engleski

Influence of gallic acid on calcium oxalate precipitation

Gallic acid (GA) or 3, 4, 5-trihydroxybenzoic acid is phenolic acid in the plant kingdom. It consists of three hydroxyl groups and a carboxylic acid group attached to a benzene ring. The bonding of the hydroxyl groups in an ortho position results in a coplanar and bent configuration, which is favorable for antioxidative activities. GA is used to prevent the oxidative damage that takes place in biomolecules. The main goal of this study was to observe the effect of gallic acid on calcium oxalate precipitation. Calcium oxalates are calcium salts of oxalic acid and are the most common constituents of kidney stones. They crystallize in three forms: calcium oxalate monohydrate (COM), calcium oxalate dihydrate (COD) and calcium oxalate trihydrate (COT). The precipitation methods were based on the mixing of calcium and oxalate solutions whose pH values have been previously adjusted to 6.50. The experiment took place inside a thermostated reactor with a capacity of 400 cm3. The experiments were performed were at two temperatures 25 °C and 48 °C. In this study the influence of the additive addition was monitored, where changes in the morphology, hydrate phase and reaction kinetics were observed. Infrared spectroscopy (FT-IR), powder X-ray diffraction (PXRD) and thermogravimetric analysis (TGA) were used to characterize the presence of individual hydrate phase in precipitated systems. The morphological characteristics were determined by a light microscope and scanning electron microscopy (SEM). The higher concentration of aditive favors the formation of the COD, while the increase in the temperature value of media causes the formation of COT.

gallic acid ; calcium oxalates monohydrate ; calcium oxalate dihydrate

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