Sodium Dodecylsufate Research Articles

Exploration of aspartame as a green and sustainable corrosion inhibitor for T95 steel in 28 wt.% HCl at elevated temperatures: effect of sodium dodecylsufate and KI addition on performance

Acidizing is a vital oil well stimulation exercise but must be done with an effective corrosion inhibitor to reduce corrosion risk. It is, however becoming increasingly difficult to find a corrosion inhibitor that is ecologically compatible and effective in strong acids and high temperatures. In this scientific communication, aspartame (ASP), sodium dodecylsufate (SDS), and potassium iodide (KI) blend is presented as a highly efficient inhibitor for T95 steel in 28 wt.% HCl solution at 60–90 °C. The corrosion inhibition investigation was performed using weight loss and electrochemical (electrochemical impedance spectroscopy [EIS] and potentiodynamic polarization [PDP]) techniques complemented by surface analysis of the corroded steel without and with the inhibitor using scanning electron microscope (SEM)/energy dispersive x-ray spectrophotometer (EDX), and 3D optical profilometry (OP). ASP is an effective corrosion inhibitor for T95 steel in an acidizing environment. The inhibition efficiency (IE) increased with an increase in concentration and temperature. The additives (SDS and KI) enhanced the inhibitive performance of ASP due to synergistic effects, especially at 90 °C where an IE of 96% is tenable. Results from SEM/EDS and OP disclose apparent ASP-based inhibitor adsorption on the T95 surface and a high level of protection.

Self-organization of lysozyme—Ionic surfactant complexes at the aqueous-air interface as studied by tritium bombardment

The self-organization of lysozyme with cationic (dodecyltrimethylammonium bromide) and anionic (sodium dodecylsufate) surfactants at an aqueous-air interface was studied by means of tritium planigraphy. It was found that even if the surfactant concentration is too low to induce significant structural changes in the protein globule, the surfactant can bind with the protein via both electrostatic and hydrophobic interactions and can displace the protein from the interface. Different mechanisms of complex formation are suggested for lysozyme mixed with SDS or DTAB. SDS molecules screen positively charged groups of amino acid residues via electrostatic interactions and form hydrogen bonds with polar groups of amino acid residues. SDS also penetrates the protein globule via hydrophobic interactions. In contrast, DTAB interacts with hydrophobic amino acid residues, screening them from tritium atoms. For both surfactants, it was found that lysozyme maintains a longways-on orientation in the mixed adsorption layer.

FTIR analysis of water structure and its influence on the flotation of arcanite (K2SO4) and epsomite (MgSO4·7H2O)

The flotation chemistry of soluble salts has been studied for many decades. In this work, the flotation behavior of arcanite (K2SO4) and epsomite (MgSO4·7H2O) with both the cationic collector, dodecylamine hydrochloride (DAH), and the anionic collector, sodium dodecyl-sufate (SDS), has been studied. The results show that K2SO4 can be floated with both the cationic and anionic collectors at natural pH. In contrast, MgSO4·7H2O cannot be floated by either collector. The results indicate that the flotation response of these salts cannot be explained based on surface charge considerations. It is now known that interfacial water structure has been found to be a significant factor in the explanation of soluble salt flotation.In this regard, the water structure of K2SO4 and MgSO4 solutions was investigated by FTIR-transmission and FTIR-ATR methods which are useful to detect changes in water structure as influenced by dissolved salts. FTIR transmission spectra suggest that MgSO4 is a water structure making salt, while it is expected that K2SO4 is a structure breaker, although such an expectation is not confirmed from FTIR transmission spectra due to the low solubility of K2SO4.In this regard, FTIR-ATR measurements can also be used to determine the influence of dissolved salts on water structure. After subtraction of the O–H band spectrum of salt solutions from that of pure water, the change in the “ice-like” water structure as influenced by the dissolved salt (K2SO4 and MgSO4) can be observed even in solutions of K2SO4 at low concentrations. In summary, the results from FTIR spectroscopy of solutions show that K2SO4 is a water structure breaker, while MgSO4 is a water structure maker. This conclusion is further confirmed from a macroscopic view point by viscosity measurements. Again for these sulfate salts flotation is achieved with DAH and SDS as collectors if the salt is a water structure breaker.

