A B S T R A C TThe interaction of tetracycline (TC) and oxytetracycline (OTC) with nanoscale zero-valent iron (nZVI) was examined with a batch experimental series in order to determine the removal efficiency and transformation products. Experimental variables, such as solution pH, nZVI dosage, contact time, initial TCs concentration, and reaction temperature, were systematically studied. Adsorption kinetics showed that equilibrium was reached within 2 h according to the pseudo-second-order model. The adsorption behavior was pH-dependent and favored at pH 6 regardless of TC type considered due to electrostatic attraction between nZVI and TCs. The adsorption capacity of TC was more than that of OTC. The results of LC-MS-MS showed that main transformation product was 4-epi-tetracycline for TC and insignificant for OTC. On the other hand, desorption studies exhibited that nZVI adsorbed not only parent compounds but also transformation products. The results showed that the removal mechanism of TC and OTC by using nZVI surface was mainly the adsorption relatively than the degradation process.

Bu çalışmada kimyasal indirgeme yöntemi ile hazırlanan nano ölçekli sıfır değerlikli demir (nZVI) ile klortetrasiklinin (CTC) sulu ortamlardaki giderim mekanizması incelenmiştir. Çözelti pH'ı, nZVI dozajı, temas süresi ve reaksiyon sıcaklığı sistematik olarak incelenmiş ve maksimum klortetrasiklin gideriminin gerçekleştiği optimum işletme şartlarında klortetrasiklin parçalanma ürünleri belirlenmiştir. Adsorpsiyon davranışının pH'a bağlı olduğu tespit edilmiş ve klortetrasiklinin maksimum giderim verimi pH 6' da gerçekleşmiştir. 0,4-0,6 g/L aralığındaki nZVI dozajlarında giderim veriminde önemli değişiklik gözlenmediği için optimum dozaj 0,4 g/L olarak belirlenmiştir. Adsorpsiyon kinetiğinin 2 saat içerisinde dengeye ulaştığı ve yalancı ikinci dereceden hız modeline uyduğu belirlenmiştir.

Pharmaceutically active compounds are gaining the recognition of emerging environmental contaminants classified as recalcitrant bio-accumulative compounds hence they are regarded as toxic and hazardous chemicals. In this context, efficient treatment processes are needed. Nanotechnology can adequately address many of the water quality issues by using different types nanomaterials. Nano zero valent iron (nZVI) has been applied to remove various organic compounds from aqueous solutions since the removal mechanism depends on adsorption and degradation. This article summarizes the recent knowledge of nZVI in pharmaceutical degradation considering the key factors such as initial contaminant concentration, dosage of bare and modified nZVI, pH of aqueous matrix and reaction time which are mainly examined in the experiments. Additionally, the degradation mechanism of studied pharmaceutical compounds monitored by observing intermediates and end-products is presented.

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