Synergy of surfactants and hyperbranched PVAc copolymer emulsion enabling ecological sand fixation in high salt-affected sandy land

Abstract

To mitigate the impact of salt crystallization damage in highly saline sandy lands, this study first evaluated the salt tolerance of three surfactants (SDS, L23 and CTAB), their effects on NaCl crystallization behavior, and their influence on microbial growth in sandy soil. Surfactant L23 was subsequently selected for further investigation. Given the importance of its interactions, the adsorption characteristics of L23 on sand particle surfaces under varying salinity conditions were systematically examined. Additionally, changes in the properties and morphology of the emulsion after the addition of different amounts of L23 and 3% NaCl were analyzed. Finally, the sand-fixing performance of the L23-emulsion composite material, including compressive strength, wind erosion resistance, thermal aging stability, freeze–thaw stability, and water retention, was comprehensively evaluated. Field experiments were also conducted to assess its promoting effects on plant and microbial growth in saline deserts, so as to elucidate its ecological impact. The experimental results demonstrated that L23 effectively modulated the crystallization morphology of salt in sandy soil. When incorporated into the saline-tolerant P(VAc-DBM-AA-AM-IA-HBP) hyperbranched emulsion, L23 significantly enhanced its mechanical properties. Further studies confirmed that the L23-emulsion composite material markedly reduced the agglomeration damage caused by NaCl crystallization to sand-fixing materials, thereby improving sand fixation effectiveness. The composite also exhibited outstanding thermal aging resistance, freeze–thaw stability, and water retention capacity, enabling it to withstand temperature fluctuations in desert environments. The positive growth of plants and microorganisms observed in field experiments verified its reliable ecological benefits. This study provides a novel strategy for developing ecological sand-fixing materials aimed at combating desertification in saline desert areas.