Highly Porous Expanded Graphite: Thermal Shock vs. Programmable Heating

Highly porous expanded graphite was synthesized by the programmable heating technique using heating with a constant rate (20 °C/min) from room temperature to 400–700 °C. The samples obtained were analyzed by scanning electron microscopy, energy-dispersive spectroscopy, low-temperature nitrogen adsorption, X-ray photoelectron spectroscopy, Raman spectroscopy, thermogravimetry, and differential scanning calorimetry. A comparison between programmable heating and thermal shock as methods of producing expanded graphite showed efficiency of the first one at a temperature 400 °C, and the surface area reached 699 and 184 m2/g, respectively. The proposed technique made it possible to obtain a relatively higher yield of expanded graphite (78–90%) from intercalated graphite. The experiments showed the advantages of programmable heating in terms of its flexibility and the possibility to manage the textural properties, yield, disorder degree, and bulk density of expanded graphite.

Download Full-text

Microwave-assisted immobilization of metallophthalocyanines in mesoporous channels of MCM-41

Journal of Porphyrins and Phthalocyanines ◽

10.1142/s1088424607000151 ◽

2007 ◽

Vol 11 (02) ◽

pp. 118-124 ◽

Cited By ~ 7

Author(s):

Mahtab Pirouzmand ◽

Mostafa M. Amini ◽

Nasser Safari

Keyword(s):

Microwave Irradiation ◽

Textural Properties ◽

Nitrogen Adsorption ◽

Scanning Calorimetry ◽

X Ray ◽

Solvent Free Conditions ◽

Short Period ◽

Vis Spectroscopy ◽

Adsorption Desorption ◽

Mcm 41

Metallophthalocyanines have been assembled in MCM-41 channels by microwave irradiation of a mixture of ion-exchanged MCM-41, and 1,2-dicyanobenzene under solvent-free conditions in a considerably short period of time. The prepared materials have been characterized by diffuse reflectance UV-vis spectroscopy, X-ray powder diffraction XRD, differential scanning calorimetry DSC, and Brunauer-Emmett-Teller BET nitrogen adsorption desorption techniques. The X-ray diffraction and Brunauer-Emmett-Teller results showed that the textural properties of MCM-41 were preserved during microwave irradiation.

Download Full-text

Pristine and Magnetic Kenaf Fiber Biochar for Cd2+ Adsorption from Aqueous Solution

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18157949 ◽

2021 ◽

Vol 18 (15) ◽

pp. 7949

Author(s):

Anwar Ameen Hezam Saeed ◽

Noorfidza Yub Harun ◽

Suriati Sufian ◽

Muhammad Roil Bilad ◽

Zaki Yamani Zakaria ◽

...

Keyword(s):

Adsorption Capacity ◽

Photoelectron Spectroscopy ◽

Textural Properties ◽

Ion Concentration ◽

Solution Temperature ◽

Maximum Adsorption Capacity ◽

Magnetic Biochar ◽

X Ray ◽

Study Results ◽

Capacity Surface

Development of strategies for removing heavy metals from aquatic environments is in high demand. Cadmium is one of the most dangerous metals in the environment, even under extremely low quantities. In this study, kenaf and magnetic biochar composite were prepared for the adsorption of Cd2+. The synthesized biochar was characterized using (a vibrating-sample magnetometer VSM), Scanning electron microscopy (SEM), X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The adsorption batch study was carried out to investigate the influence of pH, kinetics, isotherm, and thermodynamics on Cd2+ adsorption. The characterization results demonstrated that the biochar contained iron particles that help in improving the textural properties (i.e., surface area and pore volume), increasing the number of oxygen-containing groups, and forming inner-sphere complexes with oxygen-containing groups. The adsorption study results show that optimum adsorption was achieved under pH 5–6. An increase in initial ion concentration and solution temperature resulted in increased adsorption capacity. Surface modification of biochar using iron oxide for imposing magnetic property allowed for easy separation by external magnet and regeneration. The magnetic biochar composite also showed a higher affinity to Cd2+ than the pristine biochar. The adsorption data fit well with the pseudo-second-order and the Langmuir isotherm, with the maximum adsorption capacity of 47.90 mg/g.

