Nanoparticles of HNO 3 -Treated Clinoptilolite Load with Iron: An Innovative Approach for Magnetic Recovery of Fenton Catalyst

The heterogeneous Fenton process is a promising technology for the removal of persistent pollutants in aqueous media. However, the development of solid catalysts that do not leach iron particles from the structure, that can be easily recovered and used in multiple reaction cycles is still a challenge. Therefore, the objective of this study was to propose the design of a new heterogeneous Fenton catalyst supported on pre-treated clinoptilolite nanoparticles with HNO 3 , with magnetic recovery. The zeolite was reduced to nanoparticles using a ball mill and then pre-treated with nitric acid in a reflux system. Iron particles were fixed on the support through the wet impregnation method, and the material was subjected to physicochemical characterization. The catalytic activity was tested in the degradation of the textile dye Reactive Blue (RB250) under batch conditions, and different effects were evaluated. The results showed that the modifications on the clinoptilolite support enhanced its specific surface area and pore volume, while Mössbauer results confirmed that the applied synthesis process resulted in excellent magnetic catalysts that can be easily recovered. The 15Fe/CPGT catalyst completely degraded the contaminant in 60 min, following pseudo-second-order kinetics (k = 1.14 L g −1 .min −1 ). The reuse tests indicated the ease of removing the catalyst particles through magnetism and high catalytic performance even after eleven consecutive runs. Toxicological tests and chemical parameters such as TOC and COD confirmed the reduction of effluent toxicity. Finally, the developed magnetic Fenton catalyst is a material with high catalytic potential for application in the Fenton-like process. Graphical Abstract