Redox properties and dechlorination capacities of landfill-derived humic-like acids

• Published in: Environmental pollution (1987) Vol. 253; pp. 488 - 496
• Main Authors: Xiao, Xiao, Xi, Bei-Dou, He, Xiao-Song, Zhang, Hui, Li, Yan-Hong, Pu, Shengyan, Liu, Si-Jia, Yu, Min-Da, Yang, Chao
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.10.2019
• Subjects: Aging and minerals; Dechlorination capacities; Electron transfer capacities (ETC); Humic-like acids (HLA); Landfill; Electron transfer capacities (ETC); Dechlorination capacities; Aging and minerals; Landfill; Humic-like acids (HLA)
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2019.07.044

Electron transfer capacities (ETC) of humic-like acids (HLA) and their effects on dechlorination are dependent on their redox-active properties. Aging and minerals can affect the chemical compositions and structures of HLA. However, the underlying mechanism and the impacts on the dechlorination capacities of HLA are poorly understood. We investigated how redox properties change in association with the intrinsic chemical natures and exterior minerals of the HLA extracted from landfilled solid wastes. Furthermore, the ETC of the landfill-derived HLA could be strengthened by increasing landfill age and demineralization, thereby facilitating the dechlorination of pentachlorophenol (PCP). The HLA molecules started to polymerize aromatic macromolecules during landfilling, leading to an increase in ETC and dechlorination capacities. Macromolecular HLA were dissociated to smaller molecules and exposed more aromatic and carboxyl groups when separated from minerals, which enhanced the ETC and the dechlorination abilities of the HLA. Microbial-mediated dechlorination was an effective way to degrade PCP, and almost 80% of the PCP was transformed after 40 days of demineralized HLA and Shewanella oneidensis MR-1 incubation. The demineralization and aging further facilitated the microbial-mediated PCP dechlorination. The findings provide a scientific base for improving in-situ bioremediation of chlorinated compound-contaminated soils using freshly synthesized HLA. [Display omitted] •Aging and minerals can affect the compositions and structures of the HLA.•Macromolecular HLA were dissociated to smaller ones, separated from minerals.•The HLA molecules started to polymerize aromatic macromolecules during aging.•Demineralization and aging increased the ETC of the landfill-derived HLA.•Demineralization and aging facilitated the microbial-mediated PCP dechlorination. Demineralization and aging enhanced the PCP dechlorination capacities mediated by humic-like acids.