scholarly journals Influence of the reaction time during the treatment of bacterial cellulose with sulfuric acid solution

2019 ◽  
Vol 9 (5) ◽  
pp. 4301-4304 ◽  
Keyword(s):  
Sulfuric Acid ◽  
Reaction Time ◽  
Acid Solution ◽  
Bacterial Cellulose ◽  
Sulfuric Acid Solution ◽  
Crystallinity Index ◽  
Acid Solutions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sulfuric Acid Solutions

Biomaterials are one of the most important parts of the medical device industry. Being used frequently in the development of Scaffolds for the tecidual regeneration. Bacterial cellulose is a biomaterial widely used in tissue regeneration. Due to its high content of hydrogen bonds, its crystallinity is high and its solubility is low, which makes its use difficult. Studies carried out with anteriority showed the modification suffered by bacterial cellulose treated with sulfuric acid solutions. The objective of this work was to study the influence of reaction time on crystallinity in the treatment of bacterial cellulose with sulfuric acid solution. Bacterial cellulose was modified by acid hydrolysis with sulfuric acid solutions of 48 or 64% for 60, 120 and 240 min. In all cases, the hydrolysed cellulose was washed with distilled water until pH 7, subsequently the cellulose was washed with ethanol and dried in an oven at 37 ° C until a constant mass. The samples obtained were characterized by X-ray diffraction and the crystallinity index, the apparent crystallite size, the crystallite inner chains and the Z-discriminant function were determined. The results showed that the reaction time has a statistically significant influence on the crystallinity of bacterial cellulose.

scholarly journals Solid state interactions in the systems CaO(CaCO3)-Fe2O3 and CuFe2O4-CaO

2005 ◽  
Vol 41 (1) ◽  
pp. 67-77 ◽  
Author(s):  
B.S. Boyanov
Keyword(s):  
Sulfuric Acid ◽  
Solid State ◽  
Acid Solution ◽  
Diffraction Analysis ◽  
Sulfuric Acid Solution ◽  
Formation Process ◽  
X Ray Diffraction ◽  
Exchange Reactions ◽  
X Ray ◽  
Ferrite Formation

The solid state interactions in the systems CaO(CaCO3)-Fe2O3 and CuFe2O4-CaO have been studied using X-ray diffraction analysis. The influence of the temperature on the ferrite formation process has been investigated in the range of 900-1200 oC and duration up to 360 min. It has been shown that a mixture of ferrites forms at 1000 oC and interaction of 240 min. The exchange reactions in the systems CuFe2O4-CaO and Cu0.5Zn0.5Fe2O4-CaO have been studied, too. It has been established that Ca2+ ions exchange Cu2+ and Zn2 partially and the solubility of copper and zinc in a 7 % sulfuric acid solution increases 10-15 times.

scholarly journals Evaluation of an Epoxy-Based Nanosilicacomposite Lining in H2SO4 Solution for Anticorrosion of Sewerage Concrete Structures

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Chau Van Dinh
Keyword(s):  
Electron Microscopy ◽  
Sulfuric Acid ◽  
Acid Solution ◽  
Sulfuric Acid Solution ◽  
Substrate Surface ◽  
Concrete Structures ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Corrosive Environments

This work presents the performance of a SiO2-epoxy nanocomposite lining for the anticorrosion of the concrete structures in sewer networks. Nanocomposite lining on the concrete substrate surface of the 15 phr (part per hundred epoxy resin) amine-cured epoxy polymer containing 3.0 phr of nano-SiO2 was prepared by intercalating epoxy into the SiO2 via direct mixing process. The silica exfoliation was monitored by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The barrier feature of epoxy the base nanocomposite against water and sulfuric acid solution was evaluated. The results showed that the nanocomposite lining was of a great barrier against these corrosive environments due to the intercalation and exfoliation caused by the dispersion of the SiO2 nanoparticles into the epoxy matrix. The rate of the H2SO4 into the nanocomposite lining was also investigated by measurement of the depth of the sulfur element penetrated layer using the coupled Scanning Electron Microscopy (SEM)/Energy dispersive X-ray spectrometer (EDS). Deterioration behavior of the adhesion strength of the nanocomposite lining was studied. The nanocomposite lining shows a significant improvement of bond strength in comparison to the neat epoxy lining. The durability of the nanocomposite lining adhesion when the lining systems exposed to water and the sulfuric acid solution is also improved significantly.

