scholarly journals Facile Controlling of the Physical Properties of Zinc Oxide and Its Application to Enhanced Photocatalysis

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Tuan Vu Anh ◽  
Thi Anh Tuyet Pham ◽  
Van Hung Mac ◽  
Thanh Hung Nguyen
Keyword(s):  
Physical Properties ◽  
Synthesis Method ◽  
Catalytic Performance ◽  
High Photocatalytic Activity ◽  
Spherical Particles ◽  
Bandgap Energy ◽  
Order Kinetic ◽  
The Hierarchical Structure ◽  
Order Kinetic Model ◽  
Carnation Flower

In this study, the physical properties of ZnO were facile controlled by the synthesis method with the addition of capping and precipitation agents. As-prepared ZnO samples had different morphologies such as carnation flower-like ZnO (CF-ZnO), rose-flower-like ZnO (RF-ZnO), rod-like ZnO (R-ZnO), and nanoparticle ZnO (N-ZnO) and were characterized by SEM, XRD, N2 adsorption/desorption isotherms, FT-IR, and DR/UV-vis. All samples had a crystallite structure of hexagonal wurtzite type. The CF-ZnO and RF-ZnO samples had the hierarchical structure like a carnation flower and a beautiful rose, respectively. R-ZnO was composed of many hexagonal rods and few spherical particles, while N-ZnO microstructures were made up of nanoparticles with approximately 20–30 nm, exhibiting the largest surface area, pore volume, and pore width among as-prepared samples, and their crystal size and bandgap energy were 17.8 nm and 3.207 eV, respectively. The catalytic performances of ZnO samples were evaluated by degradation of Tartrazine (TA) and Caffeine (CAF) under low UV irradiation (15 W). N-ZnO showed a high photocatalytic activity compared to other samples. Besides, the reaction kinetics was investigated by the first-order kinetic model, and the catalytic performance of ZnO was evaluated through several organic pollutants.

scholarly journals Photocatalytic Phenol Degradation by Silica-Modified Titanium Dioxide

2021 ◽  
Vol 11 (19) ◽  
pp. 9033
Author(s):  
Diana Rakhmawaty Eddy ◽  
Soraya Nur Ishmah ◽  
Muhamad Diki Permana ◽  
M. Lutfi Firdaus ◽  
Iman Rahayu ◽  
...  
Keyword(s):  
Titanium Dioxide ◽  
Anatase Phase ◽  
Phenol Degradation ◽  
High Photocatalytic Activity ◽  
Beach Sand ◽  
Order Kinetic ◽  
Particle Size Analyzer ◽  
Bet Analysis ◽  
Order Kinetic Model ◽  
Supporting Material

Titanium dioxide (TiO2) has been widely applied as a photocatalyst for wastewater treatment due to its high photocatalytic activity and it can remove various harmful organic pollutants effectively. Under heated system, however, TiO2 is prone to agglomeration that decrease its abilities as a photocatalyst. In order to overcome the agglomeration and increase its thermal resistance, addition of silica (SiO2) as supporting material is proposed in this research. Silica or silicon dioxide can be extracted from natural resources such as beach sand. Here, we report the application of a composite photocatalyst of TiO2/SiO2 to remove phenolic compounds in wastewater. The photocatalyst was synthesized by adding SiO2 from beach sand onto TiO2 through impregnation methods. The results of the X-ray diffraction (XRD) showed that TiO2 was present in the anatase phase. The highest crystallinity was obtained by TiO2/SiO2 ratios of 7:1. SEM results showed that the shape of the particles was spherical. Further characterizations were conducted using Fourier-transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) analysis, and a particle size analyzer (PSA). By using the optimized condition, 96.05% phenol was degraded by the synthesized photocatalyst of TiO2/SiO2, under UV irradiation for 120 min. The efficiency of the TiO2/SiO2 is 3.5 times better than commercial TiO2 P25 for the Langmuir–Hinshelwood first-order kinetic model.

scholarly journals Synthesis of Fe3O4@mZrO2-Re (Re = Y/La/Ce) by Using Uniform Design, Surface Response Methodology, and Orthogonal Design & Its Application for As3+ and As5+ Removal

