Effect of calcination temperature on the catalytic activity of nanosized TiO2 for ozonation of trace 4-chloronitrobenzene

2012 ◽  
Vol 66 (3) ◽  
pp. 479-486 ◽  
Author(s):  
Miaomiao Ye ◽  
Zhonglin Chen ◽  
Tuqiao Zhang ◽  
Weiyun Shao
Keyword(s):  
Catalytic Activity ◽  
Ph Value ◽  
Average Pore Size ◽  
Average Crystallite Size ◽  
Catalytic Ozonation ◽  
Solution Ph ◽  
Average Pore ◽  
Paramagnetic Resonance ◽  
Calcination Temperatures ◽  
Titanium Dioxides

Nanosized titanium dioxides were synthesized by hydrolysis of TiCl4 followed by calcination at different temperatures ranging from 300 to 1,000 °C. The as-prepared samples were characterized by X-ray diffraction, N2 adsorption–desorption, and zeta potential analysis. The catalytic activities of the TiO2 nanoparticles were tested by catalytic ozonation of trace 4-chloronitrobenzene (4-CNB) in water. Moreover, the catalytic ozonation activity of a sample calcined at 400 °C (denoted as T400) was tested in aqueous solution using electron paramagnetic resonance (EPR) spin trapping technique with 5,5-dimethyl-1-pyrroline N-oxide (DMPO) spin trap. It was found that with increasing calcination temperatures, the average crystallite size and average pore size increased, in contrast the BET surface areas decreased. However, the isoelectric point (IEP) first increased, and then decreased. The ozone adsorption on the catalyst surface played an important role in determining their catalytic activity. Sample T400 with the IEP of 7.0, farthest away from the 4-CNB solution pH value (pH = 5.3), showed the best catalytic activity. The EPR experiments further confirmed that the hydroxyl radicals TiO2-catalyzed ozonation followed a radical-type mechanism.

Adsorption of Nickel and Cobalt Ions on Magnesium Silicate

2013 ◽  
Vol 726-731 ◽  
pp. 2855-2858
Author(s):  
Hua Yang ◽  
Hai Zeng Wang
Keyword(s):  
Ph Value ◽  
Average Pore Size ◽  
Chemical Properties ◽  
Magnesium Silicate ◽  
Solution Ph ◽  
Average Pore ◽  
Cobalt Ions ◽  
Physico Chemical ◽  
Short Time ◽  
Adsorption Desorption

Magnesium silicate (MS) was successfully prepared and the physico-chemical properties were determined by N2adsorption/desorption isotherm and Scanning Electron Microscopy (SEM). Surface area and the average pore size were 120 cm3·g-1and 10 nm. Adsorption experiments of removal of nickel and cobalt ions were investigated as the function of initial concentration, adsorbent dose, adsorption time and solution pH value. The maximum removal was reached with pH equal to 5 for the removal of nickel and cobalt ions. Adsorption process was rapid and adsorption equilibriums were attained in a short time.

Synthesis, characterization, and photocatalytic activity of silver and zinc co-doped TiO2 nanoparticle for photodegradation of methyl orange dye in aqueous solution

2019 ◽  
Vol 97 (9) ◽  
pp. 642-650 ◽  
Author(s):  
Gabriel O. Oladipo ◽  
Akinola K. Akinlabi ◽  
Samson O. Alayande ◽  
Titus A.M. Msagati ◽  
Hlengilizwe H. Nyoni ◽  
...  
Keyword(s):  
Methyl Orange ◽  
Pore Size ◽  
Average Pore Size ◽  
Sol Gel ◽  
Average Crystallite Size ◽  
Rutile Phase ◽  
Absorption Bands ◽  
Average Pore ◽  
Methyl Orange Dye ◽  
Co Doped

In this study, TiO2 nanocrystals, 1 mol% Ag-doped TiO2, and 1 mol% Ag and 0.6 mol% Zn co-doped TiO2 powders were synthesized by the sol–gel route. Their photocatalytic activities on methyl orange dye under visible irradiation were investigated. The powders were characterized by X-ray diffraction (XRD), UV–visible spectroscopy (UV–vis), Brunauer–Emmett–Teller (BET), and Fourier transform infrared spectroscopy (FTIR). The XRD results revealed the presence of a rutile phase with an average crystallite size of 9 and 11 nm. The UV–vis spectra showed a red-shift towards a longer wavelength with the corresponding decrease in band gap from 2.9 to 2.5 eV. The BET surface areas of the nanoparticles ranged from 4.7 to 11.8 m2 g−1 with an average pore size between 18.9 and 56.6 nm. The Ag-doped TiO2 has the largest surface area of 11.8 m2 g−1, whereas the Ag–Zn co-doped TiO2 was found to have the highest pore size and volume. The absorption bands at 750–500 cm−1 were attributed to the –O–Ti–O– bond in the TiO2 lattice. The photocatalytic efficiency was highest at an optimum pH of 4.1 for Ag–Zn co-doped TiO2. The results confirmed that Ag-doped and Ag–Zn co-doped TiO2 were more effective than pure TiO2. The kinetic data were fitted into a pseudo first-order equation using a Langmuir–Hinshelwood kinetic model.

