Calcium Oxalate Case Study

Reactive crystallization is widely used in the production of fine chemicals, pigments, catalysts, photochemicals, ceramics, food stuffs etc. Recent applications include crystalline materials for electronic devices, speciality applications such as healthcare products [1,2] (Zauner, 1999; Jones et al., 2005). One of the important challenges in the field of industrial crystallization is to match the changing and growing product requirements across all industrial sectors (pharmaceutical, chemical, process industries, food, nutrition and agro-chemistry) by controlling the crystal morphology, size distribution and polymorphism. The crystal size and shape of particles affects the dissolution rate, which affects the drugs in terms of benefit verses
Calcium oxalate (CaOx) being a major inorganic constituent of human kidney stones, contributes around 70-80% of the kidney stone. In India, approximately 5-7 million patients are suffering from kidney stone disease [6] (Kaladhar et al., 2012). Urinary oxalate is found to be a major factor for calcium oxalate stone formation. As the molar ratio of oxalate-to-calcium is normally 1:10, slight changes in urinary oxalate concentration may cause crystallization and stone formation as compared to calcium concentration [7] (Siener et al., 2013). Carvalho investigated that during process of water conservation in body, kidney supersaturates urine. Supersaturation being a driving force may cause crystal formation (calcium oxalate). If inhibitors of the crystal formation (protein, citrate etc.) in body are not able to take proper action and control their size, it may end up with nephrolithiasis, a recurrent disease which has been found to be associated with an increased risk of hypertension, coronary artery disease, diabetes, and metabolic syndrome [8] (Ivanovski1 and Tilman, 2013). Hence, formation of kidney stones is a complex process which involves several factors. In urine, nucleation and growth of calcium oxalate crystals are affected by the level of supersaturation
Nielsen [9] (1960) studied the kinetics of calcium oxalate precipitation and observed that for concentrations below 1mM, calcium oxalate precipitation is surface reaction control whereas for above 1mM, the reaction is diffusion control. Garside et al. [10] (1982) studied nucleation, growth kinetics, effect of temperature on precipitation of calcium oxalate from aqueous solution using the steady state crystal size distribution in an MSMPR (mixed-suspension mixed-product removal) crystallizer. The distribution of hydrates of calcium oxalate in calcium oxalate precipitation using lab-scale batch crystallizer investigated by Brecevic et al. [11] (1989) investigated. The distribution was found to be dependent on the type and order of mixing of the feed solutions, the feed composition, type of stirring, and the degree of mechanical grinding imposed on the crystals. To study the influence of similar factors on calcium oxalate precipitation for both MSMPR and semi-batch mode, Houcine et al. [12] 1997 used a pilot tank of capacity 20 liter. They used laser sheet visualization and image processing technique for studying mixing characteristics. Thermodynamically stable monohydrate was found to present in all the precipitations. Grases et al [13] (1990) presented a comparative study for production of calcium oxalate monohydrate, dihydrate and trihydrate. Monohydrate was found to be the only