Ammonium peroxydisulfate oxidative chemical

Electropolymerization in acidic media affords free-standing films that are believed to contain varying degrees of cross-linking [267,292,304]. The miscibility of aniline with water allows for a variety of aqueous oxidants, such as ammonium peroxydisulfate, to be used [305]. Chemical polymerization of aniline can also be performed in chloroform through the use of tetrabutyl ammonium periodate [306]. Accordingly, a number of alkyl [301] and alkoxy-substituted [307] aniline derivatives have been chemically polymerized. Unfortunately, functionalization of the aniline nucleus often leads to a decrease in performance in the resulting polymers [308,309]. 

Polyaniline was first prepared at the turn of the century. Several oxidation states are known. The conductivity and the color of the material vaiy progressively with oxidation. Only one form, however, known as the emeraldine salt, is truly conducting. The material can be prepared readily by either electrochemical or chemical oxidation of aniline in aqueous acid media. Common oxidants, such as ammonium peroxydisulfate, can be used. Flexible emeraldine films can be cast from solutions of A methylpyrrolidone and made conductive by protonic doping. This is done by dipping the films in acid or exposing them to acid vapors. The process results in protonation of the imine nitrogen atoms ... 

Aniline was the first example of the conjugated polymers doped by proton, it can be chemically oxidized by ammonium peroxydisulfate (APS). PANI has the advantages of easy synthesis, low-cost, proton doping mechanism, and is controlled by both oxidation and protonation state. Polyanilines are commonly prepared by the chemical or electrochemical oxidative potymerization of the respective monomers in acidic solution. But, other potymerization techniques have also been developed, including ... 

Chemical oxidation polymerization in dilute and semi-dilute solutions of poly(sodium 4-styrenesulfonate) (PSS) was demonstrated for the synthesis of PANI nanocolloids (particle size ca. 2-3 nm) [271]. A similar approach was performed to synthesize PANI nanoparticles using ammonium peroxydisulfate in aqueous medium comprising poly(fi-caprolactone)-PEO-poly(e-caprolactone) amphiphiUc triblock copolymer micelle [272]. Micelle size conspicuously affects the morphology of the PANI nanoparticle, and the PANI nanoparticle size is strongly dependent on PEO molecular weight. The diameter of the nanoparticle increased from 30 nm to lOOnm as the PEO molecular weights decreased. 

In addition, one-phase smfactant-assisted chemical method has been utilized to synthesize PANI nanofiber, which was doped with CSA and 2-acrylamido-2-methyl-l-propanesulfonic acid, in large quantities [291]. A chemical oxidative polymerization of aniline has been carried out using ammonium peroxydisulfate as an oxidizing agent in the presence of nonionic surfactant. A precipitate of doped emeraldine salt is composed of PANI nanofiber, which has the diameter of 30-50 nm and exhibits the conductivity of 1 -5 S cm at RT. Another piece of research has been done through chemical oxidation polymerization of aniline in a surfactant gel, which was formed by a mixture of hexadecyltrimethylammonium chloride, acetic acid, anihne, and water at - 7 °C [292]. The dendritic PANI nanofiber has the diameter of 60-90 nm and the length of 1 -2 jim. Extended works have been performed by the electrospinning method [293]. It should be taken into account that PANI-CSA fiber shape could be influenced by the synthetic variables such as solvent, surface tension, viscosity, and solution conductivity. 

The emeraldine salt form of conventional polyaniline was chemically synthesized from aniline by oxidative polymerization using ammonium peroxydisulfate in an acidic media (7). Washing the salt form with 0.1 M ammonium hydroxide produces the emeraldine base form of polyaniline. Conventional polyaniline solutions were prepared in hexafiuoroisopropanol (HFIP), at a concentration of 2 mg/mL, or in A -methylpyrrolidinone (NMP), at a concentration of 1 mg/mL. 