Small angle neutron scattering study of deuterated sodium dodecylsulfate micellization in dilute poly((2–dimethylamino)ethyl methacrylate) solutions

Poly((2–dimethylamino)ethyl methacrylate) with 60,000 g/mol and a narrow polydispersity (1.12) was synthesized using group transfer polymerization in order to investigate the structure of poly((2–dimethylamino)ethyl methacrylate)/sodium dodecylsufate complexes in water. The synthesized polymer chain conformation in water was studied as a function of deuterated sodium dodecylsulfate concentration using small angle neutron scattering. We found three transitions of the poly((2–dimethylamino)ethyl methacrylate) chain conformation induced by the added deuterated sodium dodecylsulfate. The transitions resulted from interactions between the polymer and the surfactant, so that micelles are formed along the polymer backbone above the critical aggregation concentration. The structure of micelles in a poly((2–dimethylamino)ethyl methacrylate)/deuterated sodium dodecylsulfate solution was analyzed through model fitting of the small angle neutron scattering data measured at the condition where the poly((2–dimethylamino)ethyl methacrylate) was contrast-matched with a mixture of 80% H 2O and 20% D 2O.

Kinetics of Ethanol Oxidation Catalyzed by Yeast Alcohol Dehydrogenase in Aqueous Solutions of Sodium Dodecylsulfate

A study has been made of the effect of sodium dodecylsufate (SDS) addition on the oxidation of ethanol catalyzed by yeast alcohol dehydrogenase. Experiments were performed at pH = 8.1 and SDS concentrations employed were below and above the surfactant critical micelle concentration (CMC). The double reciprocal plots obtained in the absence and in the presence of the surfactant were compatible with a sequential bi-bi ordered mechanism. In the presence of the surfactant the initial reaction rates were consistently lower than in pure buffer at all the surfactant concentrations considered (0.5-50 mM). This effect is mainly due to an increase in the dissociation constant of beta-NAD(+) which reaches its maximum value (7,100 +/- 1,700 microM) at the CMC. Above the CMC the effect of the surfactant is mainly due to an increase in the Michaels constants of the alcohol, with values of 41 +/- 1 mM for 15 mM SDS and 50 +/- 1 mM for 50 mM SDS. The catalytic rate constant was found to be practically independent of the presence of the surfactant in the range of concentrations considered (up to 50 mM).

Avaliação de contaminantes inorgânicos e orgânicos em álcool combustível utilizando eletroforese capilar

This work reports the analysis of inorganic and organic contaminants in alcohol fuel samples using capillary electrophoresis. Chloride and sulfate were analyzed in nitrate/ monochloroacetic acid at 10 mmol L-1 concentration each under indirect UV detection (210 nm). The analysis of aldehydes is based on the 216 nm detection of 3-methyl-2-benzothiazoline hydrazone adducts. The running buffer consisted of 20 mmol L-1 tetraborate , 40 mmol L-1 sodium dodecyl sufate and 12 mmol L-1 b-ciclodextrin. Both methodologies were applied to real samples indicating inorganic ion concentrations from 0.15 to 6.64 mg kg-1 and aldehydes from 32.0 to 91.3 mg L-1.

The influence of structure and composition of a reverse SDS microemulsion on enzymatic activities and electrical conductivities

The activity of the enzyme horse radish peroxidase (HRP) is studied in a series of reverse microemulsions composed of dodecane, aqueous buffer, sodium dodecylsufate (SDS) and alcohols of the homologous series 1-butanol to 1-octanol. The HRP catalyzed reaction is the oxidation of a classical water soluble substrate, the 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) by hydrogen peroxide. In parallel electrical conductivity measurements are performed on the same solutions. The structural changes in the microemulsions, as inferred by the conductivity measurements, correlate remarkably well with the changes in the enzymatic activities. In particular it is found that (a) the maximum activity of the enzyme is always related to its optimum hydration and that this hydration can be related to the microemulsion structures, (b) the enzyme inhibition caused by the alcohols in microemulsions is a consequence of both the solubility of the alcohols in the buffer and the rigidity of the interfacial film. Consequently, it can be concluded that enzymatic activity measurements are a valuable tool to study confined systems such as microemulsions and, in particular, the amount of available hydration water. Enzymatic activities can be finely tuned by small changes in microemulsion structures, probably in a predictive way.

