THE IMPORTANCE OF AXIAL DISPERSION IN LIQUID-PHASE FIXED-BED ADSORPTION OPERATIONS

Abstract The competitive simultaneous removal of petrochemical hydrocarbons including benzene, toluene, ethylbenzene and isomers of xylene (BTEX) from an aqueous solution by polystyrenic resin (PAD 910) was investigated at dynamic conditions in a packed bed column. The column was operated under conditions of bed length (Z = 30–90 cm), flow rate (Q = 18.5–53.5 cm/min), bed diameter (D = 2.5–5 cm) and initial concentration of (C0 = 5–14.5 mg/l) to investigate the adsorption characteristics of BTEX at an influent pH of 6.85. There was evidence of improved column performance with increasing operating height and decreased flow rate. Breakthrough curves of fixed-bed adsorption process were developed by the constant-pattern approach using a constant driving force model in the liquid phase. A fairly good fit to the experimental data was obtained using the constant-pattern approach and a Langmuir isotherm model obtained from previous work. In addition, a prediction of volumetric mass transfer coefficient correlation in the liquid phase was suggested. Desorption from polystyrenic resin adsorbed with BTEX was investigated by using two different organic solvents as desorbates.

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Breakthrough analysis for hexavalent chromium removal from drinking water in a fixed bed column

Water Science & Technology Water Supply ◽

10.2166/ws.2009.714 ◽

2009 ◽

Vol 9 (6) ◽

pp. 661-670 ◽

Cited By ~ 2

Author(s):

S. P. Dubey ◽

K. Gopal

Keyword(s):

Aqueous Solution ◽

Hexavalent Chromium ◽

Fixed Bed ◽

Entropy Change ◽

Spectroscopic Technique ◽

Fixed Bed Column ◽

Chromium Vi ◽

Fixed Bed Adsorption ◽

Optimal Column ◽

Eucalyptus Bark

The activated carbon of Eucalyptus globulus was tested for their effectiveness in removing hexavalent chromium from aqueous solution using column experiments. Result revealed that adsorption of chromium(VI) on eucalyptus bark carbon was endothermic in nature. Thermodynamic parameters such as the entropy change, enthalpy change and Gibbs free energy change were found to be 1.39 kJ mol−1 K−1, 1.08 kJ mol−1 and −3.85 kJ mol−1, respectively. Different chromium concentrations were used for the fixed bed adsorption studies. The pre- and post-treated adsorbents were characterized using a FTIR spectroscopic technique. It was concluded that Eucalyptus bark carbon column could be used effectively for removal of hexavalent chromium from aqueous solution at optimal column conditions. This study showed that this biological material is potential adsorbent of Cr(VI) from water.

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Modeling of aerated upflow fixed bed reactors for nitrification

Water Science & Technology ◽

10.2166/wst.1999.0193 ◽

1999 ◽

Vol 39 (4) ◽

pp. 85-92 ◽

Cited By ~ 7

Author(s):

J. Behrendt

Keyword(s):

Mathematical Model ◽

Mass Transfer ◽

Liquid Phase ◽

Gas Phase ◽

Fixed Bed ◽

Fixed Bed Reactor ◽

Bulk Liquid ◽

Initial Value ◽

Fixed Bed Reactors ◽

Number Of Cells

A mathematical model for nitrification in an aerated fixed bed reactor has been developed. This model is based on material balances in the bulk liquid, gas phase and in the biofilm area. The fixed bed is divided into a number of cells according to the reduced remixing behaviour. A fixed bed cell consists of 4 compartments: the support, the gas phase, the bulk liquid phase and the stagnant volume containing the biofilm. In the stagnant volume the biological transmutation of the ammonia is located. The transport phenomena are modelled with mass transfer formulations so that the balances could be formulated as an initial value problem. The results of the simulation and experiments are compared.

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Axial dispersion in the liquid phase in a horizontal two-phase tube reactor

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19911249 ◽

1991 ◽

Vol 56 (6) ◽

pp. 1249-1252

Author(s):

Marie Fialová ◽

Ctirad Verner ◽

Lothar Ebner

Keyword(s):

Liquid Phase ◽

Flow Regimes ◽

Basic Flow ◽

Axial Dispersion ◽

Two Phase ◽

Tube Reactor

The characteristics of axial dispersion in the liquid phase were measured for two basic flow regimes in a horizontal two-phase tube reactor. The data obtained indicate that in some flow regions, axial dispersion can be quite significant.

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