In this study, the g-C
3
N
4
with simultaneous isotype heterojunction and porous structure showed superior photocatalytic decomposition of tetracycline hydrochloride (TCH) under white LED light ...irradiation fabricated via a thermal polycondensation method using melamine and thiourea as precursors and NH
4
Cl as soft-template. X-ray diffraction and transmission electron microscopy demonstrated the successful fabrication of the heterojunction between two different phases of g-C
3
N
4
metal-free semiconductor. Besides, the increase in surface area as well as the porosity of g-C
3
N
4
isotype heterojunction compared with CN-M (the g-C
3
N
4
was synthesized using melamine as precursor) or CN-T (the g-C
3
N
4
was synthesized using thiourea as precursor) was confirmed through nitrogen adsorption–desorption isotherms. The improved photocatalytic degradation of TCH over CN-MT (the g-C
3
N
4
was synthesized using melamine and thiourea as precursors and NH
4
Cl as soft-template) compared to CN-M and CN-T could be assigned to the visible light absorption expansion, the increase in surface area as well as the porosity and reduction of photo-generated electron–hole pair recombination. Specifically, the CN-MT-1:1 isotype heterojunction revealed the highest photocatalytic activity for TCH degradation (81.55%) within 180 min. Furthermore, this catalyst can be recycled four times, which demonstrates the potential of CN-MT as a visible light-sensitive catalyst for organic pollutant removal.
Graphical Abstract
Pollution of waste and natural waters by antibiotics is a major health issue that induces the development of resistant pathogens. Pollutant may be removed by photocatalysis, yet classical ...photocatalysis is limited by the short carrier lifetime. Here, we review multicomponent photocatalysts for the synergic degradation of antibiotics. Components include metallic nanoparticles, semiconductors and adsorbents. The synergy of these components provide photocatalysts with advantages such as extended visible-light range with bandgap energy lower than 2.8 eV, improved charge transfer properties, enhanced adsorption capacity and more active reaction sites. The removal of the antibiotics, based on the decrease of the initial concentration, reaches 80–100%, but mineralization is rarely measured in reports. Proposed mechanisms for the photocatalytic degradation of antibiotics over single and multicomponent photocatalysts are discussed.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Bismuth vanadate, BiVO
4
, is a visible-light response semiconductor for photocatalysis applications such as organic pollutants degradation, oxygen production and carbon dioxide reduction. However, ...as a single-phase photocatalyst, BiVO
4
efficiency is limited by the unpreferable recombination of the photoexcited electron (e
−
) and hole (h
+
). Thus, strategies have been designed to enhance the photocatalytic efficiency by promoting the separation of electrons and holes. This can be done by controling the morphology and crystallographic facets of BiVO
4
, and by building p–n junction photocatalytic systems with a combination of n-type semiconductors (BiVO
4
) and p-type semiconductors or a monoclinic–tetragonal heterostructure of BiVO
4
. In particular, a direct p–n junction photocatalytic system with tetragonal zircon-structured BiVO
4
(t-z) and monoclinic scheelite-structured BiVO
4
(m-s) combination has recently attracted attention. Here we review the synthesis of the monoclinic–tetragonal heterostructured BiVO
4
photocatalyst (m–t BiVO
4
) by calcination, hydrothermal, microwave-assisted hydrothermal and solvothermal methods. m–t BiVO
4
formation and the transmission phase between t-z and m-s are controlled by the calcining temperature, precursor pH, metal doping content, type of solvent, implementation of precursors and reaction conditions. We discuss m–t BiVO
4
crystal structure, optical characteristics and photocatalytic principles. Successful formation of BiVO
4
crystals with a m-s/t-z heterostructure is based on data from X-ray diffraction (XRD), Raman and ultraviolet–visible diffuse reflectance spectroscopy (UV–Vis DRS). In the m–t BiVO
4
heterostructure, a direct p–n junction photocatalytic system is established. When this system is exposed to visible light, the electrons in the conduction band of m-s BiVO
4
, a n-type semiconductor, migrate easily to the conduction band of t-z BiVO
4
, while the holes on valence band of t-z BiVO
4
, a p-type semiconductor, move to the valence band of m-s BiVO