Download Full-text

Pore Modification and Phosphorus Doping Effect on Phosphoric Acid-Activated Fe-N-C for Alkaline Oxygen Reduction Reaction

Nanomaterials ◽

10.3390/nano11061519 ◽

2021 ◽

Vol 11 (6) ◽

pp. 1519

Author(s):

Jong Gyeong Kim ◽

Sunghoon Han ◽

Chanho Pak

Keyword(s):

Phosphoric Acid ◽

Photoelectron Spectroscopy ◽

Structural Changes ◽

Electronic States ◽

Nitrogen Adsorption ◽

Reduction Reaction ◽

Phosphorus Doping ◽

X Ray ◽

Precious Metal Catalysts ◽

Adsorption Desorption

The price and scarcity of platinum has driven up the demand for non-precious metal catalysts such as Fe-N-C. In this study, the effects of phosphoric acid (PA) activation and phosphorus doping were investigated using Fe-N-C catalysts prepared using SBA-15 as a sacrificial template. The physical and structural changes caused by the addition of PA were analyzed by nitrogen adsorption/desorption and X-ray diffraction. Analysis of the electronic states of Fe, N, and P were conducted by X-ray photoelectron spectroscopy. The amount and size of micropores varied depending on the PA content, with changes in pore structure observed using 0.066 g of PA. The electronic states of Fe and N did not change significantly after treatment with PA, and P was mainly found in states bonded to oxygen or carbon. When 0.135 g of PA was introduced per 1 g of silica, a catalytic activity which was increased slightly by 10 mV at −3 mA/cm2 was observed. A change in Fe-N-C stability was also observed through the introduction of PA.

Download Full-text

pH-controlled synthesis of sustainable lauric acid/SiO2 phase change material for scalable thermal energy storage

Scientific Reports ◽

10.1038/s41598-021-94571-0 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Shafiq Ishak ◽

Soumen Mandal ◽

Han-Seung Lee ◽

Jitendra Kumar Singh

Keyword(s):

Electron Microscopy ◽

Phase Change ◽

Lauric Acid ◽

Photoelectron Spectroscopy ◽

Phase Change Materials ◽

Precursor Solution ◽

Thermal Reliability ◽

Scanning Calorimetry ◽

X Ray ◽

Heating And Cooling

AbstractLauric acid (LA) has been recommended as economic, eco-friendly, and commercially viable materials to be used as phase change materials (PCMs). Nevertheless, there is lack of optimized parameters to produce microencapsulated PCMs with good performance. In this study, different amounts of LA have been chosen as core materials while tetraethyl orthosilicate (TEOS) as the precursor solution to form silicon dioxide (SiO2) shell. The pH of precursor solution was kept at 2.5 for all composition of microencapsulated LA. The synthesized microencapsulated LA/SiO2 has been characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-Ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM), and Transmission electron microscopy (TEM). The SEM and TEM confirm the microencapsulation of LA with SiO2. Thermogravimetric analysis (TGA) revealed better thermal stability of microencapsulated LA/SiO2 compared to pure LA. PCM with 50% LA i.e. LAPC-6 exhibited the highest encapsulation efficiency (96.50%) and encapsulation ratio (96.15%) through Differential scanning calorimetry (DSC) as well as good thermal reliability even after 30th cycle of heating and cooling process.

Download Full-text

Study of the Effect of TiO2 Layer on the Adsorption and Photocatalytic Activity of TiO2-MoS2 Heterostructures under Visible-Infrared Light

International Journal of Photoenergy ◽

10.1155/2020/8740825 ◽

2020 ◽

Vol 2020 ◽

pp. 1-9 ◽

Cited By ~ 2

Author(s):

N. Cruz-González ◽

O. Calzadilla ◽

J. Roque ◽

F. Chalé-Lara ◽

J. K. Olarte ◽

...

Keyword(s):

Electron Microscopy ◽

Photocatalytic Activity ◽

Photoelectron Spectroscopy ◽

Diffuse Reflectance Spectroscopy ◽

Nitrogen Adsorption ◽

High Photocatalytic Activity ◽

Infrared Light ◽

Polluted Water ◽

Light Spectrum ◽

X Ray

In the last decade, the urgent need to environmental protection has promoted the development of new materials with potential applications to remediate air and polluted water. In this work, the effect of the TiO2 thin layer over MoS2 material in photocatalytic activity is reported. We prepared different heterostructures, using a combination of electrospinning, solvothermal, and spin-coating techniques. The properties of the samples were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), X-ray diffraction (XRD), nitrogen adsorption-desorption isotherms, UV-Vis diffuse reflectance spectroscopy (UV-Vis-DRS), and X-ray photoelectron spectroscopy (XPS). The adsorption and photocatalytic activity were evaluated by discoloration of rhodamine B solution. The TiO2-MoS2/TiO2 heterostructure presented three optical absorption edges at 1.3 eV, 2.28 eV, and 3.23 eV. The high adsorption capacity of MoS2 was eliminated with the addition of TiO2 thin film. The samples show high photocatalytic activity in the visible-IR light spectrum.

