Müşerref Arda

Removal of Cr(VI) by solvent impregnated resins (SIR) containing aliquat 336

Abstract Solvent impregnated resins (SIR) have been prepared by a wet-impregnation technique using two different polymer matrices, Diaion HP-20 and HP-2MG. Diaion HP-20 possesses a hydrophobic styrene–divinylbenzene polymeric structure whereas HP-2MG is a hydrophilic methacrylic based polymer. Aliquat 336 was employed as the extractant and acetone as the solvent for impregnation. Batch sorption studies have shown that solvent impregnated resins containing Aliquat 336 can be effectively used for the removal of hexavalent chromium from aqueous solutions. The Langmuir adsorption isotherm gave a satisfactory fit of the equilibrium data. A kinetic study has been performed for SIR at two different concentrations of Cr(VI) (2×10 −4 and 4×10 −4 M). A finite-bath diffusion-control model with changing bulk concentration was used for sorption of Cr(VI) by SIR. Increasing the impregnation ratio from 0.5 to 1.0 (g Aliquat 336/g polymer adsorbent) increased the breakthrough capacity in a column-mode sorption study. The Cr(VI) bound by the SIR has been quantitatively desorbed using 0.1 M NaOH–0.1 M NaCl mixture.

Effect of feed characteristics on the separation performances of monovalent and divalent salts by electrodialysis

Abstract In this study, separation performance for monovalent salts (NaCl, KCI) and divalent salts (CaCl2 MgCl2) was investigated by electrodialysis at pH 6.0–6.5, 4.0 and 2.0 using constant voltage mode of operation. TS-1–10 electrodialysis equipment (Tokuyama) modified with rotameters was employed in experimental studies. The effect of electrical potential, pH and ion valency on separation performance was studied at room temperature using a constant flow rate. The efficiencies of each run were evaluated as specific power consumption with the electrical energy consumed only in stack.

Removal of Fluoride from Geothermal Water by Electrodialysis (ED)

Abstract Removal of fluoride from geothermal water by electrodialysis (ED) was studied. ED operation was performed according to two methods. In the first method, before the ED operation, the pH of geothermal waters was adjusted to 7−7.5 by the addition of the HCl solution to prevent the precipitation of divalent salts in the concentrate compartment. In the second method, geothermal water was pretreated to precipitate the calcium ions. It was obtained that fluoride was effectively removed from geothermal water by electrodialysis using both of these pretreatment methods. However, it is preferable to use the first method because of its technically simple procedure and lower cost of chemicals used.

Effect of temperature on seawater desalination-water quality analyses for desalinated seawater for its use as drinking and irrigation water

The effect of feed seawater temperature on the quality of product water in a reverse osmosis process was investigated using typical seawater at Urla Bay, Izmir region, Turkey. The tests were carried out at different feed seawater temperatures (11–23°C) using two RO modules with one membrane element each. A number of variables, including pH, conductivity, total dissolved solids, salinity, rejection percentage of a number of ions (Na+, K+, Ca2+, Mg2+, Cl−, HCO3−, and SO42−), and the levels of boron and turbidities in collected permeates, were measured. The suitability of these permeates as irrigation and drinking water was checked by comparison with water quality standards.

Removal of cadmium from phosphoric acid solution by solvent-impregnated resins (sirs) - sorption kinetics and equilibria studies

Cyanex-302 (bis [2,4,4-trimethylpentyl] monothiophosphinic acid) was impregnated into macroporous Diaion HP-10 and HP-1MG polymeric resin matrices and used as an extractant to recover cadmium from concentrated phosphoric acid. The optimum conditions for batchwise extraction of cadmium were established, and equilibrium data in the concentration range 0-200 mg/L Cd were obtained in 40% H 3 PO 4 solution. A Langmuir adsorption isotherm gave the best fit of the adsorption equilibrium data. A preliminary kinetic study was carried out in order to elucidate the rate-controllingmechanism. The uptake of trace cadmium onto Cyanex 302 containing solvent-impregnated resins from 40% phosphoric acid appears to be particle diffusion controlled.

Investigation of Selectivity and Kinetic Behavior of Strong‐Base Ion Exchange Resin Purolite A 520E for Nitrate Removal from Aqueous Solution

Abstract The aim of this work is to present experimental results on the removal of nitrate by nitrate selective ion exchange resin, Purolite A 520E. The resin particle size, nitrate concentration, temperature, and stirring speed were investigated as experimental parameters and the optimum conditions for nitrate removal were determined. Nitrate removal by strong base anion exchange resin Purolite A 520E was carried out with the batch method in the presence of chloride and sulfate ions. The existence of a high concentration of competing ions in a solution resulted in a reduction of nitrate removal. Nitrate removal ratios decreased from 98% to 85% and 88%, respectively, in the presence of chloride and sulfate ions when the chloride and sulfate ratios were increased in solution. The process kinetics were predicted by using Homogenous Diffusion Models. It was seen that about 98% of nitrate in the aqueous solution could be removed using optimum conditions.

Equilibrium and Kinetic Studies on Lithium Adsorption from Geothermal Water by λ-MnO2

ABSTRACT The adsorption equilibria of lithium from geothermal water were investigated by using both powdery and granulated forms of λ-MnO2 derived from spinel-type lithium manganese dioxide. Optimum amounts of adsorbents were 1.0 g adsorbent/L-geothermal water for powdery λ-MnO2 and 6.0 g adsorbent/L-geothermal water for granulated λ-MnO2. The adsorbents exhibited the promising adsorption capacities and their adsorption equilibria of lithium agreed well with the Langmuir adsorption isotherm model. The kinetic data of lithium adsorption have been evaluated using pseudo-first-order, pseudo-second-order kinetics models, as well as Elovich kinetic model. In addition, intra-particle diffusion model has been used for evaluating the kinetic data to evaluate the adsorption mechanism. The adsorption kinetic process was attributed to the gradual adsorption stage where intra-particle diffusion was found as the rate-controlling step.

Elimination of boron and lithium coexisting in geothermal water by adsorption-membrane filtration hybrid process

ABSTRACT Direct release of geothermal waters to the environment may cause some damages to some plants because they contain toxic species such as boron, arsenic, fluoride etc. along with valuable minerals including lithium. In this study, a hybrid process combining adsorption and membrane filtration was used to separate boron and lithium simultaneously from geothermal water. According to the results obtained, separation efficiencies for lithium and boron from geothermal water were 100% and 83% using boron selective ion exchange resin Dowex XUS-43594.00 and lithium selective λ-MnO2 adsorbent, respectively. The kinetic data of lithium and boron adsorption have been evaluated using pseudo-first order and pseudo-second-order kinetic models.

Effect of Operational Conditions on Separation of Lithium from Geothermal Water by λ-MnO2 Using Ion Exchange–Membrane Filtration Hybrid Process

ABSTRACT A hybrid system coupling ion exchange and ultrafiltration (UF) was employed to separate lithium from lithium-spiked geothermal water. The effect of process parameters such as adsorbent type, adsorbent dosage, permeate flow rate, and replacement speeds of fresh and saturated adsorbents have been evaluated to determine the efficiency of the hybrid system. According to the results obtained using λ-MnO2 derived from spinel-type lithium manganese dioxide, the optimal operating conditions to separate lithium from geothermal water were found with powdery λ-MnO2 with an adsorbent concentration of 1.5 g adsorbent/L solution, replacement rates of fresh and saturated adsorbents of 6.0 mL/min, and a permeate flow rate of 5.0 mL/min. The ion exchange–UF hybrid system providing an advantage to work with very fine particles easily can be considered as a favorable process for the separation of lithium from geothermal water.