# Synthesis of Iron Nanoparticles from Spartina alterniflora for Cadmium Immobilization in Coastal Wetland Sediments

## TL;DR

This study uses invasive Spartina alterniflora plants to create iron nanoparticles that help reduce cadmium pollution in coastal wetlands.

## Contribution

A novel green synthesis method for iron nanoparticles using Spartina alterniflora leaf extract to immobilize cadmium in wetland sediments.

## Key findings

- Sa-FeNPs reduced the weak-acid-extractable fraction of Cd by 34.63–38.39% at a 7% application rate.
- The nanoparticles' functional groups and iron redox reactions are key to Cd immobilization.

## Abstract

In this research, we tackled two environmental issues in coastal wetlands-cadmium (Cd) contamination and excessive S. alterniflora biomass-with a sustainable strategy. We converted this invasive plant into iron-based nanoparticles (Sa-FeNPs) to immobilize the toxic metal. Experiments demonstrated that Sa-FeNPs significantly reduced the hazardous bioavailable fraction of Cd in sediments. The nanoparticles act by trapping Cd and promoting its conversion into a stable, immobile state. Our work presents a circular economy solution, turning an ecological problem into a tool for decontamination, thereby promoting sustainable coastal management.

A green synthesis method for iron nanoparticles was developed using the leaf extract of the invasive plant Spartina alterniflora (Sa-FeNPs), targeting the remediation of cadmium (Cd) in coastal sediments. The obtained Sa-FeNPs, characterized as amorphous Fe-O-C composites, significantly reduced the amount of bioavailable Cd. Specifically, Sa-FeNPs achieved a 34.63–38.39% decrease in the weak-acid-extractable fraction at a 7% application rate. The primary mechanisms underlying the adsorption and complexation of Cd are the large specific surface area of the Sa-FeNPs, their rich functional groups (-OH, -COOH, C=C, C-O), iron redox reactions, and total organic carbon (TOC) conversion. This study offers an environmentally friendly and low-cost remediation strategy for the utilization of excessive S. alterniflora biomass resources and controlling Cd pollution in coastal wetlands.