Removal of estrone (E1), 17β-estradiol (E2), and 17α-ethinylestradiol (EE2) from wastewater by liquid–liquid extraction

With the recent wide spread concerns of the environmental and public health effects of endocrine disrupting chemicals (EDCs), it is becoming important to develop new techniques to remove these substances from wastewater. EDCs find their way to the environment mainly via effluents from WWTPs. They are often cited as moderately hydrophobic, hence they have tendency to distribute to organic solvents and can then be removed using liquid–liquid extraction (LLE) techniques. However, despite being a mature chemical engineering unit operation, LLE has not been studied for the removal of EDCs in water. This study investigated the removal of three EDCs of concerns including estrone (E1), 17β-estradiol (E2), and 17α-ethinylestradiol (EE2) using decamethylcyclopentasiloxane (D5) as an extraction solvent in three water matrix types (Milli-Q, tap water, and a secondary treated wastewater). The study showed that all three EDCs were distributed to D5 but at varying distribution coefficients: KE1 = 2.66, KE2 = 0.61 and KEE2 = 1.67 ± 5% at pH 6 and 20 °C. Due to the high pKa values of the three EDCs, pH had no significant effect on KEDCs up to about pH 9.5 but higher pHs reduced the distribution ratios up to almost zero at pH 12. Van’t Hoff equation described the effect of temperature on KEDCs and showed that the process was endothermic. The overall estrogenic potency of the three EDCs in mixtures was quantified with an E2 equivalent potency, which was found to distribute well into the solvent at a KE2EQ = 1.43. The study suggests that LLE is an effective method to remove estrogenic potency of wastewater

Pb doped ZnO nanoparticles for the sorption of Reactive Black 5 textile azo dye

In this study, Pb doped ZnO nanoparticles were synthesized by a sol-gel technique for the sorption of Reactive Black 5 (RB5) textile dye in aqueous solution. The ZnO:Pb (2 and 4%) nanoparticles have been characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and cryogenic nitrogen adsorption method. The average size of the synthesized nanoparticles was less than 100 nm and the surface areas were 18.8 and 20.8 m2/g, respectively for ZnO:Pb 2% and ZnO:Pb 4%. Batch sorption experiments were performed for color removal of RB5 dye at ambient temperature and 30 mg/L dye concentration. The central composite design with response surface methodology was used to study the effect of sorption condition (pH, nanoparticles dose and contact time). The significance of independent variables and their interactions was tested by analysis of variance. The optimum conditions of color removal were pH = 7, 2 g/L dose of nanoparticles and a contact time of 79 min. The color removal performance was 79.4 and 98.1% for ZnO:Pb 2 and 4% respectively. The pseudo-second-order model described well the removal rates while the Langmuir model fitted well the adsorption isotherms

Robust Magnetic γ-Fe2O3/Al–ZnO Adsorbent for Chlorpyriphos Removal in Water

In this research, the removal of the pesticide chlorpyriphos (CPE) from water by adsorption using a novel adsorbent made of γ-Fe2O3/Al-ZnO nanocomposite was studied. The adsorbent was characterized using Fourier-transformed infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) surface area, and vibrating sample magnetometry (VSM). The main parameters affecting the adsorption process, including the initial pH (2–12), the concentration of pesticide (10–70 ppm), the %Fe2O3 of the adsorbent, and the adsorption time (≤60 min), were studied. The results demonstrated that the adsorption of CPE depended on the pH, with a maximum removal of 92.3% achieved at around neutral pH. The adsorption isotherm was modelled and the results showed that the Freundlich model fitted the experimental data better than the Langmuir and Temkin models. The kinetics of adsorption were also studied and modelled using the pseudo-first-order and pseudo-second-order models, with the former being found more suitable. Energy dispersive X-ray (EDX) analysis confirmed the adsorption of CPE on γ-Fe2O3/Al-ZnO, while FTIR analysis suggested that the hydroxyl, N-pyridine, and chloro functional groups governed the adsorption mechanism. Furthermore, VSM analysis revealed that the magnetization saturation of γ-Fe2O3/Al-ZnO nanocomposite, after CPE adsorption, was slightly lower than that of fresh γ-Fe2O3/Al-ZnO but remained adequate for the efficient separation of the adsorbent simply using a magnet. This study demonstrates that binary γ-Fe2O3/Al-ZnO magnetic nanocomposites are effective for the removal of chlorpyriphos and could be highly promising materials for the removal of emerging pollutants in wastewater

