopy, an existing dissolution model is completed. The results have far reaching significance for the preparation of nanostructures, distinctly shaped despite their unequalled small dimensions.