Yuting Tu

Catalytic wet air oxidation of 2-chlorophenol over sewage sludge-derived carbon-based catalysts.

A sewage sludge derived carbon-supported iron oxide catalyst (FeSC) was prepared and used in the Catalytic Wet Air Oxidation (CWAO) of 2-chlorophenol (2-CP). The catalysts were characterized in terms of elemental composition, surface area, pHPZC, XRD and SEM. The performances of the FeSC catalyst in the CWAO of 2-CP was assessed in a batch reactor operated at 120°C under 0.9MPa oxygen partial pressure. Complete decomposition of 2-CP was achieved within 5h and 90% Total Organic Carbon (TOC) was removed after 24h of reaction. Quite a straight correlation was observed between the 2-CP conversion, the amount of iron leached in solution and the pH of the reaction mixture at a given reaction time, indicating a strong predominance of the homogeneous catalysis contribution. The iron leaching could be efficiently prevented when the pH of the solution was maintained at values higher than 4.5, while the catalytic activity was only slightly reduced. Upon four successive batch CWAO experiments, using the same FeSC catalyst recovered by filtration after pH adjustment, only a very minor catalyst deactivation was observed. Finally, based on all the identified intermediates, a simplified reaction pathway was proposed for the CWAO of 2-CP over the FeSC catalyst.

Separation and determination of degradation products of acid orange 7 by capillary electrophoresis/capacitively coupled contactless conductivity detector.

Capillary electrophoresis (CE) with capacitively coupled contactless conductivity detector (C(4)D) was developed to separate azo-dyestuff acid orange 7 (AO7) and its six degradation products. The analyzed products were sulfamic acid, oxalic acid, benzenesulfonic acid, 4-hydroxybenzene sulfonic acid, phthalic acid, and 4-aminobenzene sulfonic acid. In developing the method, types and concentrations of running buffers, injecting voltage and time, and applied voltage were tested to obtain optimum conditions to analyze target compounds. The separation was successfully achieved within 10 min using a fused-silica capillary under the following conditions: 20 mmol L(-1) acetate acid buffer, electrokinetic injection of -12 kV × 10 s, and applied voltage of -13 kV. The developed method was applied to analyze degradation products in situ during the reaction of AO7 with Fenton reagent (Fe(II)+H2O2 at pH 4.0).

Efficient degradation of nitrobenzene by an integrated heterogeneous catalytic ozonation and membrane separation system with active MgO(111) catalyst

AbstractAn integrated heterogeneous catalytic ozonation and membrane separation system was studied for continuous degradation of refractory organic pollutants in water. MgO nanosheets with dominant (111) facets showed large amounts of medium and strong basic sites due to the particular structure of alternating monolayers of exclusively oxygen and exclusively magnesium atoms. MgO(111) acted as the ozonation catalyst for the first time, it was found that efficient degradation of nitrobenzene was achieved with 25.0 mmol/L of MgO(111) catalysts in a wide pH range of 4.0–12.0. In view of practical application, engineering problems to recover fine size catalysts from the treated water were resolved by applying membrane separation technology in the system. Experimental results showed that the membrane could successfully intercept MgO(111) particles in the reactor by the synergistic cooperative sieving of the bare and dynamic membranes. The long-term continuous experiments demonstrated that the removal rate of ni...