Polyvinylidene fluoride membranes impregnated at optimised content of pristine and functionalised multi-walled carbon nanotubes for improved water permeation, solute rejection and mechanical properties

Pristine (CNTs-P) and oxygen-plasma-functionalised (CNTs-O) multi-walled carbon nanotubes were incorporated in polyvinylidene fluoride (PVDF) membranes using the phase inversion technique. N-methyl 2-pyrolidone solvent gave good dispersion and stability of the CNTs and hence was used for membrane fabrication. The membranes were characterised and their performances in water permeation and solutes (NOM, BrO3−, Br− and Cl−) rejection were evaluated at different CNT contents. SEM imaging of the membranes showed asymmetric finger-like porositic structure with small channelling tubes in the top layer that connect with larger channelling tubes in the deeper side. The finger-like pores were shallower in CNTs-O/PVDF membranes than the PVDF or CNTs-P/PVDF membranes. Due to oxygenated groups imparted by CNTs-O, CNTs-O/PVDF membranes were more wettable, presented higher electronegativity and hence better rejection of the anions. CNTs have increased membrane porosities and mean pore sizes and have lead to significantly enhanced water flux by up to 3.3 (CNTs-O) and 3.7 (CNTs-P) times that of pure PVDF membranes. They have also improved the rejections of NOM, bromate, bromide, and chloride at absolute values as high as 93.4%, 21.7%, 10.5%, and 9.2% respectively for CNTs-O/PVDF membrane. CNTs have also enhanced significantly the mechanical properties of the PVDF membranes and a CNT content of 0.2 mass% was optimal

Aloe sp. leaf gel and water glass for municipal wastewater sludge treatment and odour removal

Aloe gel (Alg), which is a natural extract from the Aloe sp. plant, was evaluated in this study for its potential use as a bioflocculant to treat urban wastewater sewage sludge. The gel was used alone and combined with water glass (WG) under controlled conditions in laboratory experiments. Alg was found effective to settle the flocculated sludge rapidly and remove distinctive unpleasant odours of the sludge as highlighted by gas chromatography-mass spectrometry (GC/MS) analysis. Furthermore, Alg was pH tolerant and had no effect in changing the pH of the wastewater. The optimum dose of Alg was 3% at which a sludge volume index (SVI) of 45.4 mL/g was obtained within 30 min settling time. To enhance the treatment performances of Alg, WG was also evaluated as an alkali agent to further reduce the chemical oxygen demand (COD) and ammonia (NH4-N) in the wastewater. At equal doses of 3% of WG and Alg each, the combined treatment outcomes showed high turbidity and NH4-N removals of 83 and 89%, respectively, but the overall COD removal was at best 25%. The settling rate of treated sludge with combined Alg/WG was very rapid giving an SVI of 25.4 mL/g within only 5 min

A Modified Indigo Method for the Determination of Ozone in Nonaqueous Solvents

The indigo method for the analysis of aqueous ozone was modified to allow analysis of dissolved ozone in nonaqueous liquid phases. The method was tested using the solvent decamethylcyclopentasiloxane 245 and a vegetable oil. The molar absorptivity at 600 nm of the indigo trisulphonate molecule was re-checked and found to be 20,069 ± 412 L mol−1 cm−1 which is in agreement with the generally accepted value. Linear correlation between liquid phase and gas phase ozone concentrations confirmed that ozone solubility in decamethylcyclopentasiloxane 245 obeyed Henry's law with a constant of 1.71 ± 0.09 mg L−1 per mg L−1 in the gas phase. Ozone solubility in the vegetable oil followed a power law model with k = 0.148 and n = 0.767 (liquid and gas phase concentrations in mg L−1). The stoichiometry of the reaction between ozone in the nonaqueous phase and indigo trisulfonate in acidic solution was also confirmed as being about one. Moreover, the reaction products were confirmed by chromatographic analysis. This method was found effective to analyze ozone in nonaqueous solvents with a lower limit of detection of 2.6 μg L−1 and upper limit of detection of 142.7 mg L−1

