Zeolite supported iron nanoparticles for the catalytic Fenton oxidative remediation of theophylline in aqueous medium

Pharmaceutical active compounds (PhACs) are an emerging class of contaminants found in water and wastewater. The objective of this study was to develop and test a novel catalyst for the treatment of theophylline - a commonly occurring xanthine (a PhAC) for heterogeneous Fenton oxidation (HFO). The catalyst used was iron nanoparticle-loaded zeolite developed through coprecipitation of iron salts. Elemental composition, particle size and its distribution and Brunauer-Emmett-Teller surface area of the catalyst were determined. The deposition of iron nanoparticles was ensured through Fourier-transform infrared spectroscopy and X-ray diffraction techniques. Effect of treatment variables (pH, iron to oxidant ratio, and oxidation time) was evaluated through batch mode oxidation experiments. The experimental design was carved using response surface methodology and optimization done using Design-Expert v. 10.0 software. pH and iron to oxidant ratio were determined to be the most influencing parameters for theophylline removal. Moreover, it was observed that interaction between pH and iron to oxidant ratio, significantly affects the theophylline removal. Effective theophylline removal (similar to 95%) was observed at pH 7, oxidation time of 60 min and iron to oxidant ratio of 3. Theophylline was transformed into its degradation product, that is, 1,3-methyluric acid after heterogeneous Fenton oxidation of theophylline. The developed catalyst was stable, durable and reusable for at least three experimental runs without compromising the catalyst performance. The treatment cost of theophylline using HFO was $14.41/m(3).