The Mechanism of Gelation of Latexes

1952 ◽  
Vol 25 (3) ◽  
pp. 596-608
Author(s):  
R. M. Panich ◽  
K. A. Kalyanova ◽  
S. S. Voyutskiĭ
Keyword(s):  
Zinc Oxide ◽  
Sodium Hydroxide ◽  
Strong Influence ◽  
Aqueous Ammonia ◽  
Ammonium Hydroxide ◽  
Ammonium Ion ◽  
Ammonium Ions ◽  
Alkali Solutions ◽  
Hydroxyl Ion ◽  
High Alkalinity

Abstract 1. The solubility of zinc oxide in ammonia and sodium hydroxide solutions was studied. In this case the presence of an ammonium salt in the system has a strong influence, and increases the solubility of zinc oxide, because the ammonium ion inhibits dissociation of ammonium hydroxide into NH4+ and OH− ions, and thus aids the formation of complex zinc-ammonium ions. We established that, in the 0–60° range, the temperature has little effect on the solubility of zinc oxide in aqueous ammonia. 2. The action of the zinc-ammonium ion on solutions of stabilizers of the soap type is explained, and it is shown that, at sufficiently high alkalinity, zinc-ammonium soaps do not precipitate from solution, but remain in a colloid state, stabilized by the alkaline soap or hydroxyl ion. 3. It is established that, in the absence of the ammonium ion, zinc oxide does not cause gelation of latexes stabilized by soaps. 4. The effect of formaldehyde on the gelation of latexes stabilized with soaps has been studied. 5. The reactions which can take place when zinc oxide is added to ammonia and alkali solutions, to ammonium and alkaline soap solutions, and to ammoniated and non-ammoniated latexes are discussed. A scheme of successive reactions which must take place during the gelation of latexes stabilized with soaps is presented.

scholarly journals Investigating the Effects of Surface Adsorbates on Gold and Palladium Deposition on Carbon

2021 ◽  
Author(s):  
Bethany Bowden ◽  
Josh A. Davies-Jones ◽  
Matthew Davies ◽  
Philip R. Davies ◽  
David J. Morgan ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Ammonium Hydroxide ◽  
Ammonium Ion ◽  
Metallic State ◽  
Chloroauric Acid ◽  
Final State ◽  
Ammonium Thiosulfate ◽  
Surface Adsorbates ◽  
Surface Hydroxyls ◽  
High Concentrations

AbstractSurface functional groups have a strong influence on the deposition and final state of nanoparticles adsorbed on to the surface, a role discussed by Professor Spencer in his work. This tribute to Spencer explores the formation of hydroxyls, thiosulfates, sulfites and sulfur atoms on carbon (HOPG) surfaces and their effect on the deposition of gold and palladium from aqueous solutions. Hydroxyls formed from ammonium hydroxide treatment have identical behaviour to those formed by acid treatment, and gold adsorption from Au3+ solutions gives Au0 initially, with Au3+ formed at higher concentrations on these surfaces. In contrast, palladium adsorption is hindered by the presence of the hydroxyls and there is no indication of any reduction to the metallic state. Ammonium thiosulfate adsorbs dissociatively from aqueous solutions on HOPG if the surface is pre-activated by the presence of surface hydroxyls. At low concentrations of ammonium thiosulfate, adsorbed sulfite and sulfur are formed in equimolar concentrations whereas adsorption of high concentrations of ammonium thiosulfate gives some degree of molecular adsorption, with evidence in XP spectra for an ammonium ion and a sulfur 2p peak at 282.9 eV attributed to the undissociated thiosulfate ion. Both sulfur and the sulfite are stable at the surface in neutral solutions but the sulfite desorbs when treated with acidified solutions (~ pH ≤ 6). These two groups are also stable at 373 K but begin to desorb by 473 K. Exposure to a weak chloroauric acid solution causes the desorption of the sulfite and formation of a gold species with an XP binding energy of 84.6 eV; we cannot determine from the present data whether this peak is due to a Au(I) state or very small nanoparticles of Au(0). Graphic Abstract

scholarly journals Molecular recognition of organic ammonium ions in solution using synthetic receptors

2010 ◽  
Vol 6 ◽  
Author(s):  
Andreas Späth ◽  
Burkhard König
Keyword(s):  
Molecular Recognition ◽  
Hydrophobic Interactions ◽  
Covalent Bond ◽  
Ammonium Ion ◽  
Synthetic Receptors ◽  
Ammonium Ions ◽  
Wide Range ◽  
Covalent Bond Formation ◽  
Reversible Covalent ◽  
Ion Receptors

Ammonium ions are ubiquitous in chemistry and molecular biology. Considerable efforts have been undertaken to develop synthetic receptors for their selective molecular recognition. The type of host compounds for organic ammonium ion binding span a wide range from crown ethers to calixarenes to metal complexes. Typical intermolecular interactions are hydrogen bonds, electrostatic and cation–π interactions, hydrophobic interactions or reversible covalent bond formation. In this review we discuss the different classes of synthetic receptors for organic ammonium ion recognition and illustrate the scope and limitations of each class with selected examples from the recent literature. The molecular recognition of ammonium ions in amino acids is included and the enantioselective binding of chiral ammonium ions by synthetic receptors is also covered. In our conclusion we compare the strengths and weaknesses of the different types of ammonium ion receptors which may help to select the best approach for specific applications.

