Valorization of Pea-Pod Waste into SustainSynthesis of Nitrogen-Doped Carbon Quantum Dots for Efficient Photocatalytic Degradation of Sulphamethoxazol

Abstract

The increasing presence of pharmaceutical pollutants like sulfamethoxazole (SMX) in water bodies presents a significant environmental concern. Nitrogen-doped carbon quantum dots(NCQDs) have emerged as a promising photocatalyst due to their visible-light responsiveness and sustainable synthesis. This study focuses on utilizing nitrogen-rich pea waste to synthesize NCQDs via an eco-friendly process, contributing to both environmental remediation and waste valorization. The primary objective of this research is to synthesize N-CQDs from pea waste and evaluate their photocatalytic performance in degrading sulfamethoxazole (SMX) under visible-light irradiation. Fresh pea pods are washed, dried (60- 70°C), and ground into fine powder. Pea pod powder is mixed and transferred to a Teflon-lined autoclave and heated. After cooling, the solution is filtered to obtain N-CQDs. The N-CQDs are purified using dialysis or ultrafiltration and further separated via centrifugation for 15-20 minutes to remove residual impurities. The synthesized N-CQDs was characterized using XRD, SEM, FTIR, UV-Vis DRS. and PL techniques to confirm its structure, morphology, and optical properties. The NCQDs photocatalyst was tested for the degradation of SMX under visible light. The N-CQDs exhibited a layered nanoplate structure with a band gap of 2.7 eV. It achieved 97% degradation of SMX within 20 minutes, attributed to the generation of O and OH radicals. This demonstrates the high potential of pea waste-derived N-CQDs for environmental remediation.