One step to stabilize calcium sodium phosphate crystals acting as photocatalysts embedded in a glass matrix

Abstract

Unstable calcium sodium phosphate (CaNaPO4) in aqueous solution can be stabilized and shows photocatalytic activity in a glass matrix. This research presents one-step melt quenching to prepare stable CaNaPO4 crystals in a glass material. The CaNaPO4 glass ceramic was produced with stoichiometric amounts of SiO2, B2O3, P2O5, CaO, Na2O and TiO2 at 1,200 °C for 4 h. The CaNaPO4 glass ceramic samples were confirmed by XRD, SEM, and TEM techniques. The photocatalytic activity of the CaNaPO4 glass ceramic was investigated by monitoring methyl orange degradation with the addition of H2O2. Notably, the CaNaPO4 glass ceramic demonstrates the high-efficiency photocatalytic degradation of methyl orange (MO) under UV irradiation. The CaNaPO4 glass ceramic can be reused several times. After 8 cycles, the catalyst is still stable and effective in decomposing 100% of methyl orange within 5 h/cycle. In addition, the solid phase photocatalytic activity of the CaNaPO4 glass ceramic was examined by bleaching adsorbed MB under UV light within 25 h. It can also inhibit the growth of E. coli bacteria after UV irradiation for 20 minutes. Therefore, the CaNaPO4 glass ceramic might be an alternative photocatalytic material for wastewater treatment.