EFFECT OF IRON ON THE NATURE OF PRECIPITATION PRODUCTS OF ALUMINUM

1987 ◽  
Vol 67 (1) ◽  
pp. 135-145 ◽  
Author(s):  
TEE BOON GOH ◽  
M. J. DUDAS ◽  
S. PAWLUK ◽  
P. M. HUANG
Keyword(s):  
Molar Ratio ◽  
Ambient Conditions ◽  
Crystalline Materials ◽  
Molar Ratios ◽  
Iron Aluminum ◽  
Initial Ph ◽  
Oxide Phases ◽  
Key Words Iron ◽  
Rate Of Hydrolysis ◽  
Mixed Systems

Solutions Of AlCl3 (5 × 10−3 mol L−1) and FeCl2 were mixed and aged for 3 yr under ambient conditions at the initial pH of 7.0 and Fe:Al molar ratios of 0, 0.1, 0.3, 0.5 and ∞ (Fe at 5 × 10−3 mol L−1). Fe2+ was readily oxidized in this experiment so that only the mutual interaction between Fe3+ and Al3+ can be reported. The initial Fe:Al molar ratio was an important parameter in determining the rate and amount of hydrolysis and precipitation of Fe and Al. At Fe:Al molar ratios ≤ 0.3, hydrolysis was delayed when compared to that in pure Al suspensions. At higher ratios more acidity was produced by hydrolytic reactions. The acidity was contributed by both Al and Fe. The fractions of Fe and Al precipitated were greater at lower Fe:Al molar ratios. Aluminum and iron were mutually interfering cations during crystallization. In mixed systems, the fractions of crystalline materials were greatly reduced. Between the crystalline compounds, gibbsite was more abundant than bayerite and this evolution was governed by pH and the interference of Fe on the subsequent rate of hydrolysis and crystallization. Iron substitution was not evident in the crystalline Al(OH)3 polymorphs. Crystalline Fe oxides could not be detected even at the Fe: Al molar ratio of 0.1. Two discrete oxide phases were formed in the mixed Fe-Al systems consisting of crystalline Al(OH)3 and a mixed Fe-Al oxide of indeterminate composition. In the pure ferric suspension, maghemite was formed. The results presented are used to explain the distribution of aluminum hydroxide polymorphs in soil and the genesis of gibbsite and iron oxide containing horizons of Oxisols. Key words: Iron, aluminum, gibbsite, bayerite, maghemite, Fe-Al surface coatings

Optimization of Bioscorodite Crystallization for Treatment of As(III)-Bearing Wastewaters

2017 ◽  
Vol 262 ◽  
pp. 555-558 ◽  
Author(s):  
Masahito Tanaka ◽  
Tsuyoshi Hirajima ◽  
Keiko Sasaki ◽  
Naoko Okibe
Keyword(s):  
Molar Ratio ◽  
Seed Crystals ◽  
Molar Ratios ◽  
Initial Ph ◽  
Applicable Range ◽  
Acidianus Brierleyi ◽  
The Stability ◽  
Reaction Speed

Arsenic (As) is a major impurity contaminated in metal refinery wastewaters. To immobilize As ions, we have previously reported microbial scorodite (FeAsO4·2H2O) crystallization using the thermo-acidophilic iron-oxidizing archaeon, Acidianus brierleyi. In order to extend the applicable range of As (III)-bearing metal refinery wastewaters (especially for dilute As (III) concentrations of 250–1500 ppm), this study investigated the effect of several factors possibly affecting the bioscorodite crystallization efficiency; (i) [Fe (II)]ini/[As (III)]ini molar ratio at different target As (III) concentrations, (ii) initial pH, and (iii) seed scorodite with different morphologies. The [Fe (II)]ini/[As (III)]ini molar ratio strongly affected the bioscorodite crystallization efficiency at each target As (III) concentration. Whilst the [Fe (II)]ini/[As (III)]ini molar ratio of 1.4 was most effective at 500–1500 ppm As (III), the optimal molar ratios for treating more dilute concentrations (< 500 ppm) were shown to be relatively higher. However, further increasing the [Fe (II)]ini/[As (III)]ini molar ratio resulted in formation of unwanted potassium jarosite (KFe3(OH)6(SO4)2) together with scorodite. Lowering the initial pH from 1.5 to 1.2 resulted in earlier scorodite nucleation, but lesser overall As immobilization. Feeding chemical-and bio-scorodite seed crystals differently affected the reaction speed and the stability of newly-precipitated bioscorodite. The TCLP test indicated that scorodite formed on bioscorodite seeds is more stable than that formed on chemically-synthesized scorodite seeds.

