PHOTOCATALYTIC OPTIMIZATION OF MR DYE BY K-ZnO AND ZnO CATALYSTS UNDER VISIBLE IRRADIATION

2021 ◽  
Vol 4 (4) ◽  
pp. 67-76
Author(s):  
Yusuf Ibrahim ◽  
Yusuf Usman Jibrin ◽  
Zaharaddeen Muhammad ◽  
Mujahid Abubakar
Keyword(s):  
Band Gap ◽  
Rate Constant ◽  
Band Gap Energy ◽  
First Order Kinetics ◽  
Successive Formation ◽  
Ft Ir ◽  
Visible Irradiation ◽  
Uv Visible ◽  
Arrhenius Expression ◽  
Energy Determination

The lucubration on the visible light methyl red (MR) degradation using K-ZnO and undoped ZnO photo catalyst was investigated. The successive formation of K-ZnO was ascertained by several techniques such as scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), and UV-Visible spectrophotometer and solid state UV-Vis band gap energy determination by comparing the Kubelka-Monk equation with Tauc equation and the energy band gap was calculated to be 3.28ev. The influence of reaction variables such as MR concentration, reaction pH, catalyst loadings and temperature have been investigated for both process. The kinetics model was developed for both doped and undoped ZnO photocatalyst using pseudo first and second order kinetics, the result indicated that both doped and undoped ZnO followed pseudo first order kinetics due to higher correlation coefficient (R2) value of 0.985 and 0.922 with rate constant (k) of 0.026 min-1 and 0.062 min-1, respectively. Based on the rate constant value (k) obtained at different reaction temperatures, the Arrhenius expression was derived. The derived activation energy (Ea) for the degradation of MR by K-ZnO photocatalysis was 32.109x103JK-1. The optimum condition for K-ZnO showed nearly complete degradation (95%) of the dye molecules with slightly higher degradation efficiency compares to ZnO (91%). 

scholarly journals Synthesis and Photoactivity of Fe3O4/TiO2-Co as a Magnetically Separable Visible Light Responsive Photocatalyst

2018 ◽  
Vol 18 (3) ◽  
pp. 403 ◽  
Author(s):  
Eko Sri Kunarti ◽  
Indriana Kartini ◽  
Akhmad Syoufian ◽  
Karolina Martha Widyandari
Keyword(s):  
Methylene Blue ◽  
Visible Light ◽  
Dopant Concentration ◽  
Band Gap Energy ◽  
Methylene Blue Solution ◽  
Magnetic Photocatalyst ◽  
Blue Solution ◽  
Degradation Reaction ◽  
Visible Irradiation ◽  
Uv Visible

Synthesis of magnetic photocatalyst, Fe3O4/TiO2-Co, with characterization and photoactivity examination have been conducted. The synthesis was initiated by preparation of Fe3O4 particles using coprecipitation method. The Fe3O4 particles were then coated with TiO2-Co at a various ratio of Fe3O4:TiO2 and concentration of Co(II) dopant. The Fe3O4/TiO2-Co was characterized by FTIR, XRD, TEM, SEM-EDX, VSM, and SR UV-visible methods. Photoactivity of the Fe3O4/TiO2-Co was carried out using methylene blue as a target molecule in degradation reaction within a batch system. By using optimum conditions, the degradation of methylene blue solution was performed under exposure to UV, visible light and dark condition. Results showed that the Fe3O4/TiO2-Co formation was confirmed by the presence of Fe3O4 and anatase diffraction peaks in the X-ray diffractogram. SR UV-Vis spectra indicated that the Fe3O4/TiO2-Co was responsive to visible light. Band gap energy of the Fe3O4/TiO2-Co with dopant concentration of 1; 5; 10 and 15% were 3.22; 3.12; 3.09 and 2.81 eV, respectively. The methylene blue solution can be well photodegraded at a pH of 10 for 210 min. The Fe3O4/TiO2-Co has the highest ability to methylene blue photodegradation with dopant concentration of 10% gave degradation yield of 80.51 and 95.38% under UV and visible irradiation, respectively.

