A bio-based salt-tolerant hydrogel dust suppressant for long-term control of dust emissions from saline-alkali soils

Dust emissions from saline-alkali soils pose significant risks to air quality, human health, and ecological security. However, the limited salt tolerance of existing dust suppressants substantially constrains their long-term effectiveness. This study aimed to develop a salt-tolerant, environmentally friendly hydrogel dust suppressant specifically designed for saline soil environments and to systematically evaluate its structural characteristics and dust suppression performance. A novel bio-based polymer hydrogel (HA-AM-AMPS/OMMT) was synthesized by grafting acrylamide (AM) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) onto humic acid (HA) and intercalating organically modified montmorillonite (OMMT). Dodecyl dimethyl betaine (BS-12) was further incorporated to obtain a salt-resistant humic acid-based hydrogel dust suppressant (SRSD). Based on single-factor experiments, the optimal preparation conditions were 14 wt% HA, 40 wt% AMPS, 2.2 wt% KPS, 0.18 wt% MBA, and 3 wt% OMMT. Salt-resistance tests demonstrated that HA-AM-AMPS/OMMT retained more than 35% of its swelling capacity and viscosity in saline solutions with NaCl concentrations ranging from 500 to 5000 mg/l. FTIR, XRD, SEM, and TGA results verified successful grafting and intercalation, as well as improved thermal stability. Performance evaluations indicated that SRSD outperformed water and a commercial dust suppressant (WFF), exhibiting strong resistance to wind erosion, water erosion, freeze-thaw cycles, and compressive stress. SRSD maintained more than 95% dust suppression efficiency at a wind speed of 15 m/s and effectively reduced TSP, PM₁₀, and PM₂.₅ emissions over a 90-day period. Degradation and cost analyses further demonstrated its environmental compatibility and economic feasibility. Overall, SRSD provides a sustainable and salt-tolerant solution for dust control in saline-alkali soils.