Zero‐Waste Production of Copper Nanoparticles and Activated Carbon from <i>Erigeron canadensis</i> L.: A Sustainable Approach for Environmental and Health Applications

Abstract This study presents a novel, zero‐waste process for producing copper nanoparticles (CuNPs), activated carbons (ACs), and oil extract (OE) from a plant Erigeron canadensis L. in Sp. Pl.: 863 (1753). This method optimizes resource utilization and eliminates waste, offering a sustainable approach to green synthesis. The NPs were characterized using XRD, SEM, and FTIR. Their effectiveness was evaluated through comparative studies on methylene blue removal, antioxidant capacity, and antibacterial activity. The prepared OE exhibited superior antibacterial properties, particularly against Klebsiella pneumoniae subsp . pneumoniae ATCC 13883 (inhibition zone: 19 ± 0 mm) and Proteus vulgaris RSKK 96029 (inhibition zone: 18.7 ± 0.6 mm). The AC demonstrated exceptional dye adsorption efficiency, ranging from 98.62% to 99.50%. Antioxidant tests revealed that CuNPs possessed strong antioxidant capacity, with an IC 50 of 0.023 ± 0.002 mg/mL in the DPPH radical scavenging test and 0.41 ± 0.07 mg/mL in the iron chelation test. The OE demonstrated lower DPPH scavenging capacity (0.43 ± 0.01) but significant iron‐chelating ability (41.94 ± 1.06). In comparison, standard antioxidants EDTA and BHT showed lower effectiveness in their respective tests. These experimental findings underscore the potential of this green approach for bio zero‐waste‐derived products in environmental and biomedical applications, highlighting its broad applicability.