scholarly journals Preparation and Characterization of Nanoporous Activated Carbon Derived from Prawn Shell and Its Application for Removal of Heavy Metal Ions

Materials ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 241 ◽  
Author(s):  
Jian Guo ◽  
Yaqin Song ◽  
Xiaoyang Ji ◽  
Lili Ji ◽  
Lu Cai ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Activated Carbon ◽  
Metal Ions ◽  
Heavy Metal Ions ◽  
Ph Value ◽  
Average Pore Size ◽  
High Specific Surface Area ◽  
Koh Activation ◽  
Average Pore ◽  
Effects Of Ph

The aim of this study was to optimize the adsorption performance of activated carbon (AC), derived from the shell of Penaeus vannamei prawns, on heavy metal ions. Inexpensive, non-toxic, and renewable prawn shells were subjected to carbonization and, subsequently, KOH-activation to produce nanoporous K-Ac. Carbonized prawn shells (CPS) and nanoporous KOH-activated carbon (K-Ac) from prawn shells were prepared and characterized by FTIR, XRD, BET, SEM, and TEM. The results showed that as-produced K-Ac samples were a porous material with microporous and mesoporous structures and had a high specific surface area of 3160 m2/g, average pore size of about 10 nm, and large pore volume of 2.38 m3/g. Furthermore, batches of K-Ac samples were employed for testing the adsorption behavior of Cd2+ in solution. The effects of pH value, initial concentration, and adsorption time on Cd2+ were systematically investigated. Kinetics and isotherm model analysis of the adsorption of Cd2+ on K-Ac showed that experimental data were not only consistent with the Langmuir adsorption isotherm, but also well-described by the quasi-first-order model. Finally, the adsorption behaviors of as-prepared K-Ac were also tested in a ternary mixture of heavy metal ions Cu2+, Cr6+, and Cd2+, and the total adsorption amount of 560 mg/g was obtained.

Polymer Embedded Nanocrystalline Titania Sorbent for 99Mo-99mTc Generator

2008 ◽  
Vol 8 (9) ◽  
pp. 4447-4452 ◽  
Author(s):  
Rubel Chakravarty ◽  
Rakesh Shukla ◽  
Shyamla Gandhi ◽  
Ramu Ram ◽  
Ashutosh Dash ◽  
...  
Keyword(s):  
Saline Solution ◽  
Average Pore Size ◽  
Average Crystallite Size ◽  
Activity Level ◽  
X Ray Diffraction ◽  
Average Pore ◽  
X Ray ◽  
Nano Crystalline ◽  
99Mtc Generator

A new sorbent material, polymer embedded nano crystalline titania (Titanium Polymer-TiP) has been developed, from titanium (IV) chloride and isopropyl alcohol, for the adsorption of 99Mo, which is a precursor to 99mTc, a workhorse in radio-pharmaceuticals. The infrared absorption spectra of the TiP showed peaks corresponding to Ti-O groups. X-ray diffraction pattern of the adsorbent corresponded to rutile TiO2. The surface area of this polymer was 30 m2/g with an average pore size of 40 nm. The average crystallite size of TiO2, embedded in polymer, was found to be 5 nm. TEM micrograph of the adsorbent revealed the networkof polymer with dispersed titania phase. Potential of this adsorbent for the preparation of 99Mo-99mTc generator has been explored. 99Mo could be adsorbed on to the adsorbent column containing TiP at pH 1 from which 99mTc could be eluted with normal (0.9%) saline solution with an elution yield of ∼80%. The quality of the 99mTcO−4 obtained was in accordance with the international specifications applicable for radiopharmaceutical use. A process demonstration run was carried out with 1.1 GBq (30 mCi) 99Mo activity level making use of the above adsorbent and consistent results were obtained over a period of one week, which is generally the shelf life of 99Mo-99mTc generator.

scholarly journals Biodiesel Processing Using Sodium and Potassium Geopolymer Powders as Heterogeneous Catalysts

Molecules ◽  
2020 ◽  
Vol 25 (12) ◽  
pp. 2839 ◽  
Author(s):  
Renata F. Botti ◽  
Murilo D.M. Innocentini ◽  
Thais A. Faleiros ◽  
Murilo F. Mello ◽  
Danilo L. Flumignan ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Heterogeneous Catalysts ◽  
Average Pore Size ◽  
Thermal Shrinkage ◽  
Average Pore ◽  
Base Catalysts ◽  
Sodium And Potassium

