Rong-Chi Wang

Adsorption of Phenols onto Granular Activated Carbon in a Liquid–Solid Fluidized Bed

The adsorption of phenol, p-chlorophenol and p-nitrophenol onto granular activated carbon (GAC) in a liquid–solid fluidized-bed adsorber has been studied. The effects of particle sizes of activated carbon (0·937, 1·524 mm), liquid flow rate (1·2, 2·0, 4·0 dm3 min−1), initial phenol concentrations (1·12×10−4, 5·88×10−4 mol dm−3) and activated carbon mass (75, 150, 300 g) were investigated. The isotherm data were analysed by using the well-known isotherm equations to realize the adsorption characteristics of granular activated carbon. The model, which takes into account the external mass transfer with film-surface diffusion, surface adsorption equilibrium and internal mass transfer, was employed to fit the experimental data of the breakthrough curve. The model agreed with the experimental results very well when the Langmuir isotherm was employed and can be used for design and parametric studies.

Phenol degradation under visible light irradiation in the continuous system of photocatalysis and sonolysis

The combination of photocatalysis under visible light irradiation and sonolysis in the continuous system has been used to degrade an aqueous solution of phenol. ZnFe(2)O(4)/TiO(2)-GAC was employed as the photocatalysts which were obtained by sol-gel process and characterized by spectroscopic X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray microanalyses (SEM-EDX) and Brunauer-Emmett-Teller sorptometer (BET). It was observed that the rates of phenol degradation were affected by the initial pH value of phenol solution, salt addition, gas supplying and the recycling times of the recovered photocatalyst. The kinetic law for the phenol degradation can be apparently expressed as the first-order with respect to the concentration of phenol. Degradation of phenol solution in the continuous system, i.e., photocatalysis and sonolysis has synergistic effect in comparison with the photocatalytic reaction and sonolysis, respectively.

Adsorption/desorption of phenols onto granular activated carbon in a liquid–solid fluidized bed

The adsorption/desorption of phenols in aqueous solution onto coconut-shell granular activated carbon (GAC) in a liquid–solid fluidized bed adsorber approaching saturation capacity was investigated. Experiments were carried out using a 20 mm id adsorber under a variety of operating conditions including GAC particle sizes (0.937, 1.524 mm), GAC mass (12, 24 g), influent phenol concentration (0.367–1.071 mmol dm−3), surface loading of GAC (2.0, 2.5 mmol g−1) and liquid flow rate (0.15, 0.2, 0.35 dm3 min−1). The effect of repetitive adsorption/desorption cycles on the adsorption capacity has also been examined for phenol/GAC systems. The model based on the external mass transfer with film-surface diffusion, surface adsorption equilibrium and internal mass transfer was proposed to simulate the breakthrough curves of the phenol adsorption/desorption process. Using the experimentally measured Langmuir isotherm equilibrium parameters in the model has been found to describe reasonably well the experimental results. © 1999 Society of Chemical Industry