Frank Hutter

Iron(II)- or vanadium(IV)-containing siliceous gels

Iron(II)-containing SiO2 gels can be prepared by the hydrolysis and condensation of tetramethoxysilane in methanolic solutions of iron(II) chloride. These gels show an absorption at 1000 nm indicating the presence of iron(II). In opposition to that, iron(II) cannot be introduced into organically modified gels of the 3-glycidyloxypropyltrimethoxysilane type. Vanadium(IV) can be incorporated into both gels. Unlike the SiO2 gels, the organically modified gels are compact and elastic. The spectra of the vanadium(IV)-containing gels show a characteristic absorption at about 800 nm. In some cases these gels change theirs colours with time, presumably due to the exchange of ligands in the coordination sphere of vanadium.

Removal of arsenic from waste waters of the lead glass industry

Arsenic trioxide (As2O3) is widely used as refining agent for the production of lead glasses /1/. Because of its toxicity there were attempts to reduce its consumption, which have been successful mainly due to an increasing number of electric melters. The As2O3 consumption within the glass industry of the Federal Republic of Germany decreased from about 300 t/a in 1981 to 145 t/a in 1985 /2/. But it was also shown that a complete renunciation of As2O3 is not possible up to now /3/. The possible substitution of As2O3 by Sb2O3 is not recommendable for toxicological and environmental as well as for economical reasons.