Environmental sustainability in combating wind erosion: Chemical stabilization of sand dunes using acidic mulching

Highlights • Development of a novel method for stabilizing calcareous sand dunes using diluted sulfuric and phosphoric acids. • Formation of durable sand-cement crusts through in-situ chemical reactions between acidic mulching liquids and calcareous sand particles. • Achieving complete suppression of wind erosion (wind erosion modulus reduced to zero) using stabilization with diluted sulfuric acid. • Systematic investigation of key factors, including optimal sulfuric acid dilution rates and the innovative use of alcohol as a diluent for phosphoric acid. • Contribution to sustainable desertification control, offering environmentally responsible solutions to protect fragile ecosystems in arid regions. Wind erosion and desertification are pressing environmental crises in arid and semi-arid regions, causing significant ecological damage through the formation of dunes and the redistribution of sand. This study investigates a chemical stabilization method for loose sand using acidic mulching liquids to mitigate these issues. Specifically, calcareous (Aragonitic) sand particles smaller than 300 micrometers were treated with diluted sulfuric and phosphoric acids (in water or alcohol) to create effective mulching solutions. The chemical reactions between the acids and the calcareous sand led to the formation of in-situ cements: dicalcium phosphate dihydrate (Brushite) from the reaction with phosphoric acid, and Gypsum from the reaction with sulfuric acid. These substances helped bind the sand particles, forming a solid crust on the sand surface. The study employed various tests to evaluate the effectiveness of the stabilization, including penetration resistance, unconfined compressive strength, wind erosion modulus, and analytical techniques such as XRD, FESEM, and XRF. The results indicated that the appropriate concentrations and volumes of these acids can successfully form a durable sand-cement crust, which effectively controls wind erosion. Wind tunnel experiments demonstrated a significant reduction in erosion, with the wind erosion modulus decreasing from 3975 g. m −2 .min −1 for untreated sand to zero for sand stabilized with 35 % sulfuric acid. The findings offer a practical contribution to environmental management practices by introducing a feasible and impactful method to combat wind erosion and desertification in affected regions.