An amphoteric Ion-permselective membrane

A membrane made by reacting sulphochlorinated polyethylene with 1-amino-3-dimethylamino-propane containing water, was found to be amphoteric: about $\text{5}\text{6}$ of its capacity was due to dimethylamino groups while sulphonic acid groups accounted for the remaining $\text{1}\text{6}$ of its capacity. In acid the dimethylamino groups are ionised and the membrane behaves as a week anion-selective membrane. In alkali the aminogroups are deionised and the sulphonic acid groups are set free to make the membrane cation-active.These changes in ionisation with pH have the following consequences: (1)The membrane de-swells in length and in weight in its isoelectric region between pH 8–11. (2)The electric resistance increases by 3–4 orders of magnitude in this pH region as against both acid and strongly basic pH solutions. (3)In acid solutions the membrane is anion-selective, crosses the neutrality line at about pH 10 and becomes cation-selective in strongly basic solutions. (4)In the open states, that is in acid and strongly basic solutions, the membrane hardly distinguishes between the ion pairs Cl^- and SO⁼₄ or Na⁺ and K⁺. However, in the closed, high resistance, region Cl^- is transferred 7–8 times more easily than SO⁼₄. The difference between transference of the two alkali ions remains slight. (5)A bipolar (sandwich) membrane made with adjoining layers of the above-mentioned membrane and a layer of polyethylene sulphonic acid was prepared. This sandwich rectifies the current in acid solutions but has a low, voltage-independent, resistance in strong alkali where it ceases to be bipolar and changes into a cation-selective membrane. It has a high, voltage-independent, resistance in its isoelectric region where the amphoteric side is uncharged and represents a high series-resistance beside the low resistance cation-selective layer.     

Adsorption and desorption of complex metal ions in polyviologen or its polyion complexes with poly(sulphonate)s by the control of a given potential

Complex anions and a complex cation were concentrated electrostatically in the domain of polyviologen by the control of a given potential. Pyrolytic graphite electrodes were coated with polyviologen or the polyion complex of polyviologen with poly (sulphonic acid) for the concentration of complex anions or the complex cation, respectively. In an aqueous solution in which Mo(CN)^4?₈ and Fe(CN)^4?₆ coexisted, the polyviologen-coated electrode predominantly concentrated Mo(CN)^4?₈. Furthermore, the Mo(CN)^4?₈ incorporated in the film was desorbed by reducing the charge density of polyviologen. The desorption rate was proportional to the charge density of polyviologen which depended on a given potential. On the other hand. Ru(NH₃)³⁺₆ was adsorbed in the domain of the polyion complex of polyviologen with poly (sulphonic acid) and it was desorbed completely in a few seconds by reducing the overall charge density of the polyion complex. Generally, reversible adsorption-desorption of multivalentions could be performed by changing the given potential if redox-active sites were fixed or chemically bonded in the polymer matrix. Redox-active polymers were stabilized by polyion complex formation with oppositely charged polyelectrolytes.     

THE EXTRACTION OF RHODIUM FROM AQUEOUS NITRIC ACID BY DINONYLNAPHTHALENE SULPHONIC ACID

The extraction of rhodium from aqueous nitric acid using dinonylnapthalene sulphonic acid has been investigated. The extraction occurs readily from 0.1M to 1.0m nitric acid and, since the rhodium is extracted as [Rh(H₂O)₆] ³⁺into the inverted micelles of the organic solution,equilibration times are less than 5 minutes. Extraction is enhanced by the addition of nitrite ion to form [Rh(H₂O)₅NO₂] ²⁺as the extracted species.     

Fragmentation of Fluorinated Model Compounds Exposed to Oxygen Radicals: Spin Trapping ESR Experiments and Implications for the Behaviour of Proton Exchange Membranes Used in Fuel Cells

