Characterization of Silver Loaded Activated Carbon Prepared under Supercritical Water Condition

2019 ◽  
Vol 288 ◽  
pp. 59-64
Author(s):  
Narandalai Byamba-Ochir ◽  
Battseveen Buyankhishig ◽  
Nyamsuren Byambasuren ◽  
Enkhtuul Surenjav
Keyword(s):  
Electron Microscopy ◽  
Activated Carbon ◽  
Supercritical Water ◽  
Fine Particles ◽  
Batch Reactor ◽  
Reaction Times ◽  
Acetate Solution ◽  
Reaction Rate Increase ◽  
Water Condition ◽  
Low Dielectric

The synthesis of silver nanoparticles loaded on the activated carbon (AC) surface were performed under SCW condition at 673 K and 31.15 MPa in a batch reactor. In supercritical region, fine particles are rapidly synthesized due to reaction rate increase at low dielectric constant of supercritical water. Samples were prepared with different concentrations of silver acetate solution and various reaction times. The synthesized silver loaded on AC particles were characterized by the Fourier transform infrared spectroscopy (FTIR),X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM). FTIR spectrum of primary activated carbon, activated carbon treated under supercritical water condition and synthesized AC-Ag was compared. The particles size and crystallite size of silver deposited on AC surface were analyzed by TEM and XRD, respectively.

Synthesis of Silver Nanoparticles by Hydrothermal Processing

2021 ◽  
Vol 323 ◽  
pp. 1-7
Author(s):  
Enkhtuul Surenjav ◽  
Battseveen Buyankhishig ◽  
Narandalai Byamba-Ochir ◽  
Nemekhbayar Davaadorj ◽  
Zhi Qiang Song ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Supercritical Water ◽  
Batch Reactor ◽  
Acetate Solution ◽  
Silver Acetate ◽  
Silver Particles ◽  
Uniform Size ◽  
Low Dielectric ◽  
Water Treatments ◽  
Hydrothermal Water

Hydrothermal water treatments of silver acetate (CH3COOAg) were investigated to reveal the factors controlling the formation of silver nanoparticles (AgNPs) with uniform size distribution. The effects of reaction time and concentration of silver acetate solution on the synthesis of Ag nanoparticles were studied, and the fabricated products were characterized. The hydrothermal water treatments of CH3COOAg were carried out between the temperatures of 250 - 450 °C in a batch reactor. In supercritical water regions, at 400 °C and a pressure of 31.5 MPa, silver particles are rapidly synthesized due to reaction rate increases at a low dielectric constant of supercritical water. The preparation of the silver particles with 30-80 nm in size showed a highly crystalline structure identified by XRD and TEM observations.

scholarly journals Synthesis of silver nanoparticles using supercritical water

2018 ◽  
pp. 22-25
Author(s):  
Buyankhishig B ◽  
Narandalai B ◽  
Enkhtuul S
Keyword(s):  
Particle Size ◽  
Silver Nanoparticles ◽  
Electron Microscope ◽  
Reaction Time ◽  
Supercritical Water ◽  
Silver Salt ◽  
Activated Carbons ◽  
Batch Reactor ◽  
Acetate Solution ◽  
Silver Acetate

Supercritical water (SCW) technology is a relatively novel and green method compared with others for the synthesize of metal nanoparticles. It is considered one of the most suitable methods for loading nanoparticles in surface of porous materials due to the water in supercritical conditions has a high diffusivity, well dispersive and it has a same carrier characteristic as like a gas. Silver nanoparticles and silver loaded activated carbons were synthesized using silver acetate solution under supercritical water condition at 4000C and 31.15 MPa in a batch reactor. This study was investigated effect of operational parameters on the particle size of silver nanoparticles in particularly the concen-tration of silver salt solution and the reaction time. The experiments were carried out to test the silver salt concentra-tion at 0.01 M, 0.02 M, 0.05M, and the reaction time of 15 and 30 minutes. When the silver acetate concentration and reaction time increased agglomerations of silver particles were observed on the surface of activated carbons. The structure, morphology and particle size of synthesized products were determined by X-ray diffraction (XRD), Scan-ning electron microscope (SEM) and Transmission electron microscope (TEM). Суперкртитик усан орчинд мөнгөний нанопартиклыг гарган авах Хураангуй: Суперкритик усны арга нь металлын нанопартикл гарган авах бусад аргуудтай харьцуулахад харьцангуй шинэ арга юм. Суперкритик нөхцөл дахь ус нь диффузийн коэффициент өндөртэй, тархалт сайтай, хийтэй адил зөөж тээвэрлэх шинж чанар үзүүлдэг тул сүвэрхэг материал дээр нанопартикл үүсгэхэд тохиромжтой аргуудын нэг гэж үздэг. Мөнгөний нанопартикл болон идэвхжүүлсэн нүүрсэн дээр суулгасан мөнгөний нанопартиклыг суперкритик усны аргаар мөнгөний давсны усан уусмал хэрэглэн гарган авсан. Мөнгөний нанопартиклыг гарган авахад нөлөөлөх гол хүчин зүйлүүдэд хамаарах мөнгөний давсны уусмалын концентрац болон урвал явагдах хугацааны нөлөөг судалсан бөгөөд концентрацыг 0.01 М, 0.02 М ба 0.05 М, харин урвал явагдах хугацааг 15 ба 30 минут гэсэн нөхцөлүүдэд туршилтыг явуулсан. Урвал явагдах хугацаа болон мөнгөний давсны уусмалын концентрац ихсэхэд үүссэн мөнгөний жижиг хэсгүүдийн бөөгнөрөл илүү нэмэгдэж байсан. Гарган авсан материалуудын талст бүтэц, түүний хэмжээ болон морфологийн шинж чанарыг рентген дифрактометр (XRD), сканнинг электрон микроскоп (SEM) болон нэвтрүүлэлтийн электрон микроскоп (TEM) ашиглан тодорхойлсон. Түлхүүр үг: Суперкритик ус, мөнгөний нанопартикл, урвал явагдах хугацаа, уусмалын концентрац.