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2177
Author(s):  
Easar Alam ◽  
Qiyan Feng ◽  
Hong Yang ◽  
Jiaxi Fan ◽  
Sameena Mumtaz ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Rare Earth ◽  
Orthogonal Design ◽  
Uniform Design ◽  
Synthesis Method ◽  
Model Material ◽  
Langmuir Model ◽  
Molar Ratio ◽  
Order Kinetic ◽  
Order Kinetic Model

In this study, iron oxide (Fe3O4) was coated with ZrO2, and doped with three rare earth elements((Y/La/Ce), and a multi-staged rare earth doped zirconia adsorbent was prepared by using uniform design U14, Response Surface methodology, and orthogonal design, to remove As3+ and As5+ from the aqueous solution. Based on the results of TEM, EDS, XRD, FTIR, and N2-adsorption desorption test, the best molar ratio of Fe3O4:TMAOH:Zirconium butoxide:Y:La:Ce was selected as 1:12:11:1:0.02:0.08. The specific surface area and porosity was 263 m2/g, and 0.156 cm3/g, respectively. The isothermal curves and fitting equation parameters show that Langmuir model, and Redlich Peterson model fitted well. As per calculations of the Langmuir model, the highest adsorption capacities for As3+ and As5+ ions were recorded as 68.33 mg/g, 84.23 mg/g, respectively. The fitting curves and equations of the kinetic models favors the quasi second order kinetic model. Material regeneration was very effective, and even in the last cycle the regeneration capacities of both As3+ and As5+ were 75.15%, and 77.59%, respectively. Adsorption and regeneration results suggest that adsorbent has easy synthesis method, and reusable, so it can be used as a potential adsorbent for the removal of arsenic from aqueous solution.

scholarly journals Ultrasonic Assisted Hydrothermal Synthesis of NiO Nanocatalyst for Low Temperature 3,4-dihydropyrimidin-2-(1H)-Ones and Thiones Condensation Under Solvent-Free Conditions

2020 ◽  
Author(s):  
Leila Kafi-Ahmadi ◽  
shahin khademinia ◽  
Maryam Khashaei
Keyword(s):  
Kinetic Model ◽  
Analysis Data ◽  
Rietveld Analysis ◽  
Spherical Particles ◽  
Order Kinetic ◽  
Solvent Free Conditions ◽  
Ultrasonic Assisted ◽  
Order Kinetic Model ◽  
One Step ◽  
Biginelli Reactions

Abstract Present work reports one step hydrothermal method as a green processto synthesizenickel (II) oxide (NiO) nanoparticles using nickel nitrate, and some natural essences as surfactant including Orange blossom, Yarrow, Hibiscus tea, Green tea, Rosemary and Barberryas at 80 ºC in autoclave for 24 h followed by calcination at 700 ºC for 8 h. Rietveld analysis data revealed that the obtained NiO nanomaterials were crystallized in a pure cubic crystalsystem. Field emission scanning electron microscope (FESEM) images showed that the morphology of the obtained materials was changed from non-homogeneous particles to homogeneous spherical particles when the surfactant type was changed from Orange blossom to Barberryas. Catalytic activity of the nanomaterials was investigated in Biginelli reactions for the synthesis of heterocyclic 3,4-dihydropyrimidin-2(1H)-ones (DHPMs) compounds. The synthesis yields at optimum conditions (60 mg of catalyst, 90 ºC reaction temperature and 90 min reaction time) were 94% and 97% for S1 and S6, respectively. Langmuir–Hinshelwood kinetic model revealed that the reactions followed a pseudo-first order kinetic model.

scholarly journals The Preparation of Pd/Foam-Ni Electrode and Its Electrocatalytic Hydrodechlorination for Monochlorophenol Isomers

Catalysts ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 378 ◽  
Author(s):  
Junjing Li ◽  
Huan Wang ◽  
Liang Wang ◽  
Chang Ma ◽  
Cong Luan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Catalytic Performance ◽  
Order Kinetic ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Order Kinetic Model ◽  
Good Catalytic Activity ◽  
Promising Application

