ABSTRACT
Benzene, toluene and xylene (BTX) are volatile organic compounds released into the environment, that require urgent removal to avoid adverse health effects. In this work, the modelling and optimization of the preparation factors for magnetite coated oleic acid (MNP-OA) composite from microwave synthesis using response surface methodology were conducted to maximize BTX removal, and iron content. The influence of five crucial preparation variables: the Fe3+/Fe2+ solution volumes, microwave power, volume of ammonia water (VAW), reaction time and volume of oleic acid (VOA) on the iron content (% Fe), and BTX adsorption capacity were investigated. The analysis of variance results revealed that VOA and VAW were the most influential factors for high % Fe content, and improved BTX removal. The % Fe, and BTX adsorption capacity for MNP-OA composite at optimized experimental conditions were estimated to be 85.57%, 90.02 mg/g (benzene), 90.07 mg/g (toluene), and 96.31 mg/g (xylene).
Subject(s)
Toluene , Xylenes , Benzene , Ferrosoferric Oxide , Oleic Acid , Microwaves , IronABSTRACT
One approach for solving the problem of antibiotic resistance and bacterial persistence in biofilms is treatment with metals, including silver in the form of silver nanoparticles (AgNPs). Green synthesis is an environmentally friendly method to synthesize nanoparticles with a broad spectrum of unique properties that depend on the plant extracts used. AgNPs with antibacterial and antibiofilm effects were obtained using green synthesis from plant extracts of Lagerstroemia indica (AgNPs_LI), Alstonia scholaris (AgNPs_AS), and Aglaonema multifolium (AgNPs_AM). Nanoparticles were characterized by transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX) analysis. The ability to quench free radicals and total phenolic content in solution were also evaluated. The antibacterial activity of AgNPs was studied by growth curves as well as using a diffusion test on agar medium plates to determine minimal inhibitory concentrations (MICs). The effect of AgNPs on bacterial biofilms was evaluated by crystal violet (CV) staining. Average minimum inhibitory concentrations of AgNPs_LI, AgNPs_AS, AgNPs_AM were 15 ± 5, 20 + 5, 20 + 5 µg/mL and 20 ± 5, 15 + 5, 15 + 5 µg/mL against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria, respectively. The E. coli strain formed biofilms in the presence of AgNPs, a less dense biofilm than the S. aureus strain. The highest inhibitory and destructive effect on biofilms was exhibited by AgNPs prepared using an extract from L. indica.
ABSTRACT
Magnetite-coated pine cone biomass was successfully synthesized, characterized, and its interaction with As (III) in water evaluated in order to apply it as an efficient adsorbent. Transmission electron microscope, scanning electron microscope, and imaging studies revealed that spherical magnetite particles were evenly distributed over the pine cone surface. Adsorption studies showed that the optimum pH of As (III) adsorption was 8 and that Fe (III) leaching was negligible at this pH. The optimum Fe3O4:pine cone ratio for As (III) removal was 2.0 g Fe3O4:1.5 g pine cone with adsorption capacity of 13.86 mg/g. The pseudo-second-order model best fitted the kinetic data with activation energy of adsorption was calculated to be 23.78 kJ/mol. The Langmuir isotherm described the equilibrium data best while the values of Dubinin-Radushkevich mean free energy suggests anion-exchange process. Increasing ionic strength slightly increased As (III) capacity of MNP-PCP from 13.86 to 17.82 mg/g at optimum solution pH of 8, but As (III) adsorption reduced by [Formula: see text]anions and humic acid due to competition. Adsorption mechanism was confirmed with evidence from FTIR, XPS, pHPZC, and [Formula: see text] replacement by As (III) adsorption onto the [Formula: see text]-loaded composite.