4
through an internal electric field. As a result, the e
−
/h
+
charge carriers are spatially separated.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
In this study, a minimum-run resolution IV and central composite design have been developed to optimize tetracycline removal efficiency over mesoporous carbon derived from the metal-organic framework ...MIL-53 (Fe) as a self-sacrificial template. Firstly, minimum-run resolution IV, powered by the Design-Expert program, was used as an efficient and reliable screening study for investigating a set of seven factors, these were: tetracycline concentration (A: 5-15 mg/g), dose of mesoporous carbons (MPC) (B: 0.05-0.15 g/L), initial pH level (C: 2-10), contact time (D: 1-3 h), temperature (E: 20-40 °C), shaking speed (F: 150-250 rpm), and Na
ionic strength (G: 10-90 mM) at both low (-1) and high (+1) levels, for investigation of the data ranges. The 20-trial model was analyzed and assessed by Analysis of Variance (ANOVA) data, and diagnostic plots (e.g., the Pareto chart, and half-normal and normal probability plots). Based on minimum-run resolution IV, three factors, including tetracycline concentration (A), dose of MPC (B), and initial pH (C), were selected to carry out the optimization study using a central composite design. The proposed quadratic model was found to be statistically significant at the 95% confidence level due to a low
-value (<0.05), high R
(0.9078), and the AP ratio (11.4), along with an abundance of diagnostic plots (3D response surfaces, Cook's distance, Box-Cox, DFFITS, Leverage versus run, residuals versus runs, and actual versus predicted). Under response surface methodology-optimized conditions (e.g., tetracycline concentration of 1.9 mg/g, MPC dose of 0.15 g/L, and pH level of 3.9), the highest tetracycline removal efficiency via confirmation tests reached up to 98.0%-99.7%. Also, kinetic intraparticle diffusion and isotherm models were systematically studied to interpret how tetracycline molecules were absorbed on an MPC structure. In particular, the adsorption mechanisms including "electrostatic attraction" and "π-π interaction" were proposed.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Here, the importance of hydrogen bonding from amino (NH2) functional group on NH2−MIL-88B in oxytetracycline (OTC) adsorption mechanism has been reported. To clarify this finding, two materials ...including MIL-88B and NH2−MIL-88B derived from two different ligands of 1,4-benzene-dicarboxylic acid (H2BDC) and 2-aminobenzene-1,4-dicarboxylic acid (NH2-BDC) were synthesized and characterized. The X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FT–IR) were adopted, and proving the existence of NH2 functional group in the material structure. Comparing the adsorption efficiency among adsorbents with/without NH2 groups was evaluated through several fundamental investigations including the effect of solution pH (3.2–10.8), Na+ ionic strength (25–800 mmol/L), contact time (0–120 min) and initial concentration (20–100 mg/L). The investigations indicated that the best adsorption condition was found at pH 5.7. The OTC sorption process reached out the equilibrium nature rapidly, at 60 min. It was also demonstrated the negligible effect of Na+ ions on OTC adsorption over both MIL-88B and NH2-MIL-88B Some statistical error functions (R2, MRE, χ2, HYBRID, and MPSD) were also selected for better evaluating several nonlinearised kinetic and isothermal models. The principal outcomes revealed that the maximum adsorption capacity (94.9 mg/g) obtained from Langmuir equation by NH2−MIL-88B was above 4-fold higher than that by MIL-88B. Based on these vital evidences, the role of hydrogen bonding and plausible mechanisms in accelerating OTC adsorption has been suggested.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The present study utilized chemically modified porous carbon (CMPC) as a robust adsorbent for MB treatment. The characteristic findings revealed the existence of many functional groups (C-O/C = O, ...C-C/C = C, C-OH, - COOH, C-C = O, etc.) on the surface of the high-defect structure of CMPC. Additionally, influential factors: methylene blue (MB) concentration (116-284 mg/L), CMPC dosage (0.16-1.84 g/L), and pH (3.6-10.4) were assessed by response surface methodology. By applying optimized conditions, the highest MB removal and adsorption capacity were confirmed at 90% and 181.82 mg/g, respectively. Role of surface functional groups in adsorption mechanisms was meticulously explained.
