This study investigates the influence of multiwalled carbon nanotubes (MWCNT), as reinforcement in the AlSi9Cu3(Fe) matrix, for production of metal nanocomposite material. AlSi9Cu3(Fe) alloy found special application in the automotive industry using high pressure die casting (HPDC) process. The main goal of the experiment was development of a nanocomposite material that can achieve significant decrease in the vehicle mass, which will have a positive impact on fuel consumption and general CO2 emission into the atmosphere. Three different states of nanocomposite material were investigated: casted, naturally, and artificially aged. The produced nanocomposite was analyzed using an optical emission spectrometer and carbon-sulfur (CS) elemental analyzer to determine the chemical composition and presence of MWCNT. Tensile strength testing was carried out on the universal static testing machine, and both optical and scanning electron microscopy were used for microstructure analyses, followed by energy-dispersive X-ray spectroscopy (EDS) analysis of main microstructural constituents. A significant increase in tensile strength after 3 years of the natural aging process is caused by precipitation hardening and the occurrence of a great number of extracted small intermetallic precipitates and a more homogeneous distribution of MWCNT in the metal matrix. The heat treatment for artificial aging process has shown an insignificant increase in tensile strength in comparison with the natural aging process.

Triclosan (TCS), a persistent antimicrobial and endocrine-disrupting compound, is commonly found in surface and groundwater due to incomplete removal by conventional wastewater treatment. This study evaluated its fate in authentic rainwater runoff collected from a state road using rubber tiles made from recycled tires that were either uncoated (RRT) or coated with TiO2 via the sol–gel method (SGT). Pollutants were analyzed by a high-resolution liquid chromatography–quadrupole time-of-flight mass spectrometry system (LC/MS QTOF) before and after treatment in a flat-plate cascade reactor under UV-A irradiation. After 120 min SGT achieved >50% TCS removal, while RRT achieved ~44%. Further analysis identified degradation products (chlorocatechole, quinone, and transient dioxin-like species). ECOSAR predictions indicated moderate to high toxicity for some degradation products, but their transient and low-abundance detection suggests that photocatalysis suppresses accumulation, ultimately yielding less harmful products such as benzoic acid. These findings highlight the dual role of TiO2-coated rubber tiles: improving material durability while enabling photocatalytic degradation.

The extensive global use of rubber results in significant microplastic pollution from the release of tire wear particles and microplastic leachate, impacting the environment, human health, and ecosystems. Waste tires are normally recycled and used for the production of new products, such as rubber tiles. The presented study aims to show the possibility of further decrease in the negative environmental impact of materials based on recycled rubber. This paper presents the modification of rubber tiles with a titanium dioxide (TiO2) coating, focusing on surface integrity, rubber particle wear release, and the consequent environmental impact of leachate release. Both reference and modified rubber tiles were subjected to artificial accelerated aging in a solar simulator for 4, 6, and 8 weeks, followed by an abrasion test. The carbonyl index was calculated from FTIR characterization after each time frame to indicate the degradation of organic compounds and chemical changes caused by UV exposure. A 24 h leaching test with a liquid-to-sample ratio of 1:20 was performed on both rubber tile samples prior to and after 8 weeks of aging along with the aged wear particles for the purpose of the non-target screening of released organic leachate by LC/MS QTOF. The results of carbonyl indices showed that the TiO2 coating contributes to the stabilization of polymer degradation and, to a certain extent, reduces the leaching of organic compounds, such as phthalates. However, the increased wear and release of rubber particles and the subsequent degradation of organic leachates require further in-depth research.

Titanium dioxide (TiO2) was added in different proportions as a filler to the mixture for the production of recycled rubber tiles in order to improve their existing properties. The mechanical properties of novel rubber tiles were analyzed in the context of abrasion resistance, maximum stress (TS), stress at break (TSb), deformation at break (Eb), and hardness. An optimal mixture composition was found comparing the obtained results of mechanical tests; successful improvement of abrasion by 22.1%, Eb by 10.46% and hardness by 17.65% was achieved. Finally, the characterization of the new rubber tile by SEM/EDS and FTIR analysis was carried out, along with the stability and environmental impact assessment based on the leaching test. The accelerated aging test was conducted using a solar simulator, after which the mechanical properties, SEM/EDS, FTIR, and leaching test were re-examined. The results after the accelerated aging test showed that tiles with the addition of TiO2 have better mechanical properties compared to the reference ones; TS improved by 85.71%, Eb by 75.53%, and hardness by 9.43%. Therefore, we concluded that TiO2 as a filler in interaction with rubber and polyurethane composites significantly contributed to the improvement of the existing rubber tile, and the achieved improvements are useful for the original application of these tiles, which is the protection from injuries on playgrounds and sports fields. Also, the improvement achieved extends the service life of this type of tile, which contributes to the quality of this type of material.

