Synthesis of coal fly ash zeolite for the catalytic wet peroxide oxidation of Orange II

• Published in: Environmental science and pollution research international 2019-02, Vol.26 (5), p.4277-4287
• Main Authors: Ramírez, Herney, Núñez, María Margarita Guerra, Bogoya, Anamaria Barrera, Gomez, Daniel Fernando Blanco, Ramos, Cinthia, di Luca, Carla, Inchaurrondo, Natalia, Haure, Patricia
• Format: Article
• Language: English
• Subjects: Advanced Oxidation Technologies: State-of-the-Art in Ibero-American Countries; Aluminum; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Azo Compounds - chemistry; Batch reactors; Benzenesulfonates - chemistry; Catalysis; Catalysts; Chemical synthesis; Coal Ash - chemistry; Colombia; Discoloration; Earth and Environmental Science; Ecotoxicology; Environment; Environmental Chemistry; Environmental Health; Environmental science; Fly ash; Homogeneous mixtures; Hydrogen peroxide; Hydrogen Peroxide - chemistry; Hydrogen-Ion Concentration; Hydrothermal treatment; Iron; Microscopy, Electron, Scanning; Mineralization; Mossbauer spectroscopy; Orange II; Oxidants - chemistry; Oxidation; Oxidation-Reduction; Oxidizing agents; Peroxides - chemistry; Sodium hydroxide; Spectroscopy, Mossbauer; Surface area; Waste Water Technology; Water Management; Water Pollution Control; X-Ray Diffraction; Zeolites; Zeolites - chemical synthesis; Zeolites - chemistry
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-018-3315-1

Fly ash, a coal combustion residue produced by Termotasajero in Colombia, has been hydrothermally treated after an alkaline fusion to produce zeolite without addition of silicon or aluminum. The starting material was thoroughly mixed with NaOH, in a 1:1.2 mass ratio, to obtain a homogeneous mixture that was heated to 100 °C during different times (6, 8, and 10 h) and three zeolite samples were produced. The samples were characterized by XRD, SEM, XRF, Mössbauer spectroscopy, and N 2 physisorption. According to characterization results (high surface area and appropriate morphological properties including crystallinity) and synthesis time, zeolitic catalyst synthesized with 8 h of hydrothermal treatment was selected to perform further analysis. This sample consisted of a mixture of zeolite X and zeolite A of high surface area (301 m 2  g −1 ) and a Fe content of 6% wt/wt. The zeolite was used as a catalyst for the Fenton oxidation of Orange II. Experiments were performed in a laboratory batch reactor at 70 °C and constant pH = 3, using different concentrations of H 2 O 2 . When the stoichiometric amount of H 2 O 2 was used, good mineralization ( X TOC  = 45%), complete discoloration, and oxidant consumption were obtained after 240 min of reaction. The sample retained activity after 16 h of usage. The presence of Fe in the reaction media was always detected and a homogeneous Fenton mechanism induced by surface-leached iron is suggested.