Effects of Some Surfactants as Stabilizers to Reduce the Phase Separation Rates of Blended Pastes for Warp Sizing

Reducing the phase-separation rates of starch/PVA blend pastes for warp sizing by adding a small amount of surfactant as a stabilizer is investigated. The effects of reducing the separation rates or raising the stability of the blended pastes are evaluated in terms of initial demixing time and volume percentage of phase separation. Surfactants such as sodium dodecylsulfate, sodium dodecylsulfonate, Tween 20, and Span 20 are individually evaluated. The type and amount of the surfactant strongly affect the phase-separation rates or the paste stability. Sodium dodecylsufate and sodium dodecylsulfonate effectively retard phase separation and enhance paste stability, whereas Tween 20 and Span 20 do not. Increasing the amount of sodium dodecylsulfate favorably reduces the separation rates. Moreover, the effects of starch content and PVA type on the separation are also investigated.

Phosphorescence of molecules of polycyclic aromatic hydrocarbons in aqueous micellar solutions of sodium dodecylsulfate at room temperature

Deactivation of the excited states of pyrene, benzanthracene, and fluorene molecules in aqueous micellar solutions of sodium dodecylsufate is studied using steady and pulsed fluorimetry. Quenching of the singlet states of polyatomic hydrocarbons by thallium ions is considered. Effective, micellar, and biomolecular constants for the quenching rate are obtained. Phosphorescence constants for the aforementioned compounds are determined. Reasons behind the possibility of observing phosphorescence of polyaromatic compounds in micellar solutions at room temperature are ascertained.

Interaction of Magnesium and Cadmium Dodecyl Sulfates with Poly(ethylene Oxide) and Poly(vinylpyrrolidone): Conductance, Self-Diffusion and Fluorescence Probing Investigations

The interaction of magnesium and cadmium dodecyl sulfates (Cd(DS)2and Mg(DS)2) with poly(ethylene oxide) and poly(vinylpyrrolidone) (PEO and PVP) has been investigated in order to assess the effect of the surfactant counterion on the interaction. Electrical conductance, spectrofluorometry, and time-resolved fluorescence quenching were used to determine the critical micellar concentration (cmc), micelle ionization degree, surfactant binding range, and micelle aggregation numbers. Electrical conductance and cation self-diffusion measurements in solutions of NaCl, Cd(NO3)2, and Mg(ClO4)2were used to study the binding of the cations to the same polymers. The results show that the interaction between dodecyl sulfates with divalent counterions and PEO or PVP and the interaction between sodium dodecyl sufate and the same polymers are qualitatively similar. The surfactant aggregation begins at a concentration lower than the cmc of the surfactants investigated, the aggregation numbers of bound aggregates are lower than those for the corresponding free micelles and increase with surfactant concentration; and the bound aggregates are more ionized than the free micelles. The decrease in the aggregation number of the bound aggregates with increasing temperature was larger with PEO than with PVP, a result that can be explained in terms of the increasing hydrophobicity of PEO with temperature. In terms of bound charges per polymer repeat unit, the interaction of Cd2+and Mg2+ions with PEO or PVP is stronger than that of Na+ions with the same polymers. The interaction strength thus follows the same sequence as the counterion degree of binding to free micelles. However, the values of the free energy of transfer of a dodecylsulfate ion from a free micelle to a polymer-bound aggregate are not very different with Na+and divalent metal counterions, and are extremely small. The results obtained with the salt/polymer systems confirm the binding of cations by PEO and PVP in aqueous solutions.