Supercritical Hydrothermal Synthesis of Ultra-Fine Copper Particles Using Different Precursors

2017 ◽  
Vol 744 ◽  
pp. 493-497 ◽  
Author(s):  
Pan Pan Sun ◽  
Shu Zhong Wang ◽  
Yan Hui Li ◽  
Tuo Zhang
Keyword(s):  
Hydrothermal Synthesis ◽  
Supercritical Water ◽  
Fine Particles ◽  
Copper Ions ◽  
Synthesis Method ◽  
Reaction Times ◽  
Copper Particles ◽  
Supercritical Hydrothermal Synthesis ◽  
Ultra Fine Particles ◽  
Fine Copper

Supercritical hydrothermal synthesis is a green synthesis method for metal and metal oxide ultra-fine particles. Ultra-fine copper particles are of great interests for the researchers because of the excellent performance in recent years. In this paper, supercritical hydrothermal synthesis of copper ultra-fine particles with three different precursors (CuSO4, Cu(NO3)2, Cu(HCOO)2) are reported. This thesis reports that different products are produced with different precursors. Also, three kinds of reaction mechanisms with different precursors in supercritical water were explained. The conversion of copper ions in the reaction of Cu(HCOO)2 in supercritical water is the highest, the value reaches 100.0%. In the process of synthesizing ultra-fine copper particles, different additional HCOOH concentrations (0, 0.1 mol/L, 0.2 mol/L) and different reaction times (5 mins, 10 mins) were applied. Zero-valent ultra-fine copper particles without impurity were synthesized. The synthesized copper ultra-fine particles were cubic aggregations with micro-meter size

Hydrothermal process development for the treatment of crocidolite asbestos waste

2019 ◽  
Vol 37 (9) ◽  
pp. 914-924
Author(s):  
CT Nzogo Metoule ◽  
S Delaby ◽  
JH Ferrasse ◽  
O Boutin
Keyword(s):  
Electron Microscopy ◽  
Supercritical Water ◽  
Process Development ◽  
Batch Reactor ◽  
Hydrothermal Process ◽  
Ultrapure Water ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Electron Microscopy Analysis ◽  
First Results

The asbestos-containing waste management is a public health topic for countries which have used this mineral. Treatment of chrysotile (white asbestos), a phyllosilicate from serpentine, crocidolite (blue asbestos, first results on this kind of asbestos), one of the five asbestos varieties of amphibole family and asbestos-containing waste conversion process is proposed by using hydrothermal treatment in supercritical water. All samples were treated in an Inconel Batch Reactor. The treatment durations range is from 1 to 6 hours, temperatures range is from 400°C to 750°C, mass concentration range is from 0.02 to 170 mg. mL−1 and pressures are higher than 23 MPa. Ultrapure water is used for sample preparation. This ultrapure water is used to monitor mineral leaching on the aqueous phase and to avoid particle cross-contamination. Transmission electron microscopy analyses were carried out to check the presence or not of asbestos phase. According to these analyses, the best conditions of conversion were 1 hour and 0.02 mg. mL−1 for chrysotile, 3 hours and 0.02 mg. mL−1 for crocidolite and 1 hour and 20 mg. mL−1 for asbestos-containing waste, at T = 750°C. Supercritical water conditions were maintained during the whole treatment. The X-ray diffraction showed that the main phases present after treatments were riebeckite and magnetite (crocidolite), forsterite and enstatite (chrysotile), and calcite, spurrite and gehlenite (asbestos-containing waste). Finally, a scanning electron microscopy analysis was performed to monitor morphological fibre change. The elongated structure, partially fragmented, was found in all samples.

