Enhancing soil hydrophobicity through octadecylamine modification to prevent heavy metal pollution in red soil
Year: 2025
Type: article
Abstract: Heavy-metal contamination from industrial activities and wastewater discharge poses a critical threat to soil environmental security, owing to the high mobility and toxicity of metal ions. Water infiltration is the principal pathway for vertical leaching and horizontal transport of heavy metals in soil; thus, establishing a hydrophobic barrier is regarded as an effective source-control strategy. In this study, octadecylamine (ODA), a long-chain organic amine, was employed to hydrophobically modify representative red soil. The water drop penetration test (WDPT) assessed the effects of compaction, particle-size distribution, temperature, and ODA dosage on hydrophobicity, while scanning electron microscopy (SEM) and X-ray diffraction (XRD) elucidated microscopic mechanisms. Inductively coupled plasma mass spectrometry (ICP–MS) quantified residual heavy metals. Results showed that ODA bonded with soil particles via amino groups and formed a stable hydrophobic layer through the C18 chain, rapidly elevating WDPT from slight to strong or severe levels and sustaining repellency after repeated wet–dry cycles. During modification, soil pH remained near neutral (6 – 7), favoring metal adsorption, whereas electrical conductivity fluctuated nonlinearly without impairing barrier performance. ICP–MS analysis revealed that 0.5% ODA achieved blocking efficiencies of 24.3%, 62.7%, and 87.5% for Cr, Cu, and Cd, respectively. Grass cultivation confirmed that ODA < 0.5% had minimal effects on plant growth, indicating ecological safety. In summary, ODA amendment enhanced soil hydrophobicity and mitigated heavy-metal migration, offering a promising, cost-efficient source-oriented pollution-control strategy.
Authors: Yin-Lei Sun, Xi Zou, Jun-Lei Chen, Xin-Sheng Zhang
Institution: Yunnan University
Language: English
Topic: Heavy metals in environment
Subfield: Pollution
Field: Environmental Science
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,350
OpenAlex ID: W4416187025