Rf. De Farias et C. Airoldi, Thermochemical features of lamellar silica, copper, nickel and cobalt-doped forms synthesized from neutral amine route, COLL SURF A, 172(1-3), 2000, pp. 145-152
Citations number
20
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
Lamellar silica prepared from sol-gel process through neutral amine route,
was doped with cobalt, nickel or copper. X-ray diffraction pattern, thermog
ravimetry, and differential scanning calorimetry and reaction-solution calo
rimetry characterized these synthesized hybrids. The wetting enthalpy, Delt
a(wet)H(m)(theta), for lamellar matrix doped with 10.0 and 15.0 mmol of CuC
l2 gave 41.81 +/- 0.02 and 40.54 +/- 0.02 J g(-1), respectively. The enthal
py of cation adsorption was carried out by using 100.0 cm(3) of 8.0 x 10(-3
) or 0.127 mol dm(-3) solutions of Co2+ , Ni2+ or Cu2+. The measurements we
re also performed using 50.0/50.0 cm(3) mixture of Co2+ and Cu2+ solutions.
The results gave 20.73 +/- 0.07; - 69.22 +/- 0.03; 10.91 +/- 0.06 and - 34
.44 +/- 0.06 J g(-1) for nickel, copper, cobalt and copper-cobalt solutions
, for a concentration of 8.0 x 10(-3) mol dm(-3). The same sequence of cati
ons gave the enthalpic values - 97.12 +/- 0.06, - 106.90 +/- 0.01, 42.56 +/
- 0.06, 34.97 +/- 0.12 J g(-1) for 0.127 mol dm(-3) solution. The results s
howed that the lamellar sirica matrix can be used as a sequestrating agent
for these cations with a capacity of adsorption established as Ni2+ > Cu2> Co2+. The wetting enthalpic values as well as the thermal stability of th
ese matrices are associated to the crystallinity of the samples. (C) 2000 E
lsevier Science B.V. All rights reserved.