This work investigates the catalytic activity of geopolymers produced using two different alkali components (sodium or potassium) and four treatment temperatures (110 to 700 °C) for the methyl transesterification of soybean oil. The geopolymers were prepared with metakaolin as an aluminosilicate source and alkaline activating solutions containing either sodium or potassium in the same molar oxide proportions. The potassium-based formulation displayed a higher specific surface area and lower average pore size (28.64–62.54 m²/g; 9 nm) than the sodium formulation (6.34–32.62 m²/g; 17 nm). The reduction in specific surface area (SSA) after the heat treatment was more severe for the sodium formulation due to the higher thermal shrinkage. The catalytic activity of the geopolymer powders was compared under the same reactional conditions (70–75 °C, 150% methanol excess, 4 h reaction) and same weight amounts (3% to oil). The differences in performance were attributed to the influences of sodium and potassium on the geopolymerization process and to the accessibility of the reactants to the catalytic sites. The Na-based geopolymers performed better, with FAME contents in the biodiesel phase of 85.1% and 89.9% for samples treated at 500 and 300 °C, respectively. These results are competitive in comparison with most heterogeneous base catalysts reported in the literature, considering the very mild conditions of temperature, excess methanol and catalyst amount and the short time spent in reactions.

Solvents Effects on Physicochemical Properties of Nano-Porous Silica Aerogels Prepared by Ambient Pressure Drying Method

2006 ◽  
Vol 510-511 ◽  
pp. 910-913 ◽  
Author(s):  
Seung Hun Lee ◽  
Eun A Lee ◽  
Hae Jin Hwang ◽  
Ji Woong Moon ◽  
In Sub Han ◽  
...  
Keyword(s):  
Ph Value ◽  
Ambient Pressure ◽  
Average Pore Size ◽  
Porous Silica ◽  
Sodium Silicate Solution ◽  
Silicate Solution ◽  
Silica Aerogels ◽  
Ambient Pressure Drying ◽  
Drying Method ◽  
Average Pore

Hydrophobic silica aerogels were synthesized by an ambient pressure drying method from silicic acid with a different pH value, which was prepared from sodium silicate solution (water glass). In this study we chose various hydrocarbon class solvents such as pentane, hexane, heptane, and toluene, and performed surface modification in TMCS (trimethylchlorosilane)/solvent solutions in order to improve reproducibility in aerogel production. Densities of the aerogels were about 0.1 ~ 0.3 g/cm3 , and apparent porosities were 88 ~ 96 %, depending on the processing conditions. Specific surface area was approximately 730 ~ 950 m2/g, and average pore size around 10 nm.

scholarly journals INFLUENCE OF SYNTHESIS TECHNO-CHEMICAL PARAMETERS ON PHYSICOCHEMICAL CHARACTERISTICS OF BIOMIMETIC CALCIUM-PHOSPHATE NANOCOMPOSITE DOPED BY SILICATE AND CARBONATE ANIONS

2020 ◽  
Vol 5 (10) ◽  
pp. 47-56
Author(s):  
M. Troubitsin ◽  
Viet Hung Hoang ◽  
L. Furda
Keyword(s):  
Calcium Phosphate ◽  
Specific Surface ◽  
Crystallite Size ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Average Pore Size ◽  
Average Crystallite Size ◽  
Average Pore ◽  
The Impact

The object of our investigation is a biomimetic calcium-phosphate nanocomposite doped by silicate and carbonate anions (BMHAP) synthesized by chemical deposition from aqueous solutions. The obtained samples are investigated using X-ray phase analysis (XRD), FTIR spectroscopy, and low-temperature nitrogen adsorption (BET method). The influence of the techno chemical synthesis parameters on the products characteristics (including phase composition, crystal lattice parameters, average crystallite size, specific surface area) is evaluated. The study on the effect of the synthesis temperature shows that with increasing in temperature from 22°C to 80°C, reveals a slight increase in the parameters of unit cells a and c, which leads to an increase in its volume. There is also a tendency towards a decrease in the average size of coherent scattering regions of crystallites (from 7,52 to 4,65 nm) and specific surface area (from 192,51 to 74,72 m2/g), but the pore volume and average pore diameter of the synthesized powders increases. The effect of the aging time of the sediment in the mother liquor is studied from 0,5 to 24 hours. It is found that with an increase in the maturation time of the sediment, the percent crystallinity of the powders improves by 1,7 times, an increase in the specific surface area from 163,43 to 192,51 m2/g and a slight decrease in the pore volume and average pore size of the samples are observed. The impact of the stirring rate of the reagents is investigated. An increase in speed from 300 to 1300 rpm has been shown to decrease the average crystallite size from 8,80 to 6,41 nm, and as a result, to increase the specific surface area of the synthesized samples from 178,58 to 192,51 m2/g, respectively.