scholarly journals Synthesis of nanostructured conducting polyaniline in the presence of 5-sulfosalicylic acid

2008 ◽  
Vol 62 (3) ◽  
pp. 107-113 ◽  
Author(s):  
Aleksandra Janosevic ◽  
Gordana Ciric-Marjanovic
Keyword(s):  
Molecular Structure ◽  
Oxidative Polymerization ◽  
Average Diameter ◽  
Polymerization Process ◽  
Molar Ratio ◽  
Sulfosalicylic Acid ◽  
Molar Ratios ◽  
Reaction Solution ◽  
Initial Ph ◽  
Constant Molar Ratio

Oxidative polymerizations of aniline with ammonium peroxydisulfate in aqueous solution of 5-sulfosalicylic acid (SSA), were performed at the constant molar ratio [oxidant]/[monomer] = 1.25, by using various initial molar ratios of SSA to aniline. It was shown that the ratio [SSA]/[aniline] has a crucial influence on the molecular structure, morphology, and conductivity of synthesized polyaniline5-sulfosalicylate (PANI-SSA), as well as on the yield and temperature profile i.e. the mechanism of polymerization process. The yield of PANI-SSA was 80 - 86% for [SSA]/[aniline] ratios in the range 0.25-1.0. Granular PANI-SSA was obtained by the oxidative polymerization of in situ formed anilinium 5-sulfosalicylate ([SSA]/[aniline] = 1.0). The initial induction period was followed by the rapid exothermic polymerization of aniline during the oxidation of anilinium 5-sulfosalicylate with peroxydisulfate. Nanostructured PANI-SSA was synthesized by the oxidation of the mixture of dianilinium 5-sulfosalicylate and aniline ([SSA]/[aniline] = 0.25), which proceeds in two exothermic phases well separated with an athermal period. The presence of nanocylinders (nanorods, possibly nanotubes), with the average diameter of 95-250 nm and the length of 0.5-1.0 ?m has been revealed by scanning electron microscopy. It was concluded that PANI nanocylinders are formed when reaction solution has the initial pH > 3.5. Electroconductivity of synthesized polyanilines was in the range 0.01-0.17 S cm-1, and it increases with increasing molar ratio of SSA to aniline. Molecular structure of synthesized polyanilines was investigated by FTIR spectroscopy. Besides the characteristic bands of standard PANI in emeraldine form (benzenoid, quinonoid, and semiquinonoid units), the band attributable to substituted phenazine structural units was observed at -1415 cm-1 in the FTIR spectrum of nanostructured PANI-SSA sample.

Kinetics of hydrolysis of peroxodisulphate ions in acidic medium to peroxomonosulphuric acid

1981 ◽  
Vol 46 (5) ◽  
pp. 1229-1236 ◽  
Author(s):  
Jan Balej ◽  
Milada Thumová
Keyword(s):  
Ionic Strength ◽  
Rate Constants ◽  
Acidic Medium ◽  
Measured Data ◽  
Molar Ratios ◽  
Starting Solution ◽  
Kinetics Of Hydrolysis ◽  
Rate Of Hydrolysis ◽  
Kinetics Of ◽  
Hydrolysis Of