Download Full-text

Preparation and Characterization of Ni2+-Montmorillonite/Polyvinyl Alcohol Water-Soluble Nanocomposite Film

Polymers and Polymer Composites ◽

10.1177/096739110501300811 ◽

2005 ◽

Vol 13 (8) ◽

pp. 839-846 ◽

Cited By ~ 4

Author(s):

Li-Ping Wang ◽

Yun-Pu Wang ◽

Fa-Ai Zhang

Keyword(s):

Polyvinyl Alcohol ◽

Photoelectron Spectroscopy ◽

Thermal Characteristics ◽

Water Soluble ◽

Scanning Calorimetry ◽

Xps Spectra ◽

X Ray ◽

Alcohol Water ◽

Ft Ir ◽

Silicate Layers

A new type of nano-composite film was prepared from polyvinyl alcohol, Ni2+-montmorillonite (Ni2+-MMT), defoamer, a levelling agent and a plasticizer. Its thermal characteristics were studied by Differential Scanning Calorimetry (DSC). The intermolecular interactions were measured by Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS), and the tensile strength (TS) and elongation at break (%E) were measured. The microstructures were studied by X-ray diffraction (XRD) and atomic force microscopy (AFM). FT-IR and XPS spectra indicated that cross-linking has taken place between PVA and Ni2+-MMT. XRD and AFM indicate that the PVA molecules had inserted themselves into the silicate layers of MMT, exfoliating them and dispersing them randomly into the PVA matrix. Compared to pure PVA film, the TS of the films was increased and %E decreased when the Ni2+-Montmorillonite was added and the dissolution temperature of the film was also reduced.

Download Full-text

Extraordinary Stability of Structural and Electronic Properties of Tin Oxide Nanoparticles Formed by Soft Chemistry

Advances in Science and Technology ◽

10.4028/www.scientific.net/ast.75.36 ◽

2010 ◽

Vol 75 ◽

pp. 36-42 ◽

Cited By ~ 1

Author(s):

Marina Rumyantseva ◽

Irina Zhurbina ◽

Elena Varechkina ◽

Siranuysh Badalyan ◽

Alexander Gaskov ◽

...

Keyword(s):

Optical Properties ◽

Photoelectron Spectroscopy ◽

Tin Dioxide ◽

Hydrogen Reduction ◽

Nitrogen Adsorption ◽

Ammonia Solution ◽

Adsorption Method ◽

X Ray ◽

Wet Chemical Synthesis ◽

Tin Chloride

Powders of tin dioxide (SnO2) have been prepared by two different modifications of wet chemical synthesis, i.e. (i) by conventional hydrolysis of tin chloride dissolved in aqueous ammonia solution and (ii) by precipitation from tin chloride dissolved in aqueous hydrazine monohydrate (N2H4*H2O) solution. The prepared gels were dried and then annealed at different temperatures varied from 300 to 700 oC in order to form nanocrystals. Structure and optical properties of the samples were investigated by using X-ray diffraction, transmission electron microscopy, thermoprogrammable hydrogen reduction, low temperature nitrogen adsorption method, photoluminescence, infra-red absorption, Raman spectroscopy, and X-ray photoelectron spectroscopy. The samples prepared by hydrazine-based method are characterized by surface area about 127-188 m2/g with high sintering resistance. The optical spectroscopy data revealed pure crystallinity and high defect concentration for the samples prepared by hydrazine-based method. The experimental results are discussed in view of different states of chemisorbed oxygen on SnO2 nanocrystal surfaces, which determine electronic and optical properties of the prepared samples.

Download Full-text

Influence of Cu(NO3)2 content used in thermal shock method on the photocatalytic activity of Cu-Modified ZnO nanoparticles

Science and Technology Development Journal - Natural Sciences ◽

10.32508/stdjns.v5i2.1042 ◽

2021 ◽

Vol 5 (3) ◽

pp. first

Author(s):

Thế Luân Nguyễn ◽

Tiến Khoa Lê ◽

Châu Ngọc Hoàng ◽

Hữu Khánh Hưng Nguyễn ◽

Thị Kiều Xuân Huỳnh

Keyword(s):

