Calcium oxalate crystallization in SDS solutions

Abstract

Sodium dodecyl sulfate (SDS) and hydroxy isopropyl chitosan (HPCHS) are employed as modulation agents for crystallization of CaC₂O₄. The effects of concentrations of SDS and HPCHS, [Ca²⁺]/[C₂O₄^2-], [Mg²⁺]/[Ca²⁺] and ratio of <em>V</em>_ethanol/<em>V</em>_water and [Mg²⁺]/[Ca²⁺] on the crystallization are investigated. The CaC₂O₄ particles are characterized by scanning electron microscopy, powder X-ray diffraction, thermogravimetric analysis, and Fourier transform infrared spectroscopy. The results show that SDS inhibits the crystallization and growth of CaC₂O₄ particles due to the interaction between dodecyl sulfate and Ca²⁺ and also the formation of calcium dodecyl sulfate. Based on an analysis of the CaC₂O₄ and solution properties of SDS/Ca²⁺ and HPCHS/SDS/Ca²⁺, a mechanism for CaC₂O₄ crystallization in SDS solutions is proposed. This work is of significance in inhibiting abnormal mineralization.