Separation of sodium chromate from high alkaline media based on precipitation transformation using barium hydroxide

2020 ◽  
Vol 44 (28) ◽  
pp. 12048-12057
Author(s):  
Xiaoyu Tang ◽  
Haifeng Wu ◽  
Xuejun Quan ◽  
Chengfei Feng ◽  
Gang Li ◽  
...  
Keyword(s):  
Barium Hydroxide ◽  
Alkaline Media ◽  
Precipitation Process ◽  
Sodium Chromate ◽  
High Concentration ◽  
Naoh Solution

Separation and recovery of chromium from a high-concentration NaOH solution by a Ba(OH)2 precipitation process.

Preparation of Silicalite-1 Membranes on α-Al2O3 Tubes and its Concentration Performance of Low Ethanol/water Mixtures

2012 ◽  
Vol 608-609 ◽  
pp. 1337-1341
Author(s):  
Hong Liang Chen ◽  
Ji Song Yang ◽  
Yan Wang ◽  
Hui Ying Li ◽  
Xin Xin Li ◽  
...  
Keyword(s):  
Hydrothermal Synthesis ◽  
Solution Concentration ◽  
High Concentration ◽  
Separation Selectivity ◽  
Naoh Solution

Silicalite-1 membranes were successfully synthesized on α-Al2O3 tubes by in-situ hydrothermal synthesis after filling the tubes with water and glycerol mixtures, and all the membranes show high concentration performance towards ethanol/water mixtures after pretreating tubes with different NaOH solution. The results show that the flux enhances with the enhancement of NaOH solution concentration, but the separation selectivity decreases with the enhancement of NaOH solution concentration. After pretreating the α-Al2O3 tubes with different NaOH solution, the weight of all the α-Al2O3 tube decreases, but the Si/Al ratio increases, which shows that suitable pretreatment of α-Al2O3 is useful for improving the hydrophobicity of silicalite-1 membranes.

scholarly journals Preparation of Calcium Stannate from Lead Refining Dross by Roast–Leach–Precipitation Process

Minerals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 283 ◽  
Author(s):  
Dixiu Wu ◽  
Junwei Han ◽  
Wei Liu ◽  
Fen Jiao ◽  
Wenqing Qin
Keyword(s):  
Precipitation Process ◽  
Lead Smelter ◽  
Solid Ratio ◽  
Lead Refining ◽  
Average Grain Size ◽  
Naoh Solution ◽  
Leaching Solution ◽  
Leaching Parameters ◽  
Optimized Conditions ◽  
Calcium Stannate

Lead refining dross containing plenty of tin and other heavy metals, such as lead and antimony, is considered a hazardous waste generated in large quantities in lead smelter plants. In this study, calcium stannate was synthesized from lead refining dross using sodium carbonate roasting and alkaline leaching followed by precipitation with CaO. The effect of roasting and leaching parameters on the extraction efficiency of tin was investigated. The leaching efficiency of tin reached 94% under the optimized conditions: roasting with 60% Na2CO3 at 1000 °C for 45 min, and leaching using 2 mol/L NaOH solution for 90 min at 85 °C and 8 cm3/g liquid/solid ratio. Furthermore, more than 99% of tin in the leaching solution was precipitated using CaO. Finally, XRD, SEM, and ICP-OES analyses indicated that the final CaSnO3 product had a purity of 95.75% and its average grain size was smaller than 5 μm. The results indicated that the developed method is feasible to produce calcium stannate from lead refining dross.

