Efficient ofloxacin degradation via photo-Fenton process over eco-friendly MIL-88A(Fe): Performance, degradation pathways, intermediate library establishment and toxicity evaluation.

The high-throughput production of the eco-friendly MIL-88A(Fe) was achieved under mild reaction conditions with normal pressure and temperature. The as-prepared MIL-88A(Fe) exhibited efficient photo-Fenton catalytic ofloxacin (OFL) degradation upon visible light irradiation with good stability and reusability. The OFL (20.0 mg/L) was completely degraded within 50 min under visible light with the aid of MIL-88A(Fe) (0.25 g/L) and H2O2 (1.0 mL/L) in aqueous solution (pH = 7.0). The hydroxyl radicals (·OH) are the main active species during the photo-Fenton oxidation process. Meanwhile, the degradation intermediates and the corresponding degradation pathways were identified and proposed with the aid of both ultra-high performance liquid chromatography tandem quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS) and density functional theory (DFT) calculations. Finally, the degradation product library was firstly established to identify intermediate transformation products (TPs) with their variation of concentration, and their corresponding toxicologic activities were assessed via Toxtree and T.E.S.T software as well. Finally, the MIL-88A is efficient and stable with four cycles' catalysis operations, demonstrating good potential for water treatment.

[Distribution and source apportionment of n-alkanes in atmospheric particle in Taiyuan, China].

The n-alkanes in PM10 and typical emission sources samples collected during heating and non-heating periods in Taiyuan were determined with GC-MS. Meanwhile, the distribution characteristics and source identification of n-alkanes were investigated with diagnostic parameters and principal component analysis (PCA). Concentrations of n-alkanes ranged from 213.74 to 573.32 ng.m-3 and 22.69 to 150.82 ng.m-3 in the heating and non-heating seasons, respectively. The n-alkanes concentrations in suburban districts including JY, JCP, XD and SL were higher than those in urban sites in the heating quarter, and the relative concentration in JS was 7 times higher than that in SL in the other period. The correlation of the total n-alkanes in PM10 with that derived from fossil fuel was higher than the correlation with those from plant in the heating quarter, while the opposite result was detected in the other period, manifesting higher contribution of fossil fuel in the heating days. CPI and % WNA values showed that the contribution from plant wax in the non-heating period was higher than that in the heating period, and the alkanes production rate was elevated along with the increase in environmental pressures. Information on higher organic matter maturity was obtained during the heating period by Cmax and OEP and the existence of UCM bulge confirmed that vehicles were the significant contributor to n-alkanes concentration during the whole year. PCA analysis indicated the major component was the mixture of vehicle emission and higher plant, accounting for 51.28% of the total variances, followed by coal dust, accounting for 43. 14%. Cooperating control of emissions from coal combustions and vehicles would be the effective way to lower the concentrations of the corresponding n-alkanes.