Immobilisation of endogenous phosphorus and lead in sediments by composite water purification sludge hydrochar
Year: 2025
Type: article
Abstract: Sediment is a critical component of aquatic ecosystems, that acts as a natural sink for diverse pollutants such as heavy metals and phosphorus (P). However, the current research on sediment remediation has predominantly focused on single contaminants. In this study, a novel composite material, calcium peroxide/lanthanum-loaded hydrochar (CaO2–LaHyd), was synthesised through the hydrothermal carbonisation of water purification sludge, followed by the sequential loading of lanthanum ions and nano-calcium peroxide. The adsorption capacities of CaO2–LaHyd for P and Pb were evaluated via adsorption experiments, and their passivation mechanisms were investigated through sediment capping simulations. Materials were characterised using scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and energy-dispersive spectroscopy. Results indicated that CaO2–LaHyd exhibited maximum adsorption capacities of 66.05 mg·g⁻¹ for P and 230.41 mg·g⁻¹ for Pb. In the simulated capping experiments, the addition of 5% CaO2–LaHyd significantly reduced the phosphate concentrations in the overlying water. The slow release of oxygen from calcium peroxide improves sediment redox conditions, suppresses endogenous P release, and decreases interstitial P levels. Speciation analysis revealed that CaO2–LaHyd promoted the endogenous P transformation into stable forms while reducing the bioavailable P fractions. Concurrently, it enhanced Pb passivation, thereby mitigating Pb leaching risks from the sediment.
Source: Figshare
Authors: Liu, Ying, He, Liwenze, Chen, Yu, Tang, Jingxiang, Li, Haiquan, Liu, Yanxia
Language: English
Subfield: Water Science and Technology
Field: Environmental Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W6902334637
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