Activity and Selectivity of Bimetallic Catalysts Based on SBA-15 for Nitrate Reduction in Water

Nitrate from the application of nitrogen-based fertilizers in intensive agriculture is a notorious waste product, though it lacks cost-effective solutions for its removal from potential drinking water resources. Catalytic reduction appears to be a promising technique for converting nitrates to benign nitrogen gas. Mesoporous silica SBA-15 is a frequently used catalyst support that has large surface areas and highly ordered nanopores. In this work, mesoporous silica SBA-15 bimetallic catalysts for nitrate reduction were investigated. The catalyst was optimized for the selection of promoter metal (Sn and Cu), noble metal (Pd and Pt) and loading ratios of these metals at different temperatures and reduction conditions. The catalysts prepared were characterized by FT-IR, N2 physisorption, XRD, SEM, and ICP. All catalysts showed the presence of cylindrical mesoporous channels and uniform pore structures that remained even after metals loading. In the presence of a CO2 buffer, the catalysts 4Pd-1Cu/SBA-15 and 1Pt-1Cu/SBA-15 reduced at 100?C under H2 and 1Pd-1Cu/SBA-15 reduced at 200°C under H2 demonstrated very high nitrate conversion. Furthermore, the forementioned Pd catalysts had higher N2 selectivity (88% - 87%) compared to Pt catalyst (80%). Nitrate conversion by the 4Pd-1Cu/SBA-15 catalyst was significantly decreased to 81% in the absence of CO2.

High Quality Bio-Oil Obtained from Catalyzed Pyrolysis of Olive Mill Solid Wastes in a Bi-Functional Reactor

Olive Mill Solid Wastes (OMSW) released in nature without any treatment is a major environmental problem in the Mediterranean region. In this work, the catalyzed pyrolysis of OMSW has been investigated. A catalyst based on SBA-15 mesoporous silica doped with chromium ferrite nanoparticles was prepared by the double solvent technique (DS). The prepared catalyst was characterized by scanning electron microscopy (SEM), Wide and Small Angle X-ray Scattering (WAXS, SAXS), Energy Dispersive X-ray (EDX) and FT-IR spectroscopies. Reverse spinel chromium ferrite nanoparticles were located inside the SBA-15 pores as confirmed by SEM images. The obtained catalyst was tested for pyrolysis reactions of OMSW. Several parameters were studied to optimize the conditions of the pyrolysis reaction in order to increase the bio-oil conversion yield. The GC-MS results demonstrated that the quality of the obtained bio-oil was improved by decreasing the quantity of phenolic and oxygenated components as well as the size of the obtained molecules. The produced bio-oil from pyrolysis of OMSW is identical to that obtained from the pyrolysis of commercial cellulose under the same conditions. A 37% conversion yield of bio-oil was obtained for the best conditions.

Multivariate Spatial and Temporal Analysis to Study the Variation of Physico-Chemical Parameters in Litani River, Lebanon

Water quality of Litani River was deteriorated due to rapid population growth and industrial and agricultural activity. Multivariate analysis of spatio-temporal variation of water quality is useful to improve the projects of water quality management and treatment of the river. In this work, analysis of samples from different locations at different seasons was investigated. The spatio-temporal variation of physico-chemical parameters of the water was determined. A total of 11 water quality parameters were monitored over 12 months during 2018 at 3 sites located in different areas of the river. Multivariate statistical techniques were used to study the spatio-temporal evolution of the studied parameters and the correlation between the different factors. Principal Component Analysis (PCA) was applied to the responsible factors for water quality variations during wet and dry periods. The multivariate analysis of variance (MANOVA) was also applied to the same factors and gives the best results for both spatial and temporal analysis. A black point of agricultural, industrial and sewage water pollution was identified in Jeb-Jennine station from the high concentrations of ammonia, sulfate and phosphate. This difference was proved by the major changes in the values of the parameters from one station to the other. Jeb-Jennine represents a main pollution area in the river. The high ammonia, sulfate and phosphate concentrations result from the important agricultural, industrial and sewage water pollution in the area. A high bacterial activity was highlighted in Jeb-Jennine and Quaroun stations because of the presence of the high nitrite concentrations in the two locations. All parameters are highly affected by climate factors, especially temperature and precipitation. TDS, salinity, electrical conductivity and the concentrations of all pollutants increase during wet season affected by the runoff. Other factors can affect the water quality of the river for example geographical features of the region and seasonal human activity like tourism. The correlation between different parameters was evaluated using PCA statistical method. This correlation is not stable, and evolves between wet and dry season.

Evaluation of the Physico-Chemical Properties of the Waters on the Litani River Station Quaraoun

Water security is a very important purpose facing the world in the last decay as one of the main consequences related to the risks of climate change. Water quality of Litani River’s at Quaraoun Lake station in Lebanon was evaluated by measuring various physicochemical parameters between 2008 and 2018. Samples were performed and analyzed the first of every month. Different analytical methods were used to determine the values of 11 physico-chemical parameters. Different statistical methods, such as Principal Component Analysis and the Times Series Representation, were applied to the results to evaluate the water characteristics, determine the operation of the ecosystem and study the correlation between the different parameters in the Quaraoun station. Industrial, agricultural and sewage water pollution of the Litani River were demonstrated by the high concentration of sulfate, phosphate and ammonia. High bacterial activity was proved from the high decreasing of the dissolved oxygen. Important correlations between the different parameters and between the parameters of the ecosystem and the weather were proved.

