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Abstract: Ferric and manganese binary oxide (FMBO) has been successfully used to remediate arsenic-polluted river, but there still lacks sufficient data to evaluate its effects on environments. The release behaviors of iron (Fe), manganese (Mn), and arsenic (As) in different E h ranges were investigated for As-bearing FMBO sediment after remediating As-polluted DaSha River by FMBO. Under high E h range (+550 to +400mV), slight dissolution of Fe and Mn, which corresponded to 12.2% and 25.6%, and less than 5% of As release were observed in 336h. Under lower E h range (+50 to −100mV), elevated extent of the dissolution of Mn and Fe were observed, which corresponded to as high as 61.3% and 70.1%. Under such conditions, the dissolution rate of Mn was higher than that of Fe. Furthermore, from the established relationship of As release and the dissolution of Fe and Mn, the release of As seemed dominated by the dissolution of Fe. X-ray photoelectron spectroscopy (XPS) analysis demonstrated the release of Fe, Mn, As(III), and As(V) after sodium ascorbate-treatment, and the re-adsorption of As(V), as indicated from the increased binding energy of As 3d from 44.78 to 45.83eV. Surface element composition analysis indicated significant decrease of Mn from 3.22% to 0.54%, slight increase of Fe from 12.45% to 13.67%, and elevated ratio of As from 0.11% to 0.32% accordingly. The main reactions of Fe and Mn dissolution and the pathways of As release under different E h ranges were also proposed. [Copyright &y& Elsevier]

Elimination of hypophosphite (HP) was studied as an example of nickel plating effluents treatment by O 3 /H 2 O 2 and sequential Fe(II) catalytic oxidation process. Performance assessment performed with artificial HP solution by varying initial pH and employing various oxidation processes clearly showed that the O 3 /H 2 O 2 ─Fe(II) two-step oxidation process possessed the highest removal efficiency when operating under the same conditions. The effects of O 3 dosing, H 2 O 2 concentration, Fe(II) addition and Fe(II) feeding time on the removal efficiency of HP were further evaluated in terms of apparent kinetic rate constant. Under improved conditions (initial HP concentration of 50 mg L −1 , 75 mg L −1 O 3 , 1 mL L −1 H 2 O 2 , 150 mg L −1 Fe(II) and pH 7.0), standard discharge (<0.5 mg L −1 in China) could be achieved, and the Fe(II) feeding time was found to be the limiting factor for the evolution of apparent kinetic rate constant in the second stage. Characterization studies showed that neutralization process after oxidation treatment favored the improvement of phosphorus removal due to the formation of more metal hydroxides. Moreover, as a comparison with lab-scale Fenton approach, the O 3 /H 2 O 2 ─Fe(II) oxidation process had more competitive advantages with respect to applicable pH range, removal efficiency, sludge production as well as economic costs. [ABSTRACT FROM AUTHOR]

The adsorption and photocatalytic degradation performance of F-TiO 2 /SiO 2 catalyst towards a series of benzene compounds were studied. The results revealed that the F-TiO 2 /SiO 2 catalyst is superior to TiO 2 P25 in adsorption capacity and photocatalytic degradation under simulant sunlight irradiation. The adsorptive capacity for chlorobenzene is the highest and the degradation rate is the greatest among these target pollutants. The increase of absorptive organic molecules on acidic F-TiO 2 /SiO 2 catalyst benefits photocatalytic degradation. The photocatalytic reaction accords to Langmuir-Hinshelwood mechanism. The FTIR results indicated that the promoting effect of acidic centers on adsorption of benzene compounds depends on electron property of the functional groups. The electron-donating groups (-OH and -NH 2 ) of benzene compounds are weakly adsorbed on acidic centers of the catalyst due to the competitive adsorption with H 2 O, while the electron-withdrawing groups (-Cl and -NO 2 ) are adsorbed more strongly at acidic sites. The monosubstituted chlorobenzene prefers to perpendicular adsorption on acidic surface, while the disubstituted benzenes prefer to horizontal adsorption, which decreases the adsorbed amounts. A photocatalytic rate mainly depends on electron donating property of the functional group and amount of adsorptive organic molecules, but not on electron density of benzene ring., Competing Interests: Declaration of competing interest None., (Copyright © 2019 Elsevier Ltd. All rights reserved.)