Emel Ozel

Electrodialysis for the removal of copper ions from wastewater

Abstract In this work,the feasibility of the removal of Cu2+ ions in a model solution and a sample of rinse water have been studied using a recirculating electrodialysis system.Full removal of Cu2+ has been achieved from its dilute solutions and the sample of rinsewater provided from a local plating plant depending on duration of electrodialysis,applied voltage and flow rate while recovering of copper by forming concentrated copper solution in the cathode compartment.Thus,another aspect of this process is to be able to concentrate rinsewater up to the bath strength.

Production of brown and black pigments by using flotation waste from copper slag

One of the major problems in copper-producing countries is the treatment of the large amount of copper slag or copper flotation waste generated from copper slag which contains significant amounts of heavy metals such as Cu, Zn, Pb and Co. Dumping or disposal of such large quantities of flotation waste from copper slag causes environmental and space problems. In this study, the treatment of flotation waste from copper slag by a thermal method and its use as an iron source in the production of inorganic brown and black pigments that are used in the ceramic industry were investigated. The pigments were produced by calcining different amounts of flotation waste and chromite, Cr2O3, ZnO and CoO mixtures. The pigments obtained were added to transparent ceramic glazes and porcelainized tile bodies. Their colours were defined by L*a*b* measurements with a spectrophotometer. The results showed that flotation waste from copper slag could be used as an iron source to produce brown and black pigments in both ceramic body and glazes.

Synthesis and Sintering of Cordierite at Low Temperature from Kaolin and Magnesium Hydroxide

Thermal reactions of ultrafine Mg(OH)2 mixtures of ultrafine particles and kaolin mixtures were investigated to obtain cordierite at low temperatures. Magnesium hydroxide was precipitated from magnesium chloride (MgCl2) solution. Kaolin with three different chemical composition (KI, KS and KK) was mixed with Mg(OH)2 to form cordierite at different temperatures (900-1200°C). Mole ratio of mixtures were MgO:Al2O3:2SiO2. To obtain dense cordierite, boron oxide in different quantities (in the form of magnesium borate 2MgO.B2O3) were added into mixtures of kaolin and Mg(OH)2. After sintering, it was observed that, by increasing the amount of B2O3 in the mixture, the density was not changed significantly. Introduction Rankin and Merwin found cordierite, Mg2Al3Si5AlO18, to be the only ternary phase in the MgO-Al2O3-SiO2 system [1]. Cordierite as a ceramic material has a wide range of uses and applications stemming from its important properties of low thermal expansion and dielectric constant coupled with high chemical and thermal stability. In addition, cordierite is expected to have great potential as a substrate material for integrated circuit boards [2] replacing alumina, which has a relatively lower dielectric constant in the high frequency region. There are no known large deposits of natural cordierite, and it probably is never available for introduction to ceramic bodies. A body having the theoretical composition of cordierite may consist of 39.6 % talc, 47.0 % clay and 13.4 % alumina. Bodies of this composition, however, have so short vitrification range that they cannot be fired in industrial kilns. Preparing dense cordierite glassceramics also has long been a problem because of this problem [3-5]. In this study, ultrafine particles of Mg(OH)2 were precipitated from aqueous solution of magnesium chloride. Cordierite ceramics were obtained by mixing Mg(OH)2 particles with different type of kaolin and firing between 900-1200°C. To obtain dense cordierite ceramic different amounts of B2O3 were added into mixtures. Experimental Procedure Sample preparation. Three types of kaolin, designated as KI, KS and KK, mined around Turkey were used as raw material to synthesise the cordierite ceramics. The particle size distribution and chemical composition of kaolins are given in Fig. 1 and Table 1, respectively. The classified kaolin consisted of tabular particles of kaolin with mean particle sizes of 1.5, 1.3 and 0.8 μm. As a source of MgO, ultrafine particles of magnesium hydroxide were prepared as in our previous work [6]. The kaolin and Mg(OH)2 were weighed according to the molar ratio of MgO:Al2O3:2SiO2 and were mixed using an agate mortar in ethanol media to prevent aggregation. Key Engineering Materials Online: 2004-05-15 ISSN: 1662-9795, Vols. 264-268, pp 925-928 doi:10.4028/www.scientific.net/KEM.264-268.925

