Efficient Pb(II) removal from contaminated soils by recyclable, robust lignosulfonate/polyacrylamide double-network...

Soil heavy metal removal strategies are increasingly valued for effectively reducing contamination and preventing secondary pollution. In this work, a double network hydrogel (Fe₂O₃@LH), consisting of lignosulfonate (LS) and polyacrylamide with embedded Fe₂O₃ nanoparticles, was synthesized successfully via a one-pot method and subsequently applied to adsorb lead (Pb) from contaminated soil. Incorporating Fe₂O₃ into the hydrogel enhances the adsorption capacity of Fe₂O₃@LH for Pb(II). The Fe₂O₃@LH hydrogel demonstrates a maximum Pb(II) adsorption capacity of 143.11 mg g^-1, with Pb(II) removal mechanisms involving electrostatic adsorption, cation exchange, precipitation reactions, and the formation of coordination complexes, achieving a 22.3 % maximum removal efficiency in soil cultivation experiments. Additionally, the application of Fe₂O₃@LH markedly reduces the concentrations of cadmium (Cd) and arsenic (As) in the soil, meanwhile enhances the levels of total nitrogen (TN), soil organic matter (SOM), and cation exchange capacity (CEC) by 23.1 %, 10.6 %, and 16.9 %, respectively. Following 90 days of continuous application in the soil, the recovery rate of Fe₂O₃@LH remains above 75 %. The toxicity assay using zebrafish larvae indicates that Fe₂O₃@LH demonstrates good biosafety. This study demonstrates the considerable potential of Fe₂O₃@LH hydrogel for practical application in reducing Pb(II) levels in contaminated soil.