Water Stability and Environmental Effects of Nano Polymer Modified Loess

Abstract

The use of hydrophobic nano polymers to modify cadmium contaminated soil was proposed in this study. The water stability and strength of the modified soil were evaluated through immersion tests and UCS tests. Contact angle test and ICP-OES were used to measure soil water contact angle and cadmium leaching concentration, respectively, and to analyze the effects of hydrophobic polymers on soil hydrophobicity and heavy metal leaching. In addition, the mechanism of the nano polymer was studied through microstructural characterization techniques such as FTIR, TGA, and X-ray diffraction. The results showed that at a dose of 2% or higher, the soil remained intact after soaking for 24 hours, and the UCS value reached 0.799 MPa at a dose of 5% after soaking. At a dose of 5%, the soil water contact angle increased from 18.9 ° in untreated soil to 118.5 °, an increase of 6.3 times. The leaching concentration of cadmium in soil with an initial concentration of 100 mg/kg decreased to 0.78 mg/L, indicating that the nano polymer has significant hydrophobicity and excellent ability to inhibit heavy metal migration. Mechanism analysis shows that the oxysilane polymer in the nano polymer underwent hydrolysis and condensation of Si-H bonds to form Si-OH, which further reacts with hydroxyl groups on the soil surface to form a three-dimensional hydrophobic siloxane network (Si-O-Si). This network covers soil particles and effectively prevents water infiltration. In addition, surfactants based on fatty alcohols reduced the surface free energy of soil, thereby minimizing the migration of free cadmium. The research results can provide new ideas for the treatment of cadmium contaminated soil.

Keywords

cadmium contaminated soil / nanopolymer / water stability / strength / microscopic mechanism

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