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Interaction of Humic Acid with Cu/Pb‐Zn Tailings of Different Degrees of Weathering
Author(s) -
Yuan Mingrui,
Xu Zhi Ping,
Nguyen Tuan,
Baumgartl Thomas,
Huang Longbin
Publication year - 2017
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2016.04.0110
Subject(s) - tailings , humic acid , chemistry , adsorption , environmental chemistry , organic matter , leaching (pedology) , nuclear chemistry , soil water , inorganic chemistry , geology , organic chemistry , fertilizer , soil science
Core Ideas Cu‐Pb‐Zn tailings have different humic acid adsorption capacity. Fresh tailings contain more Fe/Al‐oxyhydroxides and adsorbed more humic acids. Carboxylic and phenolic groups of HA preferentially interacted with mineral particles in tailings. Acidic pH conditions favor humic acid adsorption in the tailings. Aggregation of tailings is instrumental for developing a physical environment permitting water infiltration, aeration, and root penetration. Previous research found that microaggregation of Cu‐Pb‐Zn tailings was stimulated by amendment of composted sugarcane residues. The present study aimed to identify organic functional groups in humic acids (HA) involved in the aggregation of Cu‐Pb‐Zn tailings, which were considered to be formed from long‐term organic matter decomposition in the engineered tailing‐soil. The adsorption of HA by the weathered (WT) and freshly deposited (FT) tailings was evaluated at a range of pH conditions in tailing‐HA suspension. Humic acid adsorption decreased with increasing pH from 5.0 to 9.0. The FT was found to contain more oxy‐(hydr)oxides, particularly poorly crystalline Fe and Al oxy‐(hydr)oxides than the WT, which was one of the factors attributing to FT's higher HA affinity. The Fourier transform infrared spectroscopy analysis of tailing particles before and after HA adsorption indicated that carboxylic and phenolic groups of HA preferentially interacted with tailing mineral particles, probably through ligand exchange, polyvalent cation bridge and electrostatic attraction. The pH‐dependent HA adsorption indicated the potential role of functional groups of organic matters in microaggregation of Cu/Pb‐Zn tailings. Moreover, the presence of abundant Al/Fe oxyhydroxides promoted organo‐mineral interactions. The present findings will contribute toward developing field application to engineer functional Technosols from the tailings by selecting organic matter rich in functional groups.