Highly porous hydroxyapatite derived from cuttlefish bone as TiO2 catalyst support

Abstract

Highly porous hydroxyapatite (Ca10(PO4)6(OH)2, HAp) catalyst support was prepared through hydrothermal transformation of aragonitic cuttlefish bone (Sepia Officinalis, L., Adriatic Sea) at 200 °C, preserving the natural well interconnected porous structure. To deposit the TiO2 catalyst on the pore walls of the HAp support two methods were used: i) vacuum impregnation of the support with the suspension of a commercial TiO2 nanopowder in isopropanol and ii) in situ synthesis of TiO2 on the support by sol-gel technique. XRD analysis and FTIR spectroscopy were used to determine the phase composition of the material. The morphology and microstructure of the composite samples were studied by scanning electron microscopy (SEM). The presence of TiO2 particles on the HAp surface was determined by SEM/EDX analysis. To determine the specific surface area and pore size, Brunauer-Emmett-Teller (BET) method was used. The results of the BET method showed the increased specific surface area and pore size reduction after impregnation of TiO2 into the HAp carrier. The photocatalytic activity of HAp/TiO2 samples was studied in a batch reactor with an annular UV-A lamp using salicylic acid as a model water pollutant. The results indicated the suitability of prepared HAp supported TiO2 catalysts for photocatalytic applications.

Keywords

• hydroxyapatite
• TiO2
• impregnation
• sol-gel process
• photocatalysis