Ni doped zinc oxide nanoparticles supported bentonite clay for photocatalytic degradation of anionic and cationic synthetic dyes in water treatment

Bimetallic metal organic framework/Ni doped ZnO nanomaterials modified carbon paste electrode for selective electrochemical determination of ciprofloxacin

In this work, an efficient and sensitive electrochemical sensor for the determination of ciprofloxacin (CIP) is reported. The sensor was prepared by using a carbon paste electrode (CPE) modified with a combination of bimetallic copper/cerium-based metal organic framework (Cu/Ce-MOF) and nickel doped zinc oxide nanoparticles (NZP). The modifiers were characterized by Brunauer-Emmett-Teller (BET) analysis, Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and elemental mapping analysis (EDS). The electrochemical behavior of the modified electrode was studied by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The developed electrode was employed for the detection of CIP by differential pulse voltammetry (DPV). Under optimal conditions, the anodic peak current response of the electrode was linearly correlated with CIP concentration in the range of 0.75-100 μmol L-1 with a sensitivity of 1.29 μA μmol-1 L-1. The limit of detection and reproducibility of the method were 0.142 μmol L-1 and 2.7%, respectively. The developed sensor showed good selectivity to CIP against possible interferents. The method was applied to determine CIP in water, milk and urine samples. The results indicated that this method has potential to be applied in the analysis of residue CIP in complex matrices with high selectivity, and good reproducibility.

Sb-Doped Cerium Molybdate: An Emerging Material as Dielectric and Photocatalyst for the Removal of Diclofenac Potassium from Aqueous Media

This work reports the influence of antimony substitution in a cerium molybdate lattice for improved dielectric and photocatalytic properties. For this purpose, a series of Ce2-xSbx(MoO4)3 (x = 0.00, 0.01, 0.03, 0.05, 0.07, and 0.09) were synthesized through a co-precipitation route. The as-synthesized materials were characterized for their optical properties, functional groups, chemical oxidation states, structural phases, surface properties, and dielectric characteristics using UV-Vis spectroscopy (UV-Vis), Fourier transform infrared (FTIR) and Raman spectroscopies, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) analysis, and impedance spectroscopy, respectively. UV-Vis study showed a prominent red shift of absorption maxima and a continuous decrease in band gap (3.35 eV to 2.79 eV) by increasing the dopant concentration. The presence of Ce-O and Mo-O-Mo bonds, detected via FTIR and Raman spectroscopies, are confirmed, indicating the successful synthesis of the desired material. The monoclinic phase was dominant in all materials, and the crystallite size was decreased from 40.29 nm to 29.09 nm by increasing the Sb content. A significant increase in the dielectric constant (ε' = 2.856 × 108, 20 Hz) and a decrease in the loss tan (tanδ = 1.647, 20 Hz) were exhibited as functions of the increasing Sb concentration. Furthermore, the photocatalytic efficiency of pristine cerium molybdate was also increased by 1.24 times against diclofenac potassium by incorporating Sb (x = 0.09) in the cerium molybdate. The photocatalytic efficiency of 85.8% was achieved within 180 min of UV light exposure at optimized conditions. The photocatalytic reaction followed pseudo-first-order kinetics with an apparent rate constant of 0.0105 min-1, and the photocatalyst was recyclable with good photocatalytic activity even after five successive runs. Overall, the as-synthesized Sb-doped cerium molybdate material has proven to be a promising candidate for charge storage devices and a sustainable photocatalyst for wastewater treatment.