The compound o-anisidine was polymerized chemically in air by oxidative polymerization. A 21.60 g sample (0.17 mol) of o-anisidine (Aldrich) was dissolved in 1 M hydrochloric acid and cooled in an ice bath at 5 deg C. Ten grams of ammonium peroxydisulfate (0.4 mol, Fisher) were dissolved in 200 mL of 1 M hydrochloric acid at 5 deg C and placed in a separatory funnel above the o-anisidine solution to facilitate drop-wise addition. The cunmonium peroxydisulfate solution was slowly introduced into the o-anisidine solution over an approximately 10 minute period with constant stirring. After 1 hour of stirring at 5 deg C, the solid PANIS was filtered out, rinsed with 1 M hydrochloric acid, rinsed with distilled water, and dried under dynamic vacuum at 60 deg C. The yield of dark, emerald green crystalline product was 3.6 g (16.7%). A pressed pellet of PANIS powder exhibited a two probe resistance of less than 5 ohms when checked with an ohmmeter. 

Polvfaniline) and oob/(pyrrole) Typical, simple, "in-a-beaker" syntheses of poly(pyrrole) and poly(aniline) may now be illustratively described. Both involve use of a chemical oxidant to generate a radical cation from the monomer, which initiates the polymerization. In the case of poly(pyrrole), 2.5 M of FeCla, the oxidant, is taken in MeOH. Pyrrole (liquid) is then added slowly with stirring and cooling, in a ca. 2 5 pyrrole/FeCla molar ratio. The polymer so obtained is filtered, washed and dried. In the case of poly(aniline), aniline (liquid) is taken either neat or on a substrate, and mixed with oxidant solution, which is typically 0.1 M ammonium peroxydisulfate in 2 M HCl. The solution is cooled in an ice bath to 0 C, while stirring for several hours. The polymer obtained is washed, usually with MeOH, and dried. Variations of even these simple procedures involve use of other solvent media, e.g. acetonitrile/water mixtures, and other oxidants, e.g. CUBF4. 

As described briefly in Chapter 1, the more common typical chemical polymerization is relatively simple, involving monomer and an oxidant (usually also the dopant) in a suitable solvent medium, frequently aqueous, and temperatures in the region of -20 °C to 4-80 °C. Thus for instance, a 0.25 M solution of an oxidant such as ammonium peroxydisulfate ((NH4)2S20g) is added with stirring to a solution of 0.5 M aniline monomer in 0.5 M aqueous /7-toluene sulfonic acid solution (dopant electrolyte) at room temperature. As reaction temperature rises, the reaction bath is cooled with an ice-bath. After 2 hrs of stirring, the polymer is filtered, washed with dopant electrolyte solution, and dried in vacuo at 60 C. An optional procedure of Soxhlet extraction may be used for further purification. The polymer is then neutralized with 2 M NH4OH to yield the emeraldine base form of P(ANi). 

Direct chemical oxidation (DCO) is an ex situ treatment technology that uses acidified ammonium or sodium peroxydisulfate solutions to oxidize and destroy organic solids, liquids, and sludges. Acidified peroxydisulfate is one of the strongest oxidants available. It is equal in strength to ozone and exceeded only by fluorine and oxyfluorides. The process is designed to operate within the aqueous phase at low temperatures and ambient pressure. 

PANI and its derivatives can be synthesized by the electrochemical polymerization or chemical polymerization of aniline although some other approaches have also been reported such as solid-state polymerization [313], electroless polymerization [314], plasma polymerization [315], and emulsion polymerization [307], Various oxidants were used for oxidation of aniline monomer, such as ammonium peroxy-disulfate, sodium peroxydisulfate, potassium bichromate, and hydrogen peroxide. 

Our recent surface analyses of powdered activated carbon [5] has been extended to the more regularly defined surfaces exhibited by ACC. These adsorbents often display a "memory" in that their physical and chemical resistance submits to various solvents, albeit to a lesser extent than their parent (un-carbonised) material. We treated two microporous ACC samples with an excessive aqueous oxidizing agent, 4M NaOH, and milder conditions provided by 10 % (w/vol) aqueous ammonium and potassium peroxydisulfates solutions. The oxidation differently affects the distribution of surface carbon-oxygen structures, leading to different adsorption behaviour of ACC samples. 

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