1.
Colorimetric determination of Hg2+ in environmental water based on the Hg2+-stimulated peroxidase mimetic activity of MoS2-Au composites.
Ma, C, Ma, Y, Sun, Y, Lu, Y, Tian, E, Lan, J, Li, J, Ye, W, Zhang, H
Journal of colloid and interface science. 2019;:554-561
Abstract
A colorimetric assay is described for sensitive determination of Hg2+ ions based on the MoS2-Au composites as peroxidase mimetics, which are synthesized by microwave-assisted solvothermal method. The addition of Hg2+ stimulates their peroxidase-like activity, along with lower Michaelis constant toward the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) with H2O2, allowing the composites for direct determination of Hg2+. A broad linear response is obtained ranging from 20 nM to 20 μM with a detection limit (LOD) of 5 nM. The superior peroxidase-like activity is attributed to the large surface area of MoS2 nanosheets and the synergistic catalytic effect of MoS2 and Au. The Hg2+-stimulation effect implies the strong interaction between Hg2+ and MoS2-Au, where the XPS results confirm the presence of metallic Hg0, indicative of an Au-Hg amalgam. This colorimetric assay is successfully applied for the determination of Hg2+ in environmental water (tap water and Yellow River water) with excellent selectivity over interfering cations.
2.
Comparative study of Cu-based bimetallic oxides for Fenton-like degradation of organic pollutants.
Wang, Q, Ma, Y, Xing, S
Chemosphere. 2018;:450-456
Abstract
In order to provide useful information for the rational design of effective Fenton-like catalyst, a series of Cu-based bimetallic oxides were synthesized and their Fenton-like performances for the degradation of Orange II and ciprofloxacin were compared. The structure, chemical oxidation state, surface charge property and redox ability of the catalysts were also investigated by different characterization techniques. Among them, NiCu exhibited the highest adsorption capacity towards Orange II and the highest activity for the production of OH from H2O2 decomposition, which could be attributed to its high surface area and highly positively charged surface. However, FeCu exhibited the highest activity for the degradation of Orange II. The reason might be that FeCu has more unpaired electrons and higher redox ability, thus promoting the activation of adsorbed Orange II through the electron transfer process. By contrast, NiCu exhibited the highest activity for the removal of ciprofloxacin because ciprofloxacin was mainly degraded by OH. Finally, the main degradation intermediates of Orange II and ciprofloxacin were determined by liquid chromatography-mass spectrometry.
3.
Short-cut nitrification of domestic wastewater in a pilot-scale A/O nitrogen removal plant.
Wang, X, Ma, Y, Peng, Y, Wang, S
Bioprocess and biosystems engineering. 2007;(2):91-7
Abstract
The feasibility of nitrite accumulation in a pilot-scale A/O (anoxic/oxic) nitrogen removal plant treating domestic wastewater was investigated at various dissolved oxygen (DO) concentrations and pH levels. The results showed that the pH was not a useful operational parameter to realize nitrite accumulation. Significant nitrite accumulation was observed at the low DO concentration range of 0.3-0.8 mg/l and the maximum nitrite accumulation ratio of about 90% occurred at a DO concentration of 0.6 mg/l. This suggests a reduction of 22% in the oxygen consumption, and therefore a considerable saving in aeration. However, the nitrite accumulation was destroyed at the high DO concentration and the resumption was very slow. In addition, the average ammonia removal efficiency reached as high as 93% at the low DO level. Moreover, experimental results indicated that nitrogen could be removed by simultaneous nitrification and denitrification (SND) via nitrite in the aerobic zones at the low DO concentration, with the efficiency of 6-12%.