In the quest for sustainable and efficient wastewater treatment solutions, a groundbreaking study led by John Elisa Kumar from the Department of Chemistry at the Indian Institute of Science Education and Research (IISER) in Pune, India, has unveiled a promising advanced oxidation process (AOP) for the degradation of Tartrazine, a synthetic azo dye commonly used in industries. Published in the journal ‘Next Sustainability’ (which translates to ‘Next Sustainability’ in English), the research explores the use of a citric acid (CA)-chelated Fe(II)/sodium persulfate (SPS) system, offering a cost-effective and environmentally friendly approach to tackling dye contamination.
The study’s innovative use of citric acid as a biodegradable chelating agent has been a game-changer. “The incorporation of CA enhanced Fe(II) stability, reduced Fe(III) accumulation, and minimized sulfate radical scavenging, resulting in improved reactivity,” explains Kumar. This enhancement is due to the formation of a steric shield that inhibits hydrolytic attack, preserving Fe(II) solubility under near-neutral conditions. The predictive model developed by the team exhibited high accuracy, with optimal conditions identified as 3.602 mM SPS, 0.590 mM Fe(II), and 0.123 mM CA.
One of the most compelling aspects of this research is its broad applicability. Significant Tartrazine removal was achieved across a wide pH range (3–9), with maximum color removal of 84.3±1.4% at pH 3.0. Even in a real water matrix, the system demonstrated impressive efficiency, achieving 73.1±1.9% color removal. However, the presence of inorganic anions, particularly chloride, posed a challenge, significantly inhibiting the process. “The efficiency dropped to 5.6±1.0% at 1.0 g/L chloride concentration,” notes Kumar, highlighting the need for further optimization in the presence of such inhibitors.
The kinetic analysis revealed a two-stage removal pattern: a rapid initial stage followed by a slower degradation phase. This behavior was effectively described by the Behnajady-Modirshahla-Ghanbery (BMG) kinetic model, which outperformed traditional approaches in capturing the process accurately. The initial stage saw a removal rate of 57.6±1.7% at 5 minutes, increasing to 91.4±1.9% at 60 minutes, and reaching 96.8% at 480 minutes.
The implications of this research for the energy sector are substantial. Efficient and sustainable wastewater treatment solutions are crucial for industries that generate large volumes of dye-contaminated wastewater. The CA/Fe(II)/SPS system offers a scalable and environmentally friendly approach, reducing the environmental footprint of industrial processes. “This system not only enhances the degradation of azo dyes but also aligns with the principles of green chemistry,” says Kumar, emphasizing the broader impact of the study.
As the world continues to grapple with the challenges of water pollution and sustainability, innovations like the CA/Fe(II)/SPS system provide a beacon of hope. The research published in ‘Next Sustainability’ not only advances our understanding of advanced oxidation processes but also paves the way for future developments in wastewater treatment technologies. With further refinement and optimization, this system could become a cornerstone of sustainable industrial practices, ensuring a cleaner and healthier environment for future generations.