TY - JOUR
T1 - Metachromasy in clay minerals. Spectroscopic study of the adsorption of crystal violet by laponite
AU - Yariv, Shmuel
AU - Nasser, Ahmed
AU - Bar-on, Ptahia
PY - 1990
Y1 - 1990
N2 - The adsorption of crystal violet (CV) on laponite has been investigated by normal and comparative electronic spectroscopy. The following spectroscopic phenomena have been observed: with degrees of saturation below 44 mmol CV per 100 g clay, band α showed a bathochromic shift, indicating the adsorption of monomeric CV into the interlayer space; with degrees of saturation between 44 and 130 mmol CV per 100 g clay, metachromasy and flocculation, indicating the adsorption of dimeric CV species. Since metachromasy appeared together with flocculation it was assumed that the adsorbed dimers were located in the interparticle space of the floc. With higher saturation laponite repeptized and band α again appeared, but was not shifted to longer wavelengths as before the flocculation. At this stage the monomeric cations were adsorbed in excess of the cation-exchange capacity. Consequently, the clay was peptized and the adsorbed cations were located at the water/solid interface.
AB - The adsorption of crystal violet (CV) on laponite has been investigated by normal and comparative electronic spectroscopy. The following spectroscopic phenomena have been observed: with degrees of saturation below 44 mmol CV per 100 g clay, band α showed a bathochromic shift, indicating the adsorption of monomeric CV into the interlayer space; with degrees of saturation between 44 and 130 mmol CV per 100 g clay, metachromasy and flocculation, indicating the adsorption of dimeric CV species. Since metachromasy appeared together with flocculation it was assumed that the adsorbed dimers were located in the interparticle space of the floc. With higher saturation laponite repeptized and band α again appeared, but was not shifted to longer wavelengths as before the flocculation. At this stage the monomeric cations were adsorbed in excess of the cation-exchange capacity. Consequently, the clay was peptized and the adsorbed cations were located at the water/solid interface.
UR - http://www.scopus.com/inward/record.url?scp=0001664622&partnerID=8YFLogxK
U2 - 10.1039/FT9908601593
DO - 10.1039/FT9908601593
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AN - SCOPUS:0001664622
SN - 0956-5000
VL - 86
SP - 1593
EP - 1598
JO - Physical Chemistry Chemical Physics
JF - Physical Chemistry Chemical Physics
IS - 9
ER -