Effect of the Chemical Composition on The Pyroplastic Deformation of Sanitaryware Porcelain Body

Pyroplastic deformation is the bending of a ceramic specimen caused by gravity during heat treatment. It can be defined as the loss of shape of product during its firing. Pyroplastic deformation is related to properties of liquid phases formed during firing. Therefore, the effect of the chemical composition on the pyroplastic deformation of sanitaryware porcelain was investigated in this study. Systematical compositional arrangements were made according to different combinations of (SiO2/Al2O3) and (Na2O/K2O) ratios by using Seger formula approach. Pyroplastic deformation behaviour of compositions within a controlled firing regime was investigated by using fleximeter. The bodies were also prepared in a special form by slip casting method at laboratory scale in order to determine the pyroplastic deformation of the samples. The experimental results showed that a definite combination at SiO2/Al2O3 ratio of 5 and Na2O/K2O ratio of 4 give the lowest pyroplastic deformation in the porcelain body formulations. The pyroplastic deformation value of this composition was determined as 25 mm which is 44% lower than that of the standard composition (45 mm).

Production and Characterisation of Pigments Produced Using Grinding Waste from Cast Iron Foundry

The brown and black pigments are generally synthesised from different powders such as iron (III) and chromium (III) oxide powders. In this study, iron-chromium pigments by using grinding waste from cast iron foundry as iron source and chromite mixtures were produced. The pigments were synthesised from mixing different ratios of grinding waste and chromite with modifier oxides and calcined at different temperatures. The resulting pigments were used in both transparent glazes of wall tile and satin glazes of floor tile and were characterised using x-ray diffraction (XRD). The colours obtained after glazing are defined as L*a*b* parameters by using Spectrophotometer.

Determination of real-world emission factors of trace metals, EC, OC, BTEX, and semivolatile organic compounds (PAHs, PCBs and PCNs) in a rural tunnel in Bilecik, Turkey

A field study was performed in a rural tunnel to determine pollutant concentrations, sources and on road vehicle emission factors (EFs) of particulate matter, trace metals, elemental carbon (EC), organic carbon (OC), benzene, toluene, ethyl benzene and xylenes (BTEX), and polycyclic aromatic hydrocarbons (PAHs). Emission factors (EFs) for polychlorinated naphthalenes (PCNs) and polychlorinated biphenyls (PCBs) were also determined. A 12-day extensive sampling campaign during morning and afternoon periods at inlet and exit stations of the tunnel was conducted. Morphology of the particles was also investigated by Scanning Electron Microcopy (SEM). Correlation analysis, factor analysis and diagnostic PAH ratios were utilized to identify emission sources of trace metals. Identified sources include brake wear (33%), resuspension of road dust (15%), tyre wear (12%), exhaust emissions (10%), and lubricants (9%). Based on the PAH diagnostic ratios, major sources of PAHs were estimated as diesel emissions. EFs were comparable with the literature and varied from 31.5 to 295.4 mg vehicle-1 km-1 with an average of 129.2 ± 80 mg vehicle-1 km-1 for PM2.5. PM2.5-10 EFs varied between 15.9 and 236.1 mg vehicle-1 km-1 with an average of 96 ± 30 mg vehicle-1 km-1. Average EC EFs were 40.3 ± 9.8 mg vehicle-1 km-1 for PM2.5 samples and 19.5 ± 0.5 mg vehicle-1 km-1 for PM2.5-10 samples while OC EFs were 33.7 ± 18 and 15.5 ± 8.4 mg vehicle-1 km-1 for fine and coarse particles, respectively. EFs of elements were generally 2 (Al) to 59 (Mg) times higher than those previously reported in the literature. Compared to literature, relatively higher EFs for Σ13PAHs (range: 48.1-168 μg vehicle-1 km-1, average: 84.3 ± 46.4 μg vehicle-1 km-1) were obtained. BTEX emission factors were in the range of 4.2 ± 4.7 mg vehicle-1 km-1 (m + p-xylene) and 16.7 ± 10.5 mg vehicle-1 km-1 (toluene). Average EFs for ΣPCBs and ΣPCNs were 12.06 ± 5.3 μg vehicle-1 km-1 and 88.9 ± 70.4 ng vehicle-1 km-1, respectively.

