Ümran Yüksel

Removal of Fluoride from Water by Metal Ions (Al3+, La3+ and ZrO2+) Loaded Natural Zeolite

Abstract In this study, the ion exchange of metal ions (Al3+, La3+ and ZrO2+) on modified zeolites was carried out using batch method. Fluoride removal from water using Al3+‐, La3+‐ and ZrO2+‐ exchanged zeolite was subsequently investigated to evaluate the fluoride sorption characteristics of the sorbents. Natural zeolite samples (<45 µm) were pre‐conditioned with HNO3 solution (ZEO‐1), NaNO3 solution (ZEO‐2), and deionized water (ZEO‐3) before loading Al3+, La3+, and ZrO2+ on zeolite. ZEO‐1 type zeolite had a higher capacity than ZEO‐2 and ZEO‐3 type zeolites. Metal exchange capacities are 0.233, 0.089, 0.090 mmol/g for ZrO2+‐, La3+‐, and Al3+‐ exchanged zeolite (ZEO‐1), respectively. Equilibrium isotherms fitted well to Langmuir and Freundlich models. Percent removal of fluoride from aqueous solution containing 2.5 mg F/L was 94% using metal loaded zeolite (ZEO‐1 type) at an adsorbent concentration of 6.00 g/L.

Separation of Boron from Geothermal Water Using a Boron Selective Macroporous Weak Base Anion Exchange Resin

In this study, batch and column mode tests were performed to evaluate the efficiency of boron removal from geothermal water containing 10-11 mg B/L using Lewatit MK 51 which is a macroporous weak base anion exchange resin with polyhydroxyl groups showing a very high selectivity and capacity for boron. The optimum resin amount for boron removal from geothermal water was determined as 4.0 g resin/L-geothermal water. It was found that the sorption kinetics was influenced by particle size of the resin and temperature. The stirring rate had almost no effect on kinetic performance of the resin. According to the results of column-mode study performed, breakthrough and total capacities of the resin were obtained as 2.75 and 4.98 mg/mL-resin, respectively.

ELECTRO-DEIONIZATION OF Cr (VI)-CONTAINING SOLUTION. PART II: CHROMIUM TRANSPORT THROUGH INORGANIC ION-EXCHANGER AND COMPOSITE CERAMIC MEMBRANE

Cr (VI) transport through a composite ceramic membrane containing an ion-exchange component, namely xerogel of hydrated zirconium dioxide, was investigated. The diffusion coefficient of Cr (VI) species through the membrane, which has been determined under open circuit conditions, is 1.80 × 10−10 m2 s−1. The transport number of Cr (VI) species through the ceramic membrane was found to rise with increasing voltage and reached 0.17 under “over-limiting current” conditions. On the other hand, the transport of chromate ions through hydrogel of hydrated zirconium dioxide becomes more intensive with a decrease in potential drop through the system involving ion-exchanger bed and ceramic membrane due to decrease in the membrane resistance. The diffusion coefficient of Cr (VI) ions in hydrogel of the inorganic ion exchanger was estimated as 4.36 × 10−12 m2 s−1. A possibility of Cr (VI) removal from a weakly acidic diluted solution using an electro-deionization method was shown: the degree of solution purification was found to reach 50%. The transport of species is realized through both the solution and the ion exchanger.

Removal of Boron and Arsenic from Geothermal Water in Kyushu Island, Japan, by Using Selective Ion Exchange Resins

Abstract Batch and column mode tests were carried out to evaluate the efficiency of boron and arsenic removal from geothermal water in Kyushu Island, Japan by an ion exchange method. The geothermal water contained 34.0 mg-B/L and 3.23 mg-As/L. The sorption tests were performed using boron selective ion exchange resins (Lewatit MK 51 and Diaion CRB 03) and arsenic selective ion exchange resins (Lewatit FO 36, ArsenXnp). The optimum concentration of resin for boron removal from geothermal water was determined as 5.0 g/L-geothermal water for both Lewatit MK 51 and Diaion CRB 03 resins. On the other hand, Diaion CRB 03 performed better than Lewatit MK 51 during the column-mode study. For arsenic removal, the optimum resin amount was found as 6.0 g/L-geothermal water for both Lewatit FO 36 and ArsenXnp resins. It was observed that Lewatit FO 36 was more effective than ArsenXnp for the removal of As from geothermal water.

