Photocatalytic porous silica-based granular media for organic pollutant degradation in industrial waste-streams

Abstract

Photocatalytic treatment of organic contaminants in industrial wastewaters has gained interest due to their potential for effective degradation. However, photocatalytic slurry reactors are hindered by solution turbidity, dissolved salt content, and absorbance of light. Research presented here introduces the development and application of a novel, photocatalytic, porous silica-based granular media (SGM). SGM retains the cross-linked structure developed during synthesis through a combination of foaming agent addition and activation temperature. The resultant media has a high porosity of 88%, with a specific surface area of ~150 m2/gram. Photocatalytic capabilities are further enhanced as the resultant structure fixes the photocatalyst within the translucent matrix. SGM is capable of photocatalysis combined with diffusion of nucleophiles, electrophiles, and salts from pore space. The photocatalytic efficiencies of SGM at various silica contents were quantified in batch reactors using methylene blue destruction over time and cycles. Methylene blue concentrations of 10 mg/L were effectively degraded (>90%) within 40 minutes. This effectiveness was re-tained over multiple cycles and various methylene blue concentrations. SGM is a passive and cost-effective granular treatment system technology which can translate to other organic contaminants and industrial processes.