The application of the solar photocatalysis for the degradation of residual pollutants found in surface water was demonstrated. Semi-pilot scale flat-plate cascade reactor (FPCR) was used to study the degradation of model organic pollutants: enrofloxacin (ENRO), 17 beta-estradiol (E2) and 1H-benzotriazole (1H-BT) over TiO2 thin-film supported on glass fibers. A modular panel with full-spectra solar lamps with appropriate UVB and UVA irradiation levels was used as a simulation of sunlight. Pollutant degradation in FPCR was estimated using predictive models; intrinsic reaction rate constants (k(i)) for ENRO, E2 and 1H-BT independent of the reactor size, flow rate and irradiation conditions were determined: 9.60, 3.35 and 0.37 10(9) s(-1) W-0.5 m(1.5), respectively. Main degradation products (DPs), formed upon hydroxylation, ring opening and oxidation, were identified using LC-QTOF-MS. The ecotoxicological impact was assessed via T.E.S.T. and ECOSAR open-source tools showing the formation of less harmful DPs after sufficient reaction time. Pollutant degradation was simulated at four locations of interest, i.e. exhausts from urban wastewater treatment plants (UWWTPs) in Zagreb, Croatia (45 degrees N), Krakow, Poland (50 degrees N), Sevilla, Spain (37 degrees N) and Ioannina, Greece (39.6 degrees N). Results have proved that a simple flat-plate system with supported photocatalysts can be easily scaled up and incorporated at the outlet of UWWTP for the reduction of pollutant load and related toxicity. The exhaust canal in Zagreb with the estimated length of a photocatalytic layer of 122 m for the > 90% degradation of all target pollutants was discussed as the best installation site among studied locations.

The study describes a few significant aspects of photocatalytic studies: (i) the methodology for finding optimal support for TiO2 photocatalytic films with possible environmental application and (ii) degradation of pollutants of widespread concern including detailed kinetic study and identification of degradation products with respective in silico toxicity assessment. Different cotton textiles and glass fiber mesh were studied as flexible supports for TiO2. Preliminary experiments were done with an aqueous solution of 2-HBA in a rectangular open channel reactor under UVA light, due to known kinetics and photocatalytic degradation pathway of 2-HBA. Further environmental application of the photocatalytic film on the most appropriate support was studied in the same reactor using ciprofloxacin (CIPRO), carbamazepine (CARBA) and 17β-estradiol (E2) as model environmental pollutants under UVA and artificial solar irradiation. A detailed kinetic study, including photon absorption effects, was performed using recently published models. Degradation products were identified by means of high-resolution mass spectrometry (UHPLC-QTOF MS system) with electrospray ionization analysis of the water samples. The environmental impact of photocatalytic oxidation of CIPRO, CARBA and E2 was addressed via in silico toxicity assessment of initial pollutants and respective degradation products.

This study is performed to find ways for expanding use in industry of nanocomposites based on a light metal matrix and multiwall carbon nanotubes. Industrial tests are conducted using a high-pressure die casting process. Specimens are prepared in two ways using aluminum alloy AlSi9Cu3(Fe) with maximum specific magnesium content of 0.55 wt.%: by adding 0.2 wt.% of nanotubes directly to molten AlSi9Cu3(Fe) for the high-pressure die casting process, and by adding 0.05, 0.1 and 0.2 wt.% of nanotubes to the press ahead of the high-pressure die casting process piston. Chemical composition is determined and the effect of magnesium on improved interphase bonding leading to homogeneous distribution of multiwall carbon nanotubes is confirmed. Addition of 0.05 wt.% nanotubes results in a finer specimen microstructure, resulting in improved mechanical properties. Based on research, recommendations are proposed for the industrial scaling up and use of nanocomposites, particularly in automobile components.

The immobilization of titanium dioxide, particularly commercial TiO2 P25, on the surface of recycled rubber tiles presents a solution for achieving passive air protection. A completely new purpose for tiles was obtained by addressing air pollution and related health issues. Modified rubber tiles were prepared using a sol–gel method with three different proportions of TiO2 (2, 4, and 10 g) in the solution. The nature of TiO2 nanoparticles and their respective binding on the tile surface was determined using scanning electron microscopy (SEM) equipped with electron dispersion X-ray spectrometry (EDS) and Fourier-transform infrared (FTIR) spectroscopy. The SEM-EDS results showed that the most successful immobilization was achieved with the lowest amount of TiO2 in the sol–gel solution. The FTIR results confirmed a band at 950 cm−1 that was attributed to the Ti-O-Si bond. The stability and environmental impact of the treated rubber substrates were investigated by a leaching test. Photocatalytic oxidation was confirmed by the oxidation of NH3 to N2. Based on the results obtained, rubber substrates with an addition of 2 g of TiO2 have demonstrated prospects for further tests of the photocatalytic degradation of airborne pollutants.

