No abstract

Owing to the water crisis, the development of innovative and clean advanced oxidation processes to decompose a variety of harmful organic compounds in wastewater becomes the main challenge for many research teams. Cold discharge plasma is one of the most widely studied and developed processes, owing to its low energy cost and easy to operate. The impact of different factors on the decontamination effectiveness of discharge plasma are detailed in this review. The generation and reaction mechanisms of reactive species in discharge plasma systems have also gained a significant interest and hence discussed. Several potentials and laboratory-scale reactor design recently reported are discussed and schematically presented. The recent combination of discharge plasma decontamination and other processes in both post and pre-treatment configuration are reported. Some applications of water treatment based on discharge plasma at the pilot scale have been addressing.

No abstract

The present study investigates the alkaline modification of raw orange tree sawdust (ROS) for an optimal removal of methylene blue (MB), as a cationic dye model, from synthetic solutions. The effects of operating parameters, namely, sodium hydroxide (NaOH) concentrations, ROS doses in NaOH solutions, stirring times, and initial MB concentrations on dye removal efficiency, were followed in batch mode. The process optimization was performed through the response surface methodology approach (RSM) by using Minitab17 software. The results showed that the order of importance of the followed parameters was NaOH treatment concentrations > stirring times > initial MB concentrations > ROS doses in NaOH solutions. The optimal experimental conditions ensuring the maximal MB removal efficiency was found for a NaOH treatment concentration of 0.14 M, a stirring time of 1 h, a ROS dose in NaOH solutions of 50 g L, and an initial MB concentration of 69.5 mg L. Specific analyses of the raw and alkali-treated biomasses, e.g., SEM/EDS and XRD analyses, demonstrated an important modification of the crystalline structure of the wooden material and a significant increase in its surface basic functional groups. Kinetic and isotherm studies of MB removal from synthetic solutions by ROS and the alkali-treated material (ATOS) showed that for both adsorbents, the pseudo-second-order and Langmuir model fitted the best the experimental data, respectively, which indicates that MB removal might be mainly a chemical and a monolayer process. Furthermore, thanks to the chemical modification of the ROS, the MB maximal uptake capacity has increased from about 39.7 to 78.7 mg g. On the other hand, due to the competition phenomenon, the coexistence of MB and Zn(II) ions could significantly decrease the MB removal efficiency. A maximal decrease of about 32 % was registered for an initial Zn(II) concentration of 140 mg L. Desorption experiments undertaken at natural pH (without adjustment: pH = 6) and with different NaCl concentrations emphasized that the adsorbed MB could be significantly desorbed from both the tested materials, offering their possible reuse as efficient adsorbents. All these results confirmed that NaOH-treated orange tree sawdust could be considered as an efficient, economic, and ecological alternative for the removal of cationic dyes from industrial wastewaters.

Highlights  Novel biocomposite powder was simply prepared from Reed plant.  Ciprofloxacin and methylene blue were first time simultaneously removed.  Operating parameters were optimized by CCD-RSM methodology.  Kinetic and isotherm models were studied using Brouers-Sotolongo family equations.  Biosorption mechanisms were discussed.

To cite this version:Aymen Amine Assadi, Abdelkrim Bouzaza, Cédric Vallet, Dominique Wolbert. Use of DBD plasma, photocatalysis, and combined DBD plasma/photocatalysis in a continuous annular reactor for isovaleraldehyde elimination -Synergetic effect and byproducts identification. The Chemical Engineering Journal, Elsevier, 2014, 254, pp

Dielectric barrier discharge DBD-plasma based technologies have been widely investigated for the abatement of air pollutants. More recently, photocatalysis (TiO 2 /UVlamp) has also showed promising results for air pollution abatement. In this work, these two methods were used separately and combined (TiO 2 /UV-lamp/DBD-plasma) in order to enhance the performance of the process for air pollutants degradation/mineralization. Ammonia (NH 3) and butyraldehyde (C 4 H 8 O) have been firstly treated alone and then an equimolar mixture (NH 3 /C 4 H 8 O) was monitored in a continuous reactor. Effect of operational parameters such as pollutants inlet concentration, flowrate, humidity and specific energy of plasma were thoroughly determined. Results showed that coupling both methods in the same reactor improves removal efficiency for single pollutant or a mixture of two pollutants. This processes combination showed a synergy between DBDplasma and photocatalytic oxidation. Moreover, pollutant mineralization and potential 2 intermediate byproducts have been characterized and discussed. Coupling both processes contributes to enhanced mineralization in comparison with DBD-plasma alone regarding the CO 2 selectivity. As for selectivity of byproducts: (i) Relative Humidity (RH), (ii) mixture effect and (iii) (TiO 2 /UV-lamp/DBD-plasma) combined processes inhibit ozone production during the pollutants removal/oxidation.

Atomic force microscopy (AFM) has been extensively used for the nanoscale characterization of polymeric materials. The coupling of AFM with infrared spectroscope (AFM-IR) provides another advantage to the chemical analyses and thus helps to shed light upon the study of polymers. This paper reviews some recent progress in the application of AFM and AFM-IR in polymer science. We describe the principle of AFM-IR and the recent improvements to enhance its resolution. We also discuss the latest progress in the use of AFM-IR as a super-resolution correlated scanned-probe infrared spectroscopy for the chemical characterization of polymer materials dealing with polymer composites, polymer blends, multilayers, and biopolymers. To highlight the advantages of AFM-IR, we report several results in studying the crystallization of both miscible and immiscible blends as well as polymer aging. Finally, we demonstrate how this novel technique can be used to determine phase separation, spherulitic structure, and crystallization mechanisms at nanoscales, which has never been achieved before. The review also discusses future trends in the use of AFM-IR in polymer materials, especially in polymer thin film investigation.