scholarly journals Magnetic Porous Controlled Fe3O4–Chitosan Nanostructure: An Ecofriendly Adsorbent for Efficient Removal of Azo Dyes

Nanomaterials ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 1194 ◽  
Author(s):  
Tiago M. Freire ◽  
Lillian M. U. D. Fechine ◽  
Danilo C. Queiroz ◽  
Rafael M. Freire ◽  
Juliano C. Denardin ◽  
...  
Keyword(s):  
Azo Dyes ◽  
Average Particle Size ◽  
Molecular Size ◽  
Nitrogen Adsorption ◽  
Average Particle ◽  
Precipitation Reaction ◽  
Reactive Black 5 ◽  
Anionic Dyes ◽  
Adsorption Mechanisms ◽  
Surface Modified

In this work, chitosan/magnetite nanoparticles (ChM) were quickly synthesized according to our previous report based on co-precipitation reaction under ultrasound (US) irradiation. Besides ChM was in-depth structurally characterized, showing a crystalline phase corresponding to magnetite and presenting a spheric morphology, a “nanorod”-type morphology was also obtained after increasing reaction time for eight minutes. Successfully, both morphologies presented a nanoscale range with an average particle size of approximately 5–30 nm, providing a superparamagnetic behavior with saturation magnetization ranging from 44 to 57 emu·g−1. As ChM nanocomposites have shown great versatility considering their properties, we proposed a comparative study using three different amine-based nanoparticles, non-surface-modified and surface-modified, for removal of azo dyes from aqueous solutions. From nitrogen adsorption–desorption isotherm results, the surface-modified ChMs increased the specific surface area and pore size. Additionally, the adsorption of anionic azo dyes (reactive black 5 (RB5) and methyl orange (MO)) on nanocomposites surface was pH-dependent, where surface-modified samples presented a better response under pH 4 and non-modified one under pH 8. Indeed, adsorption capacity results also showed different adsorption mechanisms, molecular size effect and electrostatic attraction, for unmodified and modified ChMs, respectively. Herein, considering all results and nanocomposite-type structure, ChM nanoparticles seem to be a suitable potential alternative for conventional anionic dyes adsorbents, as well as both primary materials source, chitosan and magnetite, are costless and easily supplied.

Kinetics of synthesizing process for obtaining iron nanopowder by chemical-metallurgical method under isothermal conditions

2021 ◽  
pp. 72-77
Author(s):  
Tien Hiep Nguyen ◽  
◽  
Van Minh Nguyen ◽  
Keyword(s):  
Hydrogen Reduction ◽  
Average Particle Size ◽  
Chemical Deposition ◽  
Reduction Process ◽  
Nitrogen Adsorption ◽  
Specific Rate ◽  
Average Particle ◽  
Isothermal Conditions ◽  
Electron Microscopes ◽  
Kinetics Of

In this work the kinetics of synthesizing process of metallic iron nanopowder by hydrogen reduction from α-FeOOH hydroxide under isothermal conditions were studied. α-FeOOH nanopowder was prepared in advance by chemical deposition from aqueous solutions of iron nitrate Fe(NO3)3 (10 wt. %) and alkali NaOH (10 wt. %) at room temperature, pH = 11, under the condition of continuous stirring. The hydrogen reduction process of α-FeOOH nanopowder under isothermal conditions was carried out in a tube furnace in the temperature range from 390 to 470 °C. The study of the crystal structure and composition of the powders was performed by X-ray phase analysis. The specific surface area S of the samples was measured using BET method by low-temperature nitrogen adsorption. The average particle size D of powders was determined via the measured S value. The size characteristics and morphology of the particles were investigated by transmission and scanning electron microscopes. The calculation of the kinetic parameters of the hydrogen reduction process of α-FeOOH under isothermal conditions was carried out by the Gray-Weddington model and Arrhenius equation. It is shown that the rate constant of reduction at 470 °C is approximately 2.2 times higher than in the case at 390 °C. The effective activation energy of synthesizing process of iron nanopowder by hydrogen reduction from α-FeOOH was ~38 kJ/mol, which indicates a mixed reaction mode. In this case, the kinetics overall process is limited by both the kinetics of the chemical reaction and the kinetics of diffusion, respectively, an expedient way to accelerate the process by increasing the temperature or eliminate the diffusion layer of the reduction product by intensive mixing. It is show that Fe nanoparticles obtained by hydrogen reduction of its hydroxide at 410 °C, corresponding to the maximum specific rate of the reduction process, are mainly irregular in shape, evenly distributed, the size of which ranges from several dozens to 100 nm with an average value of 75 nm.

