Lignin-based multifunctional fertilizer for immobilization of Pb (II) in contaminated soil

Abstract

Excessive application of fertilizers and their losses have exerted a great threat on soil environment. Slow- or controlled-release fertilizers have been widely produced to alleviate the problem. However, most of them can not remedy contaminated soil environment, and even make it worse. To improve nutrient use efficiency and reduce soil environmental pollution, lignin, an extensive biomass source, was used to synthesize a lignin-based superabsorbent (LPA), which was then introduced into the fertilizer as an outer coating material to obtain lignin-based multifunctional fertilizer (LMF). Results showed that the introduction of LPA can improve water-holding and water-retention capacity of soil and nutrients release behavior of fertilizers. The cumulative release rates of nitrogen, phosphorus and zinc were 79.5%, 46.7% and 60.1% after 25 days, respectively. Additionally, LMF can efficiently immobilize and restrict the migration of bivalent lead (Pb(II)) by complexation with lignin. About 91.7% of Pb(II) was immobilized after soil-sand mixture with Pb(NO3)2 was treated by LMF. The pot experiments indicated that the LMF exhibited a positive effect on the growing of corn in Pb(II)-contaminated soil. Therefore, this work provides a promising fertilizer to improve the utilization efficiency of water, sustained release of nutrients, and immobilization of Pb (II) in contaminated soil.