Differential anomalous scattering study of probe molecules

Over the last several years, anomalous wide angle X-ray scattering (AWAXS) has been developed for the study of disordered solid materials like amorphous metallic, chalcogenides or isolating glasses. AWAXS is a contrast variation method, based on differential analysis of diffraction spectra recorded near and away from the absorption edge of each component in the studied material. This technique is useful in solids for exploring the medium range order over 4Åand may be considered as an extension of XAFS. AWAXS may give useful information on the pairs correlation functions in liquids, where the brownian motion limits the data extracted from XAFS. Up to now, X-ray diffraction is poorly extended to liquid. The main difficulty remains in the choice of an appropriate sample holder. For non absorbing liquid like molecules diluted in solvent, we combined reflective and transmittive geometry by using a cylindrical cell where the incident and reflected beam are always perpendicular to the window, reducing the absorption due to the window to its minimum. The ability of this cell for diffraction on liquid has been tested at the bromine K-edge on bromoethane BE solubilized in aqueous micellar solution of sodium dodecylsufate SDS. A complete data treatment up to differential structure factor has been achieved and compared to the previous known features of that liquid system.

Interactions in aqueous polypeptide derivative/surfactant systems

A new class of compounds of water-soluble polypeptide derivatives have been synthesized and the interactions with the anionic surfactan sodium dodecylsufate (SDS) studied by rheological and light scattering investigations. The viscosity of the aqueos polypeptide solution passes through a distinct maximum with increasing surfactant concentration. This behaviour, so far only known for hydrophobically modified cellulose derivatives, can be explained by a formation and decay of polymer surfactan networks. The changes caused by microscopic structural parameters through surfactant adsorption are observed by dynamic light scattering and can be correlated with the macroscopic behaviour of the solutions.

Removal of Trace Levels of Aromatic Amines from Aqueous Solution by Foam Flotation

Abstract Aromatic amines, including 4-(t-butyl)pyridine, 4-(n-butyl)aniline, benzylamine, 4-aminobiphenyl, 1- and 2-aminonaphthalene, and 2,6-xylidine, were effectively removed from water by foam flotation with the anionic surfactant sodium dodecylsufate (SDS). With initial amine concentrations of 10 mg/L or less, residual amine concentrations of less than 0.1 mg/L were generally obtained after 10–30 min of flotation. The SDS concentration and flotation time are directly related to the amount of amine removed. Amine removal is most efficient at pH values low enough so that the amine is protonated (usually about 3), and at low ionic strength. Alcohols up to 10% by volume do not appreciably affect amine removal. The mechanism of removal is dominated by ion-ion attraction between the surfactant and the protonated amine; there is also apparently some contribution from ion-dipole attraction. Benzidine is not removed effectively; evidently it is insufficiently hydrophobic.

Fibrous Proteins of Trichilemma‐oid Epidermal Keratinization without Keratohyalin Granules Formation

AbstractInteractions between the histidine‐rich protein of keratohyalin granules and keratin fibers were investigated. Keratin fibers of the stratum corneum from sole skins of both normal persons (NP) and those with hereditary palmoplantar keratoderma (HPPK) were examined. HPPK samples showed trichilemma‐oid keratinization except at the sweat duct. Epidermis around the sweat duct showed stratum granulosum formation. The keratin pattern was lost in the non‐sweat duct region; any changes in the size and distribution‐pattern of keratin fibers were, however, observed by electron microscopy. In sodium dodecylsufate polyacrylamide gel electrophoresis (SDS‐PAGE), keratin fibers in the HPPK stratum corneum, from both non‐sweat duct and sweat duct regions, and in the stratum corneum of the sole lesion of the HPPK's mother, lacked 57kd subunits, but the electrophoretic profiles of other keratin subunits were identical to those from NP samples. It was concluded that the lack of histidine‐rich protein formation causes no change in keratin fibers themselves either under electron microscopy or in SDS‐PAGE.The absence of a 57kd subunit keratin fiber may have been caused by abnormalities in the production or degeneration processes of keratin fibers of the HPPK epidermis.

