Photocatalytic Destruction of Amoxicillin in a Pilot Sunlight Reactor with Supported Titania Nano-photocatalyst

Abstract

Pharmaceuticals and Personal Care Products (PPCPs) are the emerging pollutants threatening the aquatic live even at low concentration due to their chronic discharges into surface streams. During last decades, titania photocatalysis opened a promising method for Amoxicillin (AMX) abatement in aqueous solution. However, using a photocatalytic powder creates by itself a source of a new pollution. We report on the use of the supported titania nano-photocatalyst in a pilot solar reactor for AMX removal in aqueous solutions. Titanium oxo-alkoxy nanoparticles were prepared in a sol-gel micromixing reactor and coated on a 5-mm diameter borosilicate glass beads. Further heat treatment resulted in anatase coatings of 8 nm thickness. About 450 g of the beads were placed in a main tube of a photocatalytic pilot solar reactor of 150 cm length and 5 cm diameter. Aqueous solutions of AMX 10 mg/L in distilled water were prepared and submitted to the solar tests. Thereafter, pH of the solution was adjusted at 3.5, 7.5 and 9.5 using H2SO4 and NaOH. The total duration of one run was 240 min and the accumulated UV energy was about 35 kJuv/L of solution depending on time of day. The obtained results showed that AMX degradation reaches 76% after 240 min exposure for pH 9.5 and 60% for pH 7.5. The photocatalytic reactor yield remained unchanged after 6 cycles of 240 min treatment; no appreciable deactivation and/or degradation of the nano-photocatalyst were observed. An addition of H2O2 did not appreciably affect AMX degradation. A comparison with the commercial TiO2 powder was carried out in similar experimental conditions and solar exposure in parallel run mode; it showed the higher energetic efficiency of the supported nanocatalyst.