Preparation, characterization and dechlorination property of nano Pd-Ni/γ-Al2O3 bimetallic catalyst

2019 ◽  
Vol 12 (06) ◽  
pp. 1951003 ◽  
Author(s):  
Yu Zhang ◽  
Yiyang Wang ◽  
Yalong Liao ◽  
Muyuan Guo ◽  
Gongchu Shi
Keyword(s):  
Photoelectron Spectroscopy ◽  
Inductively Coupled Plasma ◽  
Bimetallic Catalyst ◽  
Average Particle Size ◽  
Nitrogen Adsorption ◽  
Precipitation Method ◽  
Emission Spectrometry ◽  
Average Particle ◽  
Plasma Atomic Emission Spectrometry ◽  
X Ray

Nano Pd-Ni/[Formula: see text]-Al2O3 bimetallic catalyst was prepared by chemical precipitation method enhanced with ultrasonic wave. The influence of dosage of dispersant, ultrasonic intensity and mass ratio of Pd to Ni on the dechlorination property of the catalyst obtained was investigated in detail. The appearance morphology, composition and structure of the catalysts prepared were characterized with X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption, while the specific surface area was determined using the Brunauer–Emmett–Teller (BET) isotherm and the chemical composition of active gradients was tested with inductively coupled plasma-atomic emission spectrometry (ICP-AES). Results indicate that the nano Pd-Ni/[Formula: see text]-Al2O3 bimetallic catalyst prepared has uniform distribution of active ingredients with an average particle size of 4.91[Formula: see text]nm, and the chlorine content of shellac dechlorinated with the catalyst obtained is 0.34[Formula: see text]wt.% which is lower than that reported in the literature, meaning the perfect dechlorination property of the catalyst.

Porous Ceramic Humidity Sensors Using Sol-Gel Processed ZrTiO4 Nanoparticles

2006 ◽  
Vol 45 ◽  
pp. 1803-1808 ◽  
Author(s):  
I.C. Cosentino ◽  
E.N.S. Muccillo ◽  
F.M. Vichi ◽  
R. Muccillo
Keyword(s):  
Porous Ceramic ◽  
Mercury Porosimetry ◽  
Sol Gel ◽  
Average Particle Size ◽  
Nitrogen Adsorption ◽  
Zirconium Oxychloride ◽  
Average Particle ◽  
Titanium Tetraisopropoxide ◽  
X Ray Diffraction ◽  
Adsorption Analysis

Ceramic ZrTiO4 powders were prepared by a sol-gel method using zirconium oxychloride and titanium tetraisopropoxide. In situ high temperature X-ray diffraction results show that crystallization of the amorphous gel starts at 400°C. Single-phase ZrTiO4 nanoparticles of 46 nm average particle size, determined by nitrogen adsorption analysis, were obtained after heat treatment at 450°C for 1 h. After pressing these sinteractive powders, pellets with controlled pore size distribution were obtained by sintering at temperatures as low as 400°C. The analysis of pores by mercury porosimetry gives an average porosity of 45%. The electrical resistivity, determined by impedance spectroscopy measurements at 24°C under different humidity environments, shows the ability of these pellets to adsorb water vapor in the porous surfaces.

SYNTHESIS OF RELATIVELY HIGHLY MAGNETIC NANO-SIZED NiZn-FERRITE IN MICROEMULSION AT 45°C

2005 ◽  
Vol 12 (01) ◽  
pp. 97-100 ◽  
Author(s):  
VUK USKOKOVIĆ ◽  
MIHA DROFENIK
Keyword(s):  
Particle Size ◽  
Qualitative Analysis ◽  
Saturation Magnetization ◽  
Average Particle Size ◽  
Average Particle ◽  
Precipitation Reaction ◽  
Ferrite Powder

The procedure for the preparation of NiZn-ferrite powder with average particle size of 10 nm and saturation magnetization of 50 emu/g by using precipitation reaction between acidified sulphate precursor salts and NH4OH as the precipitating agent in the water-in-oil domain of the microemulsion CTAB/1-hexanol/water at 45°C is presented herein. TEM measurements have revealed relatively uniform morphology of the particles, which are associated in coral-like agglomerates. EDS measurements have been used for qualitative analysis of the sample, whereby FAAS measurement has been performed in order to reveal the proportion of the cations in the sample — Ni : Zn : Fe = 0.17 : 0.18 : 2.64.

scholarly journals Surface Modification of Attapulgite by Grafting Cationic Polymers for Treating Dye Wastewaters

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 792
Author(s):  
Huan Guo ◽  
Kai Xia ◽  
Mingzhao Cao ◽  
Xiaodong Zhang
Keyword(s):  
Dye Adsorption ◽  
Nitrogen Adsorption ◽  
Particle Size Analysis ◽  
Sem Analysis ◽  
Size Analysis ◽  
Reactive Black 5 ◽  
Anionic Dyes ◽  
Column Operation ◽  
Adsorption Capacities ◽  
Modified Attapulgite