Low‐molecular weight model compounds (MCs) for Nafion membranes used in fuel cells were exposed at 300 K to ^·OH radicals produced by UV irradiation of aqueous H₂O₂ solutions. The MCs contained fluorinated and partially fluorinated groups terminated by sulphonic or carboxylic acid groups. The fragmentation process in the MCs was studied by spin trapping electron spin resonance (ESR) methods, using 5,5‐dimethylpyrroline‐N‐oxide (DMPO), N‐tert‐butyl‐α‐phenylnitrone (PBN) and 2‐methyl‐2‐nitrosopropane (MNP) as the spin traps. The objective of these experiments was to assess the effect of the type of ionic groups (sulphonic or carboxylic) and of fluorine substitution on the spin adducts detected. DMPO experiments led to the detection of spin adducts of ^·OH and of carbon‐centred radicals (CCRs), and allowed the determination of the ^·OH attack site on the ionic and/or on the protiated or fluorinated groups. CCR adducts were also detected when using PBN as a spin trap; a key point in the interpretation of the PBN results was, however, the realisation that MNP is formed during PBN exposure to UV irradiation and oxygen or other oxidants such as H₂O₂. Experiments with MNP as the spin trap were the most informative in terms of structural details for adducts obtained from each MC. The results allowed the identification of CCRs present as adducts, based on large hyperfine splittings (hfs) from, and the number of, interacting ¹⁹F nuclei; in addition, oxygen‐centred radicals (OCRs) as MNP adducts were also identified, with much lower hfs from ¹⁹F nuclei. Taken together, the results deduced by spin trapping suggest that both sulphonic acid and acetic acid groups can be attacked by ^·OH radicals and confirm two possible degradation mechanisms in Nafion membranes: initiated at the backbone and at the side chain.     

Synthesis and Structural Elucidation of NSC Auxiliary Dispersing Agents

The synthesis, characterization, structural elucidation, and application of the dispersant (NSC) obtained from condensation of β-naphthalene sulphonic acid and formaldehyde are described. The one pot process from naphthalene, sulphuric acid, and formaldehyde leads to reproducible condensate products with n = 13 and 14 naphthalene nuclei. The ¹H and ¹³C NMR spectra were recorded in D₂O (representative spherical shape) and DMSO (representative rod-like shape). Bleaching leads to the recovery of excellent super pure material.     

Preparation of PANI–PVA composite film with good conductivity and strong mechanical property

The polyaniline (PANI)–polyvinyl alcohol (PVA) conductive composite films [doped with hydrochloride (HCl), dodecylbenzene sulphonic acid and amino sulphonic acid (NH₂SO₃H) aqueous solution] were synthesised by ‘in situ’ polymerisation, and their conductivities were compared. Among these composite films, HCl–PANI–PVA composite film possessed the highest conductivity that reached 1360?S·m^??1 [w_(PVA)?=?40%]. Meanwhile, the effects of PVA content, HCl concentration, oxidant ammonium persulphate (APS) dosage, reaction time and film drying temperature on tensile strength of the HCl–PANI–PVA composite films were studied. The tensile strength of the film was improved greatly due to effective mixture of PANI and PVA. When the PVA content was 40%, C_(HCl)?=?1.0?mol·L^??1, reaction time was 4.0?h, n_(APS)/n_(aniline)?=?1.0 and film drying temperature was 80°C, and the tensile strength of the HCl–PANI–PVA composite film reached the maximum of 60.8?MPa. At the same time, the structure of composite materials was characterised and analysed through ultraviolet spectrum and SEM.     

A novel palladium complex catalyst for carbonylation of alkynes under mild conditions

Carbonylation of alkynes has been carried out using a catalyst system consisting of Pd(OAc)₂, a monophosphine, p‐toluene sulphonic acid and semilabile anionic bidentate ligands such as pyridine or piperidine carboxylic acids. Turnover frequencies (TOF) upto 3500 h⁻¹ and 98% selectivity to 2‐substituted 2‐propenoic acid/ester have been achieved under mild CO pressures of 1–3 atm at 373 K. This revised version was published online in July 2006 with corrections to the Cover Date.     

Untersuchungen zur Sulfochlorierung von Paraffinen. VII. Untersuchungen über die Chlorierung von definierten Alkansulfochloriden

Studies on Sulphochlorination of Paraffins. VII. Studies on the Chlorination of Individual Alkane Sulphochlorides The products of the chlorination of individual C₂–C₆ alkane sulphochlorides were studied by means of ¹³C-n.m.r. spectroscopy. In no case a geminal chloro sulphochloride could be found, and only in very few cases chlorination at vicinal C H-bonds took place. As in the sulphochlorination of alkane sulphochlorides the C H-bonds geminal and vicinal to the sulphochloride group are strongly descativated. The results of ¹³C-n.m.r. analyses were confirmed by the results of gaschromatography of the sulphonic acid dimethyl amides, formed by the reaction of the chlorination mixtures with dimethyl amine.     

