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Biosortion of Nickel (ii) by Using Waste Baker's Yeast
(Izmir Institute of Technology, 2001) Özdemir, Peruze; Harsa, Hayriye Şebnem; Harsa, Hayriye Şebnem; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
3 Biological methods for removing heavy metals are in competition with chemical and physical techniques such as precipitation, ion exchange, electrochemical treatment and evaporative recovery, especially, when the concentration of the heavy metal ion is low, between 1.0 and 100 mg/L. In order to qualify for industrial applications, biosorbents have to be produced at low cost. The use of biomass from various production stages; e.g. from the pharmaceutical or the food industries, is one way to minimize the costs. This study is concerned with the binding of nickel ions onto waste biomass of Saccharomyces cerevisiae genus, obtained from the food industry. Since the biomass employed is a waste material, biosorption process described in this study may represent a cheap alternative to conventional methods.Biomass cell walls, consisting mainly of polysaccharides, proteins and lipids, offer many functional groups which can bind metal ions such as carboxylate, hydroxyl, phosphate and amino groups.The objective of this study was to investigate the adsorption of nickel on wastebaker.s yeast as a function of several factors, i.e. pretreatment, pH, temperature, biomass concentrations and initial metal concentrations, in order to determine the optimum adsorption conditions of a batch process.Pretreatment of waste yeast biomass using sodium hydroxide, formaldehyde, nitric acid and ethanol decreased the sorption of nickel (II) ions compared with live biomass. Optimum initial pH for nickel (II) ions was 5.0 at the optimum temperature of 25o C. The uptake values increased with the increasing initial nickel (II) ion concentrations up to 150 mg/L. The optimum biomass concentration for this process was determined as 1.0 g/L.The biosorption isotherms were developed at various initial pH and temperature values. The equilibrium values were expressed with the Langmuir model while nickel sorption did not fit the Freundlich plot. The Langmuir parameters qmax (14.30 mg/L) and b (0.0069 L/mg) have been calculated."qmax" increased from 7.8 to 14.30 mg/L with the increase in pH from 3.0 to 5.0. Similar trend was observed for the "b" values; an increase from 0.0025 to 0.0069 L/mg were obtained when the pH of the solution was raised from 3.0 to 5.0. Both Langmuir model parameters were found to be the highest values at pH 5.0 which is consistent with the results of the optimization studies as described above.Temperature also affected the phase equilibria of nickel (II)/S.cerevisiae system.The highest capacity for biosorption system was obtained at 25o C with the qmax and b values of 14.3 mg/L and 0.0069 L/mg at pH 5.0, respectively. The enthalpy change for the biosorption process have been evaluated by using the Langmuir constant "b", which is related to the energy of adsorption. Nickel (II) biosorption is considered to be an exothermic process since low binding occurs when the temperature increases from 25 to 45o C.The uptake of nickel (II) ions by the yeast biomass was also investigated with respect to time under optimum operating conditions. Biosorption kinetics were rapid within the first few minutes. After the initial rapid uptake, further biosorption by yeast cells continued slowly and reached an equilibrium after 2 hours at all pH values of 3.0, 4.0 and 5.0. On the other hand, the rate of adsorption was found to be the fastest at pH 5.0 with an initial rate of around 3.59 mg Ni (II) / g-min.
Preconcentration of Heavy Metals in Environmental Samples by Biosorption and Determination by Atomic Spectrometry
(Izmir Institute of Technology, 2007) Şeker, Ayşegül; Eroğlu, Ahmet Emin; Eroğlu, Ahmet Emin; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
In the assessment of environmental quality, one of the priorities must be given to the determination of heavy metals. In the present study, Spirulina platensis, a cyanobacteria (or blue-green alga) was suggested to be used as a biosorbent prior to the atomic spectrometric determination of Pb, Cd and Ni in some environmental samples. For this purpose, the parameters which might be effective on the biosorption were investigated such as pH, time, initial metal ion concentration, biosorbent amount, temperature, kinetics of sorption, repetitive reactivity and ionic competition. According to the sorption kinetics, results obeyed well the pseudo second-order model. Freundlich, Dubinin Radushkevich and Temkin isotherm models were applied in describing the equilibrium partition of the ions. Freundlich isotherm was applied to describe the design of a single-stage batch sorption system. Thermodynamic parameters (.G0, .H0 and .S0) were calculated and the sorption process was found to be largely driven towards the products and it had an endothermic nature. Faster adsorption kinetics was observed for Pb2+ ions in comparison to Cd2+ and Ni2+ ions. Based on kinetic modeling, the apparent activation energy, Ea, was calculated to be 44 kJmol-1, -16 kJmol-1 and 54 kJmol-1 for Pb2+, Cd2+and Ni2+, respectively. The measurements of the repetitive reusability of Spirulina platensis indicated a large capacity towards the three metal ions. Sorption activities in a three metal ion system were studied and at an initial metal concentration of 100.0 mgL-1, % Pb2+ was found to be still high (85%).However, it decreased to less than 20% for Cd2+ and Ni2+ indicating the relative selectivity of the biosorbent towards Pb2+. Finally, the use of Spirulina platensis, in its natural form or after be immobilized onto various matrices (alginate, silicate, carboxymethylcellulose and polysulfone) was planned for the separation of heavy metals from the sample matrix.

Sürdürülebilir Yeşil Kampüs Koleksiyonu / Sustainable Green Campus Collection

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