Volume 24 - 2022

Industrial production brings serious Cr(Ⅵ) pollution problems, so as to explore new treatment methods for Cr(Ⅵ), In this paper, modified montmorillonite was prepared by modifying montmorillonite with starch and lanthanum nitrate, and its adsorption mechanism and effect on Cr(Ⅵ) were explored. The modified mechanism and modified monundonerization properties were characterized by Zeta potential, X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR), and scanning electron microscopy analysis(SEM). The results showed that: Lanthanum-modified montmorillonite and starch-modified lanthanum-modified montmorillonite have better adsorption effects on 10 mg/L Cr(VI) polluted solution, which are 73.9% and 58.6%, respectively, while Na-based montmorillonite Cr(VI) has no adsorption capacity. Both lanthanum and starch only exist on the surface of montmorillonite, which can reduce the overall electronegativity of montmorillonite, so that montmorillonite has the ability to adsorb Cr(VI), At the same time, after the surface of montmorillonite modified by lanthanum nitrate is covered with hydroxyl groups, it is easy to form surface coordination complexes with anions, which further enhances its adsorption effect, and provides a new research idea and direction for the adsorption and removal of Cr(VI).

To assess the impact of climate change on wind regimes, we performed a statistical analysis of some meteorological parameters. Indeed, variables such as temperature, humidity, pressure, and insolation are rarely or not considered in the estimation of wind regimes and therefore in the characterization of wind sites. In setting wind farm projects, one is limited to assessing the wind potential with data that fluctuate greatly. In this work, we studied the influence of meteorological parameters on the wind regimes in the eastern part of Niger. We have firstly, based on data collected at the station of N'Guigmi, over 10 years, characterized each of the parameters by their monthly and interannual average. In a second step, we studied the interannual variability of these variables. At this level, the curves represented show large fluctuations. We then represented trend curves which showed us that during these ten years, humidity, insolation, and wind have undergone slight increases while temperature and pressure have significantly decreased. Finally, we used principal component analysis with the statistical tool XLSTAT to analyze the correlation of the different meteorological parameters on wind speed. The preponderance of the influence of each variable is evaluated from a factorial design provided by XLSTAT. Thus, after the analysis of the factorial design, we concluded that temperature is a preponderant factor in the wind flow. The second variable that conditions the wind flow is humidity. These results meet our expectations. Indeed, the wind being air in circulation, under a high temperature, its density decreases, and its circulation is facilitated. However, with humidity, it becomes heavier, and the wind circulates less quickly.

Methylene blue (MB) removal from aqueous media using hybrid bioprocess: biosorption on modified cork powder (SDS-cork) and soluble turnip peroxidase (STP) was investigated. Cork powder was modified with sodium lauryl sulphate (SDS). Chemical composition of the biosorbent were characterized by infrared before and after biosorption. The hybridization was carried out under the optimal conditions of the two processes: pH=7, T=40 °C, [H2O2]=10 mM for enzyme activity(EA)=7 U mL-1 witch it was in excess for the EA= 5 and 3 U mL-1, [H2O2] = 15 mM for EA= 9 U mL-1 and [H2O2]=15 mM for EA= 11 U mL-1 with a treatment time that equals the sum of two optimal treatment times, and a mass of SDS-cork 0.04 g with a diameter <0.16 mm. The feasibility and performance of this hybridization was tested according to two parameters the initial concentration of MB which varied between 200 and 500 mg L-1 and the enzymes activities which has varied between 3 and 11 U mL-1. The minimum removal percentage of MB was satisfactory according to 93% for [MB] = 500 mg/L and an EA of 3 U mL-1, otherwise the maximum removal percentage was very satisfactory being in the order of 99.9% for a [MB] = 200 mg L-1 and EA= 11 U mL-1.

Nanotechnology is the newest and one of the most promising areas of research in modern medical sciences. Metal nanoparticles possess extraordinary optical, thermal, chemical properties and are being widely used in industrial, electronics, and biomedical fields. It has presented its potential to contribute to solving one of the greatest problems of the worldwide wastewater treatment issue. The approach of green synthesis of metal oxide nanoparticles seems to be a cost-efficient, eco-friendly, and easy alternative approach. The current study deals with the synthesis and characterization of Magnesium Oxide nanoparticles (MgO-NPs) using leaves extract of Iresine herbsti. The characterization was done by XRD and SEM. Then MgO-NPs were applied for the remediation of Reactive Brown 9 dye following the optimization of reaction parameters (conc. of dye, conc. of nanoparticles, pH, and temperature). The maximum decolorization (95.8%) was obtained at 0.02% dye conc., 0.003 mg/L conc. of MgO-NPs, at pH 4, and temperature 40 °C. TOC and COD were used for mineralization assessment of studied dye samples and their values were found to be 88.56% and 85.34%, respectively. The magnesium oxide nanoparticles could be applied successively for the treatment of other problematic dyes as well.