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Everyday life conveniences and activities such as washing clothing made of synthetic fibers, tire wear, and plastic packaging break down in the environment may serve as an abundant source of microplastic (MP). There is plenty of evidence that microplastic is a problem due to its shape, size, and concentration and the fact that it can easily enter the food chain which causes negative impacts on human health and the environment. An important aspect of this problem is also the fact that microplastic and other contaminants of emerging concern (CEC) present in water can interact, in terms of the adsorption of CEC onto the MP surface. The adverse effect of MP in water is therefore influenced by factors affecting adsorption capacity: particle size, specific surface area, hydrophobicity, and polarity of MP as well as CEC. The aim of this study was to investigate the aquatic toxicity of pristine and photooxidative (UV) aged microplastics and pesticide atrazine samples after the sorption. For that purpose, we investigated the impact of UV aging on polyethylene terephthalate (PET) bottles and correlated it with surface properties. Polyethylene terephthalate was inspected for morphology changes using Scanning Electron Microscopy and Fourier Transformation Infrared Spectroscopy. The specific surface was investigated by using Brunauer-Emmet-Teller Analyzer to determine the adsorption capacity of MP. The fragmentation of PET bottles into microplastic particles has also been investigated. In adsorption tests, using pristine and aged PET MP, the concentration of atrazine in the aqueous phase was monitored using High-Performance Liquid Chromatography Analysis. Aquatic toxicity samples were assessed by exposing freshwater organisms to the aqueous dispersion of pristine and aged MP, without and with adsorbed pollutants. Acute toxicity bioassays were performed with the microalgae Pseudokirchneriella subcapitata (Selenastrum capricornutum) and the crustacean Daphnia magna according to standard procedures (ISO). Obtained results indicated that UV aging resulted in changes in PET bottle morphology and structure. Carboxyl groups are confirmation of surface degradation. The adsorption capacity of MP increases with a higher aging degree. Adsorption capacity is decreasing with an aging degree. Toxicity is increasing with the complexity of samples but decreases with the aging degree. Mixture (MP and CEC) confirmed higher toxicity in comparison to the individual components.

Sources of microplastic (MP) in the environment are various including inefficient wastewater treatment plants, and stormwater runoff. Also, everyday activities that produce municipal plastic waste due to unregulated waste management end up in the aquatic environment which with time can be degraded and fragmented into MP particles. Due to its shape and size, MP can easily enter the food chain and cause negative effects on the organisms. Also, it is important to notice that in atmospheric conditions waste polymer material as well as MP can release additives that are mostly residue from the synthesis or even can be produced in the process of recycling. The aim of this study was to investigate the qualitative content and aquatic toxicity of samples during the leaching process. For that purpose pristine and photooxidative (UV) aged polyethylene terephthalate (PET) bottles were exposed to the enhanced atmospheric conditions. In leaching tests, using pristine and aged MP, the concentration of bisphenol A (BPA) in the aqueous phase was monitored using High-Performance Liquid Chromatography Analysis. Heavy metal concentration was monitored using Inductively Coupled Plasma Mass Spectrometry. Acute toxicity bioassays were performed with the freshwater microalgae Pseudokirchneriella subcapitata (Selenastrum capricornutum) and the crustacean Daphnia magna as well as marine bioluminiscent bacteria Vibrio fischeri, according to standard procedures (ISO). Obtained results indicate that the fragmentation of PET bottles is enhanced for pristine PET bottles in terms of a higher percentage of smaller particles. Leachates that are released from both pristine and aged PET samples were BPA and antimony. The release of antimony was much lower from the UV-aged sample. In general, presence of leached constituents enhances overall toxicity effects in comparison with the samples that consisted of only MP particles. These results will serve as preliminary study for the further investigation of microplastic behaviour in the aquatic environment and the goal is to step forward to the more complex environmentally relevant samples which are considered as a mixture of microplastics and other pollutants.

