Gülbeyi Dursun

Investigation of zinc(II) adsorption on Cladophora crispata in a two-staged reactor

In this study, the adsorption of zinc(II) ions on Cladophora crispata, a green alga, was studied with respect to initial pH, temperature, initial metal ion and biomass concentration in order to determine the optimum adsorption conditions. Optimum initial pH values for zinc(II) ions were found to be 5.0 at optimum temperature, 25 °C. The initial adsorption rates increased with increasing initial zinc(II) ion concentration up to 100 mgdm−3. The Freundlich and Langmuir adsorption isotherms were developed at various initial pH and temperature values. Then, the adsorption of zinc(II) ions to C crispata was investigated in a two-staged mixed batch reactor. The residual metal ion concentrations (Ceq) at equilibrium at each stage for a given quantity of dried algae (Xo)/volume of solution containing heavy metal ion (Vo) ratio were calculated by using Freundlich and Langmuir isotherm constants. It was observed that the experimental biosorption equilibrium data for zinc(II) ions are in good agreement with those calculated using both Freundlich and Langmuir models. The adsorbed zinc(II) ion concentration increased with increasing Xo/Vo ratios while the adsorbed metal quantities per unit mass of dried algae decreased. © 2000 Society of Chemical Industry

Cadmium(II) adsorption on Cladophora crispata in batch stirred reactors in series

Abstract In this study, the adsorption of cadmium(II) ions onto Cladophora crispata was investigated in a two-staged batch reactor. The sorption phenomenon was expressed by the Freundlich and Langmuir adsorption isotherms and these expressions were used for the calculation of the equilibrium value of the residual cadmium(II) concentration at each stage. The experimental equilibrium values were compared with the values obtained from Freundlich and Langmuir isotherm equations. These results showed that the increase in biomass quantity or the increase of X o / V o ratios affected the quantities of cadmium removed from aqueous solution.

Mass transfer characteristics of a fermentation broth in a reactor: co-current downflow contacting reactor

Gas holdups, dispersion height, volumetric mass transfer coefficients and kLa of water and a yeast fermentation broth were studied in a co-current downflow contacting reactor. kLa and gas holdup increased with increasing superficial gas velocity and there was a parallelism between kLa and gas holdup. The values of kLa gas holdup, and dispersion height measured in the air/fermentation broth system were all lower than those in air/water system.

Yeast fermentation in a cocurrent downflow contacting reactor (CDCR)

The growth kinetics and mass transfer characteristics of Saccharomyces cerevisiae in a cocurrent downflow contacting reactor (CDCR) were studied for various glucose concentrations at constant air and liquid flow rates. Increasing glucose concentration increased the biomass concentration thus resulting in an increase in the volumetric oxygen uptake rate. The volumetric mass transfer coefficient, k L a, however, decreased with increasing glucose concentration. It was observed that the growth of S cerevisiae in the CDCR would fit the classical Monod kinetics and the maximum specific growth rate was determined to be 0.545 h -1 .

Investigation of α-Amylase Production with Bacillus amyloliquefaciens in a Cocurrent Downflow Contacting Reactor

Abstract The cocurrent downflow contacting reactor (CDCR) has a high oxygen transfer rate by providing the effective the gas-liquid contact. This property is an advantage for enzyme production. In this study, the CDCR was used for the production of α-amylase by Bacillus amyloliquefaciens for different starch concentrations in the range of 7.5–17.5 g l–1 at constant air and liquid flow rates. The values of the volumetric oxygen transfer coefficient (kLa) and specific oxygen uptake rate ( qO2

Removal of methylene blue from aqueous solution by dehydrated wheat bran carbon

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Adsorption of phenol from aqueous solution by using carbonised beet pulp.

) were determined during enzyme production. It has been found that the starch concentration has great effect on the enzyme activity. Maximum enzyme activity (1,000 IU ml–1) was obtained in the fermentation broth containing of 15 g l–1 starch concentration at 37 °C and pH 7 for 28 h. The kLa and qO2

Effects of liquid property on gas holdup and mass transfer in co-current downflow contacting column

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Kinetics of Remazol Black B adsorption onto carbon prepared from sugar beet pulp

values were determined to be 175.83 h–1 and 47.5 mg O2 g–1cell h–1, respectively.