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•Slight differences in preparing route yield specifics in the as-achieved morphology.•Photocatalysis is ruled by morphology and crystallization more than composition.•Distorted ...nanostructured titania arrays show better photocatalytic performance.•Rutile increase in lower-order-films contributes synergistically to photoconversion.•Control over evolution of nanostructured titania films by levels of order was shown.
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.
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.
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 TiO
2
-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:
k
p,int,NH3
= (3.05 ± 0.04) × 10
−3
cm
4.5
mW
−0.5
g
−1
min
−1
and
k
p,int,CH4
= (1.81 ± 0.02) × 10
−2
cm
4.5
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 NH
3
and CH
4
confirmed continuous reduction of pollutant content in the air stream due to the oxidation of NH
3
to N
2
and CH
4
to CO and CO
2
, 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 TiO
2
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.
U ovoj studiji istraživana je adsorpcija Cu(II) iona na smjesi anatasa i rutila, dviju polimorfnih formi TiO2. Istražen je učinak vremena kontakta adsorbens/adsorbat i učinak početne koncentracije ...Cu(II) na adsorpciju. Rezultati su pokazali da ravnoteža nastupa već nakon jedne minute kontakta Cu(II) i TiO2 te da kapacitet adsorpcije raste s porastom početne koncentracije Cu(II) iona. Eksperimentalni podatci obrađeni su Langmuirovom i Freundlichovom izotermom. Dobiveni rezultati ukazuju da Freundlichov model bolje opisuje ispitivani adsorpcijski sustav te da je adsorpcija fizikalne prirode.
Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna .
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.
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 TiO
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 (t
= 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 (
, W m
) using ESSDE radiation emission model. The irradiation factor, i. e. the product of absorption coefficient and incident photon flux at film surface (
(z))
was introduced into the kinetic models. Resulting reaction rate constants
(min
m
) 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 CO
The molecularly imprinted polymers (MIPs) with sulfaguanidine as a template, methacrylic acid, 4-vinylpyridine, and 2-hydroxyethyl methacrylate as functional monomers, ethylene glycol dimethacrylate ...as a cross-linker and 2,2′-azobis-isobutyronitrile as an initiator have been prepared through the cross-link reaction of polymerization. Solid-phase extraction (SPE) procedure for the extraction of sulfaguanidine from water samples using the prepared MIPs and non-imprinted (NIPs) was evaluated. The best MIP in combination with commercial sorbents was applied for simultaneous extraction of eight pharmaceuticals. New SPE cartridges were prepared by combination of optimal produced MIP and Oasis HLB in 6mL of polypropilene SPE reservoir.
The developed method which includes new SPE cartridge (MIPMAA-Oasis HLB, 400mg/6mL) and thin-layer chromatography was validated. The method provides a linear response over the concentration range of 0.5–150μg/L, depending on the pharmaceutical with the correlation coefficients>0.9843 in all cases except for norfloxacin (0.9770) and penicillin G procaine (0.9801). Also, the method has revealed low limits of detection (0.25–20μg/L), good precision (intra and inter-day), a relative standard deviation below 15% and recoveries above 95% for all eight pharmaceuticals. The developed method by using newly prepared SPE cartridge has been successfully applied to the analysis of production wastewater samples from pharmaceutical industry.
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•First sulfaguanidine-imprinted polymers.•The prepared MIPs and NIPs were characterized by FTIR and SEM.•The best MIP (MIPMAA) was used in the combination with commercial sorbents.•Validation of developed MISPE–HPTLC method for determination of 8 pharmaceuticals.•Analysis of production wastewater samples.
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).
Sodium titanate nanotubes (NaTiNTs) were prepared by hydrothermal method and functionalized with three different silane coupling agents. The existence of the chemical bond between silane molecules ...and nanoparticles was confirmed by scanning electron microscopy (SEM) equipped with electron dispersive X‐ray spectroscopy (EDS) mapping, Fourier transform infrared (FTIR) spectroscopy, and simultaneous differential scanning calorimetry–thermogravimetric analysis (DSC‐TGA). NaTiNTs before and after functionalization were characterized by X‐ray diffraction (XRD) technique. Functionalized NaTiNTs were used to prepare epoxy‐based nanocomposites with three different wt.% of nanofillers (1, 2, and 3 wt.% per epoxy). The thermal and mechanical properties of prepared nanocomposites were studied by DSC, DSC‐TGA, and dynamic mechanical analysis (DMA). The obtained results were compared to the epoxy. The results showed that the glass transition temperature increased from 72 to 79 °C. Storage modulus increased by 10.4% at 3 wt.% nanotubes. From all results appropriate functionalized NaTiNTs were chosen and nanocomposites for determination of combustion properties by cone calorimeter were prepared (1, 3, and 5 wt.% of nanofiller per epoxy). Significant reduction of the heat release rate (HRR) depending on the inorganic particles loading was observed. The peak value for HRR was reduced by about 40% compared to the epoxy, while ignition time and total heat release (THR) are not significantly affected by the presence of the inorganic particles.
The functionalization of sodium TiO2 nanotubes and nanoribbons with 3-(aminopropyl)triethoxysilane (APTES) was performed by a sol–gel process using two different methods, namely with and without ...prehydrolization of APTES. Nanoparticles were functionalized with different amounts of APTES (30, 60 and 100wt% per nanoparticles) and under different times of functionalization (2, 4 and 24h). The nature and binding of the APTES molecules on sodium TiO2 nanoparticles were determined by simultaneous differential scanning calorimetry-thermogravimetric analysis (DSC-TGA), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) equipped with electron dispersive X-ray spectrometry (EDS). DSC-TGA results showed that the amount of APTES molecules on nanoparticles increased with higher APTES ratios. The existence and binding of the APTES molecules with nanoparticles was confirmed by FTIR and SEM–EDS.
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