Different crystal forms of a photoactive material have different photocatalytic activities, usually represented by differences in band gap energies and affinity to recombination of generated charge carriers. In photocatalytic experiments, monoclinic bismuth vanadate is the most used form of bismuth vanadate. Monoclinic bismuth vanadate is a n-type visible light photocatalyst which means that the majority of charge carriers in this crystal form are electrons. In fact, low mobility of photogenerated holes is one of the main disadvantages of monoclinic BiVO4. Nevertheless, under visible light irradiation this form of BiVO4 can degrade most of organic dyes in a few hours. For degradation of complex molecules modifications of monoclinic BiVO4 are required. In past studies, bismuth vanadate was first enhanced via morphological change resulting in spherical isotype homojunction BiVO4. Second modification of photocatalytic activity was postdeposition of silver and iron nanoparticles onto its surface. Newly synthesized photocatalysts were immobilized on glass plates. With the use of response surface methodology (RSM), the best conditions (mass of nanoparticles precursor, pH and concentration of hydrogen peroxide) for degradation of 50 μM ciprofloxacin (CIP) under simulated sunlight were examined. In this study, reactive oxygen species (ROS) scavenging under the best conditions for each photo deposited material was performed. The used scavengers were: formic acid for holes, 1, 4- benzoquinone as superoxide scavenger and dimethyl sulfoxide (DMSO) as hydroxyl radical scavenger. The obtained results of photocatalytic degradation of CIP under sunlight with hydrogen peroxide show differences in mechanism of activation of hydrogen peroxide with different photodeposited nanoparticles. Those results will be combined with mass spectrometry results and toxicological studies to get the detailed pathway of CIP photodegradation under defined conditions.

Tackling hazardous substances pollution in the Danube River Basin by Measuring, Modelling-based Management and Capacity building (Danube Hazard m3c) is an Interreg project co-funded by the European Union (ERDF, IPA, ENI). 14 countries of the Danube basin are involved in the project, including Croatia. The main objective of the project is to establish a coherent and comprehensive screening of the water status of the Danube basin. According to the EU Water Framework Directive, pollution by hazardous substances is an important water quality problem in the Danube River Basin that needs to be addressed. This also applies to non-EU member states, which have committed to pursue similar goals under the International Commission for the Protection of the Danube River. The project is based on three elements of water governance: measuring, modelling, and management. Part of the project involves collecting and cataloguing available data on measurements of hazardous substances in the basin and analyzing existing rules and regulations that each country participating in the project adheres to. Conclusions are presented based on analyses of the main aspects of policies related to the management of hazardous substances in water, mainly in the following areas: national legislative frameworks, monitoring of hazardous substances in surface water, management of hazardous substances in groundwater, point source emitters, diffuse polluters, fees, analytical methods, databases and registers, and inventories of emissions of priority substances.

Microplastics (MPs) are now recognized as a new class of contaminants of emerging concern in waters. One of the concerning factors is their ability to adsorb and transport coexisting water pollutants. It has been reported so far that the adsorption of organic pollutants on MPs is governed by weak intermolecular forces, as hydrophobic interactions, van der Waals forces, electrostatic attractive and repulsive forces, π-π interactions, and hydrogen bonds. [1] However, the extent of each interaction remains unknown. Polyethylene terephthalate (PET) MPs (microPET) is one of the most frequently found types of MPs in the environment and a potential carrier of organic pollutants in water. Here we use the density functional theory (DFT) approach to identify interactions between microPET and benzene derivatives and calculate their interactions energies on different adsorption sites. Our results show that hydrogen bonds are the main mechanism controlling adsorption of small organic pollutants on microPET while π-π interactions do not play an important role. Water molecules do not act as competitive factors proving microPET can adsorb and transport organic pollutants in water. The number of adsorbed pollutants depends on the number of adsorption sites and the adsorption energy of a particular pollutant depends on the type of adsorption site. The strongest hydrogen bonds are formed with the carboxyl groups at the ends of PET chains. As ageing of microPET in the environment causes chain scissions and the formation of oxygencontaining groups, it increases the number of adsorption sites that can bind pollutants stronger. The quantitative and qualitative data presented in this work can contribute to a better understanding of the interactions between microPET and organic pollutants in the water environment.

The effect of different water matrices on the photocatalytic degradation of dissolved pharmaceuticals was explored. The focus was on the degradation efficiencies in wastewater effluent from a bioreactor and water effluent from a central wastewater treatment plant and comparing the results with degradation in deionized H$_2$O. The compounds tested included: oxytetracycline, marbofloxacin, ibuprofen, diclofenac, phenytoin, ciprofloxacin, sulfamethoxazole. For the experiments performed in this study, a compact packed-bed photocatalytic reactor was used in which the hybrid TiO$_2$ photocatalyst (sol-gel/P25) was deposited on ∼3 mm glass beads. As expected, the reactions proceed more slowly in wastewater than in deionized water, yet it is shown that removal of the compounds from the water is still possible even when other organic molecules are present. Total organic carbon measurements have shown that complete mineralization takes place albeit at slower rates than the initial degradation of parent compounds. The results show that an acidic pH can increase the reaction rates and the adsorption on the photocatalyst surface. Analyses of the degradation intermediates were performed using tandem liquid chromatography triple-quadrupole mass spectrometry system. Additionally, X-ray absorption spectroscopy was applied to get insight into the local structure of the photocatalyst before and after use. Understanding the effects that different wastewater compositions have on photocatalytic reactions will help to refine the potential applications of the technology.