Corrosion inhibition of mild steel in acidic medium by poly (aniline-co-<Emphasis Type="Italic">o</Emphasis>-toluidine) doped with <Emphasis Type="Italic">p</Emphasis>-toluene sulphonic acid

The corrosion behaviour of mild steel in 0.5 M H₂SO₄ solution containing various concentrations of a p-toluene sulphonic acid doped copolymer formed between aniline and o-toluidine was investigated using weight loss, polarization and electrochemical impedance techniques. The copolymer acted as an effective corrosion inhibitor for mild steel in sulphuric acid medium. The inhibition efficiency has been found to increase with increase in inhibitor concentration, solution temperature and immersion time. Various parameters like E _a for corrosion of mild steel in presence of different concentrations of inhibitor and ΔG _ads, ΔH ⁰, ΔS ⁰ for adsorption of the inhibitor, revealed a strong interaction between inhibitor and mild steel surface. The adsorption of this inhibitor on the mild steel surface obeyed the Langmuir adsorption equation.     

Effect of hydroxyl and nitrate ions on the sorption of ammonium ions by sulphonic cation exchangers

The sorption of ammonium ions and ammonia by the H+ form of sulphonic acid cation exchangers Amberlite 252, Lewatit 2629 and Relite C 360 from a solution containing NH₄NO₃ in the range of 0 to 0.214 equ/L and NH₃ in the range of 0.353 to 0 equ/L was investigated to establish the possibility of their application for the recovery of ammonium from caustic condensate generated in nitrogen fertilizer production. Breakthrough and elution curves were obtained, determining the concentration of ammonium with Nessler's reagent. The sorption of ammonium and ammonia depends on the concentration ratio of ammonia to ammonium nitrate [NH₃]/[NH₄NO₃]. On decreasing [NH₃]/[NH₄NO₃], the concentration ratio of hydroxyl to nitrate ions [OH⁻]/[NO⁻₃] and the effluent pH prior to NH⁺₄ breakthrough also decrease. This results in a decrease in the NH⁺₄ sorption because of a deficiency in the neutralization of hydrogen ions released (ordinary cation-exchange process). Thus, adverse circumstances create an unfavorable medium for NH⁺₄ removal from the caustic condensate. Maximum sorption of NH⁺₄ is attained at [NH₃]/[NH₄NO₃] ∼1.2. A further decrease in [NH₃]/[NH₄NO₃] is followed by a significant decrease in the effluent pH, which leads to an increase in the concentration of protonated sulphonic acid groups (-SO₃H), resulting in a decrease in the ion-exchange ability of the cation exchangers under investigation with respect to NH⁺₄ removal. The concentration (g/L) of NH₄NO₃ in the eluate from the cation-exchanger regeneration, carried out using 0.7 bed volumes (BV) of 20% HNO₃, amounts to 136.7 for Relite C 360, 119.5 for Lewatit K 2629 and 96.7 for Amberlite 252. The content of undamaged beads after 100 cycles (each cycle comprises saturation with caustic condensate, containing ammonia and ammonium, successive regeneration with 20% nitric acid and washing) is from 97 to 99.8%. Resistance to boiling in 20% HNO₃ solution is from 97 to 99.8%. These are applicable for the recovery of NH₄NO₃ from the caustic condensate in the nitrogen fertilizers production, preventing economic damage and environmental contamination from nitrogen compounds.     

Untersuchungen zur Sulfochlorierung von Paraffinen. IV. Über die Sulfochlorierung von Isobutan

Studies on Sulphochlorination of Paraffins. IV. On the Sulphochlorination of Isobutane In the sulphochlorination of isobutane at −20 to −10°C a mixture of 20–25% tert.-butyl and 75–80% of isobutyl sulphochlorides is formed. The mixture has been analyzed by ¹H- and by ¹³C-n.m.r.-spectroscopy. It is possible to transform the mixture of sulphochlorides into mixtures of the corresponding sulphonates, sulphonic acid methyl esters or sulphonic acid demithylamides. During the work-up of the sulphochlorination mixtures it is necessary to keep the temperature low, because tertiary butyl sulphochloride is desulphonated at a noticeable rate already at temperatures above 35°C.     

