Sunlight photoactivity of titania/biogenic silica catalysts for water treatment

MATOS, J.;FERNÁNDEZ, M.; ANIA, C.:
Proceedings of the XXVII International Materials Research Congress, Mexico 2018.

Introduction

Biogenic silica obtained rice husks is receiving an increasing attention in the last years for its use as adsorbent, electrode and catalyst in various application fields covering wastewater treatment, biomedicine, energy storage in batteries, and catalysis. In contrast, scarce applications have been reported in solar photocatalysis, mainly due to the low absorption coefficient in the solar range of most silica-based materials. In this sense, the main objective of the present work is to prepare silica-TiO2 hybrid materials to evaluate their activity for the photocatalytic degradation of recalcitrant dyes (i.e, rhodamine B) in aqueous medium under simulated solar light.

In this work, hybrid materials were prepared by the solvothermal treatment of rice husk (RH) as biogenic precursor in the presence and absence of TiO2. The efficiency of the bare RH-Si and hybrid photocatalysts RH-Si-Ti was evaluated in the degradation of rhodamine-B under simulated solar light. Data showed that the prepared catalysts displayed a well-developed mesoporous texture with non-negligible surface areas ranging 65 to 175 m2/g. The calcination at 350 oC improved the photocatalytic activity obtained the biogenic precursor by three times in the absence of TiO2. At converse, RH-Si-Ti photocatalyst showed 8 times higher photoactivity than the calcined sample RH-Si-Ti-350 suggesting a strong interaction between SiO2 and TiO2 along calcination. Results were correlated with the surface pH and the SiO2-TiO2 crystalline phases. We believe that this result opens new perspectives for the development of low cost novel biogenic-derived materials with a large potential as photocatalysts for environmental remediation.