Search

In our investigation, we unveil a novel, eco-friendly, and cost-effective method for crafting a bio-derived electrode using discarded cotton fabric via a carbonization procedure, marking its inaugural application in a vanadium redox flow battery (VRFB). Our findings showcase the superior reaction surface area, heightened carbon content, and enhanced catalytic prowess for vanadium reactions exhibited by this carbonized waste cloth (CWC) electrode compared to commercially treated graphite felt (TT-GF). Therefore, the VRFB system equipped with these custom electrodes surpasses its treated graphite felt counterpart (61% at an equivalent current) and achieves an impressive voltage efficiency of 70% at a current density of 100 mA cm−2. Notably, energy efficiency sees a notable uptick from 58% to 67% under the same current density conditions. These compelling outcomes underscore the immense potential of the carbonized waste cotton cloth electrode for widespread integration in VRFB installations at scale. [ABSTRACT FROM AUTHOR]

Eriochrome Black T (EBT) and chromium (Cr) are considered to be potential pollutants due to their toxicity and severe impact on the environment. In the current study, hydrotalcite-derived Mg-Ca-Al-LDO mixed metal oxide composite was prepared using a conventional co-precipitation method and explored in terms of the removal of Cr and EBT dye from aqueous solution in a batch mode adsorption process. The prepared Mg-Ca-Al-LDH, Mg-Ca-Al-LDO and spent Mg-Ca-Al-LDO adsorbents were characterized to propose the adsorption mechanism. Different adsorption parameters were examined, such as adsorbent dosage, initial concentration, pH, reaction temperature and contact time. The EBT adsorption kinetic results matched strongly with the pseudo-second-order model for both Cr (R2 = 0.991) and EBT (R2 = 0.999). The Langmuir isotherm model exhibited a maximum adsorption capacity of 65.5 mg/g and 150.3 mg/g for Cr and EBT, respectively. The structure and morphology results obtained after Cr and EBT dye adsorption reveal that the adsorption mechanism is associated with electrostatic interactions and surface complexation of Cr and EBT dye with Mg-Ca-Al-LDO surface functional groups. Moreover, more than 84% of the initial adsorption capacity of EBT and Cr can be achieved on the Mg-Ca-Al-LDO surface after five adsorption/desorption cycles. Finally, the Mg-Ca-Al-LDO mixed metal oxide composite can be potentially used as a cost-effective adsorbent for wastewater treatment processes. [ABSTRACT FROM AUTHOR]

In this study, a low-cost granular activated carbon doped with Fe2O3 nanoparticles (Fe–GAC) was prepared via a modified sol-gel technique and utilized for the elimination of lead (Pb(II)) and chromium (Cr(T)) ions from synthetic and actual brackish water. The effect of adsorption parameters on the removal of Pb(II) and Cr(T) ions from the water was evaluated in batch adsorption tests. The characterization results validated the distribution of well-defined Fe2O3 nanoparticles onto the GAC surface. GAC loaded with 5 wt.% of Fe2O3 (Fe–GAC 5) exhibited a maximum surface area of 848.2 m2 g−1. The equilibrium data of Cr(T) adsorption were in close agreement with the Langmuir and Sips models with R2 values of 0.95 and 0.96, respectively. However, the R2 values of the equilibrium data for Pb(II) adsorption were greater than 0.91 for all four models, i.e., Langmuir, and Sips, Freundlich and Redlich-Peterson. The maximum Langmuir adsorption capacities of Pb(II) and Cr(T) by Fe–GAC 5 at pH 5.6 and room temperature were 11.9 and 22.1 mg g−1, respectively. Pseudo-second order (R2Pb(II) = 0.99, R2Cr(T) = 0.99) and Elovich kinetic models (R2Pb(II) = 1, R2Cr(T) = 1) were found the most suitable for describing the adsorption kinetics data of Pb(II) and Cr(T) using Fe–GAC 5. The adsorption/desorption studies illustrated that the Fe–GAC is reusable and can be regenerated using 1.0 M HCl. Moreover, the Fe–GAC 5 was found effective to reduce heavy metals loading in actual brackish water to the allowed international standards of drinking water. Accordingly, the Fe–GAC could be a promising material for large-scale applications for the elimination of heavy metals from water. [ABSTRACT FROM AUTHOR]

