Molar Ratio Of Oxidant Research Articles

Research on a Composite Biomass Insulation Material with Geopolymers as Binders and Forestry Waste as Fillers

A composite biomass insulation material, which uses geopolymers as adhesives and forestry waste as fillers, was proposed and experimentally tested. The orthogonal experimental method was adopted to analyze the optimum theoretical oxide molar ratios and the mass ratio of mixing water to binder (mw2/mB) for preparing geopolymers. The influences of curing regimes (including one-stage and two-stage curing methods) and mw2/mB ratios of the insulation materials on mechanical, thermal, and hydraulic performances were also studied by experiment. The results indicated that the optimum combination scheme of preparing geopolymers was molar ratio xSiO2 / xNa2O = 3.3, xSiO2 / xAl2O3 = 3.2 and mw2/mB = 0.5 with the highest mechanical strength of 34.21 MPa. Besides, the best curing conditions of the composite material were the curing temperatures of 85°C and 70°C under the two-stage curing regime, which could achieve the low heat conductivity of 0.123 and 0.125 W/(m⋅K), and the high mechanical strength of 1.70 MPa and 1.71 MPa, respectively. The optimum mw2/mB ratios of the biomass material were 0.5 to 0.55 with heat conductivity of 0.114 to 0.125 W/(m⋅K). This novel composite insulation material has satisfying physical performances, which is helpful for achieving building energy conservation.

Dielectric and electrical studies on iron oxide (α-Fe2O3) nanoparticles synthesized by modified solution combustion reaction for microwave applications

Hematite (α-Fe2O3) nanoparticles were synthesized by modified solution combustion method using a mixture of hexamethylenetetramine (HMTA) and glycine fuels at fuel to oxidant molar ratio (ϕ = 1) and fuel (HMTA) to fuel (glycine) weight ratio (1:3). DC-conductivity and dielectric studies of (α-Fe2O3) nanostructures were reported as a function of temperature. Above room temperature (RT), the conductivity showed an increasing trend with temperature which confirmed the semiconducting behaviour of the material. The conductivity behaviour followed Motts law which confirmed the three dimensional variable range hopping (3D VRH) mechanism in the synthesized system. Dielectric studies were carried out at room temperature with frequency range (1000 Hz to 1.5 MHz) as well as varying temperature (100 °C to 400 °C) at different frequencies (0.1 MHz, 0.3 MHz, 1 MHz, 1.3 MHz, and 1.5 MHz).The dielectric permittivity (є’)and tangent loss (tan δ) was found to increase with increase in temperature. In this synthesised material low value of dielectric loss was observed which depicted these materials as potential candidates for microwave applications. More than that studied material was characterised by Raman spectroscopy which revealed that seven active Raman modes were present with different intensities, namely two “A1g” modes (225 and 498 cm−1) and five “Eg” modes (247, 293, 299, 412 and 613 cm−1). The most representative band present in the synthesised iron oxide nanoparticles was found at 225 cm−1.

Oxidative Desulfurization of Sour Gas Condensate and Optimization of Parameters with Response Surface Methodology

Reducing environmental pollution via elimination of sulfur compounds from gas condensate was the aim of this research. Whereby oxidative desulfurization from gas condensate with 3200 ppm initial sulfur was accomplished by hydrogen peroxide (30%wt) as oxidant and formic acid as catalyst. The sulfones after generation in the oxidation step were extracted through a method of liquid-liquid extraction by acetone as a polar solvent. The effects of variables: coefficient of oxidant to sulfur molar ratio (O/S), temperature (T), and coefficient of catalyst to oxidant molar ratio (C/O) were investigated. The experiments were designed with response surface methodology based on central composite design (CCD). The results of experiments demonstrated that none of these variables (O/S, T, and C/O) have any interaction, and among these variables, O/S plays a significant role with the most influence on desulfurization and C/O and T are of the second and third primary of importance, respectively. In addition, 86% desulfurization was obtained in the optimum conditions.

Facile fabrication, characterization and catalytic activity of a NiMo/Al2O3 nanocatalyst via a solution combustion method used in a low temperature hydrodesulfurization process: the effect of fuel to oxidant ratio.

