Prof. Irina Karadjova Profile

Prof. Irina Karadjova

at Sofia Univ. "St. Kliment Ohridski"

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Publications (2)

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Proceedings Article | 30 December 2019 Paper

Synthesis and characterization of As(V)-imprinted smart polymer gel for selective adsorption of As(V) ions

Ivanka Dakova, Tanya Yordanova, Irina Karadjova

Proceedings Volume 11332, 113320D (2019) https://doi.org/10.1117/12.2553479

KEYWORDS: Polymers, Ions, Adsorption, Arsenic, Scanning electron microscopy

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In this study, new As(V)-imprinted polymer (As(V)-IIP) for selective adsorption and separation of As(V) was prepared by synthesis procedure based on 2D imprinting approach. Initially, the polymeric core was synthesized via dispersion polymerization between glycidyl methacrylate as a functional monomer and trimethylolpropane trimethacrylate as a cross-linking agent. Then the ion imprinted layer was formed by grafting of 1-methylimidazole on the surface of the polymeric particles in presence of As(V) as a template ion. The newly synthesized As(V)-IIP was characterized using elemental microanalysis, scanning electron microscopy and nitrogen adsorption–desorption measurements. The effect of the porogen solvents acetonitrile, toluene and methanol on particle shape and morphology was presented. The adsorption properties of As(V)-IIP toward As(V) were studied by batch procedure. The optimal pH range for the quantitative sorption (> 95%) of As(V) was 7-9, and full desorption was achieved by 3 mol/L HCl. The As(V)-IIP possesses high capacity toward As(V) (9.8 μmol/g sorbent) and good mechanical and chemical stability. Experiments performed for selective determination of As(V) in water samples showed that the interfering matrix does not influence the extraction efficiency of As(V)-IIP. Finally, the prepared As(V)-imprinted smart polymer gel was successfully applied to the selective recognition and determination of As(V) ions in water samples.

Proceedings Article | 30 December 2019 Paper

Colorimetric detection of iron(III) based on sensitive and selective plasmonic response of starch-coated silver nanoparticles

Penka Vasileva, Stefan Dobrev, Irina Karadjova

Proceedings Volume 11332, 1133207 (2019) https://doi.org/10.1117/12.2553972

KEYWORDS: Iron, Ions, Silver, Nanoparticles, Absorption, Absorbance

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An optical sensor for sensitive and selective detection of iron(III) has been developed based on redox interaction of Fe(III) ions with starch-coated silver nanoparticles (Ag-NPs) in the presence of 0.001 mol/L HCl. Starch-coated Ag-NPs with an average diameter of 15.4±3.9 nm were successfully synthesized through a simple green method using D-glucose as reducing agent and soluble starch as protecting polymer. The synthesized silver nanoparticles showed a strong localized surface plasmon resonance (LSPR) band around 408 nm and linearly decreasing intensity of LSPR band with increasing concentration of Fe(III) in hydrochloric acid aqueous solution (pH ⁓3). Based on the linear relationship between LSPR intensity and concentration of Fe³⁺ ions, the as-synthesized starch-coated silver nanoparticles could be used as a smart optical probe for sensitive and selective detection of Fe³⁺ ions in water with a linear range from 0.7 to 7 mg/L Fe³⁺ and detection limit of 0.1 mg/L; the relative standard deviation values varied between 2 and 6 % for the whole calibration range. Experiments performed demonstrated that the metal ions Na⁺, K⁺, Mg²⁺, Ca²⁺, Pb²⁺, Cu²⁺, Zn²⁺ , Cd²⁺, Hg²⁺, Co²⁺, Ni²⁺, and Fe²⁺ do not interfere, due to the absence of oxidative activity of these ions, which guarantees the high selectivity of the proposed optical sensor toward Fe³⁺ ions in aqueous samples. On the basis of experimental results, a detection mechanism of oxidation–reduction reaction between Ag-NPs and Fe³⁺ ions was proposed. Moreover, the starch-coated Ag-NPs could be applied to the iron speciation in ground and tap waters.

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