Papers by Keyword: Surface Area

Abstract: Hydroxyapatite and its compounds are important and promising inorganic biomaterials that can be used in dentistry and bone surgery due to its biocompatibility with the bone tissue of a living organism. The paper presents the synthesis of carbonate-substituted hydroxyapatite powders and studies their morphology, physical and chemical characteristics and biocompatibility in vivo. The synthetic carbonate-substituted hydroxyapatite are biocompatible, and they do not cause degenerative changes in the surrounding tissues. The result of this research suggests that the carbonate-substituted hydroxyapatite is promising biomaterial for orthopedic and dental prosthetics.

Abstract: Carbon Nanotubes (CNT) have emerged and gained great interest for research in many applications because of their unique specific characteristics such as having high porosity, high surface area and the existence of a wide spectrum of surface functional groups through chemical modification. Multiwalled carbon nanotubes (MWCNT) is a type of CNT that comprises of multiple layers of concentric cylinders. The overall study of this research work is to modify MWCNT to become a good adsorbent that can adsorb CO₂ at its optimum capacity. In order to make MWCNT as an efficient adsorbent, surface treatment on pristine MWCNT is necessary to overcome the hydrophobicity issue by the introduction of carboxyl group. Upon the surface treatment, functionalization of MWCNT with 3-Aminopropyl triethoxysilane (APTS) was conducted to obtain the attachment of amine group that will assist MWCNT in adsorbing CO₂. The surface treatment and functionalization process undergone by MWCNT changed the physical properties of MWCNT such as the surface area, pore volume, and pore size distribution. These properties can be determined using surface area and pore analyzer (SAP). Sample that treated with the mixture of nitric and sulfuric acid (HNO₃/H₂SO₄) and functionalized with APTS gives the lowest surface area (22.07 m²/g) and pore volume (0.06 cm³/g). The pore size distribution also decreases due to the most presence of functional group onto the surface of modified MWCNT. This research paper is focusing on the effect of surface area, pore volume, and pore size distribution on the modified MWCNT.

Abstract: Hydrophobic silica nanoparticles were synthesized by silica sols modified with different percentage of zirconium sol using liquid modification. The hydrophobicity test demonstrated that silica zirconium nanoparticles are more hydrophobic as they showed 1% to 5% weight gain compared to 8% for pure silica nanoparticles. The synthesized silica nanoparticles were characterized using different techniques to investigate the effect of zirconium modification on silica nanoparticles characteristics. Structure and composition of unmodified silica nanoparticles and modified one were studied using FTIR; the results showed that the zirconium oxide was anchored to the surface of silica nanoparticles. TEM and BET analysis showed that the percentage of zirconium added to silica had distinct effect on the particle distribution and surface area of silica nanoparticles.

Abstract: Modification of wood surface with compositions produced on the base of boric acid esters of amin-alcohols increases its polarity, decreases specific surface area and reduces water absorption of wood twice. This improves wettability of water surface and increases adhesion strength of paint coating which is the result of intermolecular forces of interaction. The latter provides increases service life of paint coating.

Abstract: In this study, the effects of glycine-nitrate ratios and postcombustion chemical treatment on the phase evolution and surface area of CuCrO₂ powders were investigated. The pure phase of CuCrO₂ powders was obtained at a glycine-nitrate ratio of 1.2–1.4. When the glycine-nitrate ratio was higher than 1.9, the Cu ions were reduced to Cu(0) and the phase of Cu metal and Cr₂O₃ were observed. However, when the glycine-nitrate ratio was lower than 1.1, the Cu ions were partially maintained as Cu(2⁺), and a bluish residue was observed. As-combusted CuCrO₂ powder with a high surface area (50 m²/g) was obtained at a glycine-nitrate ratio of 1.2. Furthermore, a high surface area (> 60 m²/g) was obtained by leaching as-combusted CuCrO₂ powder with diluted nitric acid.

