جستجوی مقالات مرتبط با کلیدواژه « photocatalysts » در نشریات گروه « مواد و متالورژی »

In this study, CoFe2O4  (CoF) and ZnFe2O4 (ZnF) photocatalysts were successfully prepared by a facile and simple chemical precipitation method for degradation of methylene blue (MB) and methyl orange (MO) dyes under direct sunlight irradiation. The obtained ferrites were then characterized through XRD, TEM, EDS, UV-vis, and SEM. XRD and TEM results exhibited cubic nanostructures with sizes ranging from 9 to 16 nm and 11 to 18 nm for ZnF and CoF, respectively. SEM images showed homogenous, porous flat surfaces. EDS spectra confirmed the successful synthesis of ZnF and CoF nanostructures with high purity. UV-vis spectra results of MB and MO dyes showed maximum sunlight absorbance in the absence of ZnF and CoF, while a regular decrease in the sunlight absorbance was observed in the presence of ZnF and CoF within 15-60 min. The UV-vis results also showed that ZnF had higher photocatalytic activity than CoF. The experimental findings showed that the highest % degradation was 92.89% and 96.89% for MO and MB dyes, respectively, over ZnF compared to CoF photocatalyst (87.55% and 88.41% for MO and MB, respectively). These findings confirm that porous ZnF and CoF nanostructures are critical in promoting the degradation of dyes under sunlight instead of UV-vis light lamps that consume/require electrical energy.

Photocatalyst nanocomposites of ZnO/bentonite clay are synthesized by Solid-state ion exchange method. Ion exchange intercalation process of clays is used to incorporate the catalyst into the basal space of the layered structure of clays. The purpose of this study is to find a new method, which is focused on simplifying and saving time to prepare ZnO-bentonite composite with photocatalyst property. The synthesis of ZnO-doped bentonite nanocomposite is accomplished by placing bentonite in a melting bath of ZnSO4 for 10, 20, 40, 60 and 90 min. The nanocomposites are characterized by morphological (SEM), optical (UV/vis reflection) and analytical (EDX) techniques. According to SEM results, after ion exchanging, the parent structure of bentonite remains and only the distance between flakes increased significantly. EDX analysis clearly suggest the success of ion exchange of the expense of Ca2+, Na+ and Mg2+ cations with Zn2+. The calculated band gap for the composites were 3.14 eV (10 min), 2.64 eV (20 min) and 2.54 eV at longer times, respectively. All the prepared composites showed acceptable degradation performances. The greatest photocatalytic activity is detected in ZnO/bentonite composite solid-state ion exchanges which lasts 60 and 90 min. Leaching test results showed that the concentrations of Zn are less than 4 mg/l between 0 and 6 h. These results indicated that the photocatalytic property of composites would last longer