Hydrazine-assisted preparation of ZnS nanocrystals using N-acetyl-L-cysteine as capping agent

2018 ◽  
Vol 32 (22) ◽  
pp. 1850254
Author(s):  
Reza Sahraei ◽  
Ehsan Soheyli ◽  
Zahra Faraji
Keyword(s):  
Band Gap ◽  
Hydrazine Hydrate ◽  
Absorption Edge ◽  
Emission Intensity ◽  
Band Gap Energy ◽  
Capping Agent ◽  
Time Duration ◽  
Gap Energy ◽  
Ft Ir ◽  
Zns Nanocrystals

Using N-acetyl-L-cysteine (NAC) as capping agent and different amounts of hydrazine hydrate as growth promoter, in this paper, we report a simple way for preparation of aqueous-based ZnS nanocrystals (NCs). The small-sized and well-dispersed NCs with cubic zinc blende structure and size-dependent optical behavior have been characterized by XRD, TEM, FT-IR, UV-Vis, and photoluminescence (PL) measurements. Disappearance of the thiol-related peak in the FT-IR spectrum of NAC-capped ZnS NCs demonstrated the well-passivation of ZnS NCs by deprotonated NAC molecules. Variation of optical properties of ZnS NCs has been studied at different hydrazine amounts and refluxing times. The growth-assisting characteristic of hydrazine hydrate was demonstrated by redshift in absorption edge as the hydrazine amount increased from 5 to 20 mmol, and ensuing decrease in band gap energy of ZnS NCs from 4.47 eV to 4.0 eV. On the other hand, increasing the refluxing time duration up to 20 h, resulted in obvious redshift in absorption edge and subsequent decrease in the band gap energy from 4.56 eV to 3.85 eV. The optical estimation on the size of the as-prepared ZnS NCs was obtained through effective mass approximation. Results indicated that all the NCs are small enough near the excitonic Bohr radius of ZnS which revealed the presence of strong quantum confinement effects. Effect of these parameters on PL emission intensity of ZnS NCs was studied and it was observed that the best emission result is at the presence of 12.5 mmol hydrazine hydrate and during 16 h heating. Finally, analyzing chemical stability of the as-prepared ZnS NCs against H2O2 corrosion demonstrated a well-accepting stability of emission intensity even after 108 min.

An Investigation on Structural and Optical Properties of Nanocrystalline Bismuth Ferrite and Manganese Sillenite Powders

2020 ◽  
Vol 835 ◽  
pp. 317-323
Author(s):  
D.A. Rayan ◽  
E.A. Abdel-Mawla ◽  
S.K. Mohamed ◽  
A.A. Mohamed ◽  
Mohamed M. Rashad
Keyword(s):  
Optical Properties ◽  
Bismuth Ferrite ◽  
Ammonium Hydroxide ◽  
Band Gap Energy ◽  
X Ray Diffraction ◽  
Structural And Optical Properties ◽  
Munk Function ◽  
Ft Ir ◽  
Uv Visible ◽  
Co Precipitation

Nanocrystalline bismuth ferrite BFO; BiFeO3 and manganese sillenite, BMO; Bi12MnO20 (BMO) powders have been successfully elaborated using a facile co-precipitation approach. The formed materials were examined using X-ray diffraction analysis (XRD), field emission scanning electron microscopy (FE-SEM). Furthermore, the change in the optical properties was performed based on Fourier transform infrared spectroscopy (FT-IR) and UV-visible spectrophotometer. Typical, pure BiFeO3 and Bi12MnO20 phases were detected for the precursors precipitated at pH 10 based on ammonium hydroxide as a base then annealed at 500°C for 2h. Eventually, the optical band gap energy of BFO and BMO using Kubelka–Munk function based on Tauc’s plot was found to be 2.12 and 2.79 eV, respectively.

scholarly journals Synthesis and Photonics Applications of Afzelechin Conjugated Silver Nanoparticles

Coatings ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1295
Author(s):  
Shahid Ali ◽  
Muhammad Rahim ◽  
Perveen Fazil ◽  
Malik Shoaib Ahmad ◽  
Azeem Ullah ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Band Gap ◽  
Band Gap Energy ◽  
Visible Absorption ◽  
Force Microscopy ◽  
Atomic Force ◽  
Uv Visible ◽  
Size And Morphology ◽  
Average Size ◽  
20 Nm

