Alfred A. Scala

Adsorption of small organic pollutants from aqueous streams by aluminosilicate-based microporous materials

Organic pollution in industrial waste streams is of growing environmental concern. Adsorption has been applied to remove organics from aqueous solutions. Activated carbon and polymer resin are the most commonly used adsorbents. In this work, a novel class of aluminosilicate-based microporous materials with good adsorption capacity and high selectivity are investigated. In order to adsorb organic molecules selectively from aqueous solution, the adsorbents must be hydrophobic. Phenol and chlorinated phenols were adsorbed by three different adsorbents: pillared clays, silicalite and zeolite beta. Pillared clays were modified by incorporating a non-ionic surfactant of the general formula C2−14H25−290O (CH2CH20)5H (Tergitol 15S-5). Also, high SiAl ratio zeolites were used for this purpose. Factors which are important in determining the selectivity and adsorption capacity of these adsorbents are the hydrophobicity of the adsorbent, the size of the organic, and the diameter of channels which are accessible to the adsorbate.

Photoionization quantum yields. A convenient 147 nm actinometer

The photoionization quantum yields of trimethylamine, triethylamine, dipropylamine, di−iso−propylamine, and tetramethylene sulfide have been determined, at 147 nm, to be 0.38, 0.46, 0.096, 0.15, and 0.10, respectively. These ionization efficiences permit actinometry based upon saturation current measurements. This physical technique of absolute photon flux measurement is contrasted with the chemical actinometers currently in use at 147 nm.

Adsorption and characteristics of base-treated pillared clays

The effect of base treatment on the cation exchange capacity (CEC) of pillared clays and their adsorption isotherms for Cu2+, Cr3+ and Pb2+ have been investigated. Results indicate that although the CEC of pillared clays are only about 15% of that of the parent clays, a large fraction of the native clays CEC may be recovered by treatment with base. The fraction of the CEC recovered depends upon the base strength, its concentration, and the temperature. Contrary to previous suggestions the mechanism of recovery is related to the destruction of pillars which is accompanied by the loss of surface area. It is possible under conditions specified to prepare these base treated pillared clays as a new class of useful, regenerable adsorbent for heavy metal adsorption from aqueous solution.

The gas phase photolysis and γ radiolysis of ethylenimine

The vacuum ultraviolet photolysis and mass spectral cracking pattern have been used to elucidate the chemistry occurring during the gas phase γ radiolysis of ethylenimine. In the 147 nm photolysis of ethylenimine, the major primary reactions occurring are (1) C2H4NH→C2H4+NH, φ=0.38, and (2) C2H4NH→CH3+[H2CN], φ=0.47. The mass spectrum of ethylenimine indicates that in the γ radiolysis of ethylenimine, where ions as well as neutral excited states are produced, the mechanism includes the ionic analog of Reaction (2): C2H4NH+→CH3+H2CN+. The mass spectrum also suggests the inclusion of Reaction (10) in the γ‐radiolysis mechanism: (10) C2H4NH+→C2H4N+ + H. Although it cannot be proven conclusively, because hydrogen atoms and ethylenimine radicals are produced in secondary reactions, spectroscopic evidence suggests that the neutral analog of Reaction (10) may occur in the 147 nm photolysis: (9) C2H4NH→C2H4N+H. Except for reaction (1), which has no ionic analog in the mass spectrometer and which probably occurs f...

The vacuum UV photolysis of methyl-substituted tetrahydrofurans

Abstract Product distributions from the gas and solid phase (77 K) 147 nm photolyses of tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran and 2,5-dimethyltetrahydrofuran are reported. The mechanisms are similar to those proposed previously, and all involve the fragmentation of diradicals produced from initial carbon—oxygen bond cleavage. There is a pronounced preference for cleavage of the bond to the least substituted α-carbon. The products form from subsequent β cleavage of the initially formed diradicals. There is a pronounced preference for these β cleavages to produce a carbon—oxygen π bond and a trimethylene diradical, rather than a carbon—carbon π bond and the companion dimethylene oxide diradical. The hydrocarbon diradicals react further in a manner entirely consistent with predictions. The simplicity of the results from the solid phase photolyses suggests either that secondary decomposition dominates product distributions from gas phase vacuum UV photolyses, or that the excited states involved have lifetimes sufficiently long to permit quenching and intersystem crossing.

Vacuum Ultraviolet Photochemistry of Cyclobutanone

The photodecomposition of cyclobutanone in the vacuum ultraviolet is characterized by → C2H4 + CH2 + CO, → CO+C3H6. At 147.0 nm and high pressure the quantum yields of Reactions (1) and (2) are approximately 0.7 and 0.25 respectively. At 123.6 and 106.7–4.8 nm the ratio of the quantum yield of Reaction (2) relative to Reaction (1) is 0.28. The quantum yield of carbon monoxide is unity at 147.0 and 123.6 nm and 0.81 at 106.7–4.8. Although Reaction (2) is best interpreted in terms of a trimethylene diradical intermediate, at 147.0 nm Reaction (2) produces propylene in a primary process with a quantum yield of 0.09. There is no evidence for the production of primary propylene at 123.6 or 106.7–4.8 nm. Pressure studies at 106.7–4.8 nm indicate that the cyclopropane produced in Reaction (2) contains only about 90 kcal.mole of excess vibrational energy. This result requires that carbon monoxide is produced either with 175 kcal/mole of excess vibrational energy or more likely in an electronically excited state.