Étude par turbidimétrie de la cristallisation oxalocalcique en présence de quelques inhibiteurs

Abstract

The inhibition of the calcbium oxalate crystallization is investigated using a turbidimetric model by means of a UV/VIS spectrometer. The turbidity of thermostatic solution at 37° C under constant agitation is measured at 620 nm. The solutions concentrations of calcium chloride CaCl 2 and sodium oxalate C 2 O 4 Na 2 in the test were respectively 4 and 0.5 mmol.L -1 . The investigated inhibitors were magnesium ions between 2.10 -1 et 7 mmol.L -1 , citric acid between 10 -3 et 4 mmol.L -1 , fluoride between 1 et 12 mmol.L -1 and ferrous ion between 0.1 and 0.4 mmol.L -1 . We have used physiologic concentrations in order to work near the best conditions of calculus formation. The rates of inhibition obtained from the turbidimetric slopes with and without inhibitors were measured as a mean of 6 experiments. The CV observed were at 5% lower. The effect of these i nhibitors on the crystallization phases has been followed with an optical microscope photography with a polarised light. The results at the used observation scale showed that the magnesium act the nucleation and the aggregation; citric acid on the three crystallization phases (nucleation, crystalline growth and aggregation) and finally fluoride and ferrous ions on the nucleation and crystalline growth.