The silver nanoparticles were synthesized, functionalized with afzelechin and characterized using UV-Visible spectroscopy. A difference of 20 nm was observed in surface plasmon resonance of bare and functionalized silver nanoparticles which indicates afzelechin conjugation with silver nanoparticles. The atomic force microscopy (AFM) technique was used for the determination of the size and morphology of synthesized silver nanoparticles. The afzelechin conjugated silver nanoparticles were spherical and their sizes ranged from 3 to 10 nm with an average size of 8 nm while the bare silver nanoparticles were also spherical and their sizes ranged from 3 to 10 nm with an average size of 6 nm. The average sizes were also calculated by fitting their UV-Visible absorption spectra. Fitting is based on the Mie and Mie Gans models, which deduced that afzelechin conjugated silver nanoparticles were 96.5% spherical and 3.5% spheroidal with an average size of 5 nm while bare silver nanoparticles were 100% spherical with an average size of 4 nm. Both the fitting model as well as the AFM results showed a difference of 3 nm between the sizes of afzelechin conjugated silver nanoparticles while 2 nm differences was observed for bare silver nanoparticles. The band gap energy of afzelechin conjugated silver nanoparticles and bare silver nanoparticles were calculated via Tauc’s equation and were found to be 5.1 eV and 5.4 eV, respectively. A difference of 0.3 eV was observed in band gap energies of afzelechin conjugated silver nanoparticles and bare silver nanoparticles.

Effect of 2,4-dinitrophenol dye doping on tristhioureazinc(II) sulfate single crystals: a potential nonlinear optical material

2020 ◽  
Vol 53 (4) ◽  
pp. 972-981 ◽  
Author(s):  
G. Durgababu ◽  
G. J. Nagaraju ◽  
G. Bhagavannarayana
Keyword(s):  
Crystal Structure ◽  
Band Gap ◽  
Single Crystals ◽  
Nonlinear Optical ◽  
Optical Band Gap ◽  
Band Gap Energy ◽  
Optical Range ◽  
Gap Energy ◽  
Uv Visible ◽  
Crystalline Matrix

Good quality single crystals of 2,4-dinitrophenol (DNP)-doped tristhioureazinc(II) sulfate (ZTS) were successfully grown by employing the simple and cost effective slow-evaporation solution technique. To study the effect of doping on various device properties, the grown single crystals were subjected to powder X-ray diffraction (PXRD), high-resolution XRD, thermogravimetric analysis (TGA), Vickers hardness testing, and UV–visible, photoluminescence (PL) and Fourier transform IR (FTIR) spectroscopy techniques. The crystal structure of DNP-doped ZTS bulk single crystals remained the same as the crystal structure of ZTS. However, the changes in intensities of the diffraction peaks in the PXRD spectra indicated the incorporation of dopants into the crystalline matrix. FTIR studies confirm the incorporation of dopants into the crystalline matrix, shown by the shifting of certain prominent absorption bands towards higher energy. This also indicated the induced useful strain due to doping, leading to charge transfer and the enhancement of nonlinear optical properties. The cut-off wavelength and optical band gap energy of pure ZTS and DNP-doped ZTS crystals were studied by UV–visible absorption spectroscopy, revealing a slight reduction in the optical band gap energy due to doping, which in turn revealed the enhancement of the optical range. PL studies revealed an enhanced optical range of photoluminescence in ZTS crystals. Second harmonic generation (SGH) studies carried out by the Kurtz powder technique revealed the enhancement of SHG value due to DNP doping. To ensure the thermal stability and mechanical strength of the grown crystals with doping (required from the point of view of device applications), TGA and Vicker's hardness studies were performed.

