Eco-friendly remediation for lead-contaminated riverine sediment by sodium lignin sulfonate stabilized nano-chlorapatite

Abstract

Achieving high immobilization performance to reduce the toxicity and bioavailability of heavy metals is critical for the remediation of heavy metals contaminated sediment. Herein, a novel chlorapatites (SNClAP) with high stability and dispersibility is successfully synthesized using sodium lignin sulfonate (SLS) as dispersant. Scanning electron microscope (SEM) and transmission electron microscopy (TEM) characterization demonstrated that SNClAP possessed an internal layered structure, and exhibited better dispersibility, which was conducive to the immobilization of lead (Pb) in sediment. Besides, SNClAP showed excellent remediation performance towards Pb contaminated sediment, with the highest Pb immobilization efficiency of 80.29%, which was much higher than that of pristine chlorapatite (ClAP) (45.62%). The results of available phosphorus (AP) showed that the better dispersion of chlorapatites could make soluble phosphorus (P) released by chlorapatites more fully combine with Pb to form the extremely stable Pb10(PO4)6Cl2 through precipitation, thus reducing the retention of P in sediment to greatly lower the risk of eutrophication. Therefore, SLS, a by-product of pulping and papermaking industry, was used to synthesize SNClAP, which could not only improve the remediation efficiency of Pb-contaminated sediments, but also greatly promote the recycling of waste, thereby achieving harmony between materials and ecological environment.