Engineering soil health with a lignin-based hydrogel: Structural improvement and cadmium retention
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0000-0001-9134-0112 Date
2026-08
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Abstract
The increasing occurrence of soil degradation, water deficiencies, and heavy metal contamination necessitates the development of sustainable materials that improve the properties of soil and reduce the mobility of pollutants. In this study, a lignin-based hydrogel (HG) was evaluated as a multifunctional soil amendment for enhancing the physicochemical properties of soil and immobilizing cadmium ions (Cd2+). Four mineral soils with three different textures (sand, loamy sand, and sandy loam), collected from Lubelskie Voivodeship (Poland), were amended and incubated under controlled conditions. The addition of the HG positively modified the soil structure, leading to increases in the porosity and total pore surface area, accompanied by a reduction in the average pore diameter, particularly in coarse-textured soils. The application of the hydrogel resulted in an increased bioavailable potassium content and cation exchange capacity (CEC) but a decrease in bioavailable phosphate concentration. Sorption studies revealed that the hydrogel exhibited a relatively high capacity toward Cd2+ (23.28 mg/g). Among the tested soils, the highest sorption was observed on sandy loam, with the greatest content of fine fractions. Cd2+ sorption was best described by the Langmuir model for soils and the Freundlich model for the hydrogel. In turn, a pseudo-second order equation was well fitted to the experimental kinetics data, suggesting chemisorption. Soil amendment with the HG significantly enhanced Cd2+ immobilization, with the strongest effect observed for systems incubated for 1 month. A slight decrease in the sorption capacity was noted after 6 months, suggesting partial hydrogel degradation or changes in functional group availability over time. Overall, the results demonstrate that the developed lignin-based hydrogel is a promising, environmentally friendly material for improving the quality of soil and reducing the bioavailability of heavy metals, particularly in coarse-textured soils.
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Grygorczuk-Płaneta, K., Siryk, O., Guzenko, N., Kukowska-Superson, S., Vitková, J., Peth, S., Szewczuk-Karpisz, K. (2026). Engineering soil health with a lignin-based hydrogel: Structural improvement and cadmium retention. [Submitted Manuscript under Review]. https://open.icm.edu.pl/handle/123456789/27034