No abstract

Commercial nanosized zero-valent copper (nZVC) was used as hydrogen peroxide (HO) activator in conjunction with ultrasonic irradiation (US) for the oxidative degradation of norfloxacin (NOR) in this study. Compared with silent degradation system, a significantly enhanced NOR removal was obtained in sono-advanced Fenton process, which involved a synergistic effect between sonolysis and Fenton-like reaction. Almost complete removal of NOR was achieved at 30min when the operating conditions were 0.25g/L nZVC and 10mM HO with ultrasound power of 240W at 20kHz. The released Cu during the nZVC dissolution was the predominant copper species to activate HO and yield hydroxyl radicals (OH) in US/nZVC/HO system. According to the radical quenching experiments and electron paramagnetic resonance technique, hydroxyl radicals in solution (OH) were verified as the primary reactive species, and superoxide anion radicals (O) were regarded as the mediator for the copper cycling by reduction of Cu to Cu. NOR removal efficiencies were improved in various degrees when increased nZVC dosage, ultrasound power, hydrogen-ion amount and HO concentration. Moreover, the inhibitory effect of different inorganic salts on NOR degradation followed the sequence of NaSO>NaNO≈no salt>NaCl>NaHCO. Finally, eleven intermediates were identified and five oxidation pathways were proposed, the cleavage of piperazine ring and transformation of quinolone group seemed to be the major pathway.

Various transition metals (Fe, Mn, Cu and Ni) were doped into ordered mesoporous Co 3 O 4 to synthesize Co 3 O 4 -composite spinels. Their formation was evidenced by transmission electronic microscopy (TEM), X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) analysis. It was found that Co 3 O 4 -composite spinels could efficiently activate peroxymonosulfate (PMS) to remove enrofloxacin (ENR) and the catalytic activity followed the order Co . Moreover, through the calculation of the specific apparent rate constant (k sapp ), it can be proved that the Co and Cu ions had the best synergistic effect for PMS activation. The Co 3 O 4 -composite spinels presented a wide pH range for the activation of PMS, but strong acidic and alkaline conditions were detrimental to ENR removal. Higher reaction temperature could promote the PMS activation process. Sulfate radical was identified as the dominating reactive species in Co 3 O 4 -composite spinel/ PMS systems through radical quenching experiments. Meanwhile, the probable mechanisms concerning Co 3 O 4 -composite spinel activated PMS were proposed. . Parameters involved in different reaction temperatures and Co 3 O 4 -composite spinels/ PMS systems: (e) Arrhenius curves; (f) DPMS. Experimental condition: [ENR] ¼ 10 mg L À1 , [catalyst] ¼ 0.1 g L À1 , [PMS] ¼ 1 mM, pH 0 ¼ 6.This journal is Fig. 9 (a) Reusability of different Co 3 O 4 -composite spinels as catalyst for the degradation of ENR; (b) cobalt leaching concentrations in different Co 3 O 4 -composite spinels/PMS systems. Experimental condition: [ENR] ¼ 10 mg L À1 , [catalyst] ¼ 0.1 g L À1 , [PMS] ¼ 1 mM, pH 0 ¼ 6, T ¼ 25 C, reaction time ¼ 25 min.

Ever-increasing efforts have been made to develop rapid and practical conditioning methods of sludge dewatering.