Noble metal palladium modified foamed nickel electrode (Pd/foam-Ni) was prepared by electrodeposition method. The fabricated electrode showed better catalytic performance than the Pd/foam-Ni prepared by conventional electroless deposition. The catalysts were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Electrocatalytic activity of the Pd/Ni was studied for the hydrodechlorination of monochlorophenol isomers. The Pd/Ni exhibited good catalytic activity for 3-chlorophenol (3-CP). Complete decomposition of chlorophenol isomers could be achieved within 2 h, and the hydrodechlorination process conformed to the pseudo-first-order kinetic model. It showed a supreme stability after recycling for 5 times. The Pd/Ni exhibited a promising application prospect with high effectiveness and low Pd loading.

scholarly journals Composite of Hydroxyapatite-Fe3O4 for the Adsorption of Methylene Blue

2020 ◽  
Vol 20 (2) ◽  
pp. 140
Author(s):  
Nur Hafizah Zainal Abidin ◽  
Nonni Soraya Sambudi ◽  
Norashikin Ahmad Kamal
Keyword(s):  
Heavy Metal ◽  
Methylene Blue ◽  
Magnetic Properties ◽  
Kinetic Model ◽  
Spherical Particles ◽  
Order Kinetic ◽  
Freundlich Isotherms ◽  
Methylene Blue Removal ◽  
Order Kinetic Model ◽  
Pseudo Second Order

The utilization of hydroxyapatite as an adsorbent has been extensively tested to remove the dye and heavy metal. Yet the adsorbent loss to the environment may lead to secondary pollutant issues. Consequently, the hydroxyapatite was incorporated with Fe3O4 amount variation to solve the secondary pollutant problem by utilizing the magnetic properties of Fe3O4 to recollect the adsorbent. In this work, FESEM images showed a mixture of nano-sizes rods and spherical particles corresponded to the presence of hydroxyapatite and Fe3O4 as a composite. The study found that hydroxyapatite- Fe3O4 (100 wt %) could eliminate 12.434 mg methylene blue/g adsorbent after 4 hours. The hydroxyapatite also gained improvement in its surface area from 59.8m2/g to 75.2m2/g when Fe3O4 is added. In addition, the adsorption of methylene blue fits the Freundlich isotherms and pseudo-second-order kinetic model. Furthermore, the methylene blue removal using hydroxyapatite-Fe3O4 composite can be kept at 80% even after 4 times experiments, showing the recyclability of hydroxyapatite-Fe3O4.

scholarly journals Preparation of Hierarchical Structure Au/ZnO Composite for Enhanced Photocatalytic Performance: Characterization, Effects of Reaction Parameters, and Oxidizing Agent Investigations

2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Anh-Tuan Vu ◽  
Thi Anh Tuyet Pham ◽  
Xuan Truong Do ◽  
Van Anh Tran ◽  
Van Duong Le ◽  
...  
Keyword(s):  
Hierarchical Structure ◽  
Photocatalytic Performance ◽  
Uv Light ◽  
Chemical Reduction ◽  
Bandgap Energy ◽  
Order Kinetic ◽  
Reaction Parameters ◽  
Paramagnetic Resonance ◽  
X Ray ◽  
Order Kinetic Model

Zinc oxide (ZnO) has been shown as a potential photocatalyst under ultraviolet (UV) light but its catalytic activity has a limitation under visible (Vis) light due to the wide bandgap energy and the rapid recombination of electrons and holes. Thus, hierarchical structure Au/ZnO composites were fabricated by the hydrothermal method and chemical reduction method for enhanced photocatalytic performance under visible light. As-prepared composites were characterized by UV-vis diffuse reflectance spectra (DR/UV-Vis), field emission scanning electron microscope (FESEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and electron paramagnetic resonance (EPR). The Au/ZnO-5 composite showed the highest adsorption among as-prepared samples in the range of 250-550 nm, having bandgap energy of 0.13 eV. Au nanoparticles of about 3-5 nm were well dispersed on hierarchical flower ZnO with approximately 10-15 μm. The EPR signal at g = 1.965 on both ZnO and Au/ZnO samples was attributed to oxygen vacancy Vo•, but the presence of Au led to a decrease in signal strength of Au/ZnO composite, showing the degradation efficiency (DE) and reaction rate of 99.2% and 0.109 min-1, respectively; these were larger than those of other samples. The effects of reaction parameters and oxidizing agents on photocatalytic performance were investigated and showed that the presence of H2O2 and O2 could improve the reaction of composite. In addition, the kinetic and photocatalytic mechanism of tartrazine (TA) on catalysts were studied by the first-order kinetic model and characterized analyses.