The sorption of zinc species by clay minerals

1976 ◽  
Vol 29 (8) ◽  
pp. 1649 ◽  
Author(s):  
H Farrah ◽  
WF Pickering
Keyword(s):  
Ion Exchange ◽  
Alkaline Media ◽  
Precipitation Process ◽  
Zinc Ions ◽  
Clay Suspension ◽  
Acidic Media ◽  
Apparent Affinity ◽  
Charged Species ◽  
Nucleation Centre

The effect of changes in pH and the presence of ligands on the uptake of zinc ions by three types of clay mineral (kaolinite, illite and montmorillonite) has been investigated. In alkaline media the clay suspension acts as a nucleation centre for polymeric hydroxy species, and the major role of many ligands is to mask the precipitation process. Uncharged and negatively charged species are not sorbed to any measurable extent. In acidic media the adsorption capacity of the clays for zinc increases with pH and possible mechanisms are considered. For kaolinite and illite the controlling process appears to be the attachment of hydroxy species to particular sites on the particle edges; with montmorillonite ion exchange at negative lattice sites appears predominant. Of particular interest is the apparent affinity between montmorillonite and species containing nitrogen functional groups.

scholarly journals Comparison of three methods for rendering plant fat transesterification

2013 ◽  
Vol 59 (No. 2) ◽  
pp. 51-55
Author(s):  
A. Prošková ◽  
J. Kučera ◽  
Z. Kopicová ◽  
L. Škarková
Keyword(s):  
Fatty Acids ◽  
Free Acid ◽  
The Other ◽  
Alkaline Media ◽  
Optimum Temperature ◽  
Optimum Conditions ◽  
High Concentration ◽  
Reaction Velocity ◽  
Catalysed Reaction ◽  
The Difference

Three most frequently used methods for fat transesterification were compared using rendering plant fat (RPF) as model. Acid-catalysed transesterification was found to be the most effective (conversion 90%) at optimum conditions (fat: methanol ratio 1:10, sulphuric acid amount of 2% v/v, temperature 95°C). Base-catalysed transesterification of RPF on the other hand, results in much lower conversion (45%) at optimum conditions (fat:methanol ratio 1:20, NaOH amount 8% w/v, optimum temperature 95°C). The difference is done (among others) by the fact that RPF has high concentration of free acid (high acidity number) compared with the fats usually used for transesterification and that free acids are not esterified in alkaline media. Enzyme-(lipase) catalysed reaction could lead to partial esterification of free fatty acids, but with much lower reaction velocity. This fact leads to higher conversion in the case of enzyme-catalysed transesterification of RPF compared with base-catalysed reaction; nevertheless, even in this case the conversion is much lower in comparison with acid-catalysed reaction. The optimum conversion in enzyme-catalysed reaction was 55%.  

Thermal Activation on Phase Formation of Alkaline Activated Kaolin Based System

2013 ◽  
Vol 770 ◽  
pp. 262-266 ◽  
Author(s):  
Somsak Boonjaeng ◽  
Kedsarin Pimraksa ◽  
Arnon Chaipanich ◽  
Sutin Kuharuangrong ◽  
Prinya Chindaprasirt
Keyword(s):  
Calcium Silicate ◽  
Calcium Silicate Hydrate ◽  
Thermal Activation ◽  
Pozzolanic Reaction ◽  
Zeolite X ◽  
High Concentration ◽  
Phase Development ◽  
Naoh Solution ◽  
Calcium Aluminosilicate ◽  
Alkali Activated

The research aim was to investigate phase development after pozzolanic reaction between metakaolin (MK) and calcium hydroxide (CH) with alkaline and thermal activations. The CH to MK ratio (C/M) of 0.4 generating CaO/SiO2 of 1.18 was selected in this study. Various concentrations of NaOH solutions (0.01, 0.1, 1, 3, 5 and 10 M) were used. The alkali activated samples were thermally activated at 25 °C, 70 °C, 90 °C and 130 °C for 4 h. Phase development under thermal activation of alkali activated metakaolin based system were investigated. At every temperature, C/M mixtures with 0.01 and 0.1 M NaOH promoted the formations of poorly crystalline calcium silicate hydrate (C-S-H(I)) and calcium aluminosilicate hydrate (CASH) compounds. With 3 and 5 M NaOH activations, sodium aluminosilicate hydrate (NASH) and sodium calcium silicate hydrate (NCSH) was formed. 1 M NaOH was found to be a boundary of phase transformation from C-S-H(I) and CASH to NASH and NCSH. In addition, zeolite X and sodalite appeared when NaOH solution reached 10 M. Thermal activation significantly affected phase development at high concentration of alkaline activation (1-10 M). At 1 M NaOH, NASH compounds in a form of gmelinite and zeolite ZK-14 were found at 70-90 °C. At 3-5 M, katoite was found at 70-130 °C. At 10 M, zeolite X was found at 70-90 °C. Sodalite was also found at 130 °C with 10 M NaOH.

