Glass - Back to the Future!

Presenting Author:
Merve Akdemir

article posted 18 March 2016

Mrs Merve Akdemir graduated from Bogaziši (Bosphorus) University, in Turkey with BS degree in Chemistry in 2010, and received her MS degree in 2016. Since 2010 she has been working as a researcher in Glass Technology Department at Sisecam Science and Technology Center. Her main fields of expertise are the physical properties of glass, color in glass, color forming mechanism.

Experimental Investigation of the Parameters Affecting the Selenium Retention in Soda-Lime Silicate Glasses

Merve Akdemir* & Fehiman Akmaz
Sisecam Science and Technology Center, Istanbul, Turkey

Selenium is a compound often used as colorant in colored glass batches such as grey, bronze, pink etc. On the other hand selenium can also be used in clear glass batches as decolorizing agent. Depending upon the raw material used in the batches as selenium source, 30-90% of it either evaporates during the melting process or remains in colorless form. This will lead to an increase in the batch cost, and color stability problems. Besides those effects it can cause environmental problems as well. In the form of its compounds, selenium can occur in the glass structure as five different oxidation states, Se2-, Se2-, Se0, Se4+, Se6+ and depending upon the valency of selenium, the glass color observed by eyes, changes. On the other hand the oxidation state of selenium retained in the glass, is affected by several parameters such as furnace atmosphere, melting temperature, pull rate indicating the residence time and finally the amount of oxidizing and reducing agents taking part in the glass batch. An experimental study was carried out in order to investigate the parameters that affect the selenium retention in the glass. Several batches containing different amounts of oxidizing and reducing agents while having different Fe2O3 levels, were prepared and melted under the same furnace conditions (temperature, atmosphere) and the amount of selenium in the resultant glass samples were analyzed according to its valencies. The correlation between selenium retention and redox level of the glass, as well as the SO3 retention in the glass were examined. This presentation will try to summarize those results and states the effects of each parameter.