Selective lead capture using amide-containing COFs: A novel strategy for efficient soil remediation

Area of Science:

• Environmental Science
• Materials Science
• Soil Science

Background:

• Phytoremediation of heavy metal-contaminated sludge soil faces leaching risks before plant uptake.
• Cost-effective heavy metal stabilization requires selective adsorption materials.

Purpose of the Study:

• To synthesize and evaluate a novel amide-based covalent organic framework (COF-TH) as a selective stabilizer for lead (Pb).
• To assess the efficacy of COF-TH in mitigating Pb leaching during phytoremediation of sludge soil.

Main Methods:

• Synthesis of COF-TH, a novel amide-based covalent organic framework.
• Evaluation of COF-TH selectivity and adsorption capacity for Pb in multi-metal solutions.
• Pot experiments and leaching assays to determine Pb reduction and impact on other heavy metals and plant growth.

Main Results:

• COF-TH demonstrated high selectivity for Pb (K_D = 3279 mL·g^-1) and a maximum adsorption capacity of 189 mg·g^-1.
• COF-TH reduced Pb leachate concentrations by 77.8% without significantly affecting phytoextraction of other heavy metals.
• Adsorption followed Langmuir and intra-particle diffusion models, with kinetics fitting the pseudo-second-order model.

Conclusions:

• COF-TH is a highly selective and effective stabilizer for Pb, mitigating leaching risks in sludge phytoremediation.
• The material shows promise for improving soil quality and plant health, supporting sustainable land application of sludge.
• This study presents an integrated approach combining phytoremediation with novel stabilization techniques for heavy metal-contaminated soils.