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.
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).
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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.
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
-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
= (3.05 ± 0.04) × 10
cm
mW
g
min
and k
= (1.81 ± 0.02) × 10
cm
mW
g
min
, 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
and CH
confirmed continuous reduction of pollutant content in the air stream due to the oxidation of NH
to N
and CH
to CO and CO
, 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
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.
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