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Magnetic sorbents represent very promising materials for environmental applications due to their simple synthesis, separability in a magnetic field, low toxicity, wide range of possible modifications, and usability in heterogeneous systems. We report on the synthesis, characterization, and application of magnetically separable Fe3O4/SiO2 sorbent surface-modified with octadecyl chains (C18). Preparation of Fe3O4 cores by co-precipitation from Fe2＋ and Fe3＋ chlorides in an alkaline aqueous solution was followed by SiO2 shell synthesis and functionalization with C18. Fe3O4, Fe3O4/SiO2, and Fe3O4/SiO2-C18 samples were characterized by SEM, TOC, XRD, BET, and tested for purification of water contaminated by various polycyclic aromatic hydrocarbons (PAHs). Since PAHs are formed as by-products of pyrolysis, a rapidly evolving technology for transformation of waste into green chemicals, there is a need for efficient sorbents suitable for PAHs removal from the environment. The use of Fe3O4/SiO2-C18 for adsorption of 16 different PAHs has not yet been reported. The adsorption was examined by gas chromatography with mass spectrometry and studied using molecular modeling. Comparison of adsorption efficiency η for Fe3O4, Fe3O4/SiO2, and Fe3O4/SiO2-C18 revealed a positive effect of C18. When averaging all Fe3O4/SiO2-C18 doses tested (1–8 g/L), η > 80% and > 90% was found for 14 and 7 PAHs, respectively, out of a total of 16 tested PAHs. The highest η values were found for medium-heavy PAHs (178.2–228.2 g/mol). Exhibiting high efficiency and average capacity of ∼ 1 μ g/g, the Fe3O4/SiO2-C18 is suitable for pre-concentration purposes of PAHs in analytical sample extractions from water.

Ethylenediaminetetraacetic acid (EDTA) has increasing potential as an environmentally hazardous material. Although EDTA exhibits relatively low acute toxicity, it has been found to be cytotoxic and weakly genotoxic in laboratory animals. In addition, oral exposures can cause reproductive and developmental effects. EDTA is commonly used in wood industry, pulp and paper industry, textile industry, cement industry and food industry. It is also widely used in laundry applications in order to reduce the water hardness and in many cleaning solutions. Due to chemical properties of EDTA (polarity, relatively good solubility in water and chelating ability towards metal ions) it cannot be efficiently removed on common water treatment plants. As a result, the EDTA can be observed in the aquifer downstream near the outputs from water treatment plants of larger industrial entities. Therefore, the reliable monitoring of EDTA in water samples is of great importance. Commonly, the chromatographic methods are used for EDTA analysis with dominance of liquid chromatography coupled with UV-VIS or MS detectors. However, these methods suffer often from the lack of sensitivity towards EDTA at ppt levels. The combination of gas chromatography with high resolution MS can offer significantly lower detection limits (units of ug/l) as well as powerful identification tool. However, the derivatization of EDTA is required when GC-MS is being used. In addition, according to the Czech standard for EDTA determination the Programmed Temperature Vaporising (PTV) injector or cool on- column injection are recommended. In our paper we report on the GC-MS method development for determination of EDTA in water by using traditional split/splitless injector. We compare the external and internal standard methods of EDTA quantification for several different internal standards. The developed method was applied to analysis EDTA in real aqueous samples.