THE KINETICS OF THE REACTION OF SILICA WITH GROUP I HYDROXIDES

1961 ◽  
Vol 39 (6) ◽  
pp. 1221-1230 ◽  
Author(s):  
J. G. Hooley
Keyword(s):  
Silica Glass ◽  
Maximum Rate ◽  
Inverse Function ◽  
Ammonium Ion ◽  
Water Addition ◽  
Group I ◽  
Hydroxyl Ion ◽  
Naoh Solution ◽  
Ion Size ◽  
Glass Surfaces

A method is presented for preparing a reproducible silica glass or quartz surface that does not craze during rate of solution measurements in solutions of the five group I hydroxides. For silica glass, initial rates are a maximum at 8 M for at least NaOH and KOH and are an inverse function of ion size for the five cations and tetramethyl ammonium ion. A proposed mechanism of water addition followed by reaction with hydroxyl ion is used to explain the maximum rate and the effect of solution products and the substitution of methanol for water as a solvent. For quartz an explanation is offered for the lower rate and for the absence of a maximum rate below 27 M NaOH. A common temperature coefficient of 20 kcal mole−1 is reported for all reactions in water. The crazing of finely ground or polished silica glass surfaces is related to the presence of surface cracks and their enlargement by possible conversion of some silica to quartz in NaOH solution.

Effect of Calcium on the Solubility of Zinc Oxide in the Sodium Hydroxide Solution

2013 ◽  
pp. 257-263
Author(s):  
Chen Ai-liang ◽  
Xu Dong ◽  
Chen Xing-yu ◽  
Liu Xu-heng ◽  
Zhu Wei-xiong
Keyword(s):  
Zinc Oxide ◽  
Sodium Hydroxide ◽  
Sodium Hydroxide Solution ◽  
Hydroxide Solution

Orally Ingested Microencapsulated Urease and an Adsorbent, Zirconium Phosphate, to Remove Urea in Kidney Failure

1987 ◽  
Vol 10 (4) ◽  
pp. 269-274 ◽  
Author(s):  
E.A. Wolfe ◽  
T.M.S. Chang
Keyword(s):  
Renal Function ◽  
Zirconium Phosphate ◽  
Intestinal Tract ◽  
Ammonium Ion ◽  
Ammonium Ions ◽  
Dialysis Therapy ◽  
Dialysis Treatment ◽  
In Series ◽  
Removal System

Dialysis is the conventional treatment for chronic renal failure. It is cumbersome, expensive and time-consuming and thus alternate treatments have long been sought. A compact system consisting of haemoperfusion in series with ultrafiltration can nearly replace dialysis. A urea removal system is the only step required to complete this approach. The potential of combining a microencapsulated enzyme, urease, with an ammonium ion adsorbent, zirconium phosphate, to remove urea was examined in vitro. Urease converts urea to ammonium ions which are then adsorbed on-to zirconium phosphate. This combination would be most effective in the intestinal tract. The capacity of zirconium phosphate is probably not enough to effect the removal of enough urea to completely replace dialysis in patients with no renal function. However, this system could potentially 1) delay the onset of dialysis therapy in patients who still have some renal function, either alone or in combination with haemoperfusion-ultrafiltration, or 2) reduce dialysis treatment times.

Urea treatment as a means of preserving/processing moist wheat for intensively finished cattle

1999 ◽  
Vol 1999 ◽  
pp. 54-54 ◽  
Author(s):  
M. Lewis ◽  
B.G. Lowman ◽  
M. Ford
Keyword(s):  
Sodium Hydroxide ◽  
Dry Matter ◽  
Aqueous Ammonia ◽  
Wheat Variety ◽  
Urea Solution ◽  
Processing Methods ◽  
Urea Treatment

Wheat requires processing for feeding to cattle otherwise large amount remain undigested. Processing methods can be mechanical or chemical (sodium hydroxide or aqueous ammonia) but these require specialised equipment and/or the use of contractors. The objective of this trial was to evaluate moist wheat fed whole, but treated with urea at harvest as a means of generating ammonia in situ, in diets for intensively finished cattle.Eighty tonnes of wheat (variety Riband) was harvested on 21-22 August 1997 at a dry matter (DM) of 750 g/kg and treated immediately with 53 l/tonne of a urea solution (430 g urea/litre) to supply 30 g urea/kg wheat DM. Treatment was achieved by applying the urea to the wheat as it was augered into the storage silo, which was then sealed with polythene.