Novel bimetallic NiMo/Al2O3 nanocatalysts were fabricated via a solution combustion method to evaluate the role of fuel to oxidant molar ratios on their structural properties and hydrodesulfurization activity. The citric acid/oxidant ratios of 0.5, 1, 2 and 4 were selected to address the optimum ratio. Characterization results demonstrated that the content of citric acid considerably influenced the morphological and textural properties of the nanocatalysts. Such morphology modification is attributed to the consequent difference of the effluent exhaust gas during combustion. We show that with our method a relatively homogeneous distribution of the active material over the support can be achieved. The obtained data from N2 adsorption–desorption analysis illustrated that at a fuel/oxidant ratio of 4 the external and surface area were ca. 2.1 and 1.5 times more than the corresponding one in the fuel/oxidant ratio of 0.5, respectively. Furthermore, a higher amount of fuel can improve the catalyst reducibility by decreasing the interaction of metal active phase with the support surface. The catalytic performance of sulfided nanocatalysts is evaluated in a slurry reactor, operated at ambient pressure using high thiophene contamination as a model fuel. The solution combustion synthesis method was able to remove 100% of the sulfur compound in the reaction medium.

Fabrication of Zeolite-Geopolymer Hybrid Bulk Materials Based on Laterite Soils Deposit Gowa Regency, South Sulawesi, Indonesia

In this study, zeolite-geopolymer hybrid bulk materials were fabricated by using laterite soils deposit Gowa regency, South Sulawesi, Indonesia as a precursor for possible heavy metal absorbent. Laterite soils was calcined at 750°C for 6 hours to transform it into the amorphous aluminosilicate phase. Zeolite-geopolymer materials were produced through alkali activation method with curing temperature around 70°C for 2 hours. There were two different oxide molar ratios of SiO2/Al2O3 used to produce zeolite-geopolymer hybrid bulk materials and the specimens were designated as K1 and K2. The presence of zeolitic phase within geopolymer network was examined by using of XRD, FTIR, and SEM-EDS technique. The mechanical properties of the resulting material were studied by means of compressive and tensile strength. The results showed that Gowa laterite soil was succesfully fabricated as zeolite-geopolymer hybrid bulk materials, and the type of zeolite coined with geopolymers were zeolite A in sample K1 and un-named zeolite in sample K2. The mechanical strengths of zeolite-geopolymers produced in this study were below to those of pure geopolymers.

Microwave assisted purification of multi-walled carbon nanotubes by potassium permanganate; effect of acid to oxidant molar ratio and treatment time

Carbon nanotubes (CNTs) benefit from excellent electrical and physical properties and they have attracted considerable interest in different applications like sensors and nanocomposites. Synthesized CNTs usually contain carbonaceous or metallic impurities which limit their beneficial properties. In this study, we experimentally investigate the effects of acid to oxidant molar ratio and treatment time on microwave-assisted purification of MWCNTs.Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images confirm that potassium permanganate (KMnO4) can eliminate impurities such as amorphous carbon and Fe nanoparticles. In addition, an empirical equation for KMnO4 consumption rate is determined based on the results. To sum up, the proposed method can be used as an effective purification route with acceptable removal of impurities.

Intensification of diesel oxidative desulfurization via hydrodynamic cavitation.

A Hydrodynamic Cavitation Assisted Oxidative Desulfurization (HCAOD) process was applied for treatment of diesel fuel feedstock using hydrogen peroxide and formic acid as the oxidant and catalyst, respectively. Investigation on the effect of main process variables including pressure drop (3-6 bar), time of treatment (10-30 min) and formic acid to oxidant molar ratio (nA/nO) (1-5), was performed through applying Response Surface Methodology (RSM) based on Box-Behnken design. Single and interactive effects of the parameters were recognized. A remarkable 95% extent of desulfurization at optimum conditions with HC pressure drop of 4.2 bar, acid to oxidant ratio (nA/nO) of 3.2 at 29 min was achieved. The results were also compared to an oxidation system without the aid of hydrodynamic cavitation. Accordingly, HCAOD can be considered as a promising treatment scheme for intensification of diesel oxidative desulfurization.

