Lucia Ivaničová

Degradation of Reactive Black 5 by electrochemical oxidation

Degradation of commercial grade Reactive Black 5 (RB5) azo dye by chemical and electrochemical treatment was examined using a dimensionally stable anode and stainless steel cathodes as electrode materials, with NaCl as supporting electrolyte. The electrochemical treatment was compared to the chemical treatment with hypochlorite generated by electrolysis. The compounds present in the commercial grade RB5 azo dye and the products of its electrochemical degradation were separated using ion-pairing high performance liquid chromatography on reversed phase. The separated species were detected by diode array detector and electrospray ionization mass spectrometry. A suitable ion-pairing reversed phase HPLC-MS method with electrospray ionization for the separation and identification of the components was developed. The accurate mass of the parent and fragment ions were used in the determination of the empirical formulas of the components using the first-order mass spectra. Structural formulas of degradation products were proposed using these information and principles of organic chemistry and electrochemistry.

Magnetic Zeolite as Arsenic Sorbent

A natural zeolite (clinoptinolite type) was modified by iron oxides and a novel magnetic zeolite was produced. The novel sorbent was prepared by a co-precipitation of Fe(III) and Fe(II) in the presence of NaOH and natural zeolite. The zeolite structure was used as a host for the precipitated magnetic iron oxides. The new material had properties that combined the good sorption affinity for oxyanions of iron oxides with the high affinity of zeolite for cations. The particles produced could be easily used in sorption columns for dynamic studies. They had also good magnetic properties and could be separated from dispersions with the application of a magnetic field. The magnetic zeolite was tested under batch conditions for the removal of As from model water solutions. The effect of pH, arsenic concentration, temperature and solid to liquid ratio were studied. The magnetic zeolite was found effective for the removal of arsenic from water streams and its capacity was above the average capacity of sorbents studied in literature. The conditions for best arsenic removal were established.