Chitosan-based Magnetic Composites - Efficient Adsorbents for Removal of Pb(II) and Cu(II) from Aqueous Mono and Bicomponent Solutions

2018 ◽  
Vol 69 (9) ◽  
pp. 2323-2330 ◽  
Author(s):  
Daniela C. Culita ◽  
Claudia Maria Simonescu ◽  
Rodica Elena Patescu ◽  
Nicolae Stanica
Keyword(s):  
Aqueous Solutions ◽  
Metal Ions ◽  
Chemical Properties ◽  
Order Kinetic ◽  
Mass Ratio ◽  
Magnetic Adsorbent ◽  
Magnetic Composites ◽  
Initial Ph ◽  
Order Kinetic Model ◽  
Physical And Chemical

A series of three chitosan-based magnetic composites was prepared through a simple coprecipitation method. It was investigated the influence of mass ratio between chitosan and magnetite on the physical and chemical properties of the composites in order to establish the optimum conditions for obtaining a composite with good adsorption capacity for Pb(II) and Cu(II) from mono and bicomponent aqueous solutions. It was found that the microspheres prepared using mass ratio chitosan / magnetite 1.25/1, having a saturation magnetization of 15 emu g--1, are the best to be used as adsorbent for the metal ions. The influence of different parameters such as initial pH values, contact time, initial concentration of metal ions, on the adsorption of Pb(II) and Cu(II) onto the chitosan-based magnetic adsorbent was investigated in details. The adsorption process fits the pseudo-second-order kinetic model in both mono and bicomponent systems, and the maximum adsorption capacities calculated on the basis of the Langmuir model were 79.4 mg g--1 for Pb(II) and 48.5 mg g--1 for Cu(II) in monocomponent systems, while in bicomponent systems were 88.3 and 49.5 mg g--1, respectively. The results revealed that the as prepared chitosan-based magnetic adsorbent can be an effective and promising adsorbent for Pb(II) and Cu(II) from mono and bicomponent aqueous solutions.

Comparison of the fixation of several metal ions onto a low-cost biopolymer

2002 ◽  
Vol 2 (5-6) ◽  
pp. 217-224 ◽  
Author(s):  
Z. Reddad ◽  
C. Gérente ◽  
Y. Andrès ◽  
P. Le Cloirec
Keyword(s):  
Aqueous Solutions ◽  
Metal Ions ◽  
Low Cost ◽  
Operating Conditions ◽  
Order Kinetic ◽  
Adsorption Mechanisms ◽  
Equilibrium Data ◽  
Order Kinetic Model ◽  
Beet Pulp ◽  
Removal Of Metal Ions

In the present work, sugar beet pulp, a common waste from the sugar refining industry, was studied in the removal of metal ions from aqueous solutions. The ability of this cheap biopolymer to sorb several metals namely Pb2+, Cu2+, Zn2+, Cd2+ and Ni2+ in aqueous solutions was investigated. The metal fixation capacities of the sorbent were determined according to operating conditions and the fixation mechanisms were identified. The biopolymer has shown high elimination rates and interesting metal fixation capacities. A pseudo-second-order kinetic model was tested to investigate the adsorption mechanisms. The kinetic parameters of the model were calculated and discussed. For 8 × 10-4 M initial metal concentration, the initial sorption rates (v0) ranged from 0.063 mmol.g-1.min-1 for Pb2+ to 0.275 mmol.g-1.min-1 for Ni2+ ions, with the order: Ni2+ > Cd2+ > Zn2+ > Cu2+ > Pb2+. The equilibrium data fitted well with the Langmuir model and showed the following affinity order of the material: Pb2+ > Cu2+ > Zn2+ > Cd2+ > Ni2+. Then, the kinetic and equilibrium parameters calculated qm and v0 were tentatively correlated to the properties of the metals. Finally, equilibrium experiments in multimetallic systems were performed to study the competition of the fixation of Pb2+, Zn2+ and Ni2+ cations. In all cases, the metal fixation onto the biopolymer was found to be favourable in multicomponent systems. Based on these results, it is demonstrated that this biosorbent represents a low-cost solution for the treatment of metal-polluted wastewaters.

