Ivan Brnardić

Influence of Suspended Clay Minerals and Humic Matter on the Solid Phase Extraction Efficiency of Selected Pesticides from Water

The purpose of this investigation was to determine the influence of humic acids (HA) and Ca-montmorillonite (CaM) on the solid-phase extraction (SPE) efficiency of atrazine, alachlor and α-cypermethrin from water samples at various pH-values. The nature and intensity of binding of the studied pesticides to CaM were determined by X-ray diffraction analysis and termogravimetric analysis (TGA) test. The studied pesticides eluted from discs were analysed by thin-layer chromatography (TLC). The effects of CaM and humic acid were generally pH-dependent and acted independently in extraction efficiency influence. Lower recovery of pesticides was observed at higher pH values when CaM was ≥0.1 g and was attributed to greater dispersion of clay, increased surface area and subsequent adsorption. Concentrations of dissolved organic carbon (DOC) in humic acid had less effect on the extraction efficiency when water was at pH 8 compared to water at pH 2, which was probably due to greater nonpolar interactions of the pesticides to the charge-neutralized humic acid molecule.

Photocatalytic Activity of TiO2 Thin Films: Kinetic and Efficiency Study

Abstract The aim of this work was to evaluate the photocatalytic activity of two distinct anatase thin films. Films were prepared following the sol-gel procedure from titanium (IV) isopropoxide (TF-1) and from commercial TiO2 P25 as a starting material (TF-2). The films were compared based on the salicylic acid (2-dihydroxybenzoic acid, 2-HBA) photocatalytic degradation in reactors of different geometry and under different irradiation conditions. Experiments were performed in (i) an annular photoreactors operated under turbulent flow (TAR1 and TAR2) and (ii) semi-annular reactor operated under laminar flow (LFR). The TF-1 and TF-2 were immobilized on the inner side of outer wall of TAR1 and TAR2 and on the bottom of LFR. Experimental study included sorption study and four consecutive photocatalytic runs (tirr= 8 h) using TF-1 and TF-2 in each reactor. Obtained results confirmed the stability and the similar photocatalytic activity of the both films. The 2,5-dihydroxybenzoic acid (2,5-DHBA) and 2,3-dihydroxybenzoic acid (2,3-DHBA) were identified as main 2-HBA degradation by-products. Kinetic models were developed accordingly. Incident photon flux was determined along the inner reactor wall in annular reactors and on the bottom of LFR, i. e. on the thin film surface (Itf, W m−2) using ESSDE radiation emission model. The irradiation factor, i. e. the product of absorption coefficient and incident photon flux at film surface (μItf(z))m was introduced into the kinetic models. Resulting reaction rate constants ki (min−1W−0.5 m1.5) were independent of reactor geometry, hydrodynamics, irradiation condition and the optical properties of thin films. Efficiencies of TF-1 and TF-2 in studied reactors were given on the basis of quantum yields (QY) for 2-HBA oxidation and overall mineralization toward CO2.

Opinion paper about organic trace pollutants in wastewater: Toxicity assessment in a European perspective

This opinion paper focuses on the role of eco-toxicological tools in the assessment of possible impacts of emerging contaminants on the aquatic ecosystem, hence, on human health. Indeed, organic tr ...