RESUMO
Biosorption is a bioremediation approach for the removal of harmful dyes from industrial effluents using biological materials. This study investigated Methylene blue (M. blue) and Congo red (C. red) biosorption from model aqueous solutions by two marine macro-algae, Ulva fasciata and Sargassum dentifolium, incorporated within acrylic fiber waste to form composite membranes, Acrylic fiber-U. fasciata (AF-U) and Acrylic fiber-S. dentifolium (AF-S), respectively. The adsorption process was designed to more easily achieve the 3R process, i.e., removal, recovery, and reuse. The process of optimization was implemented through one factor at a time (OFAT) experiments, followed by a factorial design experiment to achieve the highest dye removal efficiency. Furthermore, isotherm and kinetics studies were undertaken to determine the reaction nature. FT-IR and SEM analyses were performed to investigate the properties of the membrane. The AF-U membrane showed a significant dye removal efficiency, of 88.9% for 100 ppm M. blue conc. and 79.6% for 50 ppm C. red conc. after 240 min sorption time. AF-S recorded a sorption capacity of 82.1% for 100 ppm M. blue conc. after 30 min sorption time and 85% for 100 ppm C. red conc. after 240 min contact time. The membranes were successfully applied in the 3Rs process, in which it was found that the membranes could be used for five cycles of the removal process with stable efficiency.
RESUMO
In this study, zinc oxide nanoparticles (ZnO-NPs) were successfully fabricated through the harnessing of metabolites present in the cell filtrate of a newly isolated and identified microalga Arthrospira platensis (Class: Cyanophyceae). The formed ZnO-NPs were characterized by UV-Vis spectroscopy, Fourier transform infrared (FT-IR), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDX), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Data showed the efficacy of cyanobacterial metabolites in fabricating spherical, crystallographic ZnO-NPs with a size ≈30.0 to 55.0 nm at a wavelength of 370 nm. Moreover, FT-IR analysis showed varied absorption peaks related to nanoparticle formation. XPS analysis confirms the presence of Zn(II)O at different varied bending energies. Data analyses exhibit that the activities of biosynthesized ZnO-NPs were dose-dependent. Their application as an antimicrobial agent was examined and formed clear zones, 24.1 ± 0.3, 21.1 ± 0.06, 19.1 ± 0.3, 19.9 ± 0.1, and 21.6 ± 0.6 mm, at 200 ppm against Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Candida albicans, respectively, and these activities were reduced as the NPs concentration decreased. The minimum inhibitory concentration (MIC) values were determined as 50 ppm for S. aureus, 25 ppm for P. aeruginosa, and 12.5 ppm for B. subtilis, E. coli, and C. albicans. More interestingly, ZnO-NPs exhibit high in vitro cytotoxic efficacy against cancerous (Caco-2) (IC50 = 9.95 ppm) as compared with normal (WI38) cell line (IC50 = 53.34 ppm).
