Ayla Özer

Comparative study of the biosorption of Pb(II), Ni(II) and Cr(VI) ions onto S. cerevisiae: determination of biosorption heats

In this study, the biosorption of Pb(II), Ni(II) and Cr(VI) ions onto inactive Saccharomyces cerevisiae was investigated as a function of initial pH, initial metal ion concentration and temperature. The Langmuir model was applied to experimental equilibrium data of Pb(II), Ni(II) and Cr(VI) biosorption depending on temperature and the maximum metal ions uptake at optimum biosorption temperature of 25 degrees C, were found to be 270.3, 46.3 and 32.6 mgg(-1), respectively. Using the Langmuir constant, b values obtained at different temperatures, the biosorption heats of Pb(II), Ni(II) and Cr(VI) were determined as -1.125, -1.912 and -2.89 kcalmol(-1), respectively. The results indicated that the biosorption of Pb(II), Ni(II) and Cr(VI) ions to S. cerevisiae is by the physical adsorption and has an exothermic nature.

APPLICATION OF FREUNDLICH AND LANGMUIR MODELS TO MULTISTAGE PURIFICATION PROCESS TO REMOVE HEAVY METAL IONS BY USING SCHIZOMERIS LEIBLEINII

The adsorption of iron(III), lead(II) and cadmium(II) ions onto Schizomeris leibleinii, a green alga, was studied with respect to initial pH, temperature, initial metal ion and biomass concentration to determine the optimum adsorption conditions. Optimum initial pH for iron(III), lead(II) and cadmium(II) ions were 2.5, 4.5 and 5.0 at optimum temperature 30°C, respectively. The initial adsorption rates increased with increasing initial iron(III), lead(II) and cadmium(II) ion concentrations up to 100, 100 and 150 mg l−1, respectively. The Freundlich and Langmuir adsorption isotherms were developed at various initial pH and temperature values. The adsorption of these metal ions to S. leibleinii was investigated in a two-stage mixed batch reactor. The residual metal ion concentrations (Ceq) at equilibrium at each stage for a given ‘quantity of dried algae (X0)/volume of solution containing heavy metal ion (V0)’ ratio were calculated using Freundlich and Langmuir isotherm constants. The experimental biosorption equilibrium data for iron(III), lead(II) and cadmium(II) ions were in good agreement with those calculated by both Freundlich and Langmuir models. The adsorbed iron(III), lead(II) and cadmium(II) ion concentrations increased with increasing X0/V0 ratios while the adsorbed metal quantities per unit mass of dried algae decreased.

A staged purification process to remove heavy metal ions from wastewater using Rhizopus arrhizus

Abstract The adsorption of iron(III), lead(II) and cadmium(II) ions onto dry cells of Rhizopus arrhizus was investigated in a four-stage batch reactor. The adsorption in multi-stage reactors can be considered as a multi-stage equilibrium depending on the adsorption equilibrium and mass balance. The Freundlich and Langmuir adsorption isotherms were developed to evaluate the biosorptive uptake capacity of the biomass. The Freundlich and Langmuir constants at optimum adsorption conditions were used to calculate the residual or adsorbed metal ion concentrations at equilibrium at each stage for a given volume of solution containing heavy metal ion/quantity of dried biomass ( V 0 X ) ratio. 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 decrease of V 0 X ratios affected the quantities of iron, lead and cadmium removed from aqueous solution.

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.

The single batch biosorption of copper(II) ions on Sargassum acinarum

AbstractIn this study, the biosorption of copper(II) ions to Sargassum acinarum, a brown seaweed, was investigated in a batch system. The optimum biosorption conditions were determined as initial pH 5.5, temperature 25°C, initial copper(II) ion concentration 100 mg/L and biosorbent concentration 1.0 g/L. At the optimum biosorption conditions, the biosorption capacity of S. acinarum for copper(II) ions was found as 36.56 mg/g algae. The Langmuir and Freundlich isotherm models were applied to the biosorption data and the biosorption equilibrium was described well by the Langmuir isotherm model, with maximum biosorption capacity of 40.50 mg/g (0.637 mmol/g algae) of copper(II) ions. The intraparticle diffusion model and the pseudo-second-order kinetic model were applied to the experimental data in order to determine the removal mechanism and biosorption kinetic of copper(II) ions by S. acinarum. The pseudo-second-order kinetic model described very well the biosorption kinetic of copper(II) ions. Results show...

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.

Competitive Biosorption of Acid Dyes from Binary Solutions onto Enteromorpha prolifera: Application of the First Order Derivative Spectrophotometric Analysis Method

The biosorption of Acid Red 274 and Acid Red 337 dyes from single and binary solutions on Enteromorpha prolifera was investigated in a single stage batch system. The first order derivative spectrophotometry was tested in order to analyse the studied binary solutions of the selected dyes. The single- and multi-component Langmuir and Freundlich isotherm models were applied to the experimental equilibrium data and the isotherm parameters were estimated. It was observed that the uptake amounts of the first component decreased with increasing concentration of the second component from binary solution. As a result, the binary biosorption of AR274 and AR337 dyes on E.prolifera have an antagonistic effect. The binary biosorption of AR274 and AR337 dyes in a single stage batch system was modelled and the equilibrium concentrations of the exit stream were found by using the experimental equilibrium curves and operating lines for the biosorption of single and binary dye solutions.

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 .

THE INVESTIGATION OF THE ADSORPTION OF ACID BLUE 121 ON BANANA SHELL IN A BATCH SYSTEM

Bu calismada, Acid Blue 121 (AB 121)’in tarimsal bir atik olan muz kabugu (MK)’na adsorbsiyonuna baslangic pH’si, sicaklik, baslangic boyar madde derisimi ve adsorbent derisiminin etkisi kesikli bir sistemde arastirilmistir. AB 121’in MK’na adsorbsiyonu denge verilerinin Langmuir izoterm modeline cok iyi uydugu; MK’nun maksimum tek tabaka adsorpsiyon kapasitesinin 141 mg/g oldugu saptanmistir. AB 121’nin MK’na adsorbsiyonu kinetiginin yalanci ikinci mertebe kinetik modeli ile temsil edilebilecegi ayrica giderimde tanecik ici ve tanecik disi difuzyonunun etkili oldugu sonucuna varilmistir. AB 121’in MK’na adsorbsiyonuna ait termodinamik parametreler belirlenmis; calisilan adsorpsiyon sisteminin ekzotermik ve kendiliginden gerceklestigi gozlenmistir. MK’nun FTIR, SEM ve EDX analizleri ile karakterizasyonu calismalari da gerceklestirilmistir.