Abstract: Two different approaches to modify the structure and reaction ability of nanocrystalline MgO have been discussed. In the first case, a series of two-component x%MOx–MgO systems (M = Fe, Co and Ni, x = 1–45 wt.%) was synthesized via sol–gel technique. Aqueous solution of inorganic salt precursor was used as a hydrolyzing agent. Samples obtained were characterized by number of physicochemical methods (differential thermal analysis, X-ray diffraction analysis, low-temperature adsorption, etc.). It was shown that presence of inorganic salt in magnesium hydroxide matrix shifts the temperature of decomposition of latter towards lower values. Structural and textural characteristics of MgO-based oxide systems were found to be strongly affected by the presence of additive and their concentration. Formation of joint phase was observed in the case of cobalt oxide only. Second way of MgO modification was represented by creating a controlled carbon coating over its surface via decomposition of C4H10 at 400 °C. The obtained x%C/MgO (x = 1–10 wt.%) samples were shown to possess the improved reaction ability in destruction sorption of CF2Cl2 as well as in catalytic dehydrochlorination of 1-chlorobutane in presence of water vapors.
Abstract: We report a method to adjust the size of silica nanoparticles from silica sand. In this study, synthesized silica nanoparticles by sol gel process from silica sand were conducted, with previously was controlled the size of silica sand by mechanical milling. Silica sand was milled by High Energy Milling in order to reduce the size into powder form. Effect of milling time shown the content of sodium and silicon is increased in sodium silicate solution obtained from various times of silica sand milling (30, 60 and 90 minutes, respectively) which is reacted with sodium hydroxide 8 M. The result of silica nanoparticles from sol gel process of sodium silicate solution were characterized using atomic absorption spectroscopy, scanning electron microscopy and X-ray diffraction techniques. It was found that the size of silica nanoparticles could be tailored with the change of milling time.
Abstract: Green synthesis of nickel oxide nanoparticles (NiO NPs) using Physalis angulata leaf extract (PALE) as weak base sources and stabilizing agents has been reported. Chemical bonding and vibration spectroscopy, crystallographic structure, optical band gap, particle size and microscopic studies of NiO NPs were also investigated. Ni-O vibration modes of NiO NPs were analyzed by FTIR and Raman instrument at ~400 and ~900 cm-1 wavenumber. XRD pattern of NiO NPs confirmed cubic crystal structure with space group Fm-3m. Optical band gap of NiO NPs determined by using Tauc plot method was about 3.42 eV. Particle size analyzer showed size distribution of NiO NPs was 64.13 nm which confirm NiO formed in nanoscale. Electron microscopic studies of NiO NPs were observed by using scanning electron microscopy and transmission electron microscopy.
Abstract: The main components of polymer carboxyl group are introduced.The effects of macromolecular carboxyl groups on the limestone-gypsum wet flue gas desulfurization (FGD) system of coal-fired power plants in China were studied by test method. The results showed that the macromolecular carboxyl groups can accelerate the chemical absorption of SO2 under the action of active agents and crystallization agents, improve the desulfurization efficiency of about 2%, and shorten the limestone ablation time of more than 40%, catalytic calcium sulfite oxidation of calcium sulfate.
Abstract: Two series of Ag-loaded β-zeolites with silica/alumina ratio of 25 and 36 were prepared by ion exchange technique. The silver loading was varied in a range of 2-10 wt%. The samples were characterized by low-temperature nitrogen adsorption, Infrared and UV-vis spectroscopy, and transmission electron microscopy. Adsorption/desorption properties of zeolites were examined using a specially designed setup. Toluene was used as a model hydrocarbon. It was found that adsorption capacity of zeolites grows up along with silver content increase till 8%, and reduces then. According to data of physicochemical methods, at low loading the silver exists in cluster and ionic forms, while at high loading agglomerated particles predominate, which worsens the adsorption properties.
Abstract: This study investigated the effect of particle size and chitosan loading on the performance of chitosan-coated natural zeolite adsorbent in post-combustion carbon dioxide capture. The adsorbents were prepared in 3 levels of average particle size (0.75 mm, 1.5 mm and 2 mm) of natural zeolite and 4 levels of chitosan loading (0, 15, 30 and 45 wt% of natural zeolite) using a simple coating procedure. The adsorbents were characterized using infrared spectroscopy, scanning electron microscopy, thermal gravimetric analysis, and differential scanning calorimetry. The capture performance of the adsorbent was measured in terms of breakthrough time. The change in chemical properties, surface morphology and thermal characteristics of natural zeolite confirms the successful coating of chitosan. The mean breakthrough time increases with decreasing particle size and increasing chitosan loading up to 15 wt% of natural zeolite.
Abstract: The microbial synthesized ZnS obtained from a pilot-scale sulfate reducing bacteria (SRB) fixed bed reactor was investigated as photocatalyst. The SRB fixed bed reactor as used to treat the Zinc containing wastewater with the influent concentration of 200~300 mg Zn/L. The microbial synthesized ZnS was used as photocatalyst for methylene blue (MB) photodegradation. The results indicated that the photodegradation process could be promoted when the dosage of microbial synthesized ZnS increased. High initial MB concentration could promote the photodegradation reaction. The excellent performance of microbial synthesized ZnS in photodegradation could be explained as the formation of ZnS nanoparticles. The photodegradation with microbial synthesized ZnS were simulated by pseudo-first-order kinetics model. The apparent first-order rate constant of the ZnS catalyst was 0.15 min-1.
Abstract: The aim of this study, the corrosion behavior of TiNiCu in artificial saliva (pH5.35) at 37°C was assessed by the use of electrochemical methods. Ti50Ni43Cu7 (at%) used in this study were made from ingots prepared by the vacuum arc melting (VAM) method. The furnace was purged with argon gas during melting. All melted ingots were then homogenized at 800°C for 3.6 ks. Open circuit potential (OCP) was monitored at 3.6 ks followed by potentiodynamic techniques. The results showed that all chemical composition of orthodontic wires by EPMA were Ti, Ni, Cu, Cr, Fe and Mn. Surface roughness was measured in order to ensure that TiNiCu and SS was significant difference which might affect corrosion resistance. It was seen that TiNiCu orthodontic wires, presented a good corrosion resistance, compared to the stainless steel, probably due to the formation of a protective oxide film mainly constituted by titanium oxide.
Abstract: This study discusses how the addition of trace amounts of Zr (0.15 wt%) affect the microstructure and change the mechanical properties of 6061 alloys. The results show that adding a trace amount of Zr can refine the grains thereby enhancing the alloy’s hardness and mechanical properties after aging heat treatment. After thermal exposure at 250°C, alloys without Zr displayed a reduction of mechanical properties because the metastable Mg2Si strengthening phase grew into the coarse β-Mg2Si equilibrium phase during the thermal exposure, while the alloys with Zr displayed a plentiful precipitation of the Al3Zr phase, which effectively hindered the movement of dislocations and thus improved their mechanical properties.
Abstract: A new test procedure for measuring the resistance to delayed hydride cracking was developed. The critical stress intensity factors for delayed hydride cracking and the crack growth velocities of Zr-3.5Sn-0.8Nb-0.8Mo alloy with different heat treatments were evaluated and compared with Zr-2.5Nb. It was found that Delayed Hydride Cracking (DHC) crack growth velocity increases with the alloy strength, and the critical stress intensity factor is independent of heat treatment history or alloy composition.