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Various treatment methods are widely used to reduce water pollution. Among these techniques, heterogeneous photocatalysis and non-thermal plasma technologies, notably dielectric barrier discharges, are currently the most suitable for water treatment. However, the use of each of these processes alone presents certain limitations. In this study, the brilliant blue (BB) photo-degradation was investigated via the dielectric barrier discharge (DBD) method. The impact of certain process factors, including the model pollutant's initial concentration (from 5 to 10 mg/L), the airflow rate (240 L/h) as well as the frequency (from 230 to 400 Hz), upon the DBD's performance in terms of bright blue decomposition and mineralisation was assessed. The latter reached 49.5% for 120 minutes, assuming optimised operating parameters (BB initial concentration of 10 mg/L, airflow rated at 240 L/h, 21 kV as an applied voltage at 400 Hz). It could be said that DBD processing has a high ecological potential for the aqueous degradation of BB. Scavenger analysis indicated that the radicals O2−°, HO2°, as well as °OH, represent the underlying oxygen reactive species in the process of brilliant blue decomposition. The study showed that both reactive nitrogen species and ROS contribute to the process of BB removal. For approximating real-life requirements, DBD tests were performed in both tap and synthetic water matrices. The degradation and mineralisation of BBs were significantly inhibited in tap water (% Degradation = 71.3, % Mineralisation = 31.6) and synthetic water (% Degradation = 65.41, % Mineralisation = 12), compared to BB degradation and mineralisation in ultrapure water (% Degradation ≥ 98, % Mineralisation = 49.5), after 120 min of irradiation. This proved that inorganic and organic molecules in tap and synthetic water reduce BB degradation efficiency. Thus, our pollutant was treated by the combination plasma-photocatalysis system using cellulose paper-supported titanium dioxide as a photocatalyst, which showed a significant improvement in BB decomposition efficiency versus considering either separate process. [ABSTRACT FROM AUTHOR]

The presence of pharmaceuticals in the environment has increased. These pollutants are toxic and non-biodegradable. Piroxicam (PRX) is a non-steroidal anti-inflammatory drug that ends up in wastewater via pharmaceutical industry activities and human being consumption. This work aimed to study the pharmaceutical pollutant removal from wastewater using agricultural by-products as low-cost adsorbent material. Different parameters were studied, such as time, initial adsorbate concentrations, and temperature. The study of the initial concentration-effect shows that the greatest amount of adsorbed is observed in low concentrations. The temperature has shown a negative effect in this study. The kinetics show that after 45min, the equilibrium is obtained; that means the exhaustion of all active sites. The representative model of this adsorption is the Langmuir isotherm according to the regression coefficient, which is equal to 0.99. The natural abundance of this material and the low cost of investment could offer a good alternative to other more expensive adsorbents such as activated carbon.

This study presents two environmental aspects: valorisation of natural oil shale (NOS), on the one hand, and, on the other hand, to study the effectiveness of adsorption of methylene blue (MB) dye onto material (NOS). In this context, the most characterisations of adsorbent before and after adsorption process were investigated by several methods such as x-ray diffraction (XRD), scanning electronic microscopy (SEM) and Fourier transforms infrared spectrometry (FTIR), according to these results, the NOS is rich in quartz and calcite, the matrix clay contains the kaolin and illite and present a layer structure. The total number of results showed that the adsorption of MB onto NOS is best by pseudo-second-order fitting model with a good correlation (R2 = 0.98), on the other hand the adsorption process was described well by Langmuir isotherm with a maximal capacity of adsorption equal 29 mg/g. The effect of temperature on the adsorption of the dye was also evaluated and the thermodynamic parameters were determined. The negative values of the three thermodynamic parameters ΔH °, ΔG ° and ΔS ° of the NOS/MB system indicate that the adsorption is spontaneous, exothermic and the activated energy indicates that the adsorption mechanism might be a physical sorption process. [ABSTRACT FROM AUTHOR]