Application of concrete surfaces as novel substrate for immobilization of TiO2 nano powder in photocatalytic treatment of phenolic water.

Mohammad Delnavaz,Hossein Ganjidoust,Sohrab Sanjabi,Bita Ayati

doi:10.1186/s40201-015-0214-y

Abstract

BackgroundIn this study, concrete application as a substrate for TiO2 nano powder immobilization in heterogeneous photocatalytic process was evaluated. TiO2 immobilization on the pervious concrete surface was done by different procedures containing slurry method (SM), cement mixed method (CMM) and different concrete sealer formulations. Irradiation of TiO2 was prepared by UV-A and UV-C lamps. Phenolic wastewater was selected as a pollutant and efficiency of the process was determined in various operation conditions including influent phenol concentration, pH, TiO2 concentration, immobilization method and UV lamp intensity.FindingsThe removal efficiency of photocatalytic process in 4 h irradiation time and phenol concentration ranges of 25–500 mg/L was more than 80 %. Intermediates were identified by GC/Mass and spectrophotometric analysis.ConclusionsAccording to the results, photocatalytic reactions followed the pseudo-first-order kinetics and can effectively treate phenol under optimal conditions.

Highlights

In this study, concrete application as a substrate for TiO2 nano powder immobilization in heterogeneous photocatalytic process was evaluated
– The solution was stirred vigorously for 10 min at 20 °C. – The slurry was sonicated for 5 min to separate the flocculated TiO2 and to obtain more uniform slurry. – One half of slurry sprayed on fresh concrete to use adhesive properties of cement. – The coated surface was placed in oven at 100 °C for 2 h to remove the moisture content. – The rest of the slurry sprayed on hardened concrete and annealed at 450 °C for 2 h to remove any organics from the surface. – The support was let to dry and was washed with pure water to eliminate the excess of the catalyst
SEM analysis showed a uniform appearance of TiO2 catalyst in Epoxy sealer method (ESM), Waterproof sealer method (WSM) and slurry method (SM) but dispersed coating in cement mixed method (CMM)

Summary

Introduction

Concrete application as a substrate for TiO2 nano powder immobilization in heterogeneous photocatalytic process was evaluated. Among AOPs, application of heterogeneous photo-catalysis by using semiconductors has been proved to be real interest as an efficient tool for degrading both aquatic and atmospheric organic contaminants [1]. When TiO2 is exposed to the appropriate wavelength of ultra-violet light (UV-A), electrons in the low-energy valence band will absorb the photon’s energy and move into the high-energy conduction band. The result of this electron excitation is a hole, or positive charge, in the valence band (h+)

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