Reconstruction of Two-Dimensional Projections of GP 32*I

1981 ◽  
Vol 39 ◽  
pp. 38-39
Author(s):  
H.A. Cohen ◽  
W. Chiu ◽  
J. Hosoda
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
Uranyl Acetate ◽  
Distilled Water ◽  
Acetate Solution ◽  
Two Dimensional ◽  
Parent Molecule ◽  
T4 Bacteriophage ◽  
Electron Imaging ◽  
Better Than

GP 32 (molecular weight 35000) is a T4 bacteriophage protein that destabilizes the DNA helix. The fragment GP32*I (77% of the total weight), which destabilizes helices better than does the parent molecule, crystallizes as platelets thin enough for electron diffraction and electron imaging. In this paper we discuss the structure of this protein as revealed in images reconstructed from stained and unstained crystals.Crystals were prepared as previously described. Crystals for electron microscopy were pelleted from the buffer suspension, washed in distilled water, and resuspended in 1% glucose. Two lambda droplets were placed on grids over freshly evaporated carbon, allowed to sit for five minutes, and then were drained. Stained crystals were prepared the same way, except that prior to draining the droplet, two lambda of aqueous 1% uranyl acetate solution were applied for 20 seconds. Micrographs were produced using less than 2 e/Å2 for unstained crystals or less than 8 e/Å2 for stained crystals.

scholarly journals Hydrothermal Carbonization (HTC) of Seaweed (Macroalgae) for Producing Hydrochar

Energies ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1805
Author(s):  
Neel Patel ◽  
Bishnu Acharya ◽  
Prabir Basu
Keyword(s):  
Batch Reactor ◽  
Reaction Times ◽  
Hydrothermal Carbonization ◽  
Process Conditions ◽  
Maritime Provinces ◽  
Heating Value ◽  
Direct Combustion ◽  
Ecological Problems ◽  
Liquid Slurry ◽  
Work Done

Waste seaweed that is collected at coastal regions of maritime provinces in Canada is creating ecological problems as it promotes an anoxic event, which produces nearly zero dissolved oxygen in water along with hydrogen sulfide emission. The work done in this study attempts to address this issue by producing a coal-like solid hydrochar and nutritious liquid slurry (processed water) by employing a rather recent thermo-chemical process called hydrothermal carbonization (HTC) on the seaweed. The HTC was carried out in a batch reactor system for three different reaction temperatures, 180 °C, 200 °C, 220 °C, and three different reaction times, 30, 60, and 120 min. Each of the produced hydrochars was characterized by different analytical methods. The effects of the process conditions on the yield and the properties of the hydrochar and process water were examined. The hydrochar produced at 220 °C and 120 min showed the highest carbon content (48.5%) and heating value (18.93 MJ/kg). The energy density and carbon to nitrogen (C/N) ratio in the hydrochar increased significantly as compared to raw seaweed. Moreover, HTC reduced the ash yield and volatile compounds of the seaweed. Thus, hydrochar can be used as a fuel for direct combustion, in soil remediation, or in carbon sequestration applications.

scholarly journals Large Optical Nonlinearity of the Activated Carbon Nanoparticles Prepared by Laser Ablation

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 737
Author(s):  
Yasin Orooji ◽  
Hamed Ghanbari Gol ◽  
Babak Jaleh ◽  
Mohammad Reza Rashidian Vaziri ◽  
Mahtab Eslamipanah
Keyword(s):  
Electron Microscopy ◽  
Activated Carbon ◽  
Laser Ablation ◽  
Carbon Nanoparticles ◽  
Morphological Properties ◽  
Excitation Wavelength ◽  
Saturable Absorption ◽  
Reverse Saturable Absorption ◽  
High Porosity ◽  
Nlo Properties

Carbon nanoparticles (CNPs) with high porosity and great optical features can be used as a luminescent material. One year later, the same group investigated the NLO properties CNPs and boron-doped CNPs by 532 nm and 1064 nm laser excitations to uncover the underlying physical mechanisms in their NLO response. Hence, a facile approach, laser ablation technique, was employed for carbon nanoparticles (CNPs) synthesis from suspended activated carbon (AC). Morphological properties of the prepared CNPs were studied by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). UV-Vis and fluorescence (FL) spectra were used to optical properties investigation of CNPs. The size distribution of nanoparticles was evaluated using dynamic light scattering (DLS). The nonlinear optical (NLO) coefficients of the synthesized CNPs were determined by the Z-scan method. As a result, strong reverse saturable absorption and self-defocusing effects were observed at the excitation wavelength of 442 nm laser irradiation. These effects were ascribed to the presence of delocalized π-electrons in AC CNPs. To the best of our knowledge, this is the first study investigating the NLO properties of the AC CNPs.

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