Effect of Precursor Type on Zinc Oxide Formation and Morphology Development during Hydrothermal Synthesis

Semiconducting metal oxide sensors have been widely studied due to their small dimensions, low cost and low power consumption. Among semiconductor oxide materials, zinc oxide (ZnO) is a very interesting one due to its chemical and thermal stability, its large exciting binding energy and band gap as n-type semiconductor, and, especially, to its high response to toxic and combustible gases. ZnO is a potential material for gas sensor applications because of its high piezoelectric coefficient, great stability of its hexagonal phase and its pyroelectric property. Hydrothermal synthesis is one of the most useful methods to produce homogeneous, nanosized ZnO powders with high purity, controlled particle size and morphology. Therefore, ZnO with various morphologies can be synthesized via simple hydrothermal reactions. The research objectives of this study were to understand formation and growth process of ZnO particles with various morphologies and to investigate role of starting materials, (i.e., zinc chloride (ZnCl2) and zinc nitrate hexahydrate (Zn(NO3)2.6H2O) on the particle morphology. In the present study, ZnO particles with various morphologies were synthesized via an unstirred hydrothermal method. When the using ZnCl2 as a precursor, the final morphology was rod like with a taped tip (length of the rod 0.5-1um ) after 12 h at 100°C. On the other hand, final morphology of the produced ZnO particles was branch rodlike (5-10um) when using Zn(NO3)2.6H2O as precursor under the same synthesis conditions. Accordingly, a proposed growth mechanism has been suggested. Keywords: ZnO; Hydrothermal synthesis; Phase development; Morphology; Growth mechanism DOI: 10.17350/HJSE19030000034 Full Text:

KAOLEN TÜRÜNÜN SAĞLIK GEREÇLERİ PORSELEN BÜNYESİNİN PİROPLASTİK DEFORMASYONU ÜZERİNE ETKİSİ

Seramik saglik gerecleri yuksek sicaklik pisirimiyle uretilen camsi porselenler olduklarindan, piroplastik deformasyon bu urunlerde siklikla karsilasilan bir problemdir. Piroplastik deformasyonu onlemede mikroyapi duzenlemesinin onemi buyuktur. Mikroyapida ignemsi mullit kristallerinin miktarinin artirilmasi ve camsi faz icerisinde mullit ve kalinti kuvars kristallerinin homojen bir sekilde dagilmasinin piroplastik deformasyonu dusurmede etkin rol oynadigi daha onceki calismalarda gozlemlenmistir. Kaolenler, porselen icerisinde en ince tane boyutlu hammaddeler olduklarindan, kristal olusumu icin sadece reaktif bilesenler olmakla kalmayip ayni zamanda mikroyapinin homojenliginde buyuk rol oynamaktadirlar. Bu calismada, standart recetede yer alan kaolen turu ve miktarinin saglik gerecleri porselen bunyesinin piroplastik deformasyon ve diger fiziksel ve mekanik ozellikleri uzerindeki etkileri incelenmistir. Seger yaklasimiyla saglik gerecleri bunyesinde kaolen turu ve miktarlarinin modifiye edilerek bunyenin proplastik deformasyon ozelliginin ve fiziksel ozelliklerin kontrol edilebilecegi ortaya cikartilmistir.

