Mechanically Activated Covalent Organic Framework as Metal Free Photocatalyst for Continuous Flow Fenton-like Degradation of Organic Pollutants and Hexavalent Chromium Reduction

Abstract

A highly active photocatalyst is unveiled for the Fenton-like reactions in visible light. A metal-free covalent organic framework (COF) was highly active via a novel mechanical pulverization process. Under visible light, the activity of pulverized COF reached an apparent quantum yield of 41% for Fenton-like degradation. The exceptional performance is due to the conduction band's induced high excited electron density. The outstanding performance does not require pH adjustment by external means, unlike metal-based photocatalysts. The pulverized COF can be recycled up to five times. For industrial scale implementation, the photocatalyst outperformed in a continuous flow channel. The photocatalytic space-time yield (PSTY) was increased by 28 times over conventional batch photocatalysis. For successful chemical reactions, an exceedingly small amount of photocatalyst is required. Additionally, a very high photoreduction rate was also observed for hexavalent chromium, which was significantly better than the parent COF.

Continuous flow synthesis of Ag-PEDOT-COF nanocomposite for sustainable photoreforming of plastic waste and chromium remediation in visible light

“…The photoreduction of Cr (VI) to Cr (III) was analysed using 1,5diphenylcarbazide (DPC) based method in UV spectrophotometer. [25,27] A complex is formed between Cr (VI) and DPC which shows a characteristic absorption peak at λ=540 nm.…”

Metal-free Conjugated Polyphenothiazine Nanostructures as Visible Light Active Photocatalysts for the Removal of Organic Pollutants and Selective Aerobic Oxidation of Sulfides

“…Photocatalysis using visible light offers an environmentally benign way to activate molecular oxygen. [6][7][8] Photocatalysts can activate molecular oxygen into several oxidizing species such as superoxide (O2 •-), singlet oxygen ( 1 O2), and hydroxyl radicals ( • OH). 9,10 Several metal-based photocatalysts are already reported for the activation of molecular oxygen.…”