In this study, the cationic polymer poly-epichlorohydrin-dimethylamine was immobilized on natural attapulgite to improve the dye adsorption capacities. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, nitrogen adsorption-desorption isotherms, scanning electron microscope (SEM) analysis, zeta potential analysis, and particle size analysis were used to determine the characteristics of modified attapulgite. Results showed that the poly-epichlorohydrin-dimethylamine had been successfully grafted onto the surface of attapulgite without altering its crystal structure. After cationic modification, the specific surface area of attapulgite obviously decreased, and its surface zeta potentials possessed positive values in the pH range from 3 to 11. The cation-modified attapulgite displayed high adsorption capacities for anionic dyes, and its maximum adsorption capacities were 237.4 mg/g for Reactive Black 5 and 228.3 mg/g for Reactive Red 239; this is corroborated by Langmuir’s isotherm studies. It was demonstrated that the two reactive dyes could be 100% removed from effluents when cation-modified attapulgite was used in column operation modes. Its treatment capacities were more than three times larger than that of activated carbon. The regeneration study verified better utilization and stability of the fabricated adsorbent in column operation. This work has conclusively confirmed the potential of the new modified attapulgite for effectively treating dye wastewaters.

Effects of Preparation Conditions on Characters of Hydrophobic Silica Granular Aerogel and its Applications

2012 ◽  
Vol 600 ◽  
pp. 190-193 ◽  
Author(s):  
Wei Wei ◽  
Jing Yi Zhang ◽  
Li Ping Wu ◽  
Guo Tong Qin
Keyword(s):  
Particle Size ◽  
Ambient Pressure ◽  
High Surface ◽  
Sol Gel ◽  
Average Particle Size ◽  
High Surface Area ◽  
Nitrogen Adsorption ◽  
Ambient Pressure Drying ◽  
Average Particle ◽  
Hydrophobic Silica

The hydrophobic silica granular aerogels were synthesized via sol-gel synthesis followed by ambient pressure drying. The tetraethyloxylane (TEOS) was used as original precursor. The aerogels were analyzed using nitrogen adsorption, scanning electron microscopy (SEM) and laser particle size analyzer. It was found that the aerogel was mesoporous material with high surface area. The aerogels were prepared in grain form by dipping into disperse solution in order to adsorption application. The average particle size of the aerogel was controlled by pH and disperse solution volume. The pH also affected gel time. The aerogels were used to absorb phenol from water. The saturated adsorption amount could reach up to 145 mg•g-1.

Synthesis and Characterization of Nanosized ZrTiO4 Powders Prepared by the Sol-Gel Method

2006 ◽  
Vol 530-531 ◽  
pp. 401-407 ◽  
Author(s):  
I.C. Cosentino ◽  
F.M. Vichi ◽  
E.N.S. Muccillo ◽  
R. Muccillo
Keyword(s):  
Mercury Porosimetry ◽  
Sol Gel ◽  
Average Particle Size ◽  
Nitrogen Adsorption ◽  
Zirconium Oxychloride ◽  
Average Particle ◽  
Titanium Tetraisopropoxide ◽  
Nanosized Powders ◽  
Gel Method ◽  
Sol Gel Method

Ceramic ZrTiO4 powders were prepared by a modified sol-gel method using zirconium oxychloride and titanium tetraisopropoxide. In situ high temperature X-ray diffraction results show that crystallization of the amorphous gel starts at 400 °C. Singlephase ZrTiO4 nanoparticles were obtained after heat treatment at 450 oC for 1 h. An average particle size of 46 nm has been determined by nitrogen adsorption analysis. After pressing these sinteractive powders, pellets with controlled pore size distribution were obtained by sintering at temperatures as low as 400 oC. The analysis of pores by mercury porosimetry shows an average porosity of 45 %. Pressing and sintering the nanosized powders prepared by that modified sol-gel technique produced pellets that are good candidates to be used in humidity sensing devices.

scholarly journals The facile one-step hydrothermal method to prepare MnO2 nanoparticles: Structural and electrochemical properties

2021 ◽  
Vol 2145 (1) ◽  
pp. 012034
Author(s):  
K Tangphanit ◽  
N Boonraksa ◽  
S Maensiri ◽  
E Swatsitang ◽  
K Wongsaprom
Keyword(s):  
Hydrothermal Method ◽  
Current Density ◽  
Average Particle Size ◽  
Nitrogen Adsorption ◽  
Spherical Particles ◽  
Average Particle ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
One Step ◽  
A Current