Crystal Structure ◽

Methylene Blue ◽

Photocatalytic Activity ◽

Thermal Shock ◽

Photoelectron Spectroscopy ◽

Copper Content ◽

Uv Light ◽

Copper Nitrate ◽

X Ray ◽

Doped Zno

The Cu doped ZnO photocatalysts were prepared on ZnO substrate modified with copper nitrate by thermal shock method with different ratio % molar Cu : Zn = 0.3, 0.5, 1.0, 2.0 and 5.0 in order to study the impacts of copper content on the photocatalytic activity of ZnO under both UV and Vis light irradiation. The crystal structure, morphology bulk and surface were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Their photocatalytic activities were studied via time-dependent degradation of methylene blue in aqueous solution. The results exhibit that crystal structure and morphology of Cu doped ZnO photocatalysts is not modified significally than ZnO original but surface charateristicschanged greatly. The photocatalyst was doped with copper content under 2% showed formation of Cu species. These samples perform photocatalytic activity higher than ZnO. The CuNZO-0.05-500 had the highest rate constants for methylene blue degradation (kUV = 6,901 h-1, kVIS = 0,224 h-1), which are about 2.2 times and 1.3 times higher than unmodified ZnO under UV light and Vis light, respectively. However, the CuNZO-5.0-500 which had the formation of CuO phase and unchangeable ZnO's surface has photocatalytic activity similar to pure ZnO.

Download Full-text

Structural and surface aspects of thermally treated copper aluminium mixed hydroxides

Canadian Journal of Chemistry ◽

10.1139/v91-223 ◽

1991 ◽

Vol 69 (10) ◽

pp. 1511-1515 ◽

Cited By ~ 5

Author(s):

Awad I. Ahmed ◽

S. E. Samra ◽

S. A. El-Hakam

Keyword(s):

Pore Structure ◽

Copper Content ◽

Textural Properties ◽

Nitrogen Adsorption ◽

Phase Changes ◽

X Ray Diffraction ◽

X Ray ◽

Surface Areas ◽

Structure Surface ◽

Adsorption Desorption

CuO–Al2O3 catalysts containing various amounts of copper oxide have been prepared by precipitation. The phase changes were studied by X-ray diffraction. The results obtained revealed that the thermal treatment of solid CuO–Al2O3 at 700 °C produced only crystalline CuO. Heating to 900 °C led to the formation of copper alumina spinel together with unreacted CuO and γ-Al2O3. The spinel content was found to increase with increasing copper content. Nitrogen adsorption–desorption isotherms on the calcined samples have been measured. Surface areas have been calculated and the pore structure analysed. The textural properties of the system were found to depend on both the copper content and the calcination temperature. Key words: CuO, Al2O3 catalysts, structure, surface area, pore structure.

Download Full-text

Biomorphic Fibrous TiO2 Photocatalyst Obtained by Hydrothermal Impregnation of Short Flax Fibers with Titanium Polyhydroxocomplexes

Catalysts ◽

10.3390/catal10050541 ◽

2020 ◽

Vol 10 (5) ◽

pp. 541

Author(s):

Mikhail F. Butman ◽

Nataliya E. Kochkina ◽

Nikolay L. Ovchinnikov ◽

Nikolay V. Zinenko ◽

Dmitry N. Sergeev ◽

...

Keyword(s):

Photocatalytic Activity ◽

Rhodamine B ◽

Sol Gel ◽

Textural Properties ◽

Nitrogen Adsorption ◽

Solution Concentration ◽

Hydrothermal Conditions ◽

Scanning Calorimetry ◽

Flax Fibers ◽

Photodegradation Efficiency

A biomimetic solution technology for producing a photocatalytic material in the form of biomorphic titanium oxide fibers with a hierarchical structure using short flax fiber as a biotemplate is proposed. The impregnation of flax fibers intensified under hydrothermal conditions with a precursor was performed in an autoclave to activate the nucleation of the photoactive TiO2 phases. The interaction between precursor and flax fibers was studied by using infrared spectroscopy (IR) and differential scanning calorimetry/thermogravimetry analysis (DSC/TG). The morphology, structure, and textural properties of the TiO2 fibers obtained at annealing temperatures of 500–700 °C were determined by X-ray diffraction analysis, scanning electron microscopy, and nitrogen adsorption/desorption. It is shown that the annealing temperature of the impregnated biotemplates significantly affects the phase composition, crystallite size, and porous structure of TiO2 fiber samples. The photocatalytic activity of the obtained fibrous TiO2 materials was evaluated by using the decomposition of the cationic dye Rhodamine B in an aqueous solution (concentration 12 mg/L) under the influence of ultraviolet radiation (UV). The maximum photodegradation efficiency of the Rhodamine B was observed for TiO2 fibers annealed at 600 °C and containing 40% anatase and 60% rutile. This sample ensured 100% degradation of the dye in 20 min, and this amount significantly exceeds the photocatalytic activity of the commercial Degussa P25 photocatalyst and TiO2 samples obtained previously under hydrothermal conditions by the sol-gel method.

Download Full-text