Enhancing phytoremediation in chamomile (Matricaria chamomilla L.) using moringa extract and zero-valent iron nanoparticles

Abstract

Increasing Wastewater (WW) contamination, especially with heavy metals like nickel (Ni), lead (Pb), and cadmium (Cd), poses serious environmental challenges. Phytoremediation offers a sustainable and cost-effective method to address these issues. This study aimed to enhance the phytoremediation capacity of Chamomile (Matricaria chamomilla L.) by using moringa leaf extract (LE) and zero-valent iron nanoparticles (ZVINPs) to improve heavy metal removal from tannery wastewater. A constructed wetland system was developed, exposing M. chamomilla to varying WW concentrations (0 %, 25 %, 50 %, and 100 %). LE and ZVINPs were applied individually and in combination to assess their impact on the plant's phytoextraction capacity. Key agronomic traits, chlorophyll content, and oxidative stress markers were measured to evaluate the effects.

The results showed a decline in agronomic traits and chlorophyll content with increasing WW concentration. However, these were significantly improved under LE and ZVINP treatments, either alone or in combination. ZVINPs demonstrated greater enhancement in growth, photosynthesis, and oxidative stress reduction compared to LE. The combined application at 100 % WW led to the highest accumulation of Pb, Ni, and Cd in the plant's leaves, roots, and shoots. For instance, Pb in leaves (33.566±0.513 to 41.7±0.91 mg/kg), roots (82.2 ± 1.31 to 93.733 ± 1.418 mg/kg), and shoots (52 ± 1 to 66.2667 ± 1.419 mg/kg); Ni in leaves (3.223 ± 0.0907 to 4.407 ± 0.090 mg/kg), roots (8.273 ± 0.064 to 9.413 ± 0.102 mg/kg), and shoots (6.22 ± 0.0907 to 7.927 ± 0.105 mg/kg); and Cd in leaves (5.007 ± 0.101 to 6.39 ± 0.062 mg/kg), roots (9.207 ± 0.257 to 12.4 ± 0.1 mg/kg), and shoots (8.14 ± 0.122 to 9.967 ± 0.153 mg/kg). The study concluded that combining ZVINPs and LE significantly enhanced the phytoremediation efficiency of M. chamomilla. This approach also improved the plant's morpho-physiological traits, offering a promising strategy for reducing metal pollutants in wastewater.