A simple method for graphene production based on exfoliation of graphite in water using 1-pyrenesulfonic acid sodium salt

In this work we use a chemical approach based on supra-molecular and non-covalent interactions between graphene and 1-pyrenesulfonic acid sodium salt (Py–1SO₃) to obtain a stable dispersion of graphene by using only water as solvent. The material has been characterized by a combination of spectroscopic and microscopic techniques. In particular, an extensive Raman analysis shows that we have ∼70% few-graphene layers (<7). We also show that the exfoliation efficiency strongly depends on the number of functional groups by comparing suspensions obtained by Py–1SO₃ and 1,3,6,8-pyrenetetrasulfonic acid (Py–4SO₃). A strong decrease in the exfoliation yield has been observed by using pyrene with 4 sulphonic groups (Py–4SO₃), as compared to one sulphonic group (Py–1SO₃). Being completely water-based, these suspensions can be used as inks for printable tattoo-based electro-chemical sensors.     

Dielectric properties of sulphonated polystyrene

Polystyrene was sulphonated with chlorosulphonic acid and the dielectric properties of the films were measured as a function of degree of sulphonation and water content at 27°C at frequencies of 10³ to 10⁶ Hz. The sulphonated samples have a high dielectric constant as compared to the unsulphonated polystyrene. The hydration of polystyrene sulphonic acid is a stepwise process.     

The acid catalysed condensation of phenol-4-sulphonic acid with formaldehyde

The reaction products formed when phenol-4-sulphonic acid reacts with formaldehyde have been investigated using ¹H and ¹³C nuclear magnetic resonance. It is shown that the reaction does not proceed readily at high phenol-4-sulphonic acid: formaldehyde ratios. As the ratio is decreased evidence of reaction is observed and further decreases lead to crosslinking. The crosslinking reaction is explained in terms of desulphonation and electrophilic substitution of the sulphonic acid group by a hydroxymethylene carbonium ion.     

The application of ozonation for the detoxification and biodegradability improvement of a textile auxiliary: Naphtalene sulphonic acid

From the environmental point of view, the textile industry dealing with operations such as fibre and fabric preparation, dyeing, finishing, printing etc. can be identified among the very chemical intensive sectors. Therefore the characterisation and management of textile auxiliaries within aqueous dyehouse effluents are becoming a challenging responsibility for the textile manufacturer. Although there is much speculation about the types and quantities of these chemicals released to the environment during textile manufacturing, there are only few data about the behaviour of these chemicals both in receiving water bodies and in wastewater treatment systems. Besides current understanding of industrial pollution control emphasizes the relevance of segregated stream management. This issue gains a further importance when segregated effluent streams containing auxiliaries with xenobiotic nature are considered.In this context the objective of the present study is to investigate the effect of ozonation on the toxicity and biodegradability of a naphthalene sulphonic acid derivative commonly applied in textile mills. The naphthalene sulphonic acid derivative prepared to simulate the actual situation in a dyebath discharge from a textile finishing industry has a COD of 1150 mg/l and a BOD of 10 mg/l, and pH of 5.5. Due to the highly soluble characteristic of the sulphonic groups the sample is completely soluble in nature. Ozonation experiments [conducted under the following conditions: 1200 mgO₃/h and 2400 mgO₃/h both at pH 5 and pH 11; 5325 mgO₃/h at both pH 12 and at the original pH (pH = 5.5)] show that the application of 5325 mgO₃/h ozone for 30 min at original pH can be considered as the optimum condition which is further evaluated in terms of inert COD fractions and acute toxicity. According to the experimental findings, raw naphtalene sulphonic acid derivative has an inert COD content of 1027 mg/l. With ozone application of 30 min 5325 mgO₃/h at original pH the inert COD concentration can be reduced down to 295 mg/l. The molecular weight cut-off experiments indicate that 58% of the COD originates from the 10 kDa-30 kDa fraction for the raw naphtalene sulphonic acid derivative. Due to chemical degradation under ozone, the fraction with the highest COD shifted to the < 1 kDa range for the ozonated naphtalene sulphonic acid derivative. Since the results related to the acute toxicity (in 50% v/v EC values) towards the marine algae Phaeodactylum tricornutum indicate that the toxicity of the formulation under investigation is increased considerably, it is recommended to run a further investigation by the use of another chemical oxidant instead of ozone.     