Removal of Nitrate from Ground Water by a Hybrid Process Combining Electrodialysis and Ion Exchange Processes

Abstract In regions where agricultural activities are highly intensive, nitrate concentrations in ground water are usually above the permissible level for nitrate in drinking water. There are several physicochemical and biological treatment processes typically used to remove nitrate contamination from ground water. In this study, an electrodialysis‐ion exchange hybrid process was used for the removal of nitrate from ground water obtained from an agricultural area in the Western Anatolia religion in Turkey. Nitrate was effectively removed from the ground water. The effect of other ionic species such as chloride and sulfates on nitrate removal by electrodialysis has also been studied using deionized water that was dosed with selected anionic and cationic species.

Separation of Low Concentration of Fluoride from Water by Electrodialysis (ED) in the Presence of Chloride and Sulfate Ions

Abstract Removal of low concentration of fluoride (2 mg F−/L) in the presence of chloride and sulfate ions from aqueous solution by electrodialysis was studied. The equivalent ratios of sulfate and/or chloride were investigated as co-existing ions on fluoride removal from aqueous solution. The separation performance was evaluated in terms of mass transfer and energy consumption. It was obtained that the separation performance increased when the equivalent ratios of chloride to fluoride and sulfate to fluoride were increased. After 13 min of operation time, 63% of fluoride was removed from the solution when a binary mixture of F− : Cl− (1 : 25) was employed. In the case of a binary mixture of F− : (1 : 25), removal of fluoride was 93% in 16 min. For a ternary mixture of F− : Cl− : (1 : 25 : 25), fluoride was separated from the mixture with a 96% of removal in 20 min.

ELECTRO-DEIONIZATION OF Cr (VI)-CONTAINING SOLUTION. PART I: CHROMIUM TRANSPORT THROUGH GRANULATED INORGANIC ION-EXCHANGER

Kinetics of Cr (VI) → OH− exchange on both hydrogel and xerogel of hydrated zirconium dioxide was investigated. Self-diffusion coefficient of Cr (VI) species has been determined by analysis of kinetic curves. Transport of Cr (VI) anions through the inorganic ion exchangers under the influence of applied voltage was also researched. In the case of hydrogel, the ions are transported mainly through the solid phase. Diffusion coefficient of chromate anions through this material was estimated as 9.00 × 10−12 m2 s−1. This is in agreement with self-diffusion coefficient of Cr (VI) obtained from kinetic measurements (1.60 × 10−12–9.92 × 10−12 m2 s−1). Owing to the rather high mobility of Cr (VI) through hydrogel of hydrated zirconium dioxide, this material was recommended for electro-deionization processes. On the other hand, the use of polymer anion-exchange membrane must be excluded to prevent poisoning of the inorganic ion exchanger with Cr (III) cations to be formed during chemical interaction of Cr (VI) with organic materials.

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.

Effect of process parameters on separation performance of nitrate by electrodialysis

Abstract The electrodialytic separation of nitrate from water was investigated as a function of feed characteristics such as applied voltage, feed flow rate, and nitrate concentration in the solution. The separation performance was evaluated in terms of percent removal of nitrate, process time, and energy consumptions. TS‐1‐10 electrodialysis equipment (Tokuyama) was used in experimental studies. During the unsteady state run of the ED system, both inlet and outlet concentrations of nitrate and conductivities of streams were measured at certain time intervals until the current drops to 0.01 A. It was obtained that the percent removal of nitrate from the solution increased when the concentration of nitrate in the feed solution increased. The operation time became shorter when a high potential was applied.