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BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
In this study, BiVO4 was successfully synthesized via the solvothermal process using a solvent mixture of ethylene glycol and water under different synthesis conditions of temperature and pH. ...Physicochemical properties such as crystal phase, morphology, and optical absorption of the as-synthesized BiVO4 samples were characterized by X-ray diffraction (XRD), Raman spectra, field emission scanning electron microscopy (FE-SEM), and ultraviolet–visible diffraction reflection spectroscopy (UV–vis DRS). The XRD analysis showed that different synthesis conditions of temperature and pH significantly affected the growth of monoclinic BiVO4 crystals oriented along (0 4 0) facets. Form SEM results, the synthesis conditions, including pH and temperature, have a great effect on the morphology of monoclinic structured BiVO4. As the pH value increases in the range of 0–9 and temperature increases from 80 °C to 180 °C, the morphology of BiVO4 changed from peanut-, rod-, and leaf-like shapes. The photocatalytic activities of as-synthesized BiVO4 photocatalysts were evaluated by the photodegradation of methylene blue (MB) dye under irradiation of white LED light. We have found that by using appropriate synthesis conditions (the synthesis temperature of 140 °C and the synthesis pH of 7) the BiVO4 exhibited high photocatalytic efficiency for MB degradation (about 82.30% after 180 min of irradiation). This result is due to the development of the BiVO4 crystals oriented along (0 4 0) facets with an increase in the intensity ratio of I(0 4 0)/I(1 2 1). The growth of BiVO4 crystals oriented along (0 4 0) facets may be beneficial to enhance the photocatalytic activity of monoclinic scheelite BiVO4.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Sigle phase scheelite-monoclinic BiVO
4
materials with different morphologies were successfully fabricated via a facile hydrothermal process by controlling pH of the precursor. The photocatalytic ...properties of the as-prepared materials were assessed via the photodecomposition of crystal violet (CV) solution under a 60 W LED (Cree-L6) visible light irradiation. The Langmuir-Hinshelwood model was utilized to present kinetic behavior. The obtained BiVO
4
exhibited a monoclinic crystalline structure and narrow bandgap energy (E
g
= 2.3-2.6 eV), which were confirmed by the X-ray diffraction (XRD), Raman and UV-vis diffuse reflectance spectra (UV-vis DRS) results. From the scanning electron microscopy (SEM) results, BiVO
4
morphologies could be facilely controlled by turning the pH value of the precursor. When pH = 0.3, the BiVO
4
products showed spherical morphologies with particle sizes in the range of 1-5 µm. Rod- and spherical like-BiVO
4
products were obtained when the pH of the precursor was adjusted to 3. Moreover, BiVO
4
with nanoparticles could be prepared under the pH of 5-7, whereas leaf-like morphologies could be achieved when pH = 9. The photocatalytic test showed that the adsorption equilibrium constant depended on the morphologies of the BiVO
4
products and the reaction rate constant was reached the highest level at pH = 3. This outcome indicated that the enhanced performance of BiVO
4
significantly depended on the morphologies of the BiVO
4
products and the effective suppression of photo-excited electrons and holes.
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BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Recently, BiVO4 photocatalysts has been received much attention in field of catalysts. Because it can be used to degrade harmful organic catalysts in visible light, irradiation produces CO2, H2O and ...less harmful organic matter. In this study, we have successfully synthesized a BiVO4 photocatalysts via co-precipitation method in the presence of urea and different calcined temperatures. The survey calcined temperatures as 300°C; 350°C; 400°C and 450°C. The obtained materials were characterized by Scanning electron microscope (SEM) and X-ray diffraction (XRD). The photocatalytic activity was evaluated by the photocatalytic degradation of rhodamine B (RhB) degradation under visible compact Philip lamp (40W) light irradiation. The result indicates that all samples calcined are monoclinic scheelite structure of BiVO4. The BiVO4-350°C sample performed the best in the photodegradation of RhB.
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