Synthesis of the CeO2 Based Pigments by Using Enriched Rare-Earth Oxides Located at Eskişehir Kızılcaören Region

Pigments based on CeO2 structure are known to give various pink–orange and red brown colour in ceramic glazes. This type of pigments is prepared by high temperature calcination of CeO2 and Pr6O11 with admixed rare-earth elements such as lanthanum oxide (La2O3) and neodymium oxide (Nd2O3). In this study, the use of enriched Eskişehir Kızılcaören region (Turkey) rare-earth oxides containing CeO2, La2O3 and Nd2O3 to synthesis CeO2-PrO2 pigments was investigated. The resulting pigments were characterised using X-ray diffraction (XRD) and were used in double firing glazes. The colour obtained after glazing was defined as L*a*b* parameters by using UV-Vis Spectrophotometer and the results were compared to pigments obtained by using pure oxides. Introduction The pigments used in ceramic industry must possess thermal and chemical stability at high temperatures in molten glazes [1]. To date, it has been impossible to obtain a bright red colour using oxide pigments except cadmium sulfoselenide, which yields a red colour but unsuitable at temperatures exceeding 900 °C and which is also toxic. Fe-zircon pigments chemically stable at 1300 °C in molten glazes but gives coral-pink hue. In recent years, the pigments based on fluorite type CeO2 have a great interest due to its high temperature stability. These pigments give various pink orange hues and are based on incorporation of praseodymium ions into the host lattice of fluorite type cerium dioxide [2]. CeO2-PrO2 system pigments are usually prepared by solid-state reactions. Pr6O11 dissolves in CeO2 during heat treatment, forming a Ce1-xPrxO2 solid solution. Different synthesis methods for CeO2-PrO2 pigments including solid-state [2], co precipitation [3] and combustion [4] have been studied. Effect of yittrium and lanthanide oxides (Ln2O3) where Ln= La, Nd, Sm, Gd, Eu, Er and Tb on colour properties of CeO2-PrO2 system was also studied and it was observed that admixture of lanthanides into Ce1-xPrxO2 systems give various light or dark pink-orange hues [5]. One of the problem with these type of pigments is the high cost due to the use of expensive pure oxides. The purpose of this study was to investigate the colour properties of CeO2 based pigments synthesised by using enriched Eskişehir Kızılcaören region (Turkey) rare-earth oxides containing CeO2, La2O3 and Nd2O3 to reduce the cost of the pigments. Experimental Procedure In this study, first of all, enrichment of rare-earth oxides was carried out. An ore bed containing fluorspar, barite and bastnazite exists in EskişehirKızılcaören region. The composition of this ore is given in Table 1. To obtain rare-earth elements from the ore, flotation studies (classification, scrubbing and flotation) were performed. During the flotation studies, rare-earth oxides were initially accumulated in the sink. After scrubbing, two stage flotation and acid leaching were applied, enriched powder was calcined at 1000°C. Industrial quality CeO2 (Aldrich), Pr6O11 (Acros Organics), Nd2O3 (Aldrich) and enriched rareearth oxides were used as raw materials in order to produce CeO2 based pigments. Pure CeO2 was progressively replaced by enriched rare-earth oxides in the pigment compositions. To determine the Key Engineering Materials Online: 2004-05-15 ISSN: 1662-9795, Vols. 264-268, pp 1553-1556 doi:10.4028/www.scientific.net/KEM.264-268.1553

Production of Blue Willemite Based Pigments by Using ZnO Powder Produced from Metal Slags

In this study, production of pigments by adding different amount of Co and calcination at different temperatures were undertaken. Co-willemite blue pigments were produced by using ZnO powders produced from metal slags. To determine the effect of the Co concentration and calcination temperature on the colour, The resulting pigments were used in double and single firing transparent glazes and porselainised stoneware. Their colour properties were characterised by using UV-Vis spectrophotometer. The colours obtained after glazing were defined by L*a*b* measurements.