Modification of Crystal Habit of Inorganic Salts with Dyes

Dyeing Crystals

“…Whetstone suggested that in some cases adsorption of foreign matter occurs on step risers that are actually perpendicular to the face that had increased markedly in area as illustrated in Figure 9. 203 This idea was consistent with developing theories of solution crystal growth involving spirals. 204,205 Phoenix carried on Whetstone's studies of dyeinduced NH 4 NO 3 habit modification to much the same effect.…”

Use of potassium ferrocyanide as habit modifier in the size reduction and phase modification of ammonium nitrate crystals in slurries

“…The disadvantage of this cocrystallization method is the amount of foreign salt required to stabilize the transition, which varies from 2 to 10% by weight [18,19]. Using a dye, acid magenta, as crystal habit modifier, morphology modification of AN is reported in the literature [3]. However, this habit modifier only modifies the morphology and not the IV ↔ III phase transition.…”

“…The characteristic morphologies obtained by glycine and potassium ferrocyanide range from cubic out growth to octahedral crystals. Potassium ferrocyanide trihydrate (KFCT), K 4 [Fe(CN) 6 ]·3H 2 O, is a yellow coloured crystalline (monoclinic) compound with a solubility of ∼27 g in 100 mL at room temperature. KFCT is known for its habit modification effect on different inorganic crystals and its anti-caking effects [6,[12][13][14].…”

“…Numerous studies have been conducted on particle configuration control techniques for controlling chemical composition, size and size distribution, surface parameters and shape of particles. Also, many routes have been utilized to control the crystal growth and eventually modifying the morphology of crystals [3][4][5]. For crystal habit modification, crystals are grown in the presence of specific impurities or crystal habit modifiers and the face-specific interactions of these crystal habit modifiers result in the modification of the crystal habit.…”

Crystallization

“…The relative effectiveness of the dyes in causing habit modification was measured in terms of the weight of inorganic substance modified by 1 grain of dye. Whetstone (104) explains that the modification of crystal habit of many inorganic salts by dyes may be due to the incorporation of dye molecules in one or more of the edge faces, thus retarding the growth of a crystal face.…”