In Situ X-ray Scattering Study of the Passive Film on Ni(111) in Sulfuric Acid Solution

2000 ◽  
Vol 104 (6) ◽  
pp. 1222-1226 ◽  
Author(s):  
O. M. Magnussen ◽  
J. Scherer ◽  
B. M. Ocko ◽  
R. J. Behm
Keyword(s):  
Sulfuric Acid ◽  
Acid Solution ◽  
Passive Film ◽  
Sulfuric Acid Solution ◽  
X Ray ◽  
X Ray Scattering ◽  
Scattering Study ◽  
Ray Scattering

scholarly journals СОСТАВ, СТРУКТУРА И ЭЛЕКТРОХИМИЧЕСКАЯ АКТИВНОСТЬ СИЛИЦИДА ТИТАНА В РЕАКЦИИ ВЫДЕЛЕНИЯ ВОДОРОДА

2021 ◽  
Vol 11 (4) ◽  
pp. 263-270
Author(s):  
V.V. Tretyakova ◽  
◽  
A.E. Ponomareva ◽  
V.V. Panteleeva ◽  
А.B. Shein ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Acid Solution ◽  
Hydrogen Evolution ◽  
Sulfuric Acid Solution ◽  
Differential Capacitance ◽  
Titanium Silicide ◽  
Silicon Dioxide Film ◽  
X Ray ◽  
Composition And Structure ◽  
Face Centered

The phase composition and structure of titanium silicide have been investigated by X-ray diffraction and X-ray spectral microanalysis methods. It has been found that the investigated silicide is a singlephase system consisting of a high-temperature TiSi2 modification with a rhombic face-centered lattice. The cathodic behavior of the TiSi2 electrode has been studied by the methods of polarization and capacitance measurements. It has been found that the cathodic potentiostatic curves of silicide in solutions of 0,5 M H2SO4; 0,5 M H2SO4 + 0,005 M NaF and1,0 M NaOHhave Tafel sections with slopes of 0,120; 0,097 and 0,109 V and they are characterized by the values of the hydrogen evolution overvoltage 0,90; 0,64 and 0,74 V (at i = 1 A/cm2), respectively. Titanium disilicide in sulfuric acid solution belongs to materials with a high overvoltage of hydrogen evolution, but in a fluoride-containing sulfuric acid solution and in an alkaline solution - to materials with a low overvoltage of hydrogen evolution. Based on measurements of the differential capacitance of the TiSi2 electrode (at f = 10 kHz), it has been concluded that a thin silicon dioxide film (Si + 2H2O → SiO2 + 4H+ + 4e–)is present on the surface of the silicide in the acidic fluoride-free electrolyte.

Behaviour of Cement CEM III / B under Acid Solutions Agression (I)

2008 ◽  
Vol 59 (6) ◽  
Author(s):  
Ion Teoreanu ◽  
Alice Pop2 ◽  
Mariana Coarna ◽  
Daniela Natac
Keyword(s):  
Compressive Strength ◽  
Chemical Composition ◽  
Phosphoric Acid ◽  
Acid Solution ◽  
Acid Corrosion ◽  
Point Of View ◽  
Acid Solutions ◽  
X Ray Diffraction ◽  
Cement Pastes ◽  
X Ray

This paper aims at investigating the behaviour of a type CEM III/B cement under acid corrosion with formation of insoluble products. Cement paste and mortar specimens have been cured in sulphuric acid and phosphoric acid solutions. The samples have been kept in water up to 28 days and further 180 days in 0.5 mol/L acid solutions. At specific terms, the samples underwent compressive strength, chemical and X-ray diffraction analysis. The tests� results pointed out significant differences of chemical composition between the corrosion layers and the uncorroded core. The corrosion products formed in each acid solution were identified. In concretes with composite, ecologic cements the corrosion noticed on the cement pastes can be avoided. For that purpose during the preparation of the concretes there have to be achieved a high compactness and, consequently, a high impermeability. The binder matrix of the concrete is therefore, performing from the point of view of the resistance against the acid corrosion.

scholarly journals Leaching of a Mixture of Palladium and Zinc Metal Using Hydrochloric and Sulfuric Acid Solutions

