Treatment of high-concentration wastewater from a chemical company by wet air oxidation (WAO) is studied. Experiments were conducted to investigate the effects of the operating pressure and temperature on the chemical oxygen demand (COD) removal. Both air and oxygen were employed as the oxygen supply for the WAO treatment process. Catalytic effects of copper sulfate, cobalt oxide, and zinc oxide on the WAO efficiency were also examined. It was found that over 50% of COD removal can be easily realized in an hour of WAO oxidation. Two kinetic models (first-order and generalized) were employed to represent the experimental data, and their fit to those experimental data was compared. The rate coefficients and the kinetic parameters of the two models were determined also.

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Titanium dioxide has been recognized as an excellent photocatalyst material applied on many fields especially for environmental science or engineering. However, the effect of acid washing treatment on the morphology or phase and pore structures of titania nanotubes (TNs) has not still been clearly investigated. The variation of morphology, formation mechanism, phase structure, and pore structure of TN were thus characterized with FE-SEM, TEM, XRD, and N 2 BET isotherms, respectively in the present work. Titania nanotube synthesized via a simple hydrothermal chemical process formed a crystalline structure with open-ended and multiwall morphologies. The XRD patterns and N 2 BET isotherms implied that the acid washing techniques could improve the TN surface area and the pore size distribution up to 292 m 2 g −1 and 40-60 nm, respectively. According to EXAFS/XANES spectra, the structure of the TN is closer to the anatase specimen and much more correlated with octahedral structure. Effects of the pore structure variation on basic dye (Basic Green 5 (BG5)) adsorption by TN were discussed in the present work. Moreover, the adsorption ability, mechanisms, and kinetics of BG5 dye onto TN were also examined with the aid of model analyses of the adsorption equilibrium and kinetic data. Therefore, the potential of TN for the removal of BG5 dye contaminant from wastewaters implied that further development would be warranted.