Experimental and Theoretical Characterization of Metal Complexation with Humic Acid

Bosire, G. O.; Kgarebe, Boitumelo; Ngila, Jane Catherine

doi:10.1080/00032719.2016.1141415

Cited by 8 publications

(3 citation statements)

References 30 publications

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“…Town and Van Leeuwen [26] obtained similar results for the adsorption of Cd 2+ , Cu 2+ , and Pb 2+ ions. Bosire et al [35] showed that Zn 2+ and Cu 2+ ions were statistically different in their adsorption capacities. Their surface complexation models showed stronger lead and copper interactions with monodentate sites compared to bidentate sites.…”

Section: Resultsmentioning

confidence: 99%

Lignitic Humic Acids as Environmentally-Friendly Adsorbent for Heavy Metals

Klučáková

Pavlíková

2017

Journal of Chemistry

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Humic acids are a part of humus material, are abundant in nature, and form a substantial pool of natural organic matter. They participate in the transport of both beneficial and harmful species. Due to their structure and properties, they can interact with metal ions and, with them, form relatively stable complexes. These substances are thus responsible for the so-called self-cleaning ability of soils. Lignite as a young coal type contains a relatively high amount of humic acids which can be used as an environmentally-friendly adsorbent for heavy metals. In this work, we compared the adsorption of single Cu2+ions with the simultaneous adsorption of several different metal ions (Cd2+, Cu2+, Pb2+, and Zn2+). The adsorption efficiency of humic acids was very high, almost 100% in the case of the single adsorption of Cu2+ions and more than 90% for the adsorption from the mixture of metal ions. The stability of formed complexes, considered on the basis of the leaching in different extraction agents, was higher than 80%; only 9–18% was in the mobile phase. After adsorption, metal ions are contained in humic acids after adsorption in mainly strongly bonded form (60–73%) and can be liberated from their structure only in low amounts.

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Section: Resultsmentioning

confidence: 99%

Lignitic Humic Acids as Environmentally-Friendly Adsorbent for Heavy Metals

Klučáková

Pavlíková

2017

Journal of Chemistry

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“…The Ca 2+ and Mg 2+ of RL were the lowest in all treatments (Figure 5d) because most of them were bound to humic acid. 48 In comparison to RL, AL had a better effect on the release of Ca 2+ and Mg 2+ . Similarly, the Ca 2+ and Mg 2+ of AML were the highest compared to other treatments.…”

Section: Resultsmentioning

confidence: 89%

“…AML exhibited more low (<10 kDa) and medium (10–50 kDa) molecules than the other treatments (Figure c), indicating the production of low-molecular-compound during the oxidation processes of catalysts. The Ca 2+ and Mg 2+ of RL were the lowest in all treatments (Figure d) because most of them were bound to humic acid . In comparison to RL, AL had a better effect on the release of Ca 2+ and Mg 2+ .…”

Section: Resultsmentioning

confidence: 93%

Activation of Humic Acid in Lignite Using Molybdate-Phosphorus Hierarchical Hollow Nanosphere Catalyst Oxidation: Molecular Characterization and Rice Seed Germination-Promoting Performances

Tang¹,

Hou²,

Yang

et al. 2020

J. Agric. Food Chem.

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Although solid-phase activation of lignite using a nanocatalyst has great potential in producing low-cost and sustainable humic acid, the large-scale application of this technology still faces challenges because of the high price and toxicity of the nanocatalyst. Additionally, the specific molecular components of humic acid in activated lignite remain unknown. In this work, a multifunctional molybdate-phosphorus hierarchical hollow nanosphere (Mo-P-HH) catalyst was successfully manufactured by a simple way followed by phosphorization. In comparison with a commercial Pd/C catalyst, the multifunctional Mo-P-HH catalyst was more effective in producing water-soluble humic acid with small molecular functional groups from lignite via solid-phase activation. Moreover, Fourier transform ion cyclotron resonance mass spectrometry revealed the molecular compositions of humic acid in activated lignite. Compared with that from raw lignite, the humic acid after Mo-P-HH activation had less aromatic structure but higher content of lipids, proteins, amino sugar, and carbohydrates. In addition, the activated humic acid simulated seed germination and seedling growth. Therefore, this study provided a high-performance hierarchical hollow nanocatalyst for activation of humic acid and also offered the theoretical basis for the application of humic acid in agriculture.

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