Kadir Gedik

Removal of cadmium from aqueous solutions using clinoptilolite: influence of pretreatment and regeneration.

In this study, Cd removal from aqueous solutions via clinoptilolite was investigated in terms of the effect of pretreatment and regeneration. Four different chemicals (NaCl, KCl, CaCl2 and HCl) were tested for this purpose. Samples treated by a total of 20 bed volume (BV) of 1M NaCl solution prepared in tap water with no pH adjustment were found to perform satisfactorily. Five exhaustion and regeneration cycles were then carried out, revealing an increasing Cd removal capacity, coupled with constant Cd elution efficiency in progressing cycles. Furthermore, the change of pH and the presence of exchangeable (Na, K, Ca and Mg) and framework cations (Si and Al) in the aqueous phase were investigated. Subsequently, these were discussed in terms of progressive conversion of clinoptilolite to its homoionic Na-form, and the presence of different Cd removal mechanisms in the system. This study emphasizes the potential of clinoptilolite to be a part of sustainable wastewater treatment technologies, enabling the recovery of both the sorbent and the metal, via demonstration of effective Cd removal and clinoptilolite recovery, besides successful concentration of metal in the regenerant solution.

Spatial distribution and source apportionment of PCBs in sediments around İzmit industrial complexes, Turkey

The spatial distribution, degree of pollution and major sources of PCBs were evaluated in surficial sediments within the heavily urbanized and industrialized İzmit Bay and its main freshwater inputs. ΣPCB concentrations range from 2.90 to 85.4ngg(-1) in marine sediments and from ND to 47.7ngg(-1) in freshwater sediments. Results suggest that high concentrations of ΣPCBs were localized around a chlor-alkali plant and an industry that handles bulk liquid, dry and drummed chemicals, and petroleum products in the Bay. Using a chemical mass balance receptor model (CMB), major sources of PCBs in the region were investigated. The CMB model identified Aroclor 1254 and 1260 to be the major PCB sources in marine sediments and the less chlorinated Aroclor 1248 and 1242 as the major PCB sources in freshwater sediments. The potential sources for the PCBs were briefly discussed in terms of their use in various industrial applications.

Assessment of temporal variation and sources of PCBs in the sediments of Mediterranean Sea, Mersin Bay, Turkey

Information on temporal distribution of polychlorinated biphenyls (PCBs) in the coastal sediments of Mediterranean Sea, Mersin was compiled using data published between 1980 and 2009, and the present study. The first congener specific PCB results from the region yield concentration levels of Σ(41)PCBs in sediments ranging from 0.61 to 1.04 ng g(-1). Sediment profiles show penta-, hexa- and hepta-chlorobiphenyls, specifically, #149 and 153 as the most abundant congeners in all samples. Comparison of total PCB concentrations over time suggests no recent PCB input to the region. Using congener specific PCB data for the region, identity and contribution of PCB sources were also predicted using a chemical mass balance -based (CMB) receptor model. The CMB model identified Aroclor 1260 to be the major PCB source in coastal sediments. The potential sources for the PCBs were briefly discussed in terms of their use in various industrial applications.

Affinity of Clinoptilolite‐based Zeolites towards Removal of Cd from Aqueous Solutions

Abstract Cd removal from aqueous solutions using as‐received and pretreated forms of two different clinoptilolite samples (denoted GC and BC) was investigated and dissimilar sorption affinities were revealed. Equilibrium behavior of systems were modeled using six different adsorption isotherms. The maximum sorption capacities, as obtained from the solubility‐normalized Dubinin‐Astakhov model for as‐received samples, were determined as 0.18 meq/g and 0.12 meq/g for GC and BC, whereas 0.72 meq/g and 0.41 meq Cd/g was determined for their pretreated forms, respectively. Examination of the release of exchangeable cations into the solution at equilibrium and the change of pH were discussed in terms of varying prevalence of ion exchange, dissolution of the sorbent and adsorption.

Levels and sources of polychlorinated biphenyls in Ankara creek sediments, Turkey

The spatial distribution, degree of pollution and major sources of polychlorinated biphenyls (PCBs) were evaluated in surficial sediments of Ankara Creek, located in the capital of Turkey and serving as one of the tributaries in the third largest watershed in Turkey. Sediment ΣPCB concentrations analyzed on Aroclor and congener basis (seven indicator congeners) range from 5.5 to 777.6 ng g−1 and 3.7 to 743.3 ng g−1 dw as Aroclor and congener based concentrations, respectively. High concentrations of ΣPCBs were observed in the samples located at the downstream sections of the Creek, after discharge from Ankara municipal wastewater treatment plant. Using a chemical mass balance receptor model (CMB), major sources of PCBs affecting the sediments were investigated. The CMB model identified Aroclor 1254 and 1260 to be the major PCB sources affecting sediments. The potential sources for the PCBs were briefly discussed in terms of their use in various industrial applications.

Positive Matrix Factorization dynamics in fingerprinting: A comparative study of PMF2 and EPA-PMF3 for source apportionment of sediment polychlorinated biphenyls.

