Abstract
Coal-based humic acid waste residue is a solid waste generated during the production of humic acid products. The extraction of coal-based humin (NHM) from such residues presents an effective approach for solid waste resource recovery. In this study, a novel calcium-based humin (Ca-NHM) was synthesized via a low-temperature-assisted method. The material was characterized and its cadmium passivation mechanism was investigated using scanning electron microscopy (SEM), zeta potential analysis (Zeta), carbon nuclear magnetic resonance (13C-CPMAS-NMR), and X-ray photoelectron spectroscopy (XPS). Soil incubation experiments were conducted to determine the actual cadmium adsorption capacity of coal-based humin in soils and to evaluate the stability of cadmium passivation. Plant cultivation experiments were carried out to verify the effects of coal-based humin on migration and transformation in soil, as well as on cadmium bioefficiency. The results showed that Ca-NHM passivated soil cadmium through multiple mechanisms such as ion exchange, electrostatic adsorption, complexation reactions, and physical adsorption. Compared with NHM, Ca-NHM exhibited a 69.71% increase in passivation efficiency, and a 2.44% reduction in cadmium leaching concentration. In Ca-NHM treatments, the above- and below-ground biomass of pakchoi increased by 18.06%, and 80.95%, respectively, relative to the control group. Furthermore, Ca-NHM enhanced the cadmium resistance of pakchoi, reduced the enrichment coefficient, activity coefficient, and activity-to-stability ratio in the above-ground portion of pakchoi, and maintained a transfer coefficient below 1, thereby alleviating cadmium toxicity. In summary, this study provides a theoretical foundation for understanding the mechanisms by which coal-based humin mitigates cadmium toxicity in pakchoi.
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Claims 8
Claim · model-written summary
Ca-NHM showed a 69.71% higher passivation efficiency than NHM.
- Material
- Ca-NHMe1
- Treatment
- Ca-NHMe1
- Outcome
- passivation efficiencye1
- Direction
- increasee1
- Value
- 69.71%e1
- Comparator
- NHMe1
Not reportedTaxon
Verbatim
e1“Compared with NHM, Ca-NHM exhibited a 69.71% increase in passivation efficiency, and a 2.44% reduction in cadmium leaching concentration”
Claim · model-written summary
Ca-NHM reduced cadmium leaching concentration by 2.44% compared with NHM.
- Material
- Ca-NHMe1
- Treatment
- Ca-NHMe1
- Outcome
- cadmium leaching concentratione1
- Direction
- reductione1
- Value
- 2.44%e1
- Comparator
- NHMe1
Not reportedTaxon
Verbatim
e1“Compared with NHM, Ca-NHM exhibited a 69.71% increase in passivation efficiency, and a 2.44% reduction in cadmium leaching concentration”
Claim · model-written summary
Ca-NHM increased above-ground biomass of pakchoi by 18.06% relative to the control group.
Verbatim
e2“In Ca-NHM treatments, the above- and below-ground biomass of pakchoi increased by 18.06%, and 80.95%, respectively, relative to the control group”
Claim · model-written summary
Ca-NHM increased below-ground biomass of pakchoi by 80.95% relative to the control group.
Verbatim
e2“In Ca-NHM treatments, the above- and below-ground biomass of pakchoi increased by 18.06%, and 80.95%, respectively, relative to the control group”
Claim · model-written summary
Ca-NHM enhanced the cadmium resistance of pakchoi.
Not reportedComparator
Verbatim
e3“Ca-NHM enhanced the cadmium resistance of pakchoi, reduced the enrichment coefficient, activity coefficient, and activity-to-stability ratio in the above-ground portion of pakchoi”
Claim · model-written summary
Ca-NHM reduced the enrichment coefficient, activity coefficient and activity-to-stability ratio in the above-ground portion of pakchoi.
- Taxon
- pakchoie3
- Organ / stage
- above-ground portione3
- Treatment
- Ca-NHMe3
- Outcome
- enrichment coefficient, activity coefficient, and activity-to-stability ratioe3
- Direction
- reducede3
Not reportedComparator
Verbatim
e3“Ca-NHM enhanced the cadmium resistance of pakchoi, reduced the enrichment coefficient, activity coefficient, and activity-to-stability ratio in the above-ground portion of pakchoi”
Claim · model-written summary
Ca-NHM maintained the transfer coefficient of pakchoi below 1, alleviating cadmium toxicity.
- Taxon
- pakchoie3
- Treatment
- Ca-NHMe3
- Outcome
- transfer coefficiente4
- Direction
- maintainede4
- Value
- below 1e4
- Qualifier
- alleviating cadmium toxicitye4
Not reportedComparator
Verbatim
e3“Ca-NHM enhanced the cadmium resistance of pakchoi, reduced the enrichment coefficient, activity coefficient, and activity-to-stability ratio in the above-ground portion of pakchoi”
e4“maintained a transfer coefficient below 1, thereby alleviating cadmium toxicity”
Claim · model-written summary
Ca-NHM passivated soil cadmium through ion exchange, electrostatic adsorption, complexation and physical adsorption.
- Material
- Ca-NHMe0
- Outcome
- passivated soil cadmiume0
- Qualifier
- ion exchange, electrostatic adsorption, complexation reactions, and physical adsorptione0
Not reportedTaxon
Verbatim
e0“Ca-NHM passivated soil cadmium through multiple mechanisms such as ion exchange, electrostatic adsorption, complexation reactions, and physical adsorption”
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