Thin films of nanostructured titania comprising different levels of lateral and vertical microstructural order and surface chemistry were prepared via the anodization of titanium. We segmented and demystified the contributions that lead to nanostructured titania and affected its photocatalytic behaviour to: (1) specific compositional (less dominant) and (2) specific (surface) morphological differences (substantial), in the as-achieved films. To shed more light on the contributions, we partitioned these films by chemically and morphologically distinctive constituents; (1) top porous non-stoichiometric titania, (2) mid tubular nanoformations, and (3) bottom dense titania.Morphology of the films was described using electron microscopy, and synchrotron grazing incidence X-ray scattering/diffraction. Narrow range of synthetic conditions allowed preparing of ordered, macroscopically homogeneous nanotubes for photovoltaics. Interestingly, somewhat different, distorted tubular nanoformations were better suited for the photo-degradation of salicylic acid (fit by pseudo-second order). In this case, rutile traces in anatase tubular formations were commonly observed, synergistically boosting photodegradation. Broad characterisations reasons the photodegradation in order of importance to: (1) controlling the evolution of type of porosity and presence of defects in the films, (2) controlling the ratio and vertical profile of anatase-to-rutile, and (3) observing the surface chemistry changes, i.e. the presence of substoichiometric titania.

Anticancer drugs pose a potential risk to the environment due to their significant consumption and biological effect even at low concentrations. They can leach into soils and sediments, wastewater, and eventually into drinking water supplies. Many conventional technologies with more effective advanced oxidation processes such as photocatalysis are being extensively studied to find an economical and environmentally friendly solution for the removal of impurities from wastewater as the main source of these pharmaceuticals. Since it is impossible to treat water by photocatalysis if there is no sorption of a contaminant on the photocatalyst, this work investigated the amount of imatinib and crizotinib sorbed from an aqueous medium to different forms of photocatalyst. In addition, based on the sorption affinity studied, the applicability of sorption as a simpler and less costly process was tested in general as a potential route to remove imatinib and crizotinib from water. Their sorption possibility was investigated determining the maximum of sorption, influence of pH, ionic strength, temperature, and sorbent dosage in form of the suspension and immobilized on the fiberglass mesh with only TiO2 and in combination with TiO2/carbon nanotubes. The sorption isotherm data fitted well the linear, Freundlich, and Langmuir model for both pharmaceuticals. An increasing trend of sorption coefficients Kd was observed in the pH range of 5–9 with CRZ, showing higher sorption affinity to all TiO2 forms, which was supported by KF values higher than 116 (μg/g)(mL/μg)1/n. The results also show a positive correlation between Kd and temperature as well as sorbent dosage for both pharmaceuticals, while CRZ sorbed less at higher salt concentration. The kinetic data were best described with a pseudo-second-order model (R2 > 0.995).

During the last decades, heterogenous photocatalysis has shown as the most promising advanced oxidation process for the removal of micropollutants due to degradation rate, sustainability, non-toxicity, and low-cost. Synergistic interaction of light irradiation, photocatalysts, and highly reactive species are used to break down pollutants toward inert products. Even though titanium dioxide (TiO2) is the most researched photocatalyst, to overcome shortcomings, various modifications have been made to intensify photocatalytic activity in visible spectra range among which is modification with multiwalled carbon nanotubes (MWCNTs). Therefore, photocatalytic oxidation and its intensification by photocatalyst’s modification was studied on the example of four micropollutants (diclofenac, DF; imidacloprid, IMI; 1-H benzotriazole, BT; methylene blue, MB) degradation. Compound parabolic collector (CPC) reactor was used as, nowadays, it has been considered the state-of-the-art system due to its usage of both direct and diffuse solar radiation and quantum efficiency. A commercially available TiO2 P25 and nanocomposite of TiO2 and MWCNT were immobilized on a glass fiber mesh by sol-gel method. Full-spectra solar lamps with appropriate UVB and UVA irradiation levels were used in all experiments. Photocatalytic degradation of DF, IMI, BT, and MB by immobilized TiO2 and TiO2/CNT photocatalysts was achieved. Mathematical modelling which included mass transfer and photon absorption was applied and intrinsic reaction rate constants were estimated: kDF=3.56 × 10−10s−1W−0.5m1.5, kIMI=8.90 × 10−11s−1W−0.5m1.5, kBT=1.20 × 10−9s−1W−0.5m1.5, kMB=1.62 × 10−10s−1W−0.5m1.5. Intensification of photocatalysis by TiO2/CNT was observed for DF, IMI, and MB, while that was not the case for BT. The developed model can be effectively applied for different irradiation conditions which makes it extremely versatile and adaptable when predicting the degradation extents throughout the year using sunlight as the energy source at any location.

