Multiple impregnation method

There are several methods for introducing the insoluble deposits into the fabric stmcture. The multiple bath method, in which the fabric is first impregnated with a water-soluble salt or salts in one bath and is then passed into a second bath which contains the precipitant, is used most often. Most semidurable retardants used on cotton are based on a combination of phosphoms and nitrogen compounds (25). 

For applications where high surface area is not important, the ceramic foam may be loaded ndi catalytic agents through single or multiple impregnation of suitable salts, followed Iw heat-treatment at moderate temperatures. Alternatively, a washcoat may be added with the same procedures used for monolithic substrates [20]. Surface areas increase from less than 1 mV to above 30 mV depending on the amount of washcoat added. In Ais way, washcoated foams have been loaded with metals and oxides [18,19], zeolites [20] and carbon [21]. Other methods, e.g. chemical vapor deposition, have also been su ested [23,24]. 

When the paper is impregnated with an organic liquid, the drying period is shortened to remove only the volatile mobile phase. The theory of unidimensional multiple development has been described [48], and the method has been used to analyze steroids [49] and amino acids [50] among other classes of compounds. Fractional chromatography is a special variation of multiple development in which a solvent of increasing polarity is employed for each subsequent development [51]. 

Even the preparation of a zeolite layer with an inherent catalytic capacity was attempted (Liu Au, 2001). In particular, the starting point is the addition of an aluminum sol to a solution of sodium meta-sUicate this mixture is then used for the growing of a zeolite layer on a ceramic tube in the autoclave. The entire procedure can be repeated more than one time to obtain multiple layers. The layer is then impregnated with a gel of La(N03)3 + Ni(N03)2 -6H20 prepared with the citrate method this operation produces an inherent catalytic capacity for the membrane, which presents a a-Al203 support with NaY crystals in form of contaminant particles (as demonstrated by SEM analysis). 

Mesoporous tantalum oxide rubidium fulleride composites were synthesised by solution impregnation and characterised by Rb and C solid-state NMR and other methods. Rb solid-state NMR of the composite materials indicated the presence of two Rb environments associated with the walls or chaimels of the mesostructure as well as several resonances associated with various fulleride species. C solid-state NMR experiments showed the presence of multiple fulleride species as well as pure fullerene, depending on the level of reduction. ... 

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