Rey-May Liou

CuO impregnated activated carbon for catalytic wet peroxide oxidation of phenol

This paper presents an original approach to the removal of phenol in synthetic wastewater by catalytic wet peroxide oxidation with copper binding activated carbon (CuAC) catalysts. The characteristics and oxidation performance of CuAC in the wet hydrogen peroxide catalytic oxidation of phenol were studied in a batch reactor at 80 degrees C. Complete conversion of the oxidant, hydrogen peroxide, was observed with CuAC catalyst in 20 min oxidation, and a highly efficient phenol removal and chemical oxygen demand (COD) abatement were achieved in the first 30 min. The good oxidation performance of CuAC catalyst was contributed to the activity enhancement of copper oxide, which was binding in the carbon matrix. It can be concluded that the efficiency of oxidation dominated by the residual H2O2 in this study. An over 90% COD removal was achieved by using the multiple-step addition in this catalytic oxidation.

Pervaporation separation water/ethanol mixture through lithiated polysulfone membrane

Abstract For dehydrating water/ethanol mixture by pervaporation, a lithiated polysulfone membrane was prepared. The separation performance of water and ethanol strongly depend on the degree of lithiation of polysulfone (PSF) membrane. The water permeation rate decreased and separation factor increased with increasing the degree of lithiation of polysulfone membrane upto 0.75. Beyond the degree of substitution 0.75, the permeation rate increased and separation factor decreased with increasing the substitution. The effect of lithiation on separation performance was due to the improvement of diffusion selectivity lithiated membrane. It was found that the diffusion selectivity was the dominant contribution to overall permselectivity. The diffusion difference between permeates through lithiated membrane was the dominant factor for separating water/ethanol mixture.

Methane emission from fields with three various rice straw treatments in Taiwan paddy soils.

Flooded rice fields are one of the major biogenic methane sources. In this study, the effects of straw residual treatments on methane emission from paddy fields were discussed. The experimental field was located at Tainan District Agricultural Improvement Station in Chia‐Yi county (23°25′08″N, 120°16′26″E) of southern Taiwan throughout the first and the second crop seasons in 2000. The seasonal methane fluxes in the first crop season with rice stubble removed, rice straw burned and rice straw incorporated were 4.41, 3.78 and 5.27 g CH4 m− 2, and the values were 32.8, 38.9 and 75.1 g CH4 m− 2 in the second crop season, respectively. In comparison of three management methods of rice straw residue, the incorporation of rice straw residue should show a significant tendency for enhancing methane emission in the second crop season. Moreover, stubble removed and straw burned treatments significantly reduced CH4 emissions by 28 ∼ 56% emissions compared to straw incorporated plot. Concerning for air quality had led to legislation restricting rice straw burning, removing of rice stubble might be an appropriate methane mitigation strategy in Taiwan paddy soils.

Removing aqueous ammonia by membrane contactor process

ABSTRACT High-tech industries have been rapidly developing for the last two decades in Taiwan, which also result in high concentrations of various nitrogenous compounds in the wastewater, such as eutrophication. Polyvinylidene fluoride (PVDF) membranes with asymmetric structures and good hydrophobicity have been prepared by a phase-inversion method and applied for removal of ammonia from water by membrane contactor. Aqueous solution containing sulfuric acid was used as stripping solution to accelerate the removal of ammonia. It was found that the investigation of membrane contactor revealed that the flux of PTFE and PVDF (12 wt%) was 193.1 and 97.4 g , respectively. Therefore, membrane contact system has great potential for future applications in wastewater treatment with high strength of ammonium.

The Effect of Metal Ions on Humic Acid Removal and Permeation Properties in an Ultrafiltration System

Abstract With a view to improving the removal of humic acid from aqueous solution, the effect of metal ion addition on the separation of humic acid from water in an utrafiltration (UF) system was investigated. The valence of the metal ion and the molar ratio of humic acid to metal ion strongly affected the permeation flux during ultrafiltration. It was found that the ionic strength, dissociation constant and operating pressure were not major factors affecting the separation performance of the ultrafiltration process. As well as indicating that a suitable ratio of humic acid to metal ion and valence of metal ion were the key factors in improving separation efficiency. The results also showed that separation of humic acid depended on the level of formation of humic acid–metal ion complexes, and on the degree of fouling on the membrane surface.

Catalytic wet peroxide oxidation of p-nitrophenol by Fe (III) supported on resin.

Fe(III) supported on resin (Fe(III)-resin) as an effective catalyst for peroxide oxidation was prepared and applied for the degradation of p-nitrophenol (PNP). Catalytic wet peroxide oxidation (CWPO) experiments with hydrogen peroxide as oxidant were performed in a batch rector with p-nitrophenol as the model pollutant. Under given conditions (PNP concentration 500 mg/L, H(2)O(2) 0.1 M, 80°C, resin dosage 0.6% g/mL), p-nitrophenol was almost completely removed, corresponding to an 84% of COD removal. It was found that the reaction temperature, oxidant concentration. and initial pH of solution significantly affected both p-nitrophenol conversion and COD removal by oxidation. It can be inferred from the experiments that Fe(III) supported on resin was an effective catalyst in the mineralization of p-nitrophenol. In an acidic environment of oxidation, the leaching test showed that there was only a slight leaching effect on the activity of catalytic oxidation. It was also confirmed by the aging test of catalysts in the oxidation.

Microbial Degradation of Phenol in a Modified Three-Stage Airlift Packing-Bed Reactor

Phenol degradation was carried out by using a modified three-stage airlift packing-bed bioreactor. A laboratory-scale airlift packing-bed reactor, with hydrodynamic flexible packing material in the three-stage bioreactor, was constructed and operated for phenol removal from synthetic wastewater. The airlift packing-bed reactor successfully degraded phenol and lowered the chemical oxygen demand (COD) of wastewater. High COD removal was observed, and much lower sludge effluent was obtained in this investigation. This airlift bioreactor showed a superior hydrodynamics performance and broad operating conditions for phenolic material removal. Different operating modes were discussed to obtain the optimal condition for phenol degradation (i.e., hydraulic retention time [HRT] and gas flowrate of airlift). The HRT and feed phenol concentration of wastewater dominated the removal efficiency of phenol and COD. In this bioreactor, surface loading up to 2.84 g phenol/ m2 x d, almost 100% phenol removal, and over 90% COD removal was achieved. The lower operating cost combined with higher phenol-removal efficiency and a low sludge effluent concentration can be achieved by using this reactor for phenol wastewater treatment.

The denitration pathway of p-nitrophenol in the hydrogen peroxide catalytic oxidation with an FeIII-resin catalyst

The liquid-phase hydrogen peroxide catalytic oxidation of p-nitrophenol was performed with an Fe(III)-resin catalyst. The conversion and mineralization of p-nitrophenol was effectively achieved at mild reaction conditions with the Fe(III)-resin catalyst. It was found that the oxidant concentration, pH, and temperature dominated the degradation rate of p-nitrophenol. The denitration pathway of p-nitrophenol was proposed, in which the concentration of H(2)O(2) and temperature showed strong influence on the conversion of nitrite to nitrate. To study the factors influencing the denitration of p-nitrophenol, a comparable kinetic study was attempted to know the possible denitration pathway of p-nitrophenol. The results of this investigation indicated that denitration was the possible step occurring with the decomposition of p-nitrophenol.