Phase Formation and Morphological Features of Calcium Copper Titanate by Modified Solid State Process

Perovskite calcium copper titanate posses giant dielectric constant making it a suitable candidate for possible applications in microelectronic components, advanced transistors, energy storage capacitors. Generally, this grade of material is synthesized by the chemical route to improving homogeneity, controlled size growth for enhanced properties. In the present research, a simple synthesis process was adopted using precursors of high purity oxides like Calcium carbonate, titania, Copper oxide without any use of complicated synthesis routes and costly chemical precursors. The molar ratio of oxides used was about 1:3:4 with mechano-chemical activation in an agate mortar for 20, 25 and 30 hours respectively in dry condition. After milling, powders obtained were made to undergo annealing at a fixed temperature of 900°C for 26 hours soaking period. Phase analysis was carried to determine the phase along with crystallite size calculation. Bonding information of the synthesized sample was analyzed to obtain the M-O coordination and vibration-stretching analysis of the bonds. Morphological features were also noted using FESEM (Field Emission Scanning Electron Microscopy) for understanding grains and granular boundaries. Both FTIR (Fourier Transform Infra-Red Spectroscopy) and XRD (X-Ray Diffractogram) analyses confirm the compound formation in terms of molecular structure responsible to obtain the proper phase.

Supported transition metal catalysts of Cu(II), Mn(II) and Co(II): synthesis, characterization, and catalytic behavior

A variety of heterogeneous transition metal Schiff base complexes have been prepared by their intercalation in layered double hydroxide, abbreviated as LDH-[SALABA-M] {where M is Cu, Mn and Co}. The synthesized catalysts are characterized by various analytical techniques like X-ray diffraction, Fourier transform infrared, scanning electron microscopy, transmission electron microscopy, inductive coupled plasma-atomic emission spectroscopy, thermogravimetric analysis, Brunauer–Emmett–Teller surface area etc. The aforesaid catalysts are employed for the oxidation of cyclohexene. Effect of various metals, substrate to oxidant molar ratio, temperature, and catalyst amount etc. have been studied so as to derive optimum conditions for obtaining maximum conversion. Tert-butyl hydroperoxide has been used as an oxidant in acetonitrile solvent. The oxidation products obtained are 2-cyclohexene-1-ol and 2-cyclohexene-1-one. The catalyst, LDH-[SALABA-Cu(II)] is recycled ten times in consecutive runs. Additionally, mechanism of reaction is found out using quenching study.

Comparison between catalytic activities of two zinc layered hydroxide salts in brilliant green organic dye bleaching

This paper reports the use of two layered hydroxide salts (LHS) (zinc hydroxide nitrate – ZHN – Zn5(OH)8(NO3)2·2H2O, and zinc hydroxide chloride – ZHC – Zn5(OH)8Cl2·H2O) as catalysts for brilliant green (BG) organic dye bleaching, using hydrogen peroxide as oxidant. The LHS were prepared by precipitation reaction between an aqueous solution of zinc salts and an aqueous ammonia solution. The solids were characterized by powder X-ray diffraction (XRD), electron paramagnetic resonance (EPR), ultraviolet-visible electronic spectroscopy (UV–Vis) and Fourier-transform infrared spectroscopy (FTIR). The catalytic activity of the solids was investigated at temperatures of 25, 35 and 45 °C, using different molar ratios of oxidant:dye:Zn2+ ions (present in the catalyst), in the absence and presence of ambient light. The kinetic aspect of the reaction was investigated considering that the reaction showed pseudo-first order behavior in relation to BG dye concentration. We propose a mechanism where superoxide radicals account for most of the bleaching taking place. The catalytic results obtained, along with the low cost and low toxicity of zinc compounds, establish ZHN and ZHC as novel catalysts for dye wastewater treatment, an area with constant demand for new methods and materials given its relationship with environmental equilibrium and human health.

