Extractive removal of micro and trace nitrofen, 2, 4-dichlorophenol and p-nitrotrophenol from water/soil by humic acid ester ether

ABSTRACT

The amphiphilic humic acid ester ether (HAEE), as a kind of solid-phase extractant with characteristics of easy separation and hydrophilic–hydrophobic amphiphilic property, was prepared and used to extract micro or trace nitrofen, 2,4-dichlorophenol and p-nitrotrophenol (NIPs) from water and soil. Degradation of NIPs and extractant regeneration were carried out by simple photocatalysis. The adsorption equilibrium of the mono- or three mixed NIPs by HAEE in aqueous could be quickly reached within 20 min. The adsorption process was fit to quasi-second-order kinetics model and Friendlich thermodynamics model. The possible adsorption interaction was discussed. Results suggested that the adsorption of NIPs onto HAEE predominated by hydrogen bonding, hydrophobic interaction and π-π interaction. The extraction capacity of mixed NIPs (80 μg/L each component) by HAEE was up to 0.38 mg/g and tended to be multi-layer adsorption, in which p-nitrotrophenol had higher adsorption competitiveness because of lower resistance to HAEE. When HAEE-NIPs were degraded by photo-catalyst Fe⁰/F-TiO₂ for 8 h, not only the adsorbed NIPs could be totally degraded and mineralized, but also the HAEE could be effectively regenerated. When the NIPs were continuously extracted from 40-year aging soil for three times (regenerative twice) by combined extractant (48 mL H₂O + 2 mL n-hexane + 0.1 g HAEE), the total extraction efficiency of NIPs could reach to 84.66%. This research could supplement the theory and technique for harmless treatment of NIPs contaminated water and soil.

GRAPHICAL ABSTRACT

KEYWORDS:

• Solid-phase extractant
• humic acid ester ether (HAEE)
• extraction and regeneration performance
• NIPs pollutants
• harmless treatment

Acknowledgements

This research was financially supported by the National Natural Science Foundation of China (no. 51641209) and the Science and Technology Department of Sichuan Province project (no. 2020YFH0162).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by National Natural Science Foundation of China: [Grant Number 51641209]; Science and Technology Department of Sichuan Province: [Grant Number 2020YFH0162].