scholarly journals Use of silver–bentonite in sorption of chloride and iodide ions

2020 ◽  
Vol 326 (3) ◽  
pp. 1795-1804
Author(s):  
Dóra Buzetzky ◽  
Noémi M. Nagy ◽  
József Kónya
Keyword(s):  
Interlayer Space ◽  
Exchange Process ◽  
Silver Ions ◽  
Exchange Capacity ◽  
Chloride Ions ◽  
Precipitation Process ◽  
High Concentration ◽  
Iodide Ions ◽  
Ion Exchange Process ◽  
Increasing Temperature

AbstractAg–bentonite was prepared by ion exchange process to sorb iodide and chloride ions in batch experiments. The modified bentonite was examined with XRF and XRD. 75% of the cation exchange capacity was exchanged by silver ions. It was found that the sorption of chloride ions is an exothermic precipitation process because the solubility decreases with increasing temperature. In the case of iodide sorption, the dissolution of AgI was observed under high concentration of non-radioactive iodide ions, which is well known in analytical chemistry. The phenomenon occurs not only in the bulk aqueous phase but also in the interlayer space of montmorillonite.

scholarly journals Corrosion Inhibition of Al-Si-Cu Alloy in the Basic Media by UsingSix Inhibitors at Four Temperatures

2008 ◽  
Vol 5 (3) ◽  
pp. 427-436
Author(s):  
Baghdad Science Journal
Keyword(s):  
Sodium Sulphate ◽  
Inorganic Materials ◽  
Sodium Oxalate ◽  
Effect Of Temperature ◽  
Sodium Chromate ◽  
Solution Ph ◽  
Protection Efficiency ◽  
Cu Alloy ◽  
Naoh Solution ◽  
Polarization Behaviour

The research involved attempt to inhibit the corrosion of Al-Si-Cu alloy in 2.5x10-3 mol.dm-3 NaOH solution (pH=11.4) by addition of six different inhibitors with three concentrations (1x10-3, 1x10-2, and 0.1 mol.dm-3). These inhibitors include three organic materials (sodium acetate, sodium benzoate, and sodium oxalate) and three inorganic materials (sodium chromate, disodium phosphate, and sodium sulphate). The data that concerning polarization behaviour are calculates which include the corrosion potential (Ecorr) and current density (icorr), cathodic and anodic Tafel slopes (bc & ba), and polarization resistance (Rp). Protection efficiency (P%) and activation energy (Ea) values were calculated for inhibition by the six inhibitors. The results indicated the effect of temperature on the inhibition in basic media.

Octadecylphosphonic Acid Self-Assembled Monolayers as Lubricant Coatings Stable in Alkaline Media

2004 ◽  
Vol 847 ◽  
Author(s):  
J. Soullier ◽  
P. Tordjeman ◽  
P. H. Mutin
Keyword(s):  
Alkaline Media ◽  
Self Assembled Monolayers ◽  
Water Contact ◽  
Force Microscopy ◽  
Assembled Monolayers ◽  
Naoh Solution ◽  
Self Assembled ◽  
The Stability ◽  
Planar Substrates ◽  
Octadecylphosphonic Acid

ABSTRACTThe formation of octadecylphosphonic acid self-assembled monolayers (SAMs) on titanium deposited by cathodic sputtering on planar substrates has been studied by water contact angle measurements and Atomic Force Microscopy (AFM). Dense monolayers were obtained after one week of reaction. Tribological experiments indicated that these monolayers had good lubricating properties, which were maintained after immersion in a 1 M NaOH solution at 65 °C for up to 100 min. The stability in alkaline media of octadecylphosphonic acid SAMs on titanium was ascribed to the high chemical stability of Ti-O-P interfacial bonds.