Microbial fuel cell (MFC) is an emerging method for extracting energy from wastewater. The power generated from such systems is low due to the sluggish electron transfer from the inside of the biocatalyst to the anode surface. One strategy for enhancing the electron transfer rate is anode modification. In this study, iron nanostructure was synthesized on a carbon cloth (CC) via a simple electroplating technique, and later investigated as a bio-anode in an MFC operated with real wastewater. The performance of an MFC with a nano-layer of iron was compared to that using bare CC. The results demonstrated that the open-circuit voltage increased from 600 mV in the case of bare CC to 800 mV in the case of the iron modified CC, showing a 33% increase in OCV. This increase in OCV can be credited to the decrease in the anode potential from 0.16 V vs. Ag/AgCl in the case of bare CC, to −0.01 V vs. Ag/AgCl in the case of the modified CC. The power output in the case of the modified electrode was 80 mW/m2—two times that of the MFC using the bare CC. Furthermore, the steady-state current in the case of the iron modified carbon cloth was two times that of the bare CC electrode. The improved performance was correlated to the enhanced electron transfer between the microorganisms and the iron-plated surface, along with the increase of the anode surface- as confirmed from the electrochemical impedance spectroscopy and the surface morphology, respectively. [ABSTRACT FROM AUTHOR]

Aluminum nitride nanoparticles (AlN-NPs) were fabricated by a RF magnetron sputtering and inert gas condensation technique. By keeping the source parameters and sputtering time of 4 h fixed, it was possible to produce AlN-NPs with a size in the range of 2–3 nm. Atomic force microscopy (AFM), Raman spectroscopy, X-ray diffraction (XRD), and UV-visible absorption were used to characterize the obtained AlN-NPs. AFM topography images showed quazi-sphere nanoparticles with a size ranging from 2 to 3 nm. The XRD measurements confirmed the hexagonal wurtzite structure of AlN nanoparticles. Furthermore, the optical band gap was determined by the UV-visible absorption spectroscopy. The Raman spectroscopy results showed vibration transverse-optical modes A1(TO), E1(TO), as well as longitudinal-optical modes E1(LO), A1(LO). [ABSTRACT FROM AUTHOR]

Nanoparticle (NP) synthesis by biological systems is more cost-effective, safe, and environmentally friendly when compared to currently used chemical and physical methods. Although many studies have utilized different plant extracts to synthesize NPs, few studies have incorporated living plants. In this study, silver nanoparticles (AgNPs) were synthesized exogenously by Tephrosia apollinea living plant system under the combined stresses of silver nitrate and different levels of drought stress simulated by Polyethylene glycol (PEG) (0, −0.1, −0.2, and −0.4 MPa for three and six days). Biomass, cell death, and H2O2 content were evaluated to determine the toxicological effect of the treatments on the plant. More severe effects were detected in day 6 plants compared to day 3 plants, and at higher drought levels. UV-visible spectrum, energy dispersive X-ray spectroscopy, X-ray diffraction, scanning electron microscope, and Fourier transform infrared spectroscopy were used to detect and characterize the T. apollinea synthesized NPs. The shapes of the NPs were spherical and cubic with different phytochemicals being the possible capping agents. Broth microdilution was used to determine the antimicrobial activity of the NPs against Escherichiacoli and Staphylococcus aureus. In this case, antimicrobial activity increased at higher PEG concentrations. Bactericidal effects were observed against E. coli, while only bacteriostatic effects were detected against S. aureus. [ABSTRACT FROM AUTHOR]

Airborne particulate matter (PM) pollutants were sampled from an urban background site in Sharjah, United Arab Emirates. The fine fraction (PM2.5) (particulates with aerodynamic diameters of less than 2.5 μm) was collected on 47-mm Teflon filters and analyzed using a combined set of non-destructive techniques in order to provide better understanding of the sources of pollutants and their interaction during transport in the atmosphere. These techniques included gravimetric analysis, equivalent black carbon (EBC), X-ray fluorescence, scanning electron microscopy, and X-ray diffraction. Generally, the PM2.5 concentrations are within the limits set by the World Health Organization (WHO) and the United States (US) Environmental Protection Agency. The EBC content is in the range of 10–12% of the total PM concentration (2–4 µg m−3), while S (as ammonium sulfate), Ca (as calcite, gypsum, and calcium carbonate), Si (as quartz), Fe, and Al were the major sources of PM pollution. EBC, ammonium sulfate, Zn, V, and Mn originate from anthropogenic sources such as fossil fuel burning, traffic, and industrial emissions. Natural elements such as Ca, Fe, Al, Si, and Ti are due to natural sources such as crustal materials (enhanced during dust episodes) and sea salts. The average contribution of natural sources in the total PM2.5 mass concentration over the sampling period is about 40%, and the contribution of the secondary inorganic compounds is about 27% (mainly ammonium sulfate in our case). The remaining 22% is assumed to be secondary organic compounds. [ABSTRACT FROM AUTHOR]