2021 ◽  
Vol 59 (7) ◽  
pp. 469-475
Author(s):  
Si Jeong Song ◽  
Viet Nhan Hoa Nguyen ◽  
Man Seung Lee
Keyword(s):  
Sulfuric Acid ◽  
Acid Solution ◽  
Reduction Potential ◽  
Chloride Ions ◽  
Acid Solutions ◽  
Optimum Conditions ◽  
Oxidizing Agents ◽  
Zinc Metal ◽  
Leaching Experiments ◽  
Sulfuric Acid Solutions

Spent electroplating solutions contain small amounts of Pd(II). Cementation of Pd(II) with zinc metal powder is practiced to concentrate the Pd. Dissolution of the cemented Pd metal is necessary to recover pure Pd metal or compounds. In this work, the leaching behavior of Pd metal in inorganic acid solutions (hydrochloric and sulfuric acid) in the presence of an oxidizing agent such as H2O2, NaClO3, or NaClO was investigated. To determine the optimum conditions for Pd leaching, experiments were conducted by adjusting the concentration of the acids and oxidizing agents, reaction temperature and time, and pulp density. Complete leaching of Pd was possible using a hydrochloric acid solution with 3 kinds of oxidizing agents, whereas only NaClO was effective in the leaching with sulfuric acid solution. The chloride ions of HCl and NaClO3/NaClO play an important role in enhancing the leaching of Pd, due to the formation of Pd chlorocomplexes and by decreasing the reduction potential of Pd(II). Compared to H2O2, NaClO3 and NaClO showed some merits as oxidizing agents in terms of reaction time, temperature and low acid concentration. Based on the optimum leaching conditions of single Pd metal, the conditions for the complete leaching of Pd and Zn from the metallic mixtures were obtained.

Convenient Method for Enhancing Hydrophobicity and Dispersibility of Starch Nanocrystals by Crosslinking Modification with Citric Acid

2018 ◽  
Vol 14 (4) ◽  
Author(s):  
Lili Ren ◽  
Yuchen Zhang ◽  
Qian Wang ◽  
Jiang Zhou ◽  
Jin Tong ◽  
...  
Keyword(s):  
Reaction Time ◽  
Citric Acid ◽  
Acid Solution ◽  
Citric Acid Solution ◽  
X Ray Diffraction ◽  
Spectroscopy Analysis ◽  
X Ray ◽  
Hydrophobic Polymer ◽  
New Interactions ◽  
Starch Nanocrystals

AbstractThis study investigated the chemical, wettability, thermal and structural properties of starch nanocrystals (SNCs) modified through crosslinking modification using citric acid in aqueous medium. The results of Fourier transform infrared spectroscopy analysis suggested that new interactions occurred between starch and citric acid after modification and an increase of the reaction time increased the degree of substitution. X-ray diffraction analysis showed that the crystalline structure of SNCs was maintained after the crosslinking modification by adjusting the pH to 3.5, and destroyed after the modification by pretreatments without adjusting the pH of the citric acid solution. Crosslinking modification decreased the size and aggregation of SNCs and longer reaction time gave rise to the smaller particle size of SNCs modified by the pretreatments of adjusting the pH of the citric acid solution. The crosslinked SNCs had lower polarity and showed stronger hydrophobicity and dispersion stability which allowed them be used as reinforcements in hydrophobic polymer matrices.

Effect of Cr Additives on the Microstructures and Properties of Laser Cladded Ni3Si

2008 ◽  
Vol 368-372 ◽  
pp. 1319-1321 ◽  
Author(s):  
Yu Feng Zheng ◽  
Jian Bin Zhang ◽  
Yao Ning Sun ◽  
Ding Fan ◽  
Min Zheng
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Corrosion Resistance ◽  
Sulfuric Acid ◽  
Acid Solution ◽  
Continuous Wave ◽  
X Ray Diffraction ◽  
X Ray ◽  
Laser Cladding Process ◽  
Scanning Electron

Three compositions, (Ni75Si25)-5Cr, (Ni75Si25)-10Cr and (Ni75Si25)-15Cr, have been cladded onto Ni-based suaperalloy substrate by pre-placing laser cladding process with a 5 kW continuous wave CO2 laser. Ni75Si25 was also cladded with the same method for comparison. The process parameters have been optimized to obtain defect free claddings. The microstructure and the hardness of the cladded layers were characterized by optical microscopy, scanning electron microscopy, X-ray diffraction and microhardness measurement. The corrosion resistance of the cladded layers was measured in a sulfuric acid solution.

Sign in / Sign up

Export Citation Format

Share Document