Production of glass ceramic from rice husk and periwinkle shells

Abstract Glass ceramic was produced by replacing the major glass forming materials, silica and calcium oxide, with derivates from rice husk and periwinkle shells respectively. Glass formulation comprising of silica extracted from the rice husk and calcium oxide from powdered calcined periwinkle shells were compounded with analytical grade sodium carbonate. Silica was extracted from rice husk and characterized using XRD. SEM/EDS of the periwinkle shell revealed a structure dominated by calcium and oxygen; however, there was a significant presence of magnesium. Glass ceramic was produced by melting the mixture at 1300 °C followed by melt quenching. FTIR of the material showed the presence of the carbonyl functional group, calcium oxide, magnesium oxide and various bond configurations of silica. SEM of the glass ceramic showed sparsely distributed particles of the crystalline phase, while XRD revealed the presence of 55% amorphous phase. Several crystalline phases were present, dominated by polymorphs of silica such as quartz (22.15 wt.%) and cristobalite (5.68 wt.%). Also present are mullite (5.58 wt.%), calcite (1.95 wt.%) and Wollastonite (6.86 wt.%). Noticeable in the crystalline phase is Whitlockite (2.33 wt.%), a magnesium and phosphorus rich animal-source bio ceramic, traceable to the periwinkle which may impart some bioactivity to the material.