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

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.