Characterization of polyazomethines in dilute solution. Correlation between the light scattering parameters and the u.v.-visible absorption spectrum

The high values 1 (up to cm³ g^?1) of the refractive index increments $\text{d}\text{n}\text{d}\text{c}$ of sulphuric and methane sulphonic acid solutions for a series of polyazomethine compounds at 546 and 628 nm are related quantitatively to the existence of a strong absorption band around 400 nm. The frequency dependence is well explained by the anomalous dispersion calculated from the decomposition of the absorption band into Gaussians. The blue shift and hypochromic effect, and the correlated decrease in $\text{d}\text{n}\text{d}\text{c}$, resulting from an aggregation process in methane sulphonic acid can be interpreted by a side-by-side arrangement of aggregates. This result is substantiated by a calculation of the optical anisotropy from the depolarized part of the scattered light.     

Introduction of bifunctionality into the phosphinic acid ion-exchange resin for enhancing metal ion complexation

In nuclear industry the role of conventional strong cation exchange resins is limited as they function less in high acid media. The phosphorous group that has got more affinity towards actinide elements is chosen as a chelating group and the phosphinic acid ion exchange resin was synthesized. The extraction ability of the phosphinic acid resin for plutonium (Pu) from HNO₃ medium as well as from H₂SO₄ medium was studied. Though the resin shows better extraction for Pu than the strong cation exchanger resins at higher acidities, its kinetics is slow. In order to enhance the kinetics as well as to improve upon selectivity, a sulphonic group is introduced into the phosphinic acid resin. To verify the effect of bifunctionality extraction studies have been carried out with Pu from different acid media of varying concentrations. Sulphonated phosphinic acid resin shows a 2-fold increase in distribution coefficient (k_d) as well as it reached equilibrium very fast compared to the phosphinic acid resin. It is postulated that the sulphonic acid ligand provides an access mechanism for the metal ions into the polymer matrix while it is the phosphinic acid group that is responsible for selective coordination of metal ions. Thus bifunctionality is coupling of an access mechanism to a recognition mechanism. The experiments carried out demonstrated the applicability of sulphonated phosphinic acid resin in the nuclear industry.     

Extraction of Fe(III) from phosphoric acid by HDDNSA

A study was conducted on the stoichiometry of the reaction that takes place on the extraction of ferric ions by didodecyl naphthalene sulphonic acid (HDDNSA) from phosphoric acid solutions. The experimental results were numerically analyzed by nonlinear regression. It was found that ferric forms two compounds with HDDNSA, namely Fe(DDNSA)₃, and FeHPO₄-DDNSA. The values of the equilibrium constants of the reactions involved were also calculated.     

The role of calcium ions and lignosulphonate plasticiser in the hydration of cement

Experiments involving equilibrium dialysis, conductivity, X-ray diffraction analysis (XRD), differential thermal analysis (DTA) and isothermal titration calorimetry (ITC) have been carried out to investigate the role of calcium ions and polymeric plasticisers in cement/admixture hydration. Results from a study of lignosulphonic acid, sodium salt, acetate as a plasticiser shows that a plasticiser has dual role; one mainly as a kinetic inhibitor (poison) in cement hydration mechanism and the other as a dispersant. Evidence of a weak Ca²⁺ binding to lignosulphonate sulphonic moieties was found at low ionic strengths of 0.1 M using ITC. No evidence of formal Ca²⁺ binding to lignosulphonate sulphonic acid moieties was found using equilibrium dialysis at higher ionic strength of 1 M (ionic strengths of 0.4 M are typically found in Portland cement pore solution), as is often suggested in cement/admixture literature.     

Electrochemical Biosensor Based on surfactant doped polypyrrole (PPy) matrix for lactose determination

Lactose biosensor based on surfactant doped polypyrrole (PPy) was developed. Galactose oxidase and β‐galactosidase was coimmobilized in PPy matrix during electropolymerization process with the presence of sodium dodecylbenzene sulphonic acid as surfactant. Bi‐enzyme entrapped PPy was characterized with Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV), and scanning electron microscopy (SEM). The response of the enzyme electrode was measured by CV in the range of ?0.1 to 1.0 V versus Ag/AgCl which was due to the electrooxidation of enzymatically produced H₂O₂. The effect of lactose concentration was investigated. Response time of biosensor was found to be 8–10 s (the time required to obtain the maximum peak current) and upper limit of the linear working portions was found to be 1.22 mM lactose concentration with a detection limit of (2.6 × 10^?6 M). The apparent Michaelis–Menten constant was found to be 0.117 mM lactose. The effects of interferents (ascorbic acid and uric acid) were determined. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40200.