The rate of hydrolysis of S2O82- ions in acidic medium to peroxomonosulphuric acid was measured at 20 and 30 °C. The composition of the starting solution corresponded to the anolyte flowing out from an electrolyser for production of this acid or its ammonium salt at various degrees of conversion and starting molar ratios of sulphuric acid to ammonium sulphate. The measured data served to calculate the rate constants at both temperatures on the basis of the earlier proposed mechanism of the hydrolysis, and their dependence on the ionic strength was studied.

scholarly journals Photocatalytic Reduction of CO2 to Methanol Using a Copper-Zirconia Imidazolate Framework

Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 346
Author(s):  
Sonam Goyal ◽  
Maizatul Shima Shaharun ◽  
Ganaga Suriya Jayabal ◽  
Chong Fai Kait ◽  
Bawadi Abdullah ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Catalyst Support ◽  
Oxidation Potential ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Molar Ratios ◽  
Optimum Parameters ◽  
Reduction Of Co2 ◽  
Enhanced Yield

A set of novel photocatalysts, i.e., copper-zirconia imidazolate (CuZrIm) frameworks, were synthesized using different zirconia molar ratios (i.e., 0.5, 1, and 1.5 mmol). The photoreduction process of CO2 to methanol in a continuous-flow stirred photoreactor at pressure and temperature of 1 atm and 25 °C, respectively, was studied. The physicochemical properties of the synthesized catalysts were studied using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectroscopy. The highest methanol activity of 818.59 µmol/L.g was recorded when the CuZrIm1 catalyst with Cu/Zr/Im/NH4OH molar ratio of 2:1:4:2 (mmol/mmol/mmol/M) was employed. The enhanced yield is attributed to the presence of Cu2+ oxidation state and the uniformly dispersed active metals. The response surface methodology (RSM) was used to optimize the reaction parameters. The predicted results agreed well with the experimental ones with the correlation coefficient (R2) of 0.99. The optimization results showed that the highest methanol activity of 1054 µmol/L.g was recorded when the optimum parameters were employed, i.e., stirring rate (540 rpm), intensity of light (275 W/m2) and photocatalyst loading (1.3 g/L). The redox potential value for the CuZrIm1 shows that the reduction potential is −1.70 V and the oxidation potential is +1.28 V for the photoreduction of CO2 to methanol. The current work has established the potential utilization of the imidazolate framework as catalyst support for the photoreduction of CO2 to methanol.

A novel separation method of the valuable components for activated clay production wastewater

2021 ◽  
Vol 19 (1) ◽  
pp. 530-540
Author(s):  
Lvshan Zhou ◽  
Tongjiang Peng ◽  
Hongjuan Sun ◽  
Dong Fu ◽  
Chuan Lai
Keyword(s):  
Aluminum Phosphate ◽  
Iron Phosphate ◽  
Acid Sites ◽  
Precipitation Method ◽  
Molar Ratio ◽  
Precipitation Process ◽  
Iron Aluminum ◽  
Phosphorus Iron ◽  
Optimized Conditions ◽  
Acidic Wastewater

Abstract The acidic wastewater produced by the wet production of activated clay contains valuable components such as iron and aluminum. The precipitation method was successfully introduced to separate iron and aluminum from the activated clay production wastewater step by step, which can not only recover the valuable components, but also avoid environmental pollution. In the separation process, gypsum, iron aluminum phosphate, alumina, and sodium sulfate were prepared, and the phase compositions of separation products were analyzed by XRD and IR. The main influencing factors in the separation of iron and aluminum components were studied by single factor experiment. The results show that at the optimized conditions, phosphorus/iron molar ratio 6.0, the system pH 3.0, the reaction temperature 343 K, and the reaction time 90 min, the iron(iii) ion in the system can form a sodium-containing aluminum iron phosphate double salt, and the filtrate after separating Fe3+ and part of Al3+ can meet the requirements for forming high-purity Al2O3. During the phosphate precipitation process, the hypothesis should be correct that Al3+ reacts with PO 4 3 − {\text{PO}}_{4}^{3-} to form an AlPO4 skeleton, Fe3+ isomorphically replaces Al3+ in the [AlO4] tetrahedron, and adsorption occurs simultaneously, with Na+ occupying the terminal acid sites, P(Al)–OH.