Abstract: Synthesising zinc oxide nanoparticles (ZnO-NPs) to get certain characteristics to be applied in Enhanced Oil Recovery (EOR) is still challenging to date. In this work, the importance of high surface area of ZnO nanoparticles as EOR agent was highlighted. A simulation on density of state (DOS), band structure and adsorption energy of hydrogen and nitrogen gases on the surface of ZnO was carried out; it is observed that from the band structure of the band gap value for ZnO is 0.808ev. For the ZnO, Zn 4s states contribute to conduction band and O 2p states contribute to valence band. ZnO-NPs were synthesised using the sol-gel method by dissolving zinc nitrate hexahydrate in nitric acid and varying the stirring time (1 and 24h) and sintering time (30 and 40 min). A microwave oven was used for annealing ZnO without insulating the samples in any casket. The results show that 30 and 40 min of annealing and stirring for 1 & 24 h influenced the morphology and size of ZnO-NPs. These parameters could be tailored to generate a range of nanoparticle morphology (flask and/with agglomerated nanoparticles in a corn shape) obtained by Field Emission Scanning Electron Microscope (FESEM) and hexagonal crystal, determined by X-ray diffractometer (XRD), with the mean size of 70.5 & 74.9 nm and a main growth at the peak (101). The prepared sample via stirring for 24h and sintering for 40 min was chosen to prepare ZnO nanofluid because it has the highest surface area (BET) among the rest of samples, 0.23 m²/g. 10% of Original Oil In Place (OOIP) was recovered successfully to prove that ZnO is a good candidate to be applied in some chemical reactions. Moreover, it was found that ZnO is a promising catalyst for ammonia synthesis based on the adsorption energy of hydrogen and nitrogen gases (-1.05 and-1.60 kcal/mol respectively).

Abstract: Biochar addition to soil and water environments has been shown to be effective in sequestering contaminants. This study evaluated the effects of biomass type and the preparation temperatures of biochars on their properties as a sorbent. Rice husk and empty fruit bunches of oil palm were used as the source of biomass for the production of biochars by heating at 300, 500 and 700°C. The biochars properties including functional sites, elemental components and BET surface area were determined to assess the biochars sorption mechanisms. The biochars produced in low temperature were found to have more polar functional groups effective in sorption of polar molecules while the highest temperature increased biochars surface area which is effective in non-selective sorption of contaminations.

Abstract: Heat-resistant concrete with liquid and water glassis widely used for the lining of thermal units and equipment. In this paper we present the results of studies on the preparation and study of the properties of the sodium silicate composite binder (SNCR) on the basis of quartzite Kulantyubinsky field for heat-resistant concrete. Refractoriness quartzite 1450-1500 ^° C. According to RFA quartzite consists of α - quartz, in addition, the sample contains kaolinite Al₂O₃ ∙ 2SiO₂ ∙ H₂O. SNCR is prepared jointly grinding quartzite and solid sodium silicate, a ball mill, taken from ootnoshenii: 90:10, 85:15, 80:20 to surface area 2800-3000 cm ²/g. To determine the optimal composition of the binder were determined flexural and compressive strength of samples, cross members 16х4х4 see Hardening SNCR carried drying in 2-stage operation in the temperature range 100-200 ^оC. Found that the bending strength of SNCR is 1.6-2.6 MPa, compressive 17,0-32,3 MPa.Refractoriness of 1320-1390 °C. The process of phase formation during heat treatment optimum binder composition.Was found that at temperatures of 1200-1300 ^° C in SNCR by quartzite than β - quartz formed vykotemperaturnaya modification quartz β - cristobalite, which increases the fire resistance of binder. Presence of cristobalite phase was also found with the mineralogical On-petrographic method as well. resulting binder can be used for acid-and heat-resistant refractory Producth with 1300 ^оC and more.

Abstract: Mesoporous TiO₂ with high surface area (S_BET) and different pore size was successfully fabricated via hydrothermal method using cetyltrimethylammonium bromide and PEO-PPO-PEO as the structure-directing agents, and tetrabutyl titanate (TBT) as titanium source. S_BET and pore size of the materials were adjusted by using different amount of TBT. S_BET was increased as TBT changing from 0.5 g to 1.0 g, and then dropped as 2.0 g TBT added. Among as-prepared samples (PC), PC-1.0 showed the highest S_BET of 92.72 m² g¹. With the increase amount of TBT, pore size increased from 10.36 nm to 12.72 nm. The phtocatalysis study showed that PC-1.0 had the highest percent degradation of 99.6 %. We believed that the design and synthesis of mesoporous TiO₂ with changing mesopores and S_BET are important for both fundamental and technological viewpoints.

Abstract: This article presents the results of the synthesis of carbon nanomaterials: Nanoscale materials obtained by carbonization of waste agricultural products (apricot kernel, Greek walnut (GW), rice husk). The results of physico-chemical characteristics of the obtained nanomaterials. Physico-chemical parameters of the synthesis of carbonized sorbents based on plant raw material are investigated along with the properties of these sorbents. The data of FTIR, ESR spectroscopy & BET-method, as well as electron microscopy are reported. It is stated that carbonized sorbents possess high specific surface area and porosity. Carboxylic, carbonyl, hydroxyl groups are detected on the surface of the synthesized sorbents. Separate fusicoccine and similar biostimulators effectively; remove LPS-endotoxines from blood plasma selectively. They may be used as carriers to introduce probiotics into intestine thanks to formation of stable colonies on their developed surface. A method of preparation of honeycomb monoliths from carbonized rice husk with developed mesoporous structure via modification of the porous structure by silica leaching has been developed.