Selcan Karakuş

Single and binary adsorption of reactive dyes from aqueous solutions onto clinoptilolite

The adsorption of Reactive Blue 21 (RB21) and Reactive Red 195 (RR195) onto clinoptilolite type natural zeolite (ZEC) has been investigated at 298.15K. The uptake of single and binary reactive dyes from aqueous solutions has been determined by UV-vis spectroscopy. Two mono-component (RB21 and RR195) and binary component (RB21 with RR195, and RR195 with RB21), isotherms were determined. The mono-component Langmuir isotherm model was applied to experimental data and the isotherm constants were calculated for RB21 and RR195 dyes. The monolayer coverage capacities of clinoptilolite for RB21 and RR195 dyes in single solution system were found as 9.652 and 3.186 mg/g, respectively. Equilibrium adsorption for binary systems was analyzed by using the extended Langmuir models. The rate of kinetic processes of single and binary dye systems onto clinoptilolite was described by using two kinetics adsorption models. The pseudo-second-order model was the best choice among the kinetic models to describe the adsorption behaviour of single and binary dyes onto clinoptilolite.

Highly sensitive electrochemical determination of captopril using CuO modified ITO electrode: the effect of in situ grown nanostructures over signal sensitivity

The study describes a new approach for the direct electro-oxidation of captopril (CAP) drug using a CuO modified ITO electrode. The modified ITO electrode consists of an in situ grown film which accommodates dense CuO nanostructures with morphological features similar to flowers. The in situ growth over the ITO substrate was achieved using a simple hydrothermal route with the assistance of malonic acid which acted as an effective growth template. The devised electrode was evaluated in reference to its slurry-derived counterpart which involved surface modification of GCE using a conventional approach (drop-casting). The competitive evaluation of the discussed electrodes against the electro-oxidation of CAP, provided significant evidence to support the importance of controlled nanostructure distribution over the electrode surface to achieve higher signal sensitivity and reproducibility. The devised ITO/CuO electrode was known to possess excellent sensing capability against CAP within the linear working range of 0.01 to 3.43 μM with signal sensitivity down to 2 × 10−3 μM. Moreover, the ITO/CuO was noted to exhibit high charge transfer co-efficient (α), diffusion co-efficient (D) and rate constant values of 0.83, 9.28 × 10−5 cm2 s−1 and 3.5 × 103 mol−1 L s−1 respectively. In addition, the successful usage of ITO/CuO for CAP determination from commercial tablets and human urine samples further indicated the practical workability of the proposed electrode system.

Investigation of the in vitro cytotoxic effects and wound healing activity of ternary composite substance (hollow silica sphere/gum arabic/methylene blue)

We aimed to test the adsorption of the methylene blue (MB) on HSEPCGUM as a dye and also to test the obtained ternary biocomposite substance (HSEPCGUM-MB) on wound healing. Hollow silica spheres (HSS) are used in the pharmaceutical and biochemical field, because of low toxic, highly biocompatible and mechanically stable by large surface areas. HSS was obtained by mechanochemistry method. The obtained HSS was treated with epichlorohydrin to carry out an epoxidation process (HSEPC). Then, HSEPC was functionalized by treatment with gum arabic (HSEPCGUM). MB was adsorbed onto HSEPCGUM and the adsorption maximum capacity of HSEPCGUM (Xmax) was obtained 333 mg g-1. For in vitro studies, according to the cytotoxicity test results, ternary biocomposite substance (HSEPCGUM-MB) was studied at non-cytotoxic concentrations 10, 50 and 100 μg/ml and wound closure was found as 55% (100 μg/ml) as compared to control.

Photocatalytic Degradation of Azo Dyes and Organic Contaminants in Wastewater Using Magnetically Recyclable Fe 3 O 4 @UA-Cu Nano-catalyst

In this study, we delineated the structural properties and catalytic behavior of nanocrystalline Fe3O4@Urocanic acid(UA)–Cu magnetically recyclable nanocatalyst (MRCs) which was produced via hydrothermal route. Here, Urocanic acid (UA) used as a linker to attach Cu nanoparticles and stabilized the iron oxide. Structural properties were examined through Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDX). Moreover, thermal and magnetic properties of MRCs were completed using thermal gravimetry (TG) and vibrating sample magnetometry (VSM) respectively. Moreover, the catalytic studies of product were recorded by UV–Vis absorption spectrophotometer for azo dyes and aromatic nitro compounds. The synthesized MRCs was found as an efficient nanocatalyst and magnetically recyclable from the reaction medium without significantly loss in its catalytic activity. Fe3O4@UA-Cu MRCs can be considered for the treatment of industrial dyes pollutants and organic contaminants from wastewater.Graphical AbstractProposed mechanism of photocatalysis degradation of dye by Fe3O4@UA-Cu MRCs.

Formation and distribution of ZnO nanoparticles and its effect on E. coli in the presence of sepiolite and silica within the chitosan matrix via sonochemistry

In this study, a new bio-nanocomposite was prepared and characterized with a focus on the formation of hexagonal ZnO and orthorhombic zinc silicate (Zn2SiO3(OH)2) phases under ultrasonic irradiation. Chitosan/sepiolite/ZnO and chitosan/silica/ZnO bio-nanocomposites were synthesized using a simple solution method in which extreme physical and chemical conditions created by cavitation within the chitosan solution allowed for the transformation of aqueous Zn(OH)2 to crystallized ZnO and Zn2SiO3(OH)2 in room temperature. Both the loading of sepiolite and silica with the zinc precursor significantly influenced the morphology and crystalline structure of the product, however, different zinc compounds were observed. Sepiolite was exfoliated, resulting in a fine, even colloidal solution through ultrasonic dispersion. Exfoliation of sepiolite nanofibers led to the homogeneous dispersion of Zinc in the form of Zn(OH)2 in chitosan matrix. When the same procedure was conducted using the silica component, a formation of ZnO and Zn2SiO3(OH)2 was observed, components that were not observed when the procedure was conducted using sepiolite. The average crystalline size of ZnO was calculated as 36nm for ZnO. In addition, the quantities of crystalline and the ZnO phase volume was determined as 15%. Through zone of inhibition, the silica nanocomposite was discovered to have antibacterial activity. In contrast, the sepiolite compound did not exhibit these properties. We thus hypothesize that HO radicals, formed during ultrasonic irradiation trigger the formation of a silicate ion (SiO32-) and formation of ZnO and Zn2SiO3(OH)2 species in chitosan/silica/ZnO bio-nanocomposite, which causes to exhibit these antibacterial properties against Gram-negative E. coli. Chemical characterization and dispersion of the structure of the ZnO and Zn2SiO3(OH)2 phases were done using X-ray diffraction (XRD) and scanning electron microscopy techniques (SEM) with EDAX and X-ray photoelectron spectroscopy (XPS).