scholarly journals Lipozyme 435-Mediated Synthesis of Xylose Oleate in Methyl Ethyl Ketone

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3317
Author(s):  
Maria Carolina Pereira Gonçalves ◽  
Jéssica Cristina Amaral ◽  
Roberto Fernandez-Lafuente ◽  
Ruy de Sousa Junior ◽  
Paulo Waldir Tardioli
Keyword(s):  
Oleic Acid ◽  
Methyl Ethyl Ketone ◽  
Molar Ratio ◽  
Methyl Ethyl ◽  
Sugar Ester ◽  
Molar Ratios ◽  
Emulsion Capacity ◽  
Ping Pong ◽  
Commercial Sugar ◽  
Repeated Use

In this paper, we have performed the Lipozyme 435-catalyzed synthesis of xylose oleate in methyl ethyl ketone (MEK) from xylose and oleic acid. The effects of substrates’ molar ratios, reaction temperature, reaction time on esterification rates, and Lipozyme 435 reuse were studied. Results showed that an excess of oleic acid (xylose: oleic acid molar ratio of 1:5) significantly favored the reaction, yielding 98% of xylose conversion and 31% oleic acid conversion after 24 h-reaction (mainly to xylose mono- and dioleate, as confirmed by mass spectrometry). The highest Lipozyme 435 activities occurred between 55 and 70 °C. The predicted Ping Pong Bi Bi kinetic model fitted very well to the experimental data and there was no evidence of inhibitions in the range assessed. The reaction product was purified and presented an emulsion capacity close to that of a commercial sugar ester detergent. Finally, the repeated use of Lipozyme 435 showed a reduction in the reaction yields (by 48 and 19% in the xylose and oleic acid conversions, respectively), after ten 12 h-cycles.

Degradation of chlorpyriphos in water by advanced oxidation processes

2010 ◽  
Vol 10 (1) ◽  
pp. 1-6 ◽  
Author(s):  
R. Murillo ◽  
J. Sarasa ◽  
M. Lanao ◽  
J. L. Ovelleiro
Keyword(s):  
Reaction Time ◽  
Light Source ◽  
Advanced Oxidation Processes ◽  
Advanced Oxidation ◽  
The Other ◽  
Molar Ratio ◽  
Optimum Conditions ◽  
Oxidation Processes ◽  
Other Hand ◽  
Initial Ph

The degradation of chlorpyriphos by different advanced oxidation processes such as photo-Fenton, TiO2, TiO2/H2O2, O3 and O3/H2O2 was investigated. The photo-Fenton and TiO2 processes were optimized using a solar chamber as light source. The optimum dosages of the photo-Fenton treatment were: [H2O2]=0.01 M; [Fe3 + ]=10 mg l−1; initial pH = 3.5. With these optimum conditions total degradation was observed after 15 minutes of reaction time. The application of sunlight was also efficient as total degradation was achieved after 60 minutes. The optimum dosage using only TiO2 as catalyst was 1,000 mg l−1, obtaining the maximum degradation at 20 minutes of reaction time. On the other hand, the addition of 0.02 M of H2O2 to a lower dosage of TiO2 (10 mg l−1) provides the same degradation. The ozonation treatment achieved complete degradation at 30 minutes of reaction time. On the other hand, it was observed that the degradation was faster by adding H2O2 (H2O2/O3 molar ratio = 0.5). In this case, total degradation was observed after 20 minutes.

