Efficiency assessment of hydrothermally synthesized Mn²⁺/³⁺ modified LaCoO₃ nanoparticles for advanced wastewater remediation

Abstract

The use of light and a particular material known as a photocatalyst to degrade hazardous dyes in wastewater is an exciting new development in the field of photocatalytic dye degradation. In this study we investigated the characteristic properties and photocatalytic dye degradation of manganese doped lanthanum cobalt (LaCoO3 (LCO)) nanoparticles (NPs). The NPs were synthesised using hydrothermal synthesis techniques and analysed its properties by utilising diverse technologies such as XRD, FeSEM with EDAX, Raman Spectroscopy, Photoluminescence spectroscopy and UV-DRS. From XRD analysis we found that the Mn doped LCO NPs have single phase rhombohedral crystal structures with R 3 ‾ $\overline{3}$ c space group and doping cause expansion of lattice. Surface morphology of the synthesised NPs was found to be altered from spherical to spine/rod like microstructure when Mn is incorporated to LCO lattice. PL spectroscopies show broad photoemission at 360–490 nm after absorbing 310 nm light. From the UV–Vis spectroscopy the optical bandgap of the materials around 4.5 eV, indicating they can absorb visible light effectively. LCO can absorb both UV and visible light, expanding its potential for outdoor applications under natural sunlight. Doping LCO with other elements can modify its bandgap and improve its activity towards specific dyes. LCO exhibits good chemical and thermal stability, making it reusable for multiple cycles. While LCO shows promise as a visible light photocatalyst for dye degradation, its efficiency can vary significantly depending on the specific conditions. We tested Congo Red (CR) dye with prepared photocatalyst to study how well they breakdown in visible light. Studies have reported degradation rates for different dyes ranging from 50 to 90 % within an hour under optimized conditions. The LCMO nanoparticles exhibited noteworthy photocatalytic activity, as evidenced by a degradation efficiency of 77 % within a 30 min timeframe. Our findings indicate that LCMO nanoparticles possess significant potential for environmental clean-up.