The study explores the innovative application of raw ilmenite nanoparticles (ILM) as photocatalysts, combined with peroxymonosulfate (PMS) and graphitic carbon nitride (g-C3N4), to effectively degrade rhodamine B dye from wastewater. This significant advancement could pave the way for more sustainable wastewater treatment solutions.
Dyes, particularly rhodamine B, are common environmental pollutants used extensively across textile, leather, and plastic industries. Their toxicity and persistence necessitate effective treatment methodologies before wastewater discharge. Conventional treatment systems often fall short, leaving hazardous substances behind. To address this, researchers are turning to advanced oxidation processes (AOPs), which utilize active species to decompose complex organic pollutants.
Conducted at Tarbiat Modares University, the experimental study employed a pilot-scale rectangular reactor with four 6 W UVC lamps operating under optimized conditions. The research achieved outstanding results, obtaining 99.7% removal of the dye from the wastewater within 180 minutes at pH 3.0, using 500 mg/L of ILM, 300 mg/L of PMS, and 200 mg/L of g-C3N4.
The study's findings revealed significant mineralization results, with chemical oxygen demand (COD) removal at 83.2% and total organic carbon (TOC) reduction at 75.8% after treatment. These metrics not only indicate effective dye removal but also suggest the breakdown of harmful byproducts, underscoring the practical benefits of this photocatalytic method.
For the photocatalytic reactions, the kinetics closely followed a pseudo-first-order model, indicating efficient degradation mechanisms. A scavenger study demonstrated the major involvement of sulfate, hydroxyl, and superoxide radicals as active species responsible for dye removal, signifying the importance of these radicals within the system.
Importantly, the researchers also monitored the leaching of ions from the ILM catalyst. Analysis using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) found leached concentrations of iron, magnesium, and calcium at levels significantly below permissible limits for wastewater discharge standards. This suggests the method not only effectively degrades pollutants but does so without introducing harmful levels of leachate back to the environment.
This innovative approach highlights the feasible and environmentally friendly application of raw ilmenite as a low-cost catalyst and the efficacy of AOPs using PMS and g-C3N4 under UV light for wastewater treatment. With increasing emphasis on sustainability, such methods present possible pathways for mitigating industrial pollution challenges, positioning this research as highly relevant for future environmental applications.