Advanced Heterogeneous Catalysts for Azo Dye Degradation: Design, Synthesis and Environmental Applications Kindle Edition

The rapid industrialization of textile, leather, and dye manufacturing sectors has led to the release of hazardous azo dyes into aquatic systems, posing severe environmental and health risks. Among these, aromatic azo dyes such as Chromotrope 2R and Orange II are particularly concerning due to their carcinogenic and non-biodegradable nature. This book presents a comprehensive study on the design, synthesis, characterization, and catalytic application of advanced heterogeneous catalysts for efficient dye degradation. Two distinct catalytic systems have been developed and investigated: (i) Molybdovanadophosphoric acid supported on kaolin (MVPA/Kaolin) representing hybrid inorganic catalysts, and (ii) iron–tungsten supported mesoporous silica (Fe–W/SBA-15) representing high surface area mesoporous catalysts. Both catalysts were synthesized using impregnation and hydrothermal approaches, respectively, and extensively characterized using XRD, SEM, TEM, FTIR, BET, and ICP-OES techniques. The catalytic wet oxidation process using hydrogen peroxide as a green oxidant demonstrated excellent degradation efficiencies of 96.7% for Chromotrope 2R and 95.8% for Orange II under mild conditions (50°C, atmospheric pressure). Mechanistic studies revealed oxidative cleavage of azo bonds leading to formation of low molecular weight acids such as oxalic and malonic acid. A comparative analysis highlights the superior surface properties of mesoporous catalysts, while hybrid catalysts offer cost-effective alternatives. The study establishes a foundation for scalable, sustainable wastewater treatment technologies. Read more