Arzu Y. Dursun

Bioaccumulation of copper(II), lead(II) and chromium(VI) by growing Aspergillus niger

Abstract The effect of copper(II), lead(II) and chromium(VI) ions on the growth and bioaccumulation properties of Aspergillus niger was investigated as a function of initial pH and initial metal ion concentration. The optimum pH values for growth and metal ion accumulation were determined as 5.0, 4.5 and 3.5 for copper(II), lead(II) and chromium(VI) ions, respectively. Although all metal ion concentrations caused an inhibition effect on the growth of A. niger , it was capable of removing of copper(II) and lead(II) with a maximum specific uptake capacity of 15.6 and 34.4 mg g −1 at 100 mg dm −3 initial copper(II) and lead(II) concentration, respectively. Growth of A. niger was highly effected by chromium(VI) ions and inhibited by 75 mg dm −3 initial chromium(VI) concentration since some inhibition occurred at lower concentrations.

The effect of Cd (II), Pb (II) and Cu (II) ions on the growth and bioaccumulation properties of Rhizopus arrhizus

Abstract The comparative growth and Cd (II), Pb (II) and Cu (II) ions bioaccumulation properties of Rhizopus arrhizus were investigated as a function of initial pH, temperature and initial metal ion concentrations. The optimum initial pH for Cd (II), Pb (II) and Cu (II) were determined as 3.5, 4.0 and 4.5 at optimum temperatures for each metal ion, respectively. Results indicated that microbial growth and metal ion uptake of R. arrhizus were significantly affected by initial metal ion concentrations. High microbial growth and Cd (II), Pb (II) and Cu (II) accumulation yields were found at low initial metal ion concentrations. R. arrhizus was more efficient in accumulating larger amounts of Cd (II) and Pb (II) ions than that of Cu (II) ions.

Removal of Chemazol Reactive Red 195 from aqueous solution by dehydrated beet pulp carbon

An agricultural low-cost by-product, dehydrated beet pulp carbon (DBPC) was used as an adsorbent for removal of Chemazol Reactive Red 195 (CRR 195) from aqueous solution. The surface area of DBPC was measured as 9.5m(2)g(-1) by using BET method. The results indicated that adsorption was strongly pH-dependent and optimum pH was determined as 1.0. The maximum dye adsorption capacity was obtained as 58.0 mg g(-1)at the temperature of 50°C at this pH value. The Freundlich and Langmuir adsorption models were used for the mathematical description of the adsorption equilibrium and it was reported that, experimental data fitted very well to Freundlich model. Mass transfer and kinetic models were applied to the experimental data to examine the mechanisms of adsorption and potential rate-controlling steps. It was found that both external mass transfer and intra-particle diffusion played an important role in the adsorption mechanisms of dye and adsorption kinetics followed the pseudo-first-order type kinetic model. The thermodynamic parameters such as, Gibbs free energy changes (ΔG°), standard enthalpy change (ΔH°) and standard entropy change (ΔS°) had been determined. The results show that adsorption of CRR 195 on DBPC is endothermic and spontaneous in nature.

Biosorption of Phenol on Dried Activated Sludge: Effect of Temperature

Abstract In this study, the effectiveness of dried activated sludge in removing phenol from aqueous solutions was examined by biosorption as a function of temperature, pH, and initial phenol concentration. Batch kinetic studies showed that an equilibrium time of 60 min was needed for the biosorption. The maximum phenol biosorption capacity was obtained as 42.7 mg g−1at the temperature of 40°C at pH = 8.0. The Freundlich and Langmuir adsorption models were used for the mathematical description of the biosorption equilibrium and it was reported that experimental data fitted very well to the Freundlich model. Adsorption rate data were analyzed using the pseudo-first order kinetic model of Lagergren and the pseudo-second order model to determine adsorption rate constants at 10, 25, and 40°C. It was reported that, the pseudo-second order kinetic model provided the best correlation of the experimental data rather than the pseudo-first order model. The thermodynamic parameters such as, Gibbs free energy changes (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°) were determined. The results show that biosorption of phenol on dried activated sludge is an endothermic and spontaneous in nature.

Application of treated eggplant peel as a low-cost adsorbent for water treatment toward elimination of Pb2+: Kinetic modeling and isotherm study

In this study, treated eggplant peel was used as an adsorbent to remove Pb2+ from aqueous solution. For this purpose batch adsorption experiments were performed for investigating the effect of contact time, pH, adsorbent dose, solute concentrations, and temperature. In order to assess adsorbent’s physical and chemical properties, Fourier transform infrared spectroscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy were used. The results showed that the adsorption parameters for reaching maximum removal were found to be contact time of 110 min, adsorbent dose of 0.01 g/ml, initial lead(II) concentration of 70 ppm, pH of 4, and temperature of 25°C. Moreover, for the experiments carried out at pH > 4 the removal occurred by means of significant precipitation as well as adsorption. Furthermore, these results indicated that the adsorption followed pseudo-second-order kinetics model implying that during the adsorption process strong bond between lead(II) and chemical functional groups of adsorbent surface took place. The process was described by Langmuir model (R2 = 0.99; maximum adsorption capacity 88.33 mg/g). Also thermodynamics of adsorption was studied at various temperatures and the thermodynamic parameters including equilibrium constant (K), standard enthalpy change, standard entropy change, and standard free energy changes were obtained from experimental data.