Physico-Chemical Properties of CuO Thin Films Deposited by Spray Pyrolysis

2017 ◽  
Vol 895 ◽  
pp. 33-36 ◽  
Author(s):  
Bouzid Boudjema ◽  
Radouane Daira ◽  
Abdenour Kabir ◽  
Rafika Djebien
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Electrical Resistivity ◽  
Band Gap ◽  
Spray Pyrolysis ◽  
Copper Chloride ◽  
Band Gap Energy ◽  
Spray Pyrolysis Method ◽  
Gap Energy ◽  
Uv Visible

Our work consists to the deposition of copper oxide (CuO) thin films onto glass substrates by the spray pyrolysis method. The precursor solution was copper chloride of 0.1 M and the deposition rate was 5 ml/h. The time of spray varied between 5 and 20 min and the substrate temperature was kept at 350°C. The structural, optical and electrical properties of CuO films were investigated, as a function of the spray time, by X-ray diffraction (XRD), Raman scattering, UV-visible spectroscopy in addition to the measurements of the thickness and the electrical resistivity. The obtained results indicated that our films were polycrystalline with a preferential orientation along the (111) planes. The peaks intensity as well as the grain size increased as a function of the spray time indicating the improvement of the films crystalline structure. The Raman spectroscopy confirmed the formation of the CuO phase. The UV-visible transmission varied between 36% and 53% and the band gap energy decreased from 2 to 1.72 eV as a function of the spray time. The electrical resistivity of the films decreased from 514 to 72 kΩcm and correlated with the decrease of the band gap energy and the increase of the grain size.

scholarly journals Poly Methyl Methacrylate (Pmma) Based Polyaniline Composite for Ammonia (Nh3) Gas Sensors

2021 ◽  
pp. 172-190
Author(s):  
Muktikanta Panigrahi ◽  
◽  
Basudam Adhikari ◽  
Keyword(s):  
Band Gap ◽  
Band Gap Energy ◽  
Dc Conductivity ◽  
Polymerization Process ◽  
Visible Absorption ◽  
Inorganic Acids ◽  
Pani Composite ◽  
Direct Band ◽  
Uv Visible

Inorganic acids (HCl, H2SO4, and H3PO4) doped-PMMA/PANI composites are prepared by in-situ technique via oxidation-polymerization process. Different techniques such as XRD, FTIR, UV-Visible, four-probe method are used to characterize the composite. Presence of different chemical group of the doped composites is analysed by ATR-FTIR spectroscopic analysis. Charge carrier behaviour of the doped composite is analyzed by UV-Visible spectroscopy. Band gap (Eg) of the doped composites is determined from UV-Visible absorption analysis using Tauc expression. The estimated direct band gap energy (Eg) is found to be 1.93 eV (for HCl doped PMMA/PANI composite), 1.19 eV (for H2SO4 doped PMMA/PANI composite), and 1.71 eV (for H3PO4 doped PMMA/PANI composite), respectively. DC-conductivity is measured with and without magnetic field. Temperature dependent DC conductivity is also measured. In addition, we were discussed the response of ammonia (NH3) gas with polyaniline-based sensor materials.

scholarly journals Carboxymethyl Cellulose Photocracking by Magnetic Recoverable Photocatalyst to Produce Biofuel in Ambient Condition

2017 ◽  
Vol 5 (2) ◽  
pp. 90
Author(s):  
Yudha Ramanda ◽  
Kevin Thomas ◽  
Saifuddin Aziz ◽  
Kurniawan Mauludi ◽  
Eko Sri Kunarti
Keyword(s):  
Carboxymethyl Cellulose ◽  
Anatase Phase ◽  
Sol Gel ◽  
Band Gap Energy ◽  
Gas Chromatography Mass Spectrometry ◽  
X Ray Diffraction ◽  
Specular Reflectance ◽  
Transmission Electron ◽  
Ft Ir ◽  
Uv Visible

Synthesis of Fe3O4/SiO2/TiO2 nanocomposite and its application as photocatalyst in Carboxymethyl Cellulose (CMC) photocracking had been conducted. Magnetite preparation was carried out by sono-coprecipitation method. The deposition of SiO2 and TiO2 were performed by sol-gel method under ultrasonic irradiation. All material products were characterized by X-ray diffraction (XRD), Fourier transform infra-red spectrophotometry (FT-IR), and transmission electron microscopy (TEM). The final material product was also analysed by specular reflectance UV-Visible (SR-UV-Vis). The product of photocracking was analysed by gas chromatography – mass spectrometry (GC-MS).The XRD diffractogram and FT-IR spectra confirmed the presence of Fe3O4, SiO2, and anatase phase of TiO2. The TEM image revealed the presence of nanocomposite with core-shell structure. The SR-UV-Vis spectrum was used to determine band gap energy of the photocatalyst and it gave a result of 3.22 eV. The GC chromatogram of photocracking product indicated some major fractions. The MS spectra showed that some major fractions were smaller molecules including methanol, the component of biofuel.

