Photocatalytic degradation of cefixime using visible light-driven Z-scheme ZnO nanorod/Zn2TiO4/GO heterostructure.

ZnO nanorod along with a Zn2TiO4/GO heterostructure with enhanced charge transfer capability was synthesized by a facile sol-gel method. FT-IR, XRD, XPS, TEM, SEM, EDX, UV-Vis DRS, photocurrent response and PL analyses were applied to characterize the as-prepared photocatalysts. To investigate the photocatalytic activity of the composite, Cefixime (CEF) removal under visible light was evaluated. The ZnO nanorod/Zn2TiO4/GO, including 65 wt% ZnO and 3 wt% graphene oxide, showed the highest CEF degradation and was selected as the optimal ternary composite. Reduction of electron-hole pair recombination rate, successful interfacial charge transfers, and more visible light reception in the Z-scheme system were the important reasons for improving the photocatalytic properties of ZnO nanorod/Zn2TiO4/GO. Effective operating parameters in the CEF photocatalytic removal process were optimized employing the response surface method and were as follows: photocatalyst dosage = 0.88 g/L, pH = 5, radiation time = 115 min, and CEF concentration = 10 ppm. The photocatalytic degradation% of CEF and total organic carbon (TOC) removal% under the optimal conditions were 71.4 and 57.5%, respectively, for the three-component composite indicating the production of intermediate species during the process. This photocatalytic reaction confirmed the first-order kinetic and using the ZnO nanorod/Zn2TiO4/GO composite was able to improve the reaction rate by about 2.7 and 6.2 times more than ZnO nanorod/Zn2TiO4 and ZnO, respectively. The effects of radiation intensity and temperature were investigated and 175 W/m2 and 35 °C were obtained as optimum values. Eventually, according to the trapping test, h+, superoxide radical, and hydroxyl radical are the most effective active species in this photocatalytic reaction, respectively.

Adsorptive removal of ibuprofen to binary and amine-functionalized UiO-66 in the aquatic environment: synergistic/antagonistic evaluation.

The removal of ibuprofen (IBP) from the aqueous solution by metal-organic frameworks such as UiO-66, UiO-66-NH2, and a binary MOF (UiO-66@5%HKUST-1) was studied. MOFs were synthesized by the solvothermal method. The synthesized MOFs were characterized by Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and N2 adsorption. BET results showed that binary MOF and UiO-66-NH2 had a smaller surface area and were mesoporous compared to UiO-66, while UiO-66 was microporous. Quantitative investigations were conducted to understand the effect of binary and functional UiO-66 in adsorbing IBP and compared to UiO-66. The results showed that UiO-66 with 213 mg/g had the highest adsorption in comparison to other adsorbents. UiO-66-NH2 showed the lowest adsorption (96 mg/g) due to a large decrease in the surface area. The binary MOF, despite a slight decrease in surface area (1277.6 m2/g), had lower adsorption than UiO-66 (147 mg/g) due to the antagonistic effects between the adsorbent and IBP. Furthermore, the pH of the solution had a great effect on the adsorption of IBP, and the results showed that increasing the pH values above 4 reduced the adsorption of IBP.

Synthesis of aqueous media stable MIL101-OH/chitosan for diphenhydramine and metronidazole adsorption.

In this study, pristine MIL101(Cr) was modified to synthesize hydroxyl-functionalized (MIL101(Cr)-OH) and chitosan (CS)-coated (MIL101(Cr)-OH/CS) metal-organic frameworks (MOFs) to enhance adsorption capacity and reusability, respectively. The synthesized adsorbents were characterized by XRD, FTIR, and BET analyses. The kinetics behavior and the equilibrium adsorption of diphenhydramine (DPH) and metronidazole (MNZ) from aqueous solution on the synthesized adsorbents and a commercial activated carbon were compared at 25°C. The pH-dependent of the adsorption capacity and reusability of MIL101-OH/CS were investigated. The results showed that upon adding OH functional group and chitosan polymer, the adsorption capacity increased; the DPH adsorption capacity on MIL101-OH and MIL101-OH/CS was 634 and 573 mg/g, respectively. Also, the maximum adsorption capacity of MNZ on MIL101-OH/CS was 600 mg/g, which was twice the adsorption capacity of MIL101 and four times the adsorption capacity of the commercial activated carbon. The equilibrium and kinetics behavior results were in good agreement with Langmuir and the pseudo-second-order models, respectively. The DPH and MNZ adsorption mechanisms on MIL101-OH/CS were hydrogen bonding and electrostatic interactions, respectively.

Production of doxorubicin-loaded PCL nanoparticles through a flow-focusing microfluidic device: encapsulation efficacy and drug release.

The present study shows a facile route for producing doxorubicin (DOX)-loaded polycaprolactone (PCL) nanoparticles using a microfluidic device with a flow-focusing platform in a single step. Indeed, the evaluation of the performance of the flow-focusing microfluidic device for the preparation of DOX-loaded PCL (DOX/PCL) nanoparticles with a uniform size distribution and high encapsulation efficiency (EE) by applying the liquid non-solvent precipitation process is very important. Accordingly, the physicochemical characteristics of the DOX/PCL nanoparticles such as their mean size, polydispersity index (PDI), and EE were investigated by studying different parameters such as the flow rate ratio (FRR) and DOX concentration. Also, the release study was carried out at two pH of 5.5 and 7.4. The mean size of DOX/PCL nanoparticles achieved was in the range of 120-320 nm with a PDI ≤ 0.29 and EE between 48% and 87%. Moreover, the release profile of DOX/PCL nanoparticles was sustained for 10 days (≤66%) at pH 7.4. This means that the production process can result in a high EE and low release of the DOX drug.

Synthesis and characterization of Fe2O3 doped ZnO supported on clinoptilolite for photocatalytic degradation of metronidazole.

ZnO/Fe2O3/Clinoptilolite photocatalyst was synthesized through sol-gel method. The photocatalyst was characterized by XRD, XRF, EDX, FE-SEM, FT-IR, BET and UV-VIS DRS analyses. According to the XRD, FT-IR, and EDX results, the presence of ZnO and Fe2O3 was confirmed on the clinoptilolite surface. Based on the XRF results, the molar ratio of Fe3+/ZnO in the photocatalyst was obtained as 0.06. The FE-SEM results confirmed stabilization of ZnO/Fe2O3 on the clinoptilolite surface. Based on the BET results, the surface area and pore volume for the photocatalyst were obtained as 291.35 m2/g and 0.23 cm3/g, respectively. According to the UV-VIS DRS results, the band gap energy of the photocatalyst was measured as 3.38 eV. The performance of the synthesized photocatalyst in degrading metronidazole from contaminated water, as one of the most widely used antibiotics in pharmaceutical industries, was evaluated by response surface methodology. Operational factors including pH (4-10), metronidazole concentration (1-100 mg/l), irradiation time (45-180 min), photocatalyst concentration (0.5-2 g/l), and H2O2 concentration (25-100 mg/l) were investigated. The optimal values of the factors in degrading 99% of the contaminant were as follows: irradiation time = 90 min, photocatalyst concentration = 1 g/l, pH = 10, H2O2 concentration = 40 mg/l, and MNZ concentration = 60 mg/l.