ABSTRACT
A new method was developed for the efficient spectrophotometric determination of methylene blue (MB) dye in solutions. The method is based on a combined dispersive solid phase and cloud point extraction using Cu(OH)2 nanoflakes (as an adsorbent). Cu(OH)2 nanoflakes were synthesized by facile and fast methods and characterized using various techniques. The developed method is based on the adsorption of MB on the Cu(OH)2 nanoflakes and transfer into a surfactant-rich phase using Triton X-114 as a nonionic surfactant. Subsequently, MB dye is desorbed from Cu(OH)2 nanoflakes using a mixture of nitric acid and methanol solution and determined by UV-Vis spectrophotometry. The effects of pH, amount of Cu(OH)2 nanoflakes, volume (concentration of Triton X-114), and temperature were investigated by designing experiments using response surface methodology (RSM). A quadratic model was utilized to predict the variables. Analysis of variance (ANOVA) was applied for the analysis of variables and their interactions, and optimal conditions were established. The results demonstrated logical agreement between experimental and predicted values of the response owing to high F value, low P value, and low lack-of-fit. The calibration graph was linear in the range of 2.0-350.0 µg L-1 of MB dye with a correlation coefficient (R) of 0.9996. The limits of detection and quantification were found to be 0.65 and 2.05 µg L-1, respectively. The developed method was successfully applied to different water samples, thereby confirming the applicability of the approach. Graphical Abstract Proposed procedure.
ABSTRACT
Novel photocatalyst membrane materials were successfully fabricated by an air jet spinning (AJS) technique from polyvinyl acetate (PVAc) solutions containing nanoparticles (NPs) of titanium dioxide (TiO2). Our innovative strategy for the production of composite nanofibers is based on stretching a solution of polymer with a high-speed compressed air jet. This enabled us to rapidly cover different substrates with TiO2/PVAc interconnected nanofibers. Surprisingly, the diameters of the as-spun fibers were found to decrease with increasing amount of NPs. Our results showed that AJS PVAc-based fibrous membranes with average fiber diameters of 505-901 nm have an apparent porosity of about 79-93% and a mean pore size of 1.58-5.12 µm. Embedding NPs onto the as-spun fibers resulted in increasing the tensile strength of the obtained composite fiber mats. The photodegradation property of TiO2 membrane mats proved a high efficiency in the decomposition of methylene blue dye. The novel fiber spinning technique discussed in this paper can provide the capacity to lace together a variety of types of polymers, fibers and particles to produce interconnected fibers layer. Our approach, therefore, opens the door for the innovation in nanocomposite mat that has great potential as efficient and economic water filter media and as reusable photocatalyst.