scholarly journals Altered Properties of TiO2 for Photocatalytic Oxidative Desulphurisation

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Che Ku Nor Liana Che Ku Hitam ◽  
Aishah Abdul Jalil
Keyword(s):  
Band Gap ◽  
High Surface ◽  
High Surface Area ◽  
Band Gap Energy ◽  
Energy Usage ◽  
Reaction Conditions ◽  
Electrolysis Method ◽  
Visible Irradiation ◽  
Carrier Separation ◽  
Adsorption Desorption

Photocatalytic oxidative desulphurisation has become a promising technique as a result of its high capability, mild reaction conditions, economical, and low energy usage. In the present study, copper oxide doped on titanium dioxide (CuO/TiO2) was prepared by facile electrolysis method. The presence of mesoporous materials with high surface area was confirmed by nitrogen (N2) adsorption-desorption analysis where the band gap energies were determined by ultraviolet-visible diffuse reflectance spectra (UV-Vis DRS). The photoactivity testing on desulphurisation of 100 mg L-1 dibenzothiophene (DBT) revealed the highest extraction (7.5 x 10-3 mM min-1) and photooxidation rates (1.8 x 10-3 mM min-1), which were acquired by 0.8 g L-1 Cu0.1T0.9 after 2 h under visible irradiation. This is attributed by the well dispersion of CuO on TiO2, suitable band gap energy, and better charge carrier separation by the synergistic interaction of both materials.

scholarly journals Enhanced photocatalytic degradation of N-doped TiO2-SiO2 composite for degradation of phenol under simulated natural light assisted by S2O8 2- anions

2021 ◽  
Vol 947 (1) ◽  
pp. 012020
Author(s):  
Huu-Tai Huynh ◽  
Minh-Vien Le ◽  
Luan Van Hoang
Keyword(s):  
Photocatalytic Degradation ◽  
Band Gap ◽  
Rate Constant ◽  
Degradation Rate ◽  
Band Gap Energy ◽  
Natural Light ◽  
Doped Tio2 ◽  
Gap Energy ◽  
Molar Ratios ◽  
Degradation Rate Constant

Abstract In recent years, TiO2 photocatalyst has been studied to increase the overall efficiency in the degradation of organic pollutants in water. Several solutions have been proposed such as non-metal doping to reduce a high band gap energy (3.2 eV) of TiO2 to increase absorption in the visible region and synthesis of composite photocatalyst to improve the efficiency of electron-hole separation and the specific surface area. Herein, the N-doped TiO2-SiO2 photocatalysts were investigated. Powder samples with three molar ratios of TiO2/SiO2 (95/5-TS5, 85/15-TS15, 75/25-TS25) were successfully synthesized, characterized, and estimated their photocatalytic activity toward the phenol degradation (initial concentration to be 10 ppm) under simulated natural light. N-doped TiO2-SiO2 samples were prepared with molar ratios of N to designed TiO2 to be 3%, 5%, 7%. The 3N-TS5 photocatalyst (3 mol % N doped TS5) shows the highest phenol efficiency degradation, to be 95% in 4 h, photocatalytic degradation rate constant of 1.02}10−2 min−1 due to its narrower band gap energy (3.05 eV). Furthermore, the addition of S2O8 2- anions at a concentration of 1 mM is enhanced degradation efficiency and degradation rate. And phenol is almost completely degraded within 60 min and achieved a degradation rate constant of 7.65*10−2 min−1, 7.5 times higher than that without the presence of S2O8 2- anions. This attractive result is attributed to the generation of sulfate radical (SO4 *“) during photolysis. Finally, N-doped TiO2-SiO2 photocatalyst assisted by S2O8 2- anions shows potential to design and improve manufacturing processes to obtain photoreactors for organic degradation from waste-water under natural light degradation.

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