Morphological and Optical Properties of Polypyrrole Nanoparticles Synthesized by Variation of Monomer to Oxidant Ratio

Abstract Among the conducting polymers, polypyrrole (PPY) has drawn a lot of interest due to its excellent environmental stability, ease of preparation and high conductivity. Here we have used chemical oxidative polymerization to synthesize PPY from its monomer pyrrole. We have studied morphological and optical properties of PPY samples by varying the monomer to oxidant molar ratio as 1:1.25 and 1:2 and denoted the samples by 1125ppy and 1200ppy respectively. The prepared samples are characterized by FTIR, UV-Vis, photoluminescence (PL) spectroscopy and FESEM. FTIR spectra reveal the required functional groups that should be present in PPY. From UV-Vis spectra, it is clear that the band gap of PPY changes due to the variation of monomer to oxidant ratio. There are two major absorption bands among which one is at about 350 nm for both the samples due to π-π* transition and another absorption band is at about 600nm for 1125ppy due to polaron band transition. The polaron band transition for 1200ppy is observed at about 650 nm. This redshift is due to the increased extent of oxidation induced by increasing the amount of oxidant. From the FESEM image, it is observed that agglomeration of particles increases with thedecreased monomer to oxidant ratio. As the ratio decreases the rate of oxidation increases and more cross-linked structure of polypyrrole is formed which resultsin more agglomerated structure. PL Spectra shows that 1125ppy has higher PL intensity than that of 1200ppy. Since agglomeration quenches PL intensity, the process is supported by our SEM results. So, PL intensity decreases with decreasing monomer to oxidant ratio

Hydrometallurgical processing of serpentine ore

Serpentine ore from the Eastern Desert of Egypt was leached with aqueous hydrochloric acid. Experimental statistical design program (ESD) was applied to study the influence of different variables on leaching efficiency (reaction temperature, leaching time and Hydrochloric acid (HCl) to Magnesium oxide (MgO) molar ratio (stoichiometry) where the liquid/solid ratio of 5:1 ml/g was maintained constant along the experiments. The mathematical model and the different contours (curves generated from ESD) were discussed. The results showed that, all the studied parameters are effective. The results have been collected at a 3-D cube showed that at high levels of parameters (4 hrs, 95 °C and 1.6 S), the Magnesium oxide recovery was about 96.5%, while M agnesium oxide recovery was 67.1% at the low levels (2 hrs, 65 °C and 1.4 Stoichiometry (S).

Solution combustion synthesis of nickel sulfide composite powders

Nickel sulfide powders were synthesized through solution combustion method using a suitable combination of thiourea fuel as reducing/sulfidizing agent with glycine fuel as auxiliary reductant agent. Effects of fuel contents on the combustion behavior, phase evolution, microstructure and optical properties were investigated by infrared spectroscopy, thermal analysis, X-ray diffractometry, electron microscopy and diffuse reflectance spectrometry techniques. Single phase NiS2 powders were formed using thiourea fuel at higher content, while a mixture of nickel sulfide phases was appeared in the presence of glycine fuel. The amount of different sulfide phases was considerably dependent on the thiourea content. Particle size of the as-combusted powders increased with the increase of thiourea; while the existence of glycine fuel together with thiourea led to the bulky microstructure. Maximum photodegradation (~ 56%) of methylene blue was achieved by as-combusted powders at a thiourea fuel to the oxidant molar ratio of 1, as a consequence of their high ability of light absorption.

Removal of cadmium (II) using CoFe2O4 powders synthesized by solution combustion method

Cobalt ferrite (CoFe2O4) powders were successfully prepared by solution combustion synthesis using metal nitrates as oxidant and glycine as fuel at various fuel to oxidant molar ratios (f=0.5, 0.75, 1 and 1.25). The structure, morphology and specific surface area of as-combusted CoFe2O4 powders were characterized by X-ray diffraction, scanning electron microscopy and nitrogen adsorption-desorption techniques. By increasing of fuel content, the specific surface area and pore volume decreased from 285 to 35 m2/g and 1.38 to 0.17 cm3/g, respectively. The as-combusted magnetic CoFe2O4 powders were used as adsorbent for removal of Cd(II). The effect of the contact time showed the kinetics of adsorption process followed the pseudo-second-order model and was controlled by film diffusion process. The adsorption isotherms were also well fitted on the Freundlich model. The as-combusted CoFe2O4 powders at f=0.75 exhibited excellent adsorption capacity (694 mg g−1) and high adsorption rate.