Abstract MnO2 nanoparticles were successfully prepared via one-step hydrothermal method. The surface are properties of the MnO2 nanoparticles were determined by BET nitrogen adsorption-desorption measurement. The XRD analyses confirm the pure phase of γ-MnO2 and α-MnO2, having orthorhombic crystal structure (JCPDS file no.14-0644 and 44-0141). FE-SEM analysis reveals the combination of massively small spherical particles with average particle size 54.8 nm. The electrochemical results revealed that the MnO2 nanoparticles delivered the specific capacitance of 200.83 F/g at a current density of 1A/g. The cycle stability was usability 30% after 500 cycles at a current density of 5 A/g. The MnO2 nanoparticles reveal a energy density of 3.62 Wh/kg under a power density of 43.11 W/kg.

scholarly journals Synthesis of Modified Starch/Polyvinyl Alcohol Composite for Treating Textile Wastewater

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 289 ◽  
Author(s):  
Kai Xia ◽  
Xin Liu ◽  
Weiwei Wang ◽  
Xizi Yang ◽  
Xiaodong Zhang
Keyword(s):  
Polyvinyl Alcohol ◽  
Chemical Activation ◽  
Average Particle Size ◽  
Fixed Bed ◽  
Textile Wastewater ◽  
Activation Process ◽  
Average Particle ◽  
Modified Starch ◽  
Reactive Black 5 ◽  
Swelling Properties

In this work, we demonstrated a strategy to design a modified starch/polyvinyl alcohol composite (CCSP), which was employed as a highly efficient and economical fixed-bed adsorbent for treating textile wastewater. Characterization revealed that most of the CCSP was shaped with the morphology of sphericity, and had some water swelling properties. The crystallinity of the CCSP was lower than that of native starch and polyvinyl alcohol, and its average particle size gradually increased with the dosage increase of cationic starch in the preparation. Adsorption experiments showed that the adsorption capacities of CCSP were more than 605 and 539 mg/g for Reactive Black 5 and Reactive Orange 131, respectively, which were over 10 times larger than that of commercial activated carbon (AC). The mixture adsorbent composed of CCSP and AC could remove starch, polyvinyl alcohol, and dyes from textile wastewater completely and simultaneously combined with the fixed-bed technique, and its adsorption capacity was conducted as a function of the bed height and flow rate. Most importantly, the disabled mixture adsorbent could be converted into regenerated AC through a chemical activation process, thereby avoiding the production of solid waste. This study will provide a new efficient green sustainable method for treating textile wastewater.

scholarly journals Synthesis and Characterization of Porous Magnetite Nanosphere Iron Oxide as a Novel Adsorbent of Anionic Dyes Removal from Aqueous Solution

2021 ◽  
Vol 11 (5) ◽  
pp. 13377-13401 ◽  
Keyword(s):  
Aqueous Solution ◽  
Contact Time ◽  
High Performance ◽  
Average Particle Size ◽  
Average Particle ◽  
Order Kinetic ◽  
Anionic Dyes ◽  
Solution Ph ◽  
Remazol Red

Porous magnetite Fe3O4 nanospheres (PMNs) are synthesized for removal from an aqueous solution of anionic dyes Acid Red 57 (AR57) and Remazol Red (RR) and are used as a high-performance adsorbent. Characterization of PMNs was carried out using various techniques, such as Fourier-transform infrared spectroscopy, the surface area measured by Brunauer Emmett-Teller (BET), and it was found 143.65m2g-1, and were spherical-shaped as determined by TEM. Surface modification was calculated using electron microscopy (SEM) scanning. The spherical morphology of the PMNs is very uniform, with an average particle size of ~25,84 nm in diameter. Variables such as initial pH, the dosage of adsorbent, contact time, and temperature were analyzed to find the optimal adsorption conditions for extracting Acid Red 57 (AR57) and Remazol Red (RR) from aqueous solutions. For respective AR57 and RR, the optimal pH for the extraction of the anionic dyes examined from water solutions was 3 and 4. The maximum adsorption potential expected for AR57 and RR dyes was 888.68 and 808.43 mgg−1, respectively. The effects of the initial solution pH, temperature, initial concentration, contact time, salinity, and dosing of PMNs were systematically analyzed. These dyes were suitable for acid pH adsorption, as the PMNs Zero-charge point (pHPZC) equals 4.3. Adsorption findings were based on the Langmuir, Freundlich, Dubinin – Radushkevich, and Temkin adsorption isotherms. The adsorption isotherm had been found to follow the Langmuir model for both dyes. The mean adsorption energy (Ea) is 20.24 and 31.3 kJmol−1 for AR57 and RR, respectively, indicating a chemisorption process. The adsorption kinetics had been found to follow the pseudo-second-order kinetic model. The adsorption process was verified to be endothermic and spontaneous by thermodynamic studies. Using ethanol as a solvent, it was also studied the process of desorption of the adsorbed anionic dyes.

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