Facile synthesis and physicochemical characterization of κ-Carrageenan-silver-bentonite based nanocatalytic platform for efficient degradation of anionic azo dyes

Water pollution due to textile industry effluents is a global concern that warrants versatile research solutions for degrading them, and for a sustainable environment. In the present work, by using the imperative role of nanotechnology, a facile one-pot synthesis has been devised to generate κ-carrageenan capped silver nanocatalyst (CSNC), and was immobilized on 2D bentonite (BT) sheets to generate nanocatalytic platform (BTCSNC) for the degradation of anionic azo dyes. The nanocomposite(s) were physicochemically characterized using UV-Vis, DLS, TEM, FESEM, PXRD, ATR-FTIR, TGA, BET and XPS etc., to obtain insights into the nanocomposite composition, structure, stability, morphology and mechanism of interaction. The obtained CNSC are monodispersed, spherical with a size of 4 ± 2 nm, and were stabilized by the functional groups (-OH, COO‾, and SO3‾) of κ-Crg. The broadening of peak corresponding to basal plane (001) of BT montmorillonite in PXRD spectra established its exfoliation upon addition of CSNC. XPS and ATR-FTIR data evidenced the absence of covalent interactions between CSNC and BT. The catalytic efficiency of CSNC and BTCSNC composites were compared for the degradation of methyl orange (MO) and congo red (CR). The reaction followed a pseudo first order kinetics, and immobilization of CSNC on BT resulted in a 3-4 fold enhancement in degradation rates. The rates achieved for the degradation kinetics are: MO degradation within 14 s (Ka 9.86 ± 2.00 min-1), and CR degradation within 120 s (Ka of 1.24 ± 0.13 min-1). Further, a degradation mechanism has been proposed by analyzing the products identified through LC-MS. The reusability studies of the BTCSNC evidenced the complete activity of the nanocatalytic platform for six cycles, and gravitational separation method for catalyst recycling. In a nutshell, the current study provided an environmentally friendly, sizable, and sustainable nano catalytic platform" for the remediation of industrial wastewater contaminated with hazardous azo dyes".

Degradation of cefadroxil drug by newly designed solar light responsive alcoholic template-based lanthanum ferrite nanoparticles

In this work, lanthanum ferrite nanoparticles were synthesized via a simple co-precipitation method. Two different templates, namely sorbitol and mannitol, were used in this synthesis to tune the optical, structural, morphological, and photocatalytic properties of lanthanum ferrite. The synthesized lanthanum ferrite-sorbitol (LFOCo-So) and lanthanum ferrite-mannitol (LFOCo-Mo) were investigated through Ultraviolet-Visible (UV-Vis), X-ray diffraction (XRD), Fourier Transform Infra-Red (FTIR), Raman, Scanning Electron Microscopy-Energy Dispersive X-ray (SEM-EDX), and photoluminescence (PL) techniques to study the effects of the templates on the tunable properties of lanthanum ferrite nanoparticles. The UV-Vis study revealed a remarkably small bandgap (2.09 eV) of LFOCo-So compared to the LFOCo-Mo having a band gap of 2.46 eV. XRD analysis revealed a single-phased structure of LFOCo-So, whereas LFOCo-Mo showed different phases. The calculated crystallite sizes of LFOCo-So and LFOCo-Mo were 22 nm and 39 nm, respectively. FTIR spectroscopy indicated the characteristics of metal-oxygen vibrations of perovskites in both lanthanum ferrite (LFO) nanoparticles, whereas a slight shifting of Raman scattering modes in LFOCo-Mo in contrast to LFOCo-So showed the octahedral distortion of the perovskite by changing the template. SEM micrographs indicated porous particles of lanthanum ferrite with LFOCo-So being more uniformly distributed, and EDX confirmed the stoichiometric ratios of the lanthanum, iron, and oxygen in the fabricated lanthanum ferrite. The high-intensity green emission in the photoluminescence spectrum of LFOCo-So indicated more prominent oxygen vacancies than LFOCo-Mo. The photocatalytic efficiency of synthesized LFOCo-So and LFOCo-Mo was investigated against cefadroxil drug under solar light irradiation. At optimized photocatalytic conditions, LFOCo-So showed higher degradation efficiency of 87% in only 20 min than LFOCo-Mo having photocatalytic activity of 81%. The excellent recyclability of the LFOCo-So reflected that it could be reused without affecting photocatalytic efficiency. These findings showed that sorbitol is a useful template for the lanthanum ferrite particles imparting outstanding features, enabling it to be used as an efficient photocatalyst for environmental remediation.