Synthesis of Functionalized Magnetite Titanium Dioxide Nanocomposite for Removal of Acid Fuchsine Dye

2018 ◽  
Vol 21 (8) ◽  
pp. 583-593 ◽  
Author(s):  
Sara Rahnama ◽  
Shahab Shariati ◽  
Faten Divsar
Keyword(s):  
Titanium Dioxide ◽  
Removal Efficiency ◽  
Magnetic Core ◽  
Fractional Factorial ◽  
Order Kinetic ◽  
Sorption Data ◽  
Salt Addition ◽  
Order Kinetic Model ◽  
Pseudo Second Order ◽  
Ft Ir

Objective: In this research, a novel magnetite titanium dioxide nanocomposite functionalized by amine groups (Fe3O4@SiO2@TiO2-NH2) was synthesized and its ability for efficient removal of Acid Fuchsine as an anionic dye from aqueous solutions was investigated. Method: The core-shell structure of Fe3O4@SiO2@TiO2 was prepared using Fe3O4 as magnetic core, tetra ethyl orthosilicate as silica and tetra butyl titanate as titanium source for shell. The synthesized nanocomposites (particle size lower than 44 nm) were characterized by FT-IR, XRD, DRS, SEM and TGA instruments. The various experimental parameters affecting dye removal efficiency were investigated and optimized using Taguchi fractional factorial design. Results: The synthesized adsorbent showed the highest removal efficiency of Acid Fuchsine (99 %) at pH= 3.5, without salt addition and during stirring at contact times less than 10 minutes. The study of kinetic models at two concentration levels showed the fast dye sorption on the surface of proposed nanocomposites with pseudo second order kinetic model (R2=1). Also, the fitting of Acid Fuchsine sorption data to Freundlich, Langmuir and Temkin isotherms suggested that Freundlich model gave a better fitting than other models (R2=0.9936, n=2). Conclusion: Good chemical stability, excellent magnetic properties, very fast adsorption kinetics and high removal efficiency make the synthesized nanocomposite as a proper recoverable sorbent for removal of Acid Fuchsine dye from wastewaters.

Positive Role of Synthesis Method and Hard Template on the Catalytic Performance of SAPO-34 in Methanol to Olefin Reaction.

2020 ◽  
Vol 23 ◽  
Author(s):  
Sajjad Rimaz ◽  
Reza Katal
Keyword(s):  
Particle Size ◽  
Synthesis Method ◽  
Catalytic Performance ◽  
Hard Template ◽  
Structure Directing Agent ◽  
Positive Role ◽  
Methanol To Olefin ◽  
Dg Method ◽  
Synthesis Procedure

: In the present study, SAPO-34 particles were synthesized using hydrothermal (HT) and dry gel (DG) conversion methods in the presence of diethyl amine (DEA) as an organic structure directing agent (SDA). Carbon nanotubes (CNT) were used as hard template in the synthesis procedure to introduce transport pores into the structures of the synthesized samples. The synthesized samples were characterized with different methods to reveal effects of synthesis method and using hard template on their structure and catalytic performance in methanol to olefin reaction (MTO). DG conversion method results in smaller particle size in comparison with hydrothermal method, resulting in enhancing catalytic performance. On the other side, using CNT in the synthesis procedure with DG method results in more reduction in particle size and formation of hierarchical structure which drastically improves catalytic performance.

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