New sol-gel silica hybrids containing pectin and some metal ions

In the present study new silica hybrids containing pectin and some metal ions have been synthesised via a sol-gel method. Pre-hydrolysed tetraetoxysilane (TEOS), low methoxylated pectin (5 wt%), Co2+, Ce3+, La3+, Co2+ +Cu2+ (1 wt%), C2H5OH, H2O and HCl have been used for the preparation of these hybrid materials. The structure of the hybrids obtained has been studied by means of XRD-analysis, FTIR-spectroscopy, SEM and UV-transmittance spectroscopy. XRD patterns show that all samples are amorphous. FTIR spectra indicate that in the presence of TEOS, pectin undergoes the process of COOCH3, hydrolysis because the bands at 1390 cm(-1) and 1750 cm(-1) disappear. The presence of Co2+ partially inhibits this process, but Ce3+ does not influence it. On the basis of these data, the authors suggest a probable structural model of inorganic-organic hybrids and metal ion/pectin complexes entrapment in the matrix. The changes of UV-optical transmittance in the processes of silica-pectin hybrid synthesis and addition of different metal ions have been established.