Improvement of photocatalytic degradation of methyl orange by impregnation of natural clay with nickel: optimization using the Box-Behnken design (BBD)

In this research work, the photocatalytic degradation of methyl orange dye was studied on nickel oxide supported on a natural Moroccan clay (Ni/NC). These catalysts have been prepared by dry impregnation of a nickel nitrate solution with different weight percentages (5, 10, 20% NiO). Experimental responses were obtained by a Box-Behnken (BBD) experimental design by varying the catalyst mass, solution pH, and initial dye concentration at three levels (low, medium, and high). The prepared catalysts were characterized using powder X-ray diffraction (XRD) to assess crystallinity and structure, Fourier transform infrared spectroscopy (FTIR) to detect different functional groups, scanning electron microscopy (SEM) combined with energy dispersive X-ray (EDX) analysis to study the surface morphology, and the optical characteristics of the catalysts were studied using absorption and diffuse reflectance measurements in the UV-visible range. The photocatalytic activity of the catalysts was evaluated in aqueous solutions under UV irradiation. ANOVA (analysis of variance) test is employed to recognize the significant factors and their interactions and then give the model equation for the percent dye degradation. The optimal values of the studied factors were determined by numerical optimization, and the results showed that about 100% degradation of the methyl orange dye could be achieved under the following optimal conditions, which are pH = 4.38, catalyst concentration of 0.99 g/L, and initial dye concentration of 30.42 mg/L.

Plant-based green fabrication of CuO-CdO-bentonite S-scheme heterojunction with enhanced photocatalytic performance for the degradation of levofloxacin

In this research, for the first time, CuO and CdO nanoparticles (NPs) were synthesized using Ferula persica and anchored on layered bentonite as a novel S-scheme nano-heterojunction (denoted as CuO-CdO-BT). Ferula persica acted as a naturally-sourced reducing agent and stabilizer for the synthesis of NPs. The performance of CuO-CdO-BT was evaluated for the degradation of levofloxacin from an aqueous solution under sunlight. The characterization results clarified that the bentonite as a support not only reduced the agglomeration of CuO and CdO NPs but also decreased the size of biosynthesized NPs, which increased the active surface of NPs and the photodegardation efficiency. The effect of operational reaction system variables was examined to optimize the photocatalytic capability of CuO-CdO-BT. Under optimum conditions (catalyst dosage = 0.4 g/L, LVF concentration = 10 mg/L and pH = 8), 96.11% of levofloxacin was degraded using CuO-CdO-BT after 30 min with degradation kinetic of 0.108 min-1, which was about 2.4 and 4.2 times higher than those of bare CuO and CdO NPs, respectively. The improvement of the photocatalytic degradation efficiency of CuO-CdO-BT compared to CuO and CdO NPs was due to preventing the recombination of charge carriers in the S-scheme system. The radical quenching experiments ascertained the generation of [Formula: see text]·OH, and [Formula: see text] species in the CuO-CdO-BT system, indicating that ·OH radicals have a more prominent role than [Formula: see text] and [Formula: see text] in the photocatalytic reaction. The six possible levofloxacin pathways of LVF degradation were suggested based on HPLC-MS analysis. Over 88.5% LVF was removed using CuO-CdO-BT after three catalyst reuse cycles, indicating a cost-effectiveness potential of the biosynthesized photocatalyst reusability. Almost complete mineralization of LVF was obtained by the CuO-CdO-BT photocatalyst after 180 min of reaction. Based on findings, the S-scheme mechanism of photo-generated electron-hole pairs transfer in the CuO-CdO-BT system was found. The unique structural features of the new generation of S-scheme heterojunction and green synthesis of NPs using plants provide promising photocatalysts to improve wastewater treatment.