Copper(II) containing chitosan hydrogel as a heterogeneous Fenton-like catalyst for production of hydroxyl radical: A quantitative study

The Fenton reaction, which generate hydroxl radical as a powerful oxidizing agent, is of interest due to its role in biological systems and wastewater treatment. However, unlike the ferrous/ferric system that is active only in acidic condition, the copper ion can operate over a wide pH range as a Fenton-like system. In this research a copper containing hydrogel (Cu/CH) was prepared by loading the Cu2+ ions into a hydrogel based on chitosan, acrylamide (AAM), and acrylic acid (AA), and used for production of hydroxyl radical in a Fenton-like reaction. The prepared catalyst was characterized by using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and energy dispersive X-ray analysis (EDAX). The catalytic activity of the hydrogels was quantitatively investigated by measuring the hydroxyl radical using the photoluminescence (PL) technique. Various parameters such as contact time, amount of metal ion, dose of hydrogen peroxide, and dose of Cu/CH were investigated. A catalytic mechanism was proposed for production of hydroxyl radical. The reusability studies showed that the Cu/CH can be reused several times without loss of its catalytic activity. In addition, various metal ions were loaded into the hydrogel and their performance in the production of hydroxyl radical were investigated.