Adsorption at Crystal-Solution Interfaces

Abstract

The previous papers1 2in this series of investigations have shown that the growth ratios of potassium and ammonium alum crystals are greatly modified when grown in the presence of dyes and other foreign substances. Thus potassium alum, when grown in the presence of diamine sky blue develops into perfect cubes having no octahedral faces. The cube faces alone are colored and the growth ratio [ioo]/[iii] undergoes a change from 1.61 to o.o in a dye concentration of 0.1%.These effects have been accounted for on the basis of (i) the residual valency force fields of the crystal planes; (2) the interionic distances within the faces; and (3) the presence and distribution of polar groups in the adsorbed material.

ADSORPTION AT CRYSTAL—SOLUTION INTERFACES. X: A Study of the Adsorption of Monoazo Dyes by Crystals of Potassium Sulfate during their Growth from Solution1

“…This then suggests a plausible reason for the differences pointed out above. The results of the quantitative measurements of the amount of adsorption of P-/3-OH-6 at a number of concentrations is graphically shown in The results are obviously in complete agreement with previous work (1,3,5,6,7,8,10,11,15,16), in that there is a minimum concentration below which no adsorption takes place and above which the adsorption gives a typical adsorption curve. The adsorption can, therefore, be represented by the expression developed earlier (3):…”

“…figure 3. The results are obviously in complete agreement with previous work(1,3,5,6,7,8,10,11,15,16), in that there is a minimum concentration below which no adsorption takes place and above which the adsorption gives a typical adsorption curve. The adsorption can, therefore, be represented by the expression developed earlier (3):…”

Adsorption at Crystal–Solution Interfaces. IX. The Concentration of Foreign Substances in Solution Relative to the Quantity Adsorbed by the Host Crystal.

“…(2) A careful checking of four x-ray powder spectrographs for the four pairs of substances (1) pure sodium chloride-sodium, chloride + urea, (2) pure sodium chloride-sodium chloride + chromic chloride, (3) pure urea-urea + sodium chloride and (4) pure lead nitrate-lead nitrate + methylene blue showed that in all cases there was no displacement of the lines produced by the contaminated crystals, and therefore no appreciable change in the lattice constant due to the adsorption of impurities. This interesting result is in agreement with work reported by earlier investigators (13,33). The absence of lattice distortion may be due to (a) the presence of too little impurity to produce a perceptible distortion, (b) some typo of interstitial adsorption such that the host crystal envelopes the molecules of impurity without alteration of its space lattice, or (c) similarity of the lattice constants in one plane of the host crystal to those in one plane of the foreign crystal so that deposition occurs in such a way that the similar planes coincide.…”

Dyeing Crystals

“…219 His first definitive DIC, potassium alum stained on the {100} faces with diamine sky blue FF, was discovered in 1928 [220][221][222] and was later the subject of the first X-ray measurements of DICs (Figure 11a). 223 France determined that the lattice constants for pure alum and dyed alum were the same within experimental error. 223,224 He studied other alum DICs subsequently.…”

“…223 France determined that the lattice constants for pure alum and dyed alum were the same within experimental error. 223,224 He studied other alum DICs subsequently. 225,226 Potassium alum is structurally similar to NaCl; both have two distinct planes, one checkerboard like ((111) alum and ( 100) NaCl ) and one with alternating layers of cations and anions ((100) alum and (111) NaCl ).…”