Inactivation of antibiotic-resistant bacteria and antibiotic-resistance genes in wastewater streams: Current challenges and future perspectives

The discovery of antibiotics, which was once regarded as a timely medical intervention now leaves a bitter aftertaste: antimicrobial resistance (AMR), due to the unregulated use of these compounds and the poor management receiving wastewaters before discharge into pristine environments or the recycling of such treated waters. Wastewater treatment plants (WWTPs) have been regarded a central sink for the mostly unmetabolized or partially metabolised antibiotics and is also pivotal tothe incidence of antibiotic resistance bacteria (ARBs) and their resistance genes (ARGs), which consistently contribute to the global disease burden and deteriorating prophylaxis. In this regard, we highlighted WWTP-antibiotics consumption-ARBs-ARGs nexus, which might be critical to understanding the epidemiology of AMR and also guide the precise prevention and remediation of such occurrences. We also discovered the unsophistication of conventional WWTPs and treatment techniques for adequate treatment of antibiotics, ARBs and ARGs, due to their lack of compliancewith environmental sustainability, then ultimately assessed the prospects of cold atmospheric plasma (CAP). Herein, we observed that CAP technologies not only has the capability to disinfect wastewater polluted with copious amounts of chemicals and biologicals, but also have a potential to augment bioelectricity generation, when integrated into bio electrochemical modules, which future WWTPs should be retrofitted to accommodate. Therefore, further research should be conducted to unveil more of the unknowns, which only a snippet has been highlighted in this study

The Rise of Misinformation in the Digital Age: Moroccan Students' Attitudes and Perceptions of Fake News Online

As today’s students spend substantial time online, there is an increasing tendency to utilize the Internet as their primary source of information. With the proliferation of user-generated content platforms and the shrinking influence of traditional gatekeeping, there is a growing abundance of misinformation available to the public that coexists alongside accurate information. In this paper, we explored the attitudes and perceptions of teenage students towards misinformation online. To this end, a web-based survey was administered to both Moroccan high school teachers and students to collect and analyze their responses regarding the issue being debated. Additionally, the present study investigated the extent to which EFL textbooks in Morocco enable learners to build skills necessary for identifying fake news. The study adopted content analysis as the primary research method for data analysis and interpretation. The results obtained are in line with the hypothesis guiding this research that a fair majority of teenage students are vulnerable to misinformation online due in large to the overwhelming information overload available at the touch of a button along with their lack of exposure to effective strategies for processing information online.  Based on the findings obtained, schools are required to develop appropriate approaches to teach digital literacy skills, particularly in empowering young learners to distinguish credible sources from unreliable ones. Equally important, teachers are called upon to help students keep up with the new, fast-moving knowledge economy, which is driven by information and technology

Development and characterization of a wire-plate air bubbling plasma for wastewater treatment using nanosecond pulsed high voltage

This study developed a prototype of a wire-plate air bubbling plasma reactor that can be easily scaled up for wastewater treatment. The electrical characteristics, including the discharge current and average power consumed, of the developed reactor were deeply investigated at different operating parameters and solution conductivities. The performance of the reactor was examined on the basis of energy efficiency and methylene blue (MB) decoloration efficiency. Moreover, the removal of the total organic carbon and the changes of the physicochemical properties of solution, including pH, conductivity, and temperature, were evaluated. The analysis of current discharge and average power consumed showed that the discharge mode in the present reactor is a filamentary streamer. Interestingly, the solution conductivity had no effect on the average power consumed at low applied voltages, due to confinement of the discharge in a small area surrounding the discharge electrode in the gas phase. However, at relatively high voltages, the effect of conductivity on the average power consumed was noticeable, yet it had no effect on the decoloration efficiency at the same average power. The present reactor showed a high energy-efficiency value of 42 g/kWh at 50% decoloration of 30 mg/l MB solution, but it dropped to 14 g/kWh at 97% decoloration. A first-order kinetics model described well the decoloration reaction rates and the overall rate constant correlated linearly to the average power