scholarly journals Synthesis of the anhydrides of α-aminoacyl glucosamines

1913 ◽  
Vol 88 (605) ◽  
pp. 455-461 ◽  
Keyword(s):  
Amino Acids ◽  
Sodium Hydroxide ◽  
Aqueous Ammonia ◽  
Degradation Products ◽  
Amino Sugars ◽  
Amino Group ◽  
Glucosamine Hydrochloride ◽  
Aliphatic Acids ◽  
Condensation Products

The behaviour of the albumin glucosides and the mucus bodies known as mucins, mucinogens, mucoids , and hyalogens , on hydrolysis suggests the probability that these complex proteins would bear the same relation to the condensation products of the sugars or the amino-sugars with the amino-acids as the simpler proteins bear to the polypeptides. Consequently, the authors decided two years ago to make a start in the synthesis of the glucoproteins by preparing the condensation products of glucosamine with the amino-aliphatic acids, in order that their properties and behaviour towards ferments could be ascertained and compared with those of the degradation products of the glucoproteins and thereby throw some light on the constitution of these complex and important organic bodies. After many failures, the method of synthesis which we eventually adopted for the condensation of glucosamine with amino-aliphatic acids was somewhat similar to one of the methods employed by Emil Fischer and his co-workers in the synthesis of the polypeptides. In brief, the method consists in condensing α -bromoacyl haloids with glucosamine hydrochloride in the presence of sodium hydroxide, and then displacing the halogen in the resulting α -bromoacyl glucosamines by an amino-group through the action of cold aqueous ammonia, viz:- α -Bromoacyl Haloid + Glucosamine Hydrochloride. sodium ↓ hydroxide. α -Bromoacyl Glucosamine. aqueous ↓ ammonia. Anhydride of α -Aminoacyl Glucosamine.

In-Situ Leaching of South Texas Uranium Ores-Part 2: Oxidative Removal of Adsorbed Ammonium Ions With Sodium Hypochlorite

1983 ◽  
Vol 23 (02) ◽  
pp. 387-396 ◽  
Author(s):  
J.M. Paul ◽  
W.F. Johnson ◽  
A. Fletcher ◽  
P.B. Venuto
Keyword(s):  
Cation Exchange ◽  
Sodium Hypochlorite ◽  
Geographical Area ◽  
Ammonium Bicarbonate ◽  
South Texas ◽  
Ion Concentration ◽  
Ammonium Ion ◽  
Side Reactions ◽  
Ammonium Ions

Abstract This paper reports a laboratory study of the oxidative destruction by sodium hypochlorite (NaOCl) of ammonium ions adsorbed on relatively reduced south Texas uranium ore. Included are an assessment of reaction stoichiometry, determination of some major reaction pathways and side reactions, and identification of several pathways and side reactions, and identification of several intermediates. Adsorbed ammonium ions were completely removed by 0.5 % NaOCl, with the concentration of NH3 in the effluent falling to a very low value after 10 to 15 PV NaOCl oxidant. A small fraction (5 to 10%) of NaOCl was utilized in reacting with NH3. After the NH3 was nearly depleted, mono-, di-, and trichloramines, the expected intermediates in NaOCl oxidation of NH3, were observed. Chloramine decomposition studies showed that all three decomposed completely within 12 days. Since the ore was relatively highly reducing, the major pan of the NaOCl was, not unexpectedly, consumed in side reactions. Substantial quantities of sulfate, reflecting oxidation of sulfide minerals such as pyrite, were formed, large amounts of uranium were leached out, and substantial amounts of calcium and magnesium ions were also produced during the presaturation with NH4HCO3 preceding the oxidation stage. Introduction A leachate that has sometimes been used for in-situ leaching of uranium ores is a solution of ammonium bicarbonate (NH4HCO3) containing an oxidant-usually hydrogen peroxide (H2O2) or oxygen (O2). The ammonium ion (NH4+) introduced into the ore body upon injection of this leachate is exchanged for cations such as calcium (Ca+2 ) and sodium (Na+), which are associated with mineral species in the formation possessing available cation exchange sites. As the indigenous groundwaters reinvade the leached zone, the adsorption process is reversed with NH4+ ions being displaced from process is reversed with NH4+ ions being displaced from the cation exchange sites and returned to the ground-waters. In general, this latter process maintains the ammonia (NH3 (or NH4+ ion) concentration well above the baseline (pre-mining) value in groundwater for extended periods of time in waters produced from wells in or near the mined zone following cessation of leachate injection. Prior to abandonment of an in-situ leach-mining site by the operator, satisfactory restoration of groundwater quality must be demonstrated. Requirements for this demonstration vary with the geographical area. A summary of applicable regulations has been provided by Kasper et al. A review of the state of restoration demonstrations to Sept. 1979 has been given by Tiepel. Most of the in-situ leach operations in south Texas have been conducted in aquifers containing indigenous waters with TDS contents in the 700- to 3,000-ppm range. Ca+ 2, magnesium (Mg+2), and bicarbonate ion (HCO3 ) concentrations are high in these slightly alkaline waters. These equilibrium water compositions indicate that an appreciable fraction of the interlayer ion exchange sites of the smectite clays in the formation are occupied by Ca+2 or Mg+2 ions. SPEJ P. 387

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