A new way for calculating the adsorption capacity from surface excess isotherms

 Adsorption of n-butanol and water from butanol–water mixtures is studied on adsorbents of different hydrophobicity (activated carbon and hydrophobized montmorillonites). The shape of the adsorption isotherms of the hydrophobized clay minerals does not indicate preferential adsorption of butanol. Therefore, the adsorption capacity cannot be determined on the basis of the Langmuir isotherm. A new equation for determining the adsorption capacity is derived by combining the free enthalpy of adsorption with the adsorption excess amount. Both collections of data are obtained from the surface excess isotherm. The reliability of the adsorption capacity is checked by X-ray diffraction measurements. Received: 1 November 1997 Accepted: 19 February 1998     

二酰胺桥联氧杂同杯[3]芳烃的合成及其对线性烷基铵离子的识别性质

The synthesis and conformation of di-O-bridged homooxacalix[3]arenes were reported. Their recognition ability towards alkylammonium ions was studied with the aid of NMR. Two of them show selective binding ability towards relatively longer linear alkylammonium ions （CH3（CH2）nNH3^＋, n = 3-5）.     

Conductance of n-alkylammonium and n-alkanolammonium chlorides and picrates in water at 25°C

Precise conductance measurement are reported at 25°C in water for ethanolammonium chloride and picrate [(EtOH)NH₃Pic], propanolammonium picrate [(ProOH)NH₃Pic], butanolammonium picrate [(BuOH)NH₃Pic], pentanolammonium picrate [(PeOH)NH₃Pic], ethylammonium chloride (EtNH₃Pic), n-propylammonium picrate (PrNH₃Pic), n-butylammonium chloride and picrate (BuNH₃Pic), n-pentylammonium chloride (PeNH₃Cl) and n-heptylammonium chloride (HepNH₃Cl). Comparison of the limiting ionic conductance for the straight chain alkylammonium ions with their terminal hydroxyl-substituted analogs reveals that only for the ethanolammonium ion is the limiting ionic conductance significantly higher. In the other cases a much smaller, nearly constant, difference is observed. These results are explained in terms of the effect of the OH group on the interaction between water and the alkyl chain in the ammonium ions.     

Analytical pyrolysis of alkylammonium tetraphenylborates

Various alkylammonium, dialkylammonium, trialkylammonium and tetraalkylammonium tetraphenylborates were prepared. The thermal decomposition curves of RNH₃BPh₄, R₂NH₂BPh₄, R₃NHBPh₄ and R₄NBPh₄ (whereR=Me, Et,n-Bu) in nitrogen atmosphere indicate that the elimination of volatile matter leads to the formation of both 1∶1 complex of trialkylamino triphenylborane and dialkylamino diphenylborene. Further elimination of volatile matter leads to the formation of borazine at 600–680°C. When borazine is further heated at 980–1090°C an exothermic change indicates the polycyclic condensation of the borazine leading to the formation of boron nitride. The volatile matter evolved in these reactions was measured quantitatively and reaction mechanisms were suggested.     

Synthesis, spectroscopic characterization and X-ray structure determination of tetrabutylammonium trans-diamminetetranitrocobaltate(III)

The cobalt(III) complex salt [(C₄H₉)₄N][trans-Co(NH₃)₂(NO₂)₄] has been synthesized in high yield by reacting equimolar quantities of [(C₄H₉)₄N]Br and K[trans-Co(NH₃)₂(NO₂)₄] in aqueous medium at room temperature. The product thus formed has been re-crystallised from acetone-water mixture, in the monoclinic space group P 2₁/n, with cell dimensions a=11.651(3) ?, b=19.005(4) ?, c=11.733(5) ?, β=90.28(3)°. The X-ray structure determination revealed the presence of discrete ions, [(C₄H₉)₄N]⁺ and [trans-Co(NH₃)₂(NO₂)₄]⁻. The central metal ion cobalt(III) in the anion is found in octahedral environment, in trans geometry, while the organic counterion is a quaternary alkylammonium cation. The crystal lattice is stabilized by electrostatic interactions between the cations and anions.Supplementary material Crystallographic data (excluding structure factors) for the structure(s) reported in this paper have been deposited with the Cambridge Crystallographic Data Centre as supplementary publication no. CCDC 291300. Copies of the data can be obtained free of charge on application to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (fax: (44) 1223 336-033; e-mail: deposit@ccdc.cam.ac.uk.     

A DFT study on a calix[5]crown-based heteroditopic receptor

The structures and binding energies of complexes formed between tris-ureido-calix[5]crown 1 and n- and 2-phenylethylammonium chloride have been determined by density functional calculations. Density functional theory analysis shows that the heteroditopic receptor 1 binds organic salt species with positive cooperativity.     

Radiochemical Analysis of 35SO2 Adsorbed on Pbo2

Abstract

The concentration of ³⁵SO₂ in air can be measured by reacting with Pbo₂ to form Pb³⁵SO₄. A method was developed which is suitable for rapid, high-protection radioassaying of ³⁵SO₄ ^2- on the surface of Pbo₂. The surface ³⁵SO₄ ^2- was extracted with a quaternary alkylammonium hydroxide in toluene and counted in an organic liquid scintillator solution with an efficiency of approximately 94%, which was constant for 30 days when corrected for natural decay. More than 99.5% of the surface sulfate was extracted in less than 5 minutes for quaternary alkylammonium concentrations 600 times in excess. This technique was shown superior to gas-flow proportional counting of the PbO₂ surface.