Slaven Dobrović

Cellular uptake and toxicity effects of silver nanoparticles in mammalian kidney cells

The rapid progress and early commercial acceptance of silver‐based nanomaterials is owed to their biocidal activity. Besides embracing the antimicrobial potential of silver nanoparticles (AgNPs), it is imperative to give special attention to the potential adverse health effects of nanoparticles owing to prolonged exposure. Here, we report a detailed study on the in vitro interactions of citrate‐coated AgNPs with porcine kidney (Pk15) cells. As uncertainty remains whether biological/cellular responses to AgNPs are solely as a result of the release of silver ions or whether the AgNPs themselves have toxic effects, we investigated the effects of Ag+ on Pk15 cells for comparison. Next, we investigated the cellular uptake of both AgNPs and Ag+ in Pk15 cells at various concentrations applied. The detected Ag contents in cells exposed to 50 mg l−1 AgNPs and 50 mg l−1 Ag+ were 209 and 25 µg of Ag per 106 cells, respectively. Transmission electron microscopy (TEM) images indicated that the Pk15 cells internalized AgNPs by endocytosis. Both forms of silver, nano and ionic, decreased the number of viable Pk15 cells after 24 h in a dose‐dependent manner. In spite of a significant uptake into the cells, AgNPs had only insignificant toxicity at concentrations lower than 25 mg l−1, whereas Ag+ exhibited a significant decrease in cell viability at one‐fifth of this concentration. The Comet assay suggested that a rather high concentration of AgNP (above 25 mg l−1) is able to induce genotoxicity in Pk15 cells. Further studies must seek deeper understanding of AgNP behavior in biological media and their interactions with cellular membranes. Copyright

Photodegradation of Natural Organic Matter in Water with UV Irradiation at 185 and 254 nm: Importance of Hydrodynamic Conditions on the Decomposition Rate

Abstract The kinetic investigation of photodegradation of the natural organic matter (NOM) in natural lake water was conducted using two low‐pressure mercury lamps of the same nominal power: a) with suprasil quartz envelope emitting at both wavelengths −254 nm and 185 nm (hereafter VUV); b) with standard quartz envelope emitting only at 254 nm (hereafter UV). In comparison to the UV process, the addition of 185 nm irradiation (VUV process) increased the degradation rate ten‐fold overall at lower and seventeen‐fold at higher Reynolds numbers, respectively. The hydrodynamic characteristics of the photoreactor are of crucial importance for total energy efficiency for VUV processes.

Pilot Studies of Ozonation for Inactivation of Artemia salina Nauplii in Ballast Water

A pilot-plant study was conducted in the Republic of Croatia to determine the applicability of ozonation for inactivation of non-indigenous species and to provide necessary information regarding use of ozone as a ballast water treatment option. Nauplii of the brine shrimp Artemia salina were used as model organisms to investigate the efficacy of ozonation at three different ozone dosages (2.4, 3.7 and 10.9 mg L−1). Mortality of Artemia nauplii at 98.6%, was achieved after 3 h of exposure in ozone-treated water with the highest ozone dosage. Our results indicated that ozonation is a promising treatment for controlling non-indigenous and potentially invasive species; however, to draw more general conclusions, several species with higher level of resistance to ozone are required and will be studied in the future.

Effect of operating conditions on the performances of multichannel ceramic UF membranes for textile mercerization wastewater treatment

ABSTRACT Textile wastewaters are rated as one of the most polluting in all industrial sectors, and membrane separation is the most promising technology for their treatment and reuse of auxiliary chemicals. This study evaluates the performance of three types of tubular ceramic ultrafiltration membranes differing by mean pore size (1, 2 and 500 kDa) treating textile mercerization wastewater from a textile mill at different operating conditions: cross-flow velocity (CFV) and temperature. Acceptable results were obtained with 1 kDa ceramic membrane, with rejection efficiencies 92% for suspended solids, 98% for turbidity, 98% for color and 53% for total organic carbon at 20°C and 3 m s−1 CFV. Highest fouling effect was observed for 500 kDa membrane and lowest CFV. According to the observed results, 1 kDa membrane could be used for the treatment of wastewater from the textile mercerization process in terms of permeate quality.