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International audience; The analysis of radiative transfer in photoreactors is often crucial for operating efficient photoreactions. This article aims to present a complete experimental and theoretical coupled approach allowing radiative transfer analysis of photoreactors containing particulate media. TiO 2 powder, widely used in photocatalysis, was selected as a case study material for this work. First, Mie theory was used and adapted to assess the effective properties of heterogenous powders. A home-made experimental bench allowing normal-hemispheric transmittance measurement was settled. Theoretical and experimental evaluations of the radiative properties were compared and appear to match each other. The second part of the work consisted in both transmittance and local radiant energy modeling through Monte Carlo and Two Flux models using the previously defined radiative properties as entry parameters. The comparison of experimental and modeled transmittance highlighted the consistence of these models which were then used to describe the radiant energy evolution inside a parallelplane photoreactor.

International audience; Activated-Carbon/Titania composites (AC/TiO2) is a relevant option to gather the dual adsorption/photodegradation property within a single material. This work aimed to investigate the composition influence on the adsorption and photodegradation properties of AC/TiO2 composites against caffeine. TiO2 grafted AC powders covering the whole composition scale were synthesized by a one-step mechanical milling process. This original simple elaboration route led to the obtention of powders which particles size and composition were homogeneous and well controlled. When the adsorbent mass ratio varied in the range 0.01−0.75, the adsorption properties, i.e. apparent kinetic and maximum adsorption capacity of the composites increased respectively by 1 and 2-log. At the opposite, the photo-oxidation rate decreased significantly when the adsorbent ratio increased. The simple elaboration route explored produces flexible AC/TiO2 composites with adjustable properties that can easily be managed to meet the requirements of different target applications.

International audience; The aim of this work was to highlight feasibility of a new approach to synthesize Activated-Carbon (AC)/TiO2 composite materials. The main interest of these materials is for pollutants removal applications thanks to their multi-functionality. AC/TiO2 composites were prepared by one-step mechanosynthesis route. Morphological and structural properties were investigated through SEM, EDS, XRD, and BET techniques. It was found that the preparation process leads to the formation of an aggregate shape homogenously composed AC/TiO2 powder with a narrow particles size distribution, which mean diameter was 3.75 μm. Initial component structural properties were found to be strongly affected by the process, resulting in significant changes of TiO2 crystallinity and AC microtexture. The introduction of 5 min pauses during the process was enough to totally preserve TiO2 phases, crystallinity, and AC microporous network. Composites multi-functional properties were investigated using batch adsorption and photodegradation experiments. Adsorption studies revealed that AC/TiO2 aggregates exhibit good adsorption capacity with caffeine and a maximum adsorbed amount of 353 mg.g−1. Photocatalytic experiments highlighted that AC/TiO2 presents a photo-oxidation ability. Photodegradation apparent kinetic rate fitted with a first-order law gave a value of 1.04 × 10-5 s-1 for the composite and ten times higher for pure TiO2. These results allowed to conclude that mechanosynthesis is an effective route to produce bi-functional AC/TiO2 composites with efficient adsorption capacity for water treatment applications. It also suggests the need of further radiative transfer studies to understand light scattering and absorption inside these materials, which could lead to some improvement of these promising materials.