Preparation of CuO Nanopowder in Aqueous Solution by Applying Ultrasonic and its CO Gas Sensitivity

2007 ◽  
Vol 544-545 ◽  
pp. 901-904 ◽  
Author(s):  
Ji Bum Yang ◽  
Tae Gyung Ko ◽  
Sang Jin Jung ◽  
Jae Hee Oh
Keyword(s):  
Aqueous Solution ◽  
Gas Sensing ◽  
Spherical Shape ◽  
Particle Morphology ◽  
High Yield ◽  
Ambient Conditions ◽  
Gas Sensitivity ◽  
Molar Ratios ◽  
Naoh Solution ◽  
Co Gas

We report on a process in which CuO nanopowder was produced in a high yield by adopting ultrasonic in aqueous solution. In our experiment, CuCl2 solution was reacted with NaOH solution and NaNO2, at ambient conditions applying ultrasonic for 5 min. Precipitation was performed by varying the molar ratios of NaOH/CuCl2 and NaNO2/CuCl2. CuO nanoparticles of ~ 5 nm and spherical shape were obtained at the NaOH/CuCl2 of 2.0 and the NaNO2/CuCl2 of 0.097. Without ultrasonication, an amorphous phase was formed at these conditions. This indicates that sonochemical reaction facilitates direct formation of the nanosized CuO particles. In addition, the particle morphology varied from sphere through ellipsoid to needle forms depending on pH. In thick films prepared with the CuO powder for gas sensing, the maximum CO gas sensitivity reached 93 % at the temperature of 250 °C and depended linearly on CO concentration in log scale over the range of 10 ~ 104 ppm.

Appearance, corrosion properties, and leach resistance of spruce and pine wood treated with Mea modified micronized copper preservative (MCu)

Holzforschung ◽  
2014 ◽  
Vol 68 (4) ◽  
pp. 477-486 ◽  
Author(s):  
Myung Jae Lee ◽  
Sedric Pankras ◽  
Paul Cooper
Keyword(s):  
Wood Species ◽  
Wood Preservative ◽  
Molar Ratio ◽  
Corrosion Properties ◽  
Pine Wood ◽  
Molar Ratios ◽  
Copper Leaching ◽  
Mold Resistance ◽  
Refractory Wood

Abstract Canadian refractory wood species treated with micronized copper (MCu) wood preservative become mottled and streaky in appearance. To overcome this issue, the MCu system was modified by adding small amounts of monoethanolamine (Mea). The modified systems were evaluated to clarify the role of Mea in terms of leaching, corrosion, and mold resistance of MCu systems. The mottled and streaky surface on treated spruce was prevented at Mea/Cu molar ratios between 0.7 and 1.5. Copper leaching remained modest and was only slightly higher than that of MCu alone up to a Mea/Cu molar ratio of 1.2. However, adding even a small amount of Mea to the MCu formulation increased fastener corrosion compared with MCu. Protonated Mea increased as more Mea was added and was identified as the main corrosion-causing electrolyte in the system.

Hydrogen-bonded bent-core blue phase liquid crystal complexes containing various molar ratios of proton acceptors and donors

RSC Advances ◽  
2016 ◽  
Vol 6 (38) ◽  
pp. 32319-32327 ◽  
Author(s):  
Chun-Chieh Han ◽  
Yu-Chaing Chou ◽  
San-Yuan Chen ◽  
Hong-Cheu Lin
Keyword(s):  
Liquid Crystal ◽  
Chain Length ◽  
Alkyl Chain ◽  
Alkyl Chain Length ◽  
Chiral Center ◽  
Molar Ratio ◽  
Core Complex ◽  
Molar Ratios ◽  
Phase Liquid ◽  
Blue Phase

The molar ratio, alkyl chain length, lateral fluoro-substitution and the chiral center of H-bonded bent-core supramolecules would affect the BP ranges of BPLC complexes. H-bonded bent-core complex PIIIC9/AIIF* (3/7 mol mol−1) displayed the widest BPI range of ΔTBPI = 12 °C.

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