scholarly journals LDH Nanocubes Synthesized with Zeolite Templates and Their High Performance as Adsorbents

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3315
Author(s):  
Moftah Essa Elkartehi ◽  
Rehab Mahmoud ◽  
Nabila Shehata ◽  
Ahmed Farghali ◽  
Shimaa Gamil ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Average Pore Size ◽  
Second Order ◽  
Polluted Water ◽  
Isotherm Models ◽  
Maximum Adsorption Capacity ◽  
Solution Ph ◽  
Average Pore ◽  
X Ray ◽  
Pseudo Second Order

In this work, the efficiency of the adsorptive removal of the organic cationic dye methylene blue (MB) from polluted water was examined using three materials: natural clay (zeolite), Zn-Fe layered double hydroxide (LDH), and zeolite/LDH composite. These materials were characterized via X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray (EDX) diffraction (XRF), low-temperature N2 adsorption, pore volume and average pore size distribution and field emission scanning electron microscopy (FE-SEM). The properties of the applied nanomaterials regarding the adsorption of MB were investigated by determining various experimental parameters, such as the contact time, initial dye concentration, and solution pH. In addition, the adsorption isotherm model was estimated using the Langmuir, Freundlich, and Langmuir–Freundlich isotherm models. The Langmuir model was the best-fitting for all applied nanomaterials. In addition, the kinetics were analyzed by using pseudo-first-order, pseudo-second-order, and intraparticle diffusion models, and the pseudo-second-order model was an apparent fit for all three applied nanomaterials. The maximum Adsorption capacity toward MB obtained from the materials was in the order zeolite/LDH composite > zeolites > Zn-Fe LDH. Thus, the zeolite/LDH composite is an excellent adsorbent for the removal of MB from polluted water.

The Microstructure and Adsorption Property of Improved Coal Gangue

2011 ◽  
Vol 382 ◽  
pp. 427-430
Author(s):  
E. Dong ◽  
Long Guan
Keyword(s):  
Specific Surface ◽  
Pore Size ◽  
Surface Area ◽  
Specific Surface Area ◽  
Ph Value ◽  
Adsorption Property ◽  
Average Pore Size ◽  
Absorption Capacity ◽  
Coal Gangue ◽  
Average Pore

Since coal gangue can destroy the environment, we aim at improving coal gangue to absorbing material by changing it in different temperature and chemical liquor. Base on the microstructure and the adsorption experiment, we detect microstructure and absorption property of improved coal gangue. The microstructure experiment shows that the average pore size and specific surface area of improved coal gangue appear distinguish obviously as the increasing of chemical liquor pH value and temperature. Absorption experiment shows that the absorption capacity of improved coal gangue decrease as the chemical liquor pH value increase, increase as the temperature increase. The adsorption capacity of improved coal gangue increases with an increase of average pore size and specific surface area.

scholarly journals Activated Carbon Microsphere from Sodium Lignosulfonate for Cr(VI) Adsorption Evaluation in Wastewater Treatment

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 236 ◽  
Author(s):  
Keyan Yang ◽  
Jingchen Xing ◽  
Pingping Xu ◽  
Jianmin Chang ◽  
Qingfa Zhang ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Ph Value ◽  
Average Pore Size ◽  
Raw Material ◽  
Maximum Adsorption Capacity ◽  
Sodium Lignosulfonate ◽  
Average Pore ◽  
Carbon Microsphere ◽  
Initial Ph ◽  
Zncl2 Activation

In this study, activated carbon microsphere (SLACM) was prepared from powdered sodium lignosulfonate (SL) and polystyrene by the Mannich reaction and ZnCl2 activation, which can be used to remove Cr(VI) from the aqueous solution without adding any binder. The SLACM was characterized and the batch experiments were conducted under different initial pH values, initial concentrations, contact time durations and temperatures to investigate the adsorption performance of Cr(VI) onto SLACM. The results indicated that the SLACM surface area and average pore size were 769.37 m2/g and 2.46 nm (the mesoporous material), respectively. It was found that the reduced initial pH value, the increased temperature and initial Cr(VI) concentration were beneficial to Cr(VI) adsorption. The maximum adsorption capacity of Cr(VI) on SLACM was 227.7 mg/g at an initial pH value of 2 and the temperature of 40 °C. The adsorption of SLACM for Cr(VI) mainly occurred during the initial stages of the adsorption process. The adsorption kinetic and isotherm experimental data were thoroughly described by Elovich and Langmuir models, respectively. SL could be considered as a potential raw material for the production of activated carbon, which had a considerable potential for the Cr(VI) removal from wastewater.

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