Three-dimensional mathematical model was developed for a rectangular TE 10n microwave heating cavity system, working at 2.45 GHz. Energy/heat, momentum equations were solved together with Maxwell's electromagnetic field equations using COMSOL MULTIPHYSICS® simulation environment. The dielectric properties, ε' and ε'', of NaY zeolite (Si/Al = 2.5) were evaluated as a function of temperature. Considering these values, the microwave heating of a porous fixed-bed made of dry NaY zeolite was simulated. Electric field distribution, axial and radial temperature profiles and temperature evolution with time were obtained. The zeolite fixed bed was heated up to 180 °C in 5 min, with 30 W power. The fixed-bed temperature evolution under non-steady state conditions showed the same trend as the one observed experimentally with only an average deviation of 10.3%. The model was used to predict microwave heating of other materials improving energy efficiency of the microwave cavity. Furthermore, the developed model was able to predict thermal runaway for zeolites. @en

A series of ruthenium-doped strontium titanate (SrTiO3) perovskite catalysts were synthesized by conventional and microwave-assisted hydrothermal methods. The structure was analyzed by X-Ray diffraction (XRD) confirming the formation of the perovskite phase with some TiO2 anatase phase in all the catalysts. Microwave irradiation decreases the temperature and time of synthesis from 220 °C for 24 h (conventional heating) to 180 °C for 1h, without affecting the formation of perovskite. A 7 wt. % ruthenium-doped SrTiO3 catalyst showed the best dielectric properties, and thus its catalytic activity was evaluated for the methane dry reforming reaction under microwave heating in a custom fixed-bed quartz reactor. Microwave power, CH4:CO2 vol. % feed ratio and gas hourly space velocity (GHSV) were varied in order to determine the best conditions for performing dry reforming with high reactants conversions and H2/CO ratio. Stable maximum CH4 and CO2 conversions of ∼99.5% and ∼94%, respectively, at H2/CO ∼0.9 were possible to reach with the 7 wt. % ruthenium-doped SrTiO3 catalyst exposed to maximum temperatures in the vicinity of 940 °C. A comparative theoretical scale-up study shows significant improvement in H2 production capability in the case of the perovskite catalyst compared to carbon-based catalysts.@en

This work proposes an innovative integration of Membrane Distillation (MD) and photo-oxidation for a continuous recovery of water from arsenic (As) contaminated solutions coupled with the oxidation of arsenite (As(III)) into arsenate (As(V)). Polyvinylidene fluoride (PVDF) mixed matrix membranes (MMMs) containing titanium dioxide nanoparticles (TiO2 NPs) as photocatalyst were developed. A systematic study elucidated the effect of TiO2 NPs on membranes’ morphology prepared via non-solvent-induced phase separation (NIPS) using triethyl phosphate (TEP) as a green solvent for PVDF solubilization. Vacuum membrane distillation (VMD) tests carried out by irradiating the MMMs with ultraviolet (UV) radiation demonstrated the possibility of recovering up to 80 % of the water from As-contaminated synthetic and real multi-ions aqueous solutions from Sila Massif (Italy). The distillate was recovered at a rate of 6.9–7.2 kg·m−2·h−1 (feed inlet temperature of 60 °C), while the presence of 7 wt% of TiO2 in PVDF membranes enabled the photo-oxidation of 95 % of the As(III) to As(V) at a first order kinetic constant of 0.0106 min−1. After 5 cycles of As-remediation experiments, post-hoc mechanical testing on the membrane suggested the emergence of polymer embrittlement induced by UV radiation (total irradiation time of 7.5 h), highlighting the urgent need for developing photocatalytic membranes with long-term stability. Overall, this study elucidates at laboratory scale the performance of a coupled and continuous Membrane Distillation (MD) and photo-oxidation system for arsenic (As) remediation, employing microporous hydrophobic green membranes doped with a photocatalyst.@en