Potassium alum growth

Potassium sulfate is used in fertilizers as a source of potassium and sulfur, both of which are essential elements for plant growth. Either in simple form or as a double salt with magnesium sulfate, potassium sulfate is one of the most widely consumed potassium salts in agricultural apphcations. It is preferred over potassium chloride for certain types of crops such as, tobacco, citrus, and other chloride—sensitive crops. Some other applications include making gypsum cements to make potassium alum in the analysis of Kjeldahl nitrogen and in medicine. 

Using this type of equipment, Palermo (PI) investigated the growth of potassium alum crystals. The following equation was derived and verified experimentally ... 

Girolami, M. W. Rousseau, R. W. 1985 Size-dependent crystal growth a manifestation of growth rate dispersion in the potassium alum-water system. AIChE Journal 31, 1821-1828. 

Recent microscopic studies of individual secondary nuclei have observed growth rate dispersion and size-dependent growth directly.31 56 Gareide et a I.52 report thei two types of potassium alum secondary... 

Salts that have been established as having solution velocity dependent growth rates include ammonium and potassium alums, nickel ammonium sulphate, sodium thiosulphate and potassium sulphate. Ammonium sulphate, ammonium and potassium dihydrogen phosphates, for example, do not. 

Garside elal. (1979) measured size distributions of seeondary nuelei and reported their variation with supersaturation. Signifieant inerease of nuelei with supersaturation is observed. Thus the proeess is not simply an attrition event alone, but is also related to the level supersaturation at whieh parent erystal is growing. Jones elal. (1986) also observed anomalous growth of seeondary nuelei in a study of the eontinuous MSMPR erystallization of potassium sulphate with eonsequenees inferred for seeondary nueleation rates. Girolami and Rousseau (1986) demonstrate the importanee of initial breeding meehanism in seeded potash alum bateh erystallization. The number of erystals... 

For the student interested in crystal growth, potassium aluminum sulfate, also called alum, is a salt available in most pharmacies. It will form... 

Desupersaturation methods for crystal growth rate measurements have been reported for ammonium alum (Bujac and Mullin, 1969), potassium sulphate (Jones and Mullin, 1973a), nickel ammonium sulphate (Ang and Mullin, 1979), potassium chloride (Nyvlt, 1989) and succinic acid (Qui and Rasmuson, 1990). 

Growth and dissolution rates of crystals can be measured conveniently in the laboratory fluidized bed crystallizer described above Figure 6.20). Some typical results for potash alum are shown in Figure 6.31, where it can be seen that dissolution rates are very much greater than growth rates under equal driving forces (Ac). Similar results have been reported for potassium sulphate (Mullin... 

For the student interested in crystal growth, potassium aluminum sulfate, also called alum, is a salt available in most pharmacies. It will form single crystals relatively easily from a supersaturated solution. Alum crystals are octahedral in shape and colorless. The related compound, chromium aluminum sulfate dodecahydrate, called chrome alum, forms dark-purple octahedral crystals. Mixing various proportions of supersaturated alum and chrome alum solutions allows the growth of mixed crystals that resemble amethysts in color. (The more alum in the mix, the lighter the purple color of the crystal.) Take the powder patterns of crnshed pnre alum and crushed pure chrome alum, and a mixture of the two compounds. After yon have grown some mixed crystals, crush some and take their powder pattern. Is it different from the two pure materials and from the mixture Explain your observations. 

Garner and his collaborators ( found that the rate of growth of patches on CuS04 5H20, ammonium, potassium, and chrome alums was decreased when water vapor was present at a pressure below the equilibrium dissociation... 

Fig. 12. Rate of growth of dehydration patches on copper sulphate, ammonium, potassium, and chrome alums as a func< tion of water vapor pressure.

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