Study of the Dispersive Component of the Surface Energy of Polylactides by Inverse Gas Chromatography at Infinite Dilution

Inverse gas chromatography at infinite dilution is a powerful technique that can be advantageously used to characterize the surface physicochemical properties of solid substrates as oxides and polymers in both forms of powder or fibres. In the case of polymer, this technique can be used to determine the second order transition phenomena temperatures. This paper was devoted to the determination of the glass transition temperature of polylactide polymer. The dispersive component of the surface energy ?of polylactides was determined by inverse gas chromatography at infinite dilution. Various theoretical models were used to deduce the dispersive component of the surface energy of the solid substrates. These models are based on the calculation of the molecular areas of adsorbed molecules on the polymer surface: geometrical model, cylindrical molecular model, liquid density model, BET method, Kiselev results and the two-dimensional Van der Waals and Redlich-Kwong equations. The curves relative to the variation of as a function of the temperature showed a specific graph with a maximum value of ?at a certain particular temperature characteristic to the investigated polylactide polymer. In fact, the maxima of ?indicated the presence of glass transition temperature Tg of polylactide whatever the molecular model used. This study showed a glass transition temperature equal to 64°C confirming that obtained by other studies.

Impact of Plastic Packaging Materials and Storage Time on the Quality Parameters of Lebanese Extra Virgin Olive Oil under Real-Time Storage Conditions

Scarce information is currently available relative to the use of polymeric materials as storage containers for extra virgin olive oil. This paper was devoted to study and compare the impact of glass and 3 types of packaging materials—polyethylene terephthalate (PET), high density polyethylene (HDPE), and polylactic acid (PLA) on Lebanese extra virgin olive oil (EVOO) up to 9 months under non-accelerated storage conditions. The acidity, peroxide value (PV), K232, K270, fatty acid profile, overall migration, and oil sorption into the packaging material were determined. Conventional titration, gas chromatography-mass spectrometry, and spectrophotometry were used to quantify the outcome measures at baseline, 3, 5, 7, and 9 months. Mixed model ANOVA was applied to assess differences according to polymer type and storage period at P 232 and K270), migration, and sorption significantly increased with increasing storage time for oil in contact with glass and plastic materials, especially between the 7th and 9th month of storage. Overall, PLA showed the least deterioration and interaction phenomena compared with PET and HDPE. While glass remains the best container for EVOO, PLA could potentially replace PET and HDPE for short-time storage under conventional storage conditions in Lebanese households.

Reuse of Treated Municipal Wastewater under Different Growing Seasons for the Spinach Production

A study was conducted in the Bekaa valley of Lebanon aiming to produce spinach leaves with treated effluent from Joub Janine plant under two growing seasons. Two experiments were laid out in a randomized complete block design. The effect of water quality on the qualitative, quantitative aspects and microbiological contamination of leaves was assessed. The results showed that the treated wastewater from Joub Janine plant was of category III. The highest mean marketable yields was recorded for T7 (4727 g·m-2) followed by T6 (3533 g·m-2) that were drip irrigated with treated wastewater. The uptake of K, Mg, Na and Cl was significantly 49.09%, 30.20%, 96.79% and 33.20%, respectively, higher in the spring than in autumn. The nitrate levels in all treatments and seasons were below the maximum level in foodstuffs as provided by the European Commission regulations. For the lipophilic fraction, there was no significant difference among treatments and also among treatments and seasons interacting together and the highest hydrophilic fraction and total phenols levels recorded for the autumn rather than the summer season. In general, pathogenic bacteria was absent on spinach leaves for all treatments and growing seasons.

Adsorption of Pyridine onto Activated Montmorillonite Clays: Effect Factors, Adsorption Behavior and Mechanism Study

Activated Montmorillonite was applied for the sorption of pyridine as a health-toxic substance. Fourier-transform Infrared spectroscopy (FTIR), zeta potential analysis, thermogravimetric analysis (TGA), N2 physisorption analysis and X-ray diffraction (XRD) method were used to investigate the structure and composition of Montmorillonite. The batch sorption system was used to study the effect of different parameters on the adsorption. Results had shown that neutral pH had a significant effect on the sorption of pyridine;thermodynamic calculations indicated that the adsorption of pyridine over Montmorillonite was exothermic reaction and the equilibrium capacity was slightly increased by using H2SO4 as activating agent by comparison with that obtained by using HCl and H3PO4. Fitting the experimental data to isotherms models indicated that the experimental data were well fitted by Fowler Guggenheim isotherm models. Finally the results obtained by FTIR and TGA proved that the relative affinity of the pyridine toward the Montmorillonite was related to the electron donor-acceptor complexes that were formed between the basic sites (nitrogen or oxygen) and hydrogens (acidic site).