Acrylate-based Polymerizable Sol–Gel Synthesis of Magnetically Recoverable TiO₂ Supported Fe₃O₄ for Cr(VI) Photoreduction in Aerobic Atmosphere

Abstract

TiO2 synthesized by polymerizable sol–gel approach is used to demonstrate the photoreduction of Cr­(VI) in aqueous medium. Fe3O4 is chosen as the magnetically recoverable support, onto which, 10, 20, 30 and 50% of TiO2 have been dispersed following the polymerizable sol–gel approach. The synthesized materials are characterized using XRD, SEM, XPS, Raman spectroscopy, diffuse reflectance spectroscopy and BET surface area measurement. Different hole-scavengers (oxalic acid, ammonium oxalate and ethanol) and an electron scavenger (potassium periodate) have been studied to compare the efficiency of Cr­(VI) photoreduction in nitrogen as well as air atmosphere. With 5 mM oxalic acid as the hole-scavenger, the TiO2/Fe3O4 materials have demonstrated superior activity to the nonsupported bulk TiO2 toward Cr­(VI) photoreduction in aerobic atmosphere. Particularly, 30% TiO2/Fe3O4 has shown the highest Cr­(VI) photoreduction rate among the lot. The 30% TiO2/Fe3O4 catalyst has also demonstrated good recoverability as well as recyclability.

Oxygen insensitive thiol–ene photo-click chemistry for direct imprint lithography of oxides

“…A major peak at 121 cm À1 along with weak peaks at 365, 482, and 603 cm À1 were observed in all cases that can be attributed to the respective vibrational symmetries of E g , B 1g , A 1g , and E g Raman-active modes of anatase TiO 2. 57,65 Due to the presence in minute quantity, the Raman peaks of rutile TiO 2 were not observed in the samples calcined at 600 and 650 C.…”

“…The PSG approach has been shown to be suitable for high-throughput step-and-ash imprint lithography for various oxides 55 and to synthesize supported oxide photo-catalysts. 56,57 Despite the high potential, the PSG approach based on free radical polymerization of methacrylates is vulnerable to radical scavenging by oxygen that could affect the degree of polymerization, which in turn could effect on the quality of imprinting. This warrants purging/bubbling of inert gas into the metal-containing resin before patterning in order to eliminate any dissolved oxygen.…”

Cr(VI) remediation from aqueous environment through modified-TiO2-mediated photocatalytic reduction

“…Therefore, the composite photocatalysts exhibited a higher rate of photoreduction of Cr(VI) as compared to the nonsupported bulk TiO 2 as well as calcined Fe 3 O 4 . In fact, 30% TiO 2 /Fe 3 O 4 has shown the highest Cr(VI) photoreduction rate due to formation of effective heterojunction by the loading of 30% TiO 2 over Fe 3 O 4 [158]. …”

“…The percentage removal of Cr(VI) was found to be 93%, 88%, and 80% for the first, second and third cycles, respectively, for TiO 2 /CdS films, indicating its high photostability [200]. Challagulla et al reported that TiO 2 /Fe 3 O 4 composite photocatalysts retained their efficiency towards reduction of Cr(VI) after the fourth cycle [158]. About 84% of it was recovered at the end of the fourth cycle.…”

Scalable Free-Radical Polymerization Based Sol-Gel Synthesis of SrTiO3 and its Photocatalytic Activity

“…On the other hand, Cr(VI) is a highly hazardous species and possesses acute toxicity as a carcinogen. Conversion of Cr(VI) to Cr(III) is considered to be a green process, as the latter is an essential metabolite for the insulin function . Figure (a) shows the photocatalytic degradation of methylene blue under UV light with 500, 700 and 900 °C calcined SrTiO 3 and the ball milled samples.…”