Removal of aqueous Clopyralid by Photoctalytic-ozonation process on Activated carbon under solar radiation: Catalyst characterization and kinetic study

Solar photocatalytic ozonation has been used to oxidize the herbicide clopyralid in aqueous solution. Activated carbon used as a catalyst was characterized by Scanning Electron Microscopy (SEM) images showed the presence of irregular cavities and pores, which have different sizes and shapes, with a great surface area of BETand a high pHpzc. The adsorption kinetics was found to follow the pseudo-second-order kinetic mode. Catalyst stability was tested by means of consecutive reuse cycles. After five cycle of reuse the adsorption efficiency reached 75% of the clopyralid removal.Clopyralid elimination kinetic by direct ozonation has been studies. The system O3/AC/Daylight significantly improves clopyralid and mineralization rate abatement if compared to runs conducted in the absence of radiation and/ or activated carbon. Clopyralid total abatement was achieved in less than 30 min when 0.5 g/L of activated carbon and under solar radiation (300-800 nm) were used. Thus, TOC removal in 180 min treatments increased from 20 to about 90 % in O3 and O3/OSAC/Daylight, respectively, under similar operating conditions

Removal of aqueous Clopyralid by Photoctalytic-ozonation process on Activated carbon under solar radiation: Catalyst characterization and kinetic study

Solar photocatalytic ozonation has been used to oxidize the herbicide clopyralid in aqueous solution. Activated carbon used as a catalyst was characterized by Scanning Electron Microscopy (SEM) images showed the presence of irregular cavities and pores, which have different sizes and shapes, with a great surface area of BETand a high pHpzc. The adsorption kinetics was found to follow the pseudo-second-order kinetic mode. Catalyst stability was tested by means of consecutive reuse cycles. After five cycle of reuse the adsorption efficiency reached 75% of the clopyralid removal.Clopyralid elimination kinetic by direct ozonation has been studies. The system O3/AC/Daylight significantly improves clopyralid and mineralization rate abatement if compared to runs conducted in the absence of radiation and/ or activated carbon. Clopyralid total abatement was achieved in less than 30 min when 0.5 g/L of activated carbon and under solar radiation (300-800 nm) were used. Thus, TOC removal in 180 min treatments increased from 20 to about 90 % in O3 and O3/OSAC/Daylight, respectively, under similar operating conditions

Study of synergetic effect, catalytic poisoning and regeneration using dielectric barrier discharge and photocatalysis in a continuous reactor: Abatement of pollutants in air mixture system

International audienceIn the present work the abatement of butyraldehyde (BUTY), dimethyl disulfide (DMDS) and their mixtures in gas phase was studied in continuous reactor at three different configurations: photocatalysis (TiO2 + UV), dielectric barrier discharge (DBD) plasma and their association in the same system (DBD+ TiO2 + UV). The effect of some operating parameters such as inlet concentration of pollutant and flowrate on planar reactor performance in term of (i) BUTY removal (ii) selectivity of CO and CO2, selectivity of byproducts has been also investigated. Moreover, ozone formation has been studied to evaluate the performance of the combined process. A synergetic effect was observed by combining (DBD) plasma and photocatalysis on BUTY removal but has not been present when it was in air mixture with dimethyl disulfide (DMDS) due to the poisoning of the catalyst. Additionally, degradation was observed as a consequence of by-products accumulation on the surface of the catalyst. Moreover, the regeneration/recovery of the initial photocatalytic activity was explored in details. A significant regeneration has been occurred by combining photocatalysis and nonthermal plasma. This trend of nonthermal plasma on catalytic surface can explain the synergetic effect during the pollutant degradation time. Moreover, the catalyst was concomitant with the time required for the hydrophobic to hydrophilic transition on the catalyst surface as followed by contact angle measurement (CA). Redox catalysis was detected by X-ray Photoelectron Spectroscopy (XPS) showing Ti4+/Ti3+ switching during the degradation, poisoning and regeneration times

Photocatalytic degradation of paracetamol mediating luminous textile: Intensification of the chemical oxidation

International audienceAn innovative photoreactor was applied as an emerging advanced oxidation process (AOP) to investigate Paracetamol (PL) degradation under different operating conditions. The system consisted of a textile woven from optical fiber and textile yarn. The luminous fiber textile was coupled to UVA LED, and the photocatalytic textile fibers is impregnated with TiO2. The effectiveness of configuration I, based on a luminous textile with UV LED, was compared with that based of TiO2 immobilized on cellulosic paper (CP) with external UV irradiation (configuration 2). The specific degradation rate obtained with configuration 1 was 40 times higher than that with configuration II. Configuration I also showed efficient performance in mineralization per Watt consumed, with values reaching 81 times higher than those obtained with configuration II. Also, to achieve high removal effi-ciency of the pollutant with the new technology of luminous textiles, the effect of operating parameters, namely pollutant concentration, UV intensity, flow rate and TiO2 mass deposited were discussed. It is worth noting that the optimal conditions for a 95.7 % degradation rate of 1 mg/L of Paracetamol were obtained with 26 g/m2 mass catalyst, 5 W/m2 UV intensity and 52.2 L/h flow rate after 340 min. In addition, upon associating two luminous textiles, the degradation efficiency reached 98.76 % after only 140 min. Besides, by adding hydrogen peroxide (H2O2) in the optimal conditions with 10 mg/L of Paracetamol concentration, the degradation efficiency reached 98.81 % after 240 min. The excellent performances in terms of degradation rate, mineralization per Watt consumed, and energy consumption make luminous textiles an attractive alternative to conventional photo-catalytic reactors designed for the removal of Paracetamol in water and wastewater