The adsorption of Cu(II) ions on a mixture of anatase and rutile, two polymorphic forms of TiO2, was investigated. The influence of the adsorbent/adsorbate contact time as well as the influence of the initial concentration of Cu(II) on the adsorption was monitored. The results showed that equilibrium occurred after only one minute of contact of Cu(II) and TiO2, and that the adsorption capacity increased with initial concentration of Cu(II) ions. Experimental data were processed by Langmuir and Freundlich isotherm. The obtained results showed that the Freundlich model better described the investigated adsorption system, and that the adsorption was of a physical nature.

Teški metali sastavni su dio Zemljine biosfere. Prisutni su u različitim kemijskim oblicima i oksidacijskim stanjima. Osim toga, uslijed ljudskog djelovanja dolazi do akumuliranja teških metala u prirodi, što predstavlja značajan ekološki problem. Toksičnost i migracija u prirodi ovisi o vrsti teških metala i njihovim kemijskim svojstvima. Dodatno, i njihova koncentracija ima značajnu ulogu u djelovanju na živi svijet. Mogućnost akumuliranja u ljudskom organizmu, sudjelovanje u staničnim reakcijama, sposobnost keliranja i stvaranja sulfida s biološki aktivnim tvarima kao što su enzimi te mogućnost tvorbe organometalnih spojeva neki su od razloga njihova štetnog utjecaja na ljudsko zdravlje.1 S obzirom na navedeno nužno je kontinuirano praćenje teških metala u vodi, tlu i zraku kao i njihovo uklanjanje.

The work is focused on the assessment of possible methods for intensification of photocatalytic degradation of common water borne pollutants. Solar photocatalysis poses certain limitations for large scale application with several possible reactor designs which have shown an optimal performance. In the current study, a comparison between two types of pilot scale reactors was made: a flat-plate cascade reactor (FPCR) and tubular reactor with a compound parabolic collector (CPC). Apart from the reactor design, another aspect of possible intensification was a photocatalyst formulation. The efficiency of photocatalytic films that consisted of pure TiO2 nanoparticles was compared to the efficiency of films that consisted of TiO2/CNT composites. Intensification assessment was performed via detailed kinetic modelling, combining the optical properties of films, irradiation conditions and reactor mass balance. Intensification was expressed via intensification indices. Results showed the advantage of the CPC-based reactor design and an unbiased effect of sensitizing agent (CNT) in the photocatalytic film formulation.

In this work, we present the application of solar photocatalysis for air purification including toxic substances such as ammonia and methane normally related to emissions from agriculture (e.g., poultry and cattle farms), landfills, etc. The study was done in three different laboratory and semi-pilot scale reactors: annular reactor (AR), mini-photocatalytic wind tunnel (MPWT), and photocatalytic wind tunnel (PWT). Reactors present a physical model for estimation of air-borne pollutant degradation over TiO2-based photocatalytic layer in respect to optimal operating conditions (relative humidity, air/gas flow, and feed concentration). All studies were performed under artificial solar irradiation with different portions of UVB and UVA light. The application of solar photocatalysis for air purification was evaluated based on thorough monitoring of pollutants in inlet and outlet streams. The kinetic study resulted with intrinsic reaction rate constants: kp,int,NH3 = (3.05 ± 0.04) × 10−3 cm4.5 mW−0.5 g−1 min−1 and kp,int,CH4 = (1.81 ± 0.02) × 10−2 cm4.5 mW−0.5 g−1 min−1, calculated using axial dispersion model including mass transfer considerations and first-order reaction rate kinetics with photon absorption effects. The results of photocatalytic oxidation of NH3 and CH4 confirmed continuous reduction of pollutant content in the air stream due to the oxidation of NH3 to N2 and CH4 to CO and CO2, respectively. The application of solar photocatalysis in outdoor air protection is still a pioneering work in the field, and the results obtained in this work represent a good basis for sizing large-scale devices and applying them to prevent further environmental pollution. In the current study, a TiO2 P25 supported on a glass fiber mesh was prepared from commercially available materials. The system designed in this way is easy to perform, operate, and relatively inexpensive.

The authors regret that, despite thoroughly reviewing the manuscript, the content of a paragraph has been duplicated and has to be ignored .