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Chlorophyll adsorption by alumina‐pillared acid‐activated clays
Author(s) -
Mokaya Robert,
Jones William,
Davies Mary E.,
Whittle Mavis E.
Publication year - 1993
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/bf02545302
Subject(s) - calcination , adsorption , chemical engineering , cation exchange capacity , materials science , specific surface area , acid strength , inorganic chemistry , mineralogy , chemistry , catalysis , organic chemistry , zeolite , geology , soil science , engineering , soil water
Clays, acid‐activated to an optimum level, have been pillared with alumina to give semi‐crystalline expanded materials with surface acidities, pore volumes and average pore diameters generally higher than those of the corresponding pillared materials derived from a clay matrix not previously acid‐activated. The chlorophyll adsorption capacity of the pillared acid‐activated materials is significantly greater than that of pillared, nonactivated clays. The procedures used in the preparation of these pillared acid‐activated clays ( i.e. , temperature of pillaring, method of drying and calcination temperature) have a significant influence on chlorophyll adsorption capacity because they influence both the physical and the chemical properties of the final pillared material. This variation provides a useful means of relating the various properties of the pillared materials to the chlorophyll adsorption capacity. As a result, a correlation has been demonstrated between adsorption capacity and a combination of pore volume and number of strong acid sites (of strength pK a < −1.5) present in the pillared material. Optimal adsorbents were obtained from freeze‐dried samples prepared by exchange at 20°C and calcination in air at 500°C.