Insecticidal impact of alumina powders against Acanthoscelides obtectus (Say)

For long-term protection of stored products there is a growing demand to replace chemical insecticides due to their effects on human health and environmental safety. Particulate materials, such as inert dusts and various submicron and nanomaterials have been extensively tested as viable alternatives. This is the first study on the insecticidal impact of alumina powder (α-Al2O3) on the bruchid pest, Acanthoscelides obtectus (Say) (Coleoptera: Chrysomelidae: Bruchinae). By altering the fuel to oxidant molar ratio (F/O: 0.5, 0.8, 1.2) in an autocombustion reaction we synthesized alumina powders with specific surface area and particle size varying from the nano- to micron scale. It was found that particle morphology influenced survival and progeny number of A. obtectus. The order of powders from low to high efficacy in reducing beetle performance (F/O-0.8 < F/O-0.5 < F/O-1.2) correlated well with increase in surface area, pore volume and diameter, and decrease in particle size. Survival was also affected by time of exposure, the applied dose and sex. The estimated median lethal concentration of the most efficient powder F/O-1.2 was significantly lower in males (LC50 = 330.4 ppm) than in females (LC50 = 409.6 ppm). Our results suggest that alumina powder can be considered for seed protection against A. obtectus, particularly during long-term storage, as it is cost effective, exerts limited toxicity to humans and demands no repetitive use like conventional pesticides.

Iron Oxide to Mitigate Hydrogen Sulfide Gas Release from Gypsum-Bedded Dairy Manure Storages

Abstract. To mitigate noxious hydrogen sulfide (H2S) gas release that has been observed from gypsum-laden dairy manure, three additives were studied in sequential investigations. Three trials with specific aims were conducted using experimental vessels containing 15 kg of dairy manure each. Trial 1 investigated two additives: iron oxide (specifically, iron oxide-hydroxide, FeOOH) and a proprietary gypsum-lime based product (DriMatt). Trial 2 investigated effective ratios of gypsum to iron oxide and a modified DriMatt additive, and trial 3 evaluated iron oxide at the most effective ratio. Manure agitation events were monitored in the first two trials, while gas releases were continuously monitored in trial 3 during and between agitations. Hydrogen sulfide concentrations were captured using electrochemical sensors or a Fourier transfer infrared (FTIR) gas analyzer assembly over an incubation period of two months for the first two trials and over 40 days for the third trial. Additionally, nutrient analyses were performed for each trial. Extremely high concentrations of H2S were observed during most manure agitation events (500 to 8000 ppm), while minimum releases (&amp;lt;10 ppm) were found when samples were static. Means of maximum concentrations of H2S were compared among treatments in each trial. Statistical tests showed that adding iron oxide to gypsum-laden manure reduced H2S production by an average of 94% compared to treatments without iron oxide. With a 1:1 molar ratio of iron oxide to gypsum, the level of H2S released was diminished to as low as the control manure (without gypsum). Therefore, iron oxide is a promising additive to mitigate H2S production in gypsum-laden dairy manure during agitation events. Keywords: Additive, Dairy, Gas, Gypsum bedding, Hydrogen sulfide, Iron oxide, Manure, Safety, Storage.

Investigation on the formation mechanism of Ti-bearing non-metallic inclusions in Fe-Al-Ti-O-N alloy by inductive separation method

Formation mechanism of Ti-bearing non-metallic inclusions was studied by inductive separation method, and characterization method was selected according to the type of each inclusion. The Al+Ti oxide was heterogeneous consisting of Al2O3 with Ti rich oxide layer. Compositional and size distribution was characterized by automated SEM observation and EDS analysis. It is formed as the reduction of Al2O3 by Ti in molten alloy at 1873K. The Al-Ti oxide was homogenous. It was liquid at 1873K characterized by EBSD. The Al/Ti molar ratio of oxide was consistent with that in each alloy as analyzed by manual SEM/EDS analysis. Its formation mechanism is proposed to be the reaction among dissolved Ti, Al, and O in molten alloy at 1873K. TiN precipitated during solidification. The fraction of TiN smaller than 1μm was larger in alloy2 than that in alloy1 as analyzed by automated SEM/EDS analysis. It is resulted from larger supersaturation degree in alloy2 during solidification.