Receptor models were typically used in air pollution studies and few publications are available for Positive Matrix Factorization (PMF) that consider the details of parameters and procedures in evaluating the trace organic pollutants in sediments. In this study, environmental fate and source composition of Lake Eymir sediments contaminated by polychlorinated biphenyls (PCBs) were explored by applying two PMF models, Paateros PMF2 and United States Environmental Protection Agencys (US EPA) EPA-PMF3. PMF2 and EPA-PMF3 rely on different algorithms; Paateros algorithm and multilinear engine algorithm, respectively. Here, the approaches of two PMF models were compared for the identification of PCB patterns taking into consideration the effects of various uncertainty matrices, residual matrices and goodness-of fit parameters. As a result of the study, it was understood that both models resolved five factors and indicated Clophen A60 as the source of PCBs. These results were consistent with the results resolved by Chemical Mass Balance model applied to the same data set in a previous study. However, source contributions identified by two models differed in quantity, but with similar patterns. This study indicates a way in understanding behavior, fate and global source of persistent organic pollutants in sediment by applying and comparing with a special data including high percentage of below detected value (38.2%) to understand the dynamics of PMF model parameters.

Chiral pollutants and their significance in the environment

Kiralite, canlı sistemlerden doğal ve sentetik organik maddelere kadar hayatımızın birçok alanında bulunmaktadır. En genel ifadeyle ayna görüntüsü kendisiyle çakışmayan maddeler olarak tanımlanan kiral moleküller, başta ilaç sanayi ve tıp olmak üzere birçok alanda kullanılmaktadır. Söz konusu maddelere ait ayna görüntülerinden her biri enantiyomer olarak adlandırılır ve kiral maddelere ait enantiyomerlerden biri kullanım amacına uygun hareket ederken diğeri veya her ikisi de çevresel ortamlarda kirliliğe ve canlılarda toksik etkiye neden olabilmektedir. Enantiyomerlerin yalnızca biyolojik değişime uğrama potansiyelleri farklılık göstermekte, bu özelliği sebebiyle kiral kirleticiler, güncel kirliliğin değerlendirilmesi amacıyla çevresel kirlilik araştırmalarına konu olmaktadır. Toprak, sediman, hava ve su ortamının yanı sıra canlılarda da, başta kromatografik yöntemler olmak üzere çeşitli metotlarla tespit edilebilmektedir. Bu derlemede, kiralite ve çevresel açıdan önem arz eden kiral bileşiklerin özellikleri, analiz yöntemleri ve çevredeki akıbetleri değerlendirilmiştir. Çeşitli avantajları nedeniyle endüstriyel uygulamalarda geniş yer bulan kiral bileşiklerden kullanım amacının dışında çevreye salınan bileşikler, biyolojik aktiviteleri nedeniyle çevresel izleme çalışmalarında önem arz etmektedir. Ülkemizde çevresel ortamlarda henüz araştırmalara konu olmaya başlayan kiral kirleticilerin akıbetinin değerlendirilmesi açısından enantiyoseçici davranışlarının anlaşılması önem arz etmektedir. Chirality exists in a wide range of objects in the universe from living creatures to natural or synthetic organic materials. As a common expression, any objects that are not superimposable on its mirror image are described as chiral molecules, and such materials are used in various fields including pharmaceutical industry and medicine. Each mirror image of chiral molecules are called enantiomer and while one of the enantiomers may be active and more toxic than the other in its application area and once they enter to the environmental compartments less-active enantiomer or both enantiomers can cause environmental pollution and toxicity on living organisms. Enantiomers show difference in biological degradation such that this property is used as a useful tool in environmental pollution assessment/research studies. In addition to the environmental compartments such as soil, sediment, air and water, they are also analyzed in living organisms by various methods including primarily the chromatographic methods. In this review, chirality and the properties, analysis methods and fate of the chiral chemicals which have significance in the environmental studies are presented. Due to various advantages, chiral chemicals are used in several industrial products and once they are released to the environment, they become environmentally concerned pollutants and play an important role in environmental monitoring studies due to their biological activities. In our country, although it is very limited, chiral pollutants have already became subject to monitoring studies, hence, understanding the enantioselective degradation of such chemicals in different environmental compartments is important to assess the fate of these chemicals. Anahtar kelimeler: Enantiyomer, Farmasötik, Kalıcı organik kirleticiler, Kromatografi, Pestisit, Rasemik

Chemical Mass Balance (CMB) Evaluation of Polychlorinated Biphenyl (PCB) Sources in Sediments of Kızılırmak River, Turkey, Near a Scrap Yard

This study presents a preliminary investigation for polychlorinated biphenyls (PCBs) on surface sediments in a reach of Kızılırmak River near a scrap yard in Kırıkkale, Turkey. PCB concentrations of up to 19.5 ng/g−1 Σ41 were observed in sediments downstream of the yard, where profiles showed predominantly the presence of penta- and hexa-chlorobiphenyls. Specifically, #138, 149, 153, 180 were the most abundant congeners in downstream samples. In contrast, no PCBs were observable in sediments upstream of the scrap yard. The contributing PCB sources to the sediments were predicted by a chemical mass balance (CMB)-based receptor model; Aroclor 1260 was identified as the major source for these sediments. Considering that Aroclor 1260 was extensively used in old transformers and capacitors, occurrence of this PCB signature point to the scrap yard as a potential source. Release of PCBs over time as indicated by the significant concentrations observed even in surface samples emphasizes the importance of the need for better environmental management in the region.