A FTIR STUDY OF DISSOLUTION AND PRECIPITA-TION OF SILICA IN BAYER PROCESS

A quantitative Fourier transform infrared (FTIR) technique mas established by comparison with chemical analysis and quantitative X-ray diffraction (XRD) analysis. By the quantitative FTIR analysis of bauxite during dissolution , the process of dissolution and precipitation of silica was found to occur in three stages. In the first stage, there was no precipitation of desilication product (DSP). All the silica dissolved from kaolinite went into the solution. In the second stage, the silica concentration in solution attained a maximum and then dropped very quickly. The precipitation of DSP was the main cause of the reduction of the silica concentration in solution. In the third stage, the concentration of DSP reached a constant level. The dissolution and precipitation process gradually attained an equilibrium. The mechanism of silica dissolution and DSP precipitation was discussed on the basis of the FTIR quantitative analysis of kaolinite and DSP in bauxite.

Decomposition and Reformulation of Banxia Baizhu Tianma Decoction:A Vasodilatory Approach

Objective To decompose and reformulate Banxia Baizhu Tianma Decoction（BBT） in order to optimize its ratio for vasodilatory effect.The fingerprints of these six component herbs were also studied via Tri-step FTIR analysis.Methods The herbal components of BBT were extracted separately with different solvents,such as 95%ethanol,50%ethanol,and distilled water.The vasodilatory effect of the extracts was studied using the in vitro pre-contracted aortic ring model.Among these extracts,the water extracts of Pinellia ternata[PT（W）]and Citri reticulatae[CR（W）],50%ethanol extracts of Castrodia elata[GE（50）]and Clycyrrhiza uralensis[GU（50）],and 95%ethanol extracts of Atractylodes macrocephala[AM（E）],and Poria cocos[PC（E）]were selected for the orthogonal stimulus-response compatibility group study due to their high effectiveness in vasodilation.Results The best combination ratio（G2） was GE（50）,GU（50）,AM（E）,PC（E）,CR（W）,and PT（W） at EC0,EC5,EC5,EC5,EC5,and EC5,with EC50 of（0.06 ± 0.01） mg/mL.Comparison between the vasodilatory effects of extracts derived from G2 and BBT were also studied.From the results,the 50%ethanol extract following G2 ratio was found to be most potent extract with the highest vasodilatory effect compared with other extracts derived from G2 or BBT,with EC50 of（0.05 ±0.005） mg/mL.Conclusion The optimum ratio and appropriate extraction method for the new BBT formulae are obtained.G2 is determined as the best formulae with the highest potency in producing the vasodilatory effect on isolated rat aortic rings.The results obtained suggest that 50%ethanol is found to be the best solvent to extract the vasoactive compounds of G2 in order to exhibit the highest efficacy of vasodilatory effect.

Spectroscopic studies of gel-grown lanthanum malonate crystals

Lanthanum malonate crystals were grown by single tube ionic diffusion through silica gel. The crystallinity of the grown crystals was analyzed by powder X-ray diffraction studies. Fourier transform infrared spectroscopy （FTIR） and fourier transform （FT） Raman studies confirmed the presence of functional groups in the title compound. The optical band gap energy of the material was extracted from diffuse reflectance spectrum.