Synthesis and Characterization of TiO2 Nanotubes (TiO2-NTs) with Ag Silver Nanoparticles (Ag-NPs): Photocatalytic Performance for Wastewater Treatment under Visible Light.

In this work, we present the influence of the decoration of TiO2 nanotubes (TiO2-NTs) with Ag silver nanoparticles (Ag-NPs) on the photocatalysis of emerging pollutants such as the antibiotic diclofenac sodium. The Ag-NPs were loaded onto the TiO2-NTs by the anodization of metallic titanium foils. Diclofenac sodium is an emerging pollutant target of the pharmaceutical industry because of its negative environmental impact (high toxicity and confirmed carcinogenicity). The obtained Ag-NP/TiO2-NT nanocomposites were characterized by X-ray diffraction (XRD), photoluminescence spectroscopy (PL), scanning electron microscopy (SEM), transmission spectroscopy (TEM), and X-ray photoelectron spectroscopy (XPS). In order to study the photocatalytic behavior of Ag-NPs/TiO2-NTs with visible cold LEDs, the possible photocatalytic mechanism of antibiotic degradation with reactive species (O2°- and OH°) was detailed. Moreover, the Langmuir-Hinshelwood model was used to correlate the experimental results with the optimized catalyst. Likewise, reuse tests showed the chemical stability of the catalyst.

Optimization of synergistic biosorption of oxytetracycline and cadmium from binary mixtures on reed-based beads: modeling study using Brouers-Sotolongo models.

The first aim of this study was to synthesize and characterize reed-based-beads (BBR), an enhanced adsorbent from Tunisian reed. The second purpose was to evaluate and optimize the BBR efficiency for the simultaneous removal of oxytetracycline (OTC) and cadmium (Cd(II)), using central composite design under response surface methodology. The third goal was to elucidate the biosorption mechanisms taking place. It was shown that under optimum conditions (4.19 g L-1 of BBR, 165.54 µmol L-1 of OTC, 362.16 µmol L-1 of Cd(II), pH of 6, and 25.14-h contact time) the highest adsorption percentages (63.66% for OTC and 99.99% for Cd(II)) were obtained. It was revealed that OTC adsorption mechanism was better described by Brouers-Sotolongo fractal equation, with regression coefficient (R2) of 0.99876, and a Person's chi-square (χ2) of 0.01132. The Weibull kinetic equation better explained Cd(II) biosorption (R2 = 0.99959 and χ2 = 0.00194). FTIR and isotherm studies confirmed that the BBR surface was heterogeneous, and that adsorption mechanisms were better described by the Freundlich/Jovanovich equation (R2 = 0.99276 and χ2 = 0.04864) for OTC adsorption, and by the Brouers-Sotolongo model (R2 = 0.9851 and χ2 = 0.77547) for Cd(II) biosorption. Overall results indicate that, at last, the BBR lignocellulosic biocomposite beads could be considered as cost-effective and efficient adsorbent, which could be of socioeconomic and environmental relevance. Graphical abstract.

Synthesis of novel biocomposite powder for simultaneous removal of hazardous ciprofloxacin and methylene blue: Central composite design, kinetic and isotherm studies using Brouers-Sotolongo family models.

Over the past decades, extensive efforts have been made to use biomass-based-materials for wastewater-treatment. The first purpose of this study was to develop and characterize regenerated-reed/reed-charcoal (RR-ChR), an enhanced biosorbent from Tunisian-reed (Phragmites-australis). The second aim was to assess and optimize the RR-ChR use for the removal of binary ciprofloxacin antibiotic (CIP) and methylene blue dye (MB), using Central Composite Design under Response Surface methodology. The third purpose was to explain the mechanisms involved in the biosorption-process. The study revealed that the highest removal-percentages (76.66 % for the CIP and 100 % for the MB) were obtained under optimum conditions: 1.55 g/L of adsorbent, 35 mg/L of CIP, 75 mg/L of MB, a pH of 10.42 and 115.28 min contact time. It showed that the CIP biosorption mechanism was described by Brouers-Sotolongo-fractal model, with regression-coefficient (R2) of 0.9994 and a Person's Chi-square (X2) of 0.01. The Hill kinetic model better described the MB biosorption (R2 = 1 and X2 = 1.0E-4). The isotherm studies showed that the adsorbent surface was heterogeneous and the best nonlinear-fit was obtained with the Jovanovich (R2 = 0.9711), and Brouers-Sotolongo (R2 = 0.9723) models, for the CIP and MB adsorption, respectively. Finally, the RR-ChR lignocellulosic-biocomposite-powder could be adopted as efficient and cost-effective adsorbent.