A adsorção do 3,5-dimetiltetrahidro-1,3,5-tiodiazina-2-tiona (dazomet) sobre betonita e clinopetilolita foi estudada em quarto temperaturas (288, 293, 298 e 303 K) e em duas soluções distintas (água e mistura água-etanol 50%, v/v). A velocidade de adsorção em baixas concentrações de dazomet foi determinada como sendo de primeira ordem. Para cada sistema em concentração fixa, a constante de velocidade aumenta com o aumento da temperatura na solução aquosa, mas diminui no caso da mistura água-álcool a 50%. Usando-se a equação de Arrhenius, as energias de ativação de cada sistema foram calculadas. Parâmetros termodinâmicos foram avaliados de acordo com a equação de Eyring. Os valores de entalpia de ativação, ∆H*, são menores que T∆S*. Os resultados indicam que o processo de adsorção é controlado entropicamente em cada sistema. As isotermas de adsorção foram determinadas a 288 e 303 K. Estas isotermas seguem a equação de Freundlich para soluções aquosas a 15 °C. Para as duas soluções a 30 °C as isotermas foram modeladas de acordo com isotermas de Langmuir e BET.The adsorption of 3,5-dimethyltetrahydro-1,3,5-thiadiazine-2-thione (dazomet) on bentonite and clinoptilolite has been studied at four temperatures (288, 293, 298 and 303 K) and two different solutions (water and water-ethyl alcohol mixture, 50% v/v). The adsorption rates at low concentrations of dazomet were found to fit the first-order kinetic equation. For each system at constant concentration, the rate constants increased with increasing temperature in aqueous solution, but these constants decreased with increasing temperature for 50% (v/v) water-ethyl alcohol mixture solution. By using the Arrhenius equation, the activation energies for each system were calculated. Thermodynamic parameters were evaluated according to Eyring's equation. The values of enthalpy of activation, ∆H*, are lower than T∆S*. The results indicated that the adsorption process was entropy-controlled for each system. Adsorption isotherms were determined at 288 and 303 K. These isotherms were fitted to Freundlich equation for aqueous solution at 15 °C, but adsorption from the two different solutions at 30 °C were modeled according to the Langmuir and BET isotherms.

No abstract

The new complexes [M(CO) 5 -DABRd] [M 5 Cr; 1, Mo; 2, W; 3], [cis-Re(CO) 4 Br-DABRd] (4), [M(CO) 5 -BRd] [M 5 Cr; 5, Mo; 6, W; 7] and [Mo(CO) 5 -L] [L 5 Rd ,8; 2CBRd,9; 2HNARd,10; IBRd,11] have been synthesized by the photochemical reactions of VIB and VIIB group metal carbonyls [M(CO) 6 ] [M 5 Cr, Mo, W] and [Re(CO) 5 Br] with 5-(4-dimethylaminobenzylidene)rhodanine (DABRd), 5-benzylidenerhodanine (BRd), rhodanine (Rd), 5-(2-chlorobenzylidene)rhodanine (2CBRd), 5-(2-hydroxynaphtylidene)rhodanine (2HNARd), 5-(4-isopropylbenzylidene)rhodanine (IBRd) and characterized by elemental analysis, FT-IR, 1 H and 13 C-f 1 Hg-NMR spectroscopy and by Mass spectrometry. The spectroscopic studies show that all rhodanine ligands act as monodentate ligands coordinating via the sulfur (C5 5S) donor atom in (1 -11).

No abstract