Green synthesis of Platinum Nanoparticle from Citrus limon and their Photocatalytic Degradation of Polystyrene

Abstract

Polystyrene is non-biodegradable that causes landfill waste and microplastic pollution. Its manufacturing and disposal release toxic substances, harming the air, water and wildlife. Photocatalytic degradation of Polystyrene (Paper Cup) using Green synthesized platinum nanoparticle synthesized from lemon peel extract for the duration of 100 hours under sunlight is an efficient way to degrade plastics. Hence, this research was designed to be environmentally friendly, pollution free, cost effective and has no side effects to the environment. Platinum nanoparticles exhibit superior photocatalytic performance due to their exceptional ability to enhance electron–hole pair separation, strong visible-light absorption, and high redox catalytic activity. These properties enable more efficient and complete degradation of polystyrene compared to conventional oxide-based catalysts such as TiO₂ and ZnO. The degradation of Polystyrene is determined with Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Analysis, Fourier Transform Infrared Spectroscopy (FTIR) and Atomic Force Microscopy (AFM). Weight loss showed a substantial mass reduction of 42.86% following sunlight-assisted photocatalytic degradation. SEM images revealed a shift from the smooth, intact surface of PS to a severely deteriorated morphology characterized by cracks, pits, and grooves, indicative of surface erosion and chalking. EDAX detected 11.69 wt% Pt on the degraded surface along with elevated oxygen levels, demonstrating catalyst adherence and progressive oxidation of the polymer matrix. FTIR analysis exhibited the appearance and broadening of carbonyl and other oxygen-containing functional bands within the 1400–1650 cm⁻¹ regions, confirming oxidative chemical transformation. AFM confirmed these findings, with surface roughness increasing from Ra = 25.00 to 31.25 nm and Rq = 31.25 to 39.40 nm, reflecting enhanced topographical irregularity attributable to polymer chain scission. The novelty of the research is that green synthesized platinum nanoparticle offers higher stability, lower toxicity and efficient degradation under mild conditions compared to other catalysts. Therefore, these results highlight the promising potential of green synthesized Pt nanoparticles for large-scale plastic waste remediation and their broader applicability in sustainable environmental nanotechnology.