Effect of Halide Anions on Anodic Behaviour and Passivation of Copper in Alkaline Media

1996 ◽  
Vol 61 (1) ◽  
pp. 85-92 ◽  
Author(s):  
Sayed S. Abd El Rehim ◽  
Essam E. Foad
Keyword(s):  
Pitting Corrosion ◽  
Passive Layer ◽  
Alkaline Media ◽  
Anode Surface ◽  
Alkali Concentration ◽  
Halide Anions ◽  
Instantaneous Nucleation ◽  
Cyclic Voltammetric Curve ◽  
Naoh Solution ◽  
Anodic Behaviour

The effect of Cl- and Br- on the anodic behaviour and passivation of copper metal in NaOH solution has been investigated by a potentiodynamic technique complemented with XPS analysis. In halide free solutions, the anodic polarization curves involve three anodic peaks correlated to the electroformation of Cu2O, CuO and Cu(OH)2 on the anode surface. The presence of these species in the passive layer has been confirmed by XPS examination. An addition of the halide anions enhances the peak currents of anodic peaks and tends to rupture the passive layer inducing the pitting corrosion. The critical pitting potentials decrease with rising halide concentration while the alkali concentration has an opposite effect. The accelerating effect of Cl- to pitting corrosion is greater than that of Br-. The pitting corrosion was explained by an instantaneous nucleation and growth of anion salt nuclei. Three cathodic peaks on cyclic voltammetric curve were assigned to the electroreduction of pitting corrosion products, Cu(II) and Cu(I) oxides, respectively.

scholarly journals Green-Synthesis of Anisotropic Peptone-Silver Nanoparticles and Its Potential Application as Anti-Bacterial Agent

Polymers ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 271 ◽  
Author(s):  
Min Kim ◽  
Seung-Cheol Jee ◽  
Surendra K. Shinde ◽  
Bhupendra M. Mistry ◽  
Rijuta Ganesh Saratale ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Protein Hydrolysate ◽  
Synthesis Method ◽  
Morphological Observation ◽  
High Concentration ◽  
Economic Significance ◽  
Bacterial Agent ◽  
Green Route ◽  
Naoh Solution ◽  
Mic Minimum Inhibitory Concentration

This study demonstrates a green-route-based synthesis of high-concentration suspensions of anisotropic silver nanoparticles (AgNPs) by peptone (Pep), a soluble protein hydrolysate and an abundantly used nutrient source in microbial-media. The transformation of Ag ions from solution into a high-concentration suspension of anisotropic Pep-AgNPs, at an extremely low concentration of peptone (0.02%), indicates that the present green-route synthesis method follows “low volume high concentration nano-synthesis”, and, hence, enhances the economic significance of the process. Process optimization with different concentrations of AgNPs (1–5 mM), NaOH solution (5–40 mM), and peptone (0.004%–0.12%) gave the optimized Pep-AgNPs synthesis at 3 mM of AgNO3, 20 mM of NaOH, and 0.02% of the peptone concentrations. The green-route synthesized Pep-AgNPs were structurally characterized by the TEM, XPS, FT-IR, and XRD analyses. The Pep-AgNPs against the clinically relevant bacteria Escherichia coli and Staphylococcus aureus gave significant anti-bacterial properties, with a MIC (minimum inhibitory concentration) of 100 ppm. The colony counting and morphological observation of the bacterial cell under SEM corroborated an anti-bacterial potential of the Pep-AgNPs. Therefore, Pep-AgNPs are green-route synthesized, anisotropic, and have a significant anti-bacterial potential that can be used in many relevant applications.

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