EFFECT OF INITIAL REACTANT MOLAR RATIO AND DOPING WITH Fe~(3+) ON THE FORMATION OF CALCIUM BILIRUBINATE IN W/O MICROEMULSIONS

摘要

A series of calcium bilirubinate nanoparticles were synthesized in microemulsions consisted of polyoxyethylene octylphenol ether (Triton X-100)-hexyl alcohol (n - C6H13OH)/cyclohexane (c - C6H_(12))/aqueous solution. The particles were characterized by Fourier transform infrared (FT-IR) spectra, powder X-ray diffraction patterns (XRD), inductively coupled plasma atomic emission spectrometry (ICP-AES), transmission electron microscopy (TEM) and zeta potential measurements, respectively. The results show that initial molar ratio of CaCl2/Na2BR and molar ratio of water to surfactant (0) influence the morphologies and microstructures of calcium bilirubinate nanoparticles as well as coordination sites of Ca2+ with BR2–. The composition of as-synthesized calcium bilirubinate is non-stoichiometric. The stability of calcium bilirubinate nanoparticles dispersed in water changes with the molar ratio of Ca2+/BR2– and pH value of solution. The doping Fe2+ ions play a role in the simulated mineralization process of calcium bilirubinate. The possible formation mechanism of calcium bilirubinate produced in inverse microemulsions was discussed.