Homogenization Effect on Nanostructure and Conductivity of Polyaniline Nanofibre Synthesis by Mini-Emulsion Polymerization Technique

Nanofibre polyaniline (n-PANI) was synthesized by mini-emulsion polymerization technique between aniline monomer and ammonium persulfate as an oxidant using homogenizer. The synthesis was performed by optimizing mixing speed from 10,000 to 30,000 rpm and time reaction between 0.5 to 24 hours at fixed monomer to oxidant molar ratio 4:1. An attempt has been made to investigate on how the speed of homogenizer affects the size and conductivity of n-PANI. The formation of n-PANI chain was confirmed by Fourier transform infrared spectroscopy (FTIR). The X-ray diffraction (XRD) spectra revealed PANI crystalline nature. Hall effect measurement used indicated that the electrical conductivity of n-PANI is increased with homogenizer speed from 5.2 to 17.5 Scm-1. The morphological properties of n-PANI performed by scanning electron microscopy (SEM) show the decreasing size of n-PANI from 50-60 nm to 20-30 nm with the increment homogenizer speed. This study indicated the optimum speed parameter of homogenizer play a role in reducing the nanostructured size and thus, increasing the electrical conductivity of n-PANI.

Magnetic properties of Li0.5Fe2.5O4 nanoparticles synthesized by solution combustion method

In this research, lithium ferrite (Li0.5Fe2.5O4) powders were prepared by solution combustion synthesis using glycine and citric acid fuels at various fuel to oxidant molar ratios (ϕ = 0.5, 1 and 1.5). Phase evolution, microstructure and magnetic properties were characterized by thermal analysis, infrared spectroscopy, X-ray diffraction, electron microscopy and vibration sample magnetometry techniques. Single-phase lithium ferrite was formed using glycine fuel at all fuel to oxidant ratios, while some impurity α-Fe2O3 phase was appeared using citric acid fuel at ϕ ≥ 1. The phase and crystallite size mainly depended on the combustion rate through fuel type. Bulky microstructure observed for citric acid fuel was attributed to its slow combustion, while the fast exhausting of gaseous products led to spongy microstructure for glycine fuel. The highest saturation magnetization of 59.3 emu/g and coercivity of 157 Oe were achieved for the as-combusted powders using glycine fuel.

Study on the phase evolution of calcium oxide–silicon dioxide–water system incorporating sucrose under hydrothermal conditions

The effect of sucrose on the reaction mechanism and product properties of the calcium oxide–silicon dioxide–water (CaO–SiO2–H2O) system under hydrothermal conditions was investigated. The reaction products with varying calcium oxide to silicon dioxide molar ratio (Ca/Si), concentration of sucrose, reaction temperature and time were characterised by X-ray diffraction, thermogravimetric/differential scanning calorimetry, Fourier transform infrared spectroscopy, scanning electron microscopy and acid-insoluble residue analysis. The concentration of Ca2+, pH value and viscosity of the reaction solutions were determined and the influence mechanism of sucrose was then clarified. The results reveal that the phase composition and morphology of the products changed due to the incorporation of sucrose. There was a critical concentration of sucrose (e.g. the sucrose/calcium oxide molar ratio was 0·05 at Ca/Si = 0·8) for the formation of tobermorite. Sucrose promoted the formation of tobermorite when its concentration was lower than the critical value, and retarded the formation once its concentration exceeded the critical value. The morphology of tobermorite changed from plate-like to lath-like or lance-like as the concentration of sucrose increased. In the presence of sucrose, the transformation of tobermorite into xonotlite was inhibited at Ca/Si = 1·0 and the tobermorite phase remained stable even at higher reaction temperatures or for longer reaction times.