Specific Polysome Immunoadsorption to Purify an Ammonium-Inducible Glutamate Dehydrogenase mRNA from Chlorella sorokiniana and Synthesis of Full Length Double-Stranded cDNA from the Purified mRNA

A specific polysome immunoadsorption procedure, employing soluble rabbit anti-NADP-GDH IgG and sheep anti-rabbit IgG covalently-linked to an insoluble cellulose matrix, was used to immunoselect polysomes translating mRNA for a chloroplastic ammonium-inducible NADP-GDH in fully induced cells of Chlorella sorokiniana. The immunoselected polysomes were dissociated, and the NADP-GDH mRNA was recovered by oligo (dT)cellulose chromatography. The translatable NADP-GDH mRNA was estimated to be 0.07 and 90% of the total polysomal poly(A)(+)RNA before and after immunoselection of the polysomes, respectively. The immunoadsorption procedure resulted in an 83% recovery and 1,291-fold purification of translatable NADP-GDH mRNA. In vitro translation of the immunoselected poly(A)(+)RNA yielded a single radioactive protein (on sodium dodecyl sufate polyacrylamide gels) with a molecular weight of 58,500, i.e. size of the putative precursor-protein of the NADP-GDH subunit in the holoenzyme in fully induced cells. The purified NADP-GDH mRNA was used for synthesis of a high proportion of nearly full-length single-stranded cDNA and double-stranded cDNA molecules.

Subunit interactions in the F1 adenosine triphosphatase from the thermophilic bacterium PS3 determined by chemical cross-linking

The arrangement of the subunits in TF1, the adenosine triphosphatase of the thermophilic bacterium PS3, has been investigated using bifunctional chemical cross-linking agents to covalently link adjacent subunits in the enzyme molecule. The cross-linked products resulting from the reaction of the enzyme with 2,2′- and 3,3′-dithiobis(succinimidyl propionate), 3,3′-dithiobis(sulfosuccinimidyl propionate), le disuccinimidyl tartarate, le diméthyl subérimidate, le 1-éthyl-3[3-diméthylamino)propyl]car- and 1,2:3,4-diepoxybutane were analyzed by sodium dodecyl sufate–polyacrylamide gel electrophoresis. Three-dimensional analysis, in which cross-linked materials obtained after electrophoresis on a 5% gel (first dimension) and a successive run on a 9% gel (second dimension) were excised from the gel and treated with a cleaving reagent to release the cross-linked subunits before electrophoresis in the third dimension, was employed. The following cross-linked dimers were identified: αα, αβ, αγ, βγ, αδ, and γε. Two trimers, α2δ and γαδ, were recognized. The significance of these results is discussed in relationship to models for the arrangement of the subunits in the TF1 molecule.

Luteinizing and follicle-stimulating hormones. Cell-free translations of messenger RNAs coding for subunit precursors.

Polyadenylated RNA prepared from pituitary glands of normal and castrate rats was translated in membrane-free heterologous cell-free systems derived from wheat germ and rabbit reticulocytes. Sodium dodecyl sufate (SDS)-polyacrylamide gel electrophoresis and autoradiography demonstrated a major [35S]methionine-labeled translation product of castrate pituitary mRNA with apparent Mr = 14,000. This Mr = 14,000 product was specifically immunoprecipitated by anti-sera to the alpha subunit of rat and bovine luteinizing hormone (LH alpha) and was much reduced in the translation products of normal pituitary RNA. Additional minor translation products of normal pituitary RNA. Additional minor translation products with apparent Mr = 15,000 and 16,000 were identified by immunoprecipitation with antisera to rat LH beta and to the beta subunit of rat follicle-stimulating hormone (FSH beta), respectively. The immunological identity of the alpha, LH beta, and FSH beta precursors was confirmed by successful competition of these immunoprecipitation reactions by unlabeled homologous LH alpha, LH beta, and FSH, respectively. These results indicate that the gonadotropin subunits are synthesized as precursors from separate mRNAs. This system is responsive to endocrine manipulations and is appropriate for studies of the regulation of gonadotropin biosynthesis.

Pro-C4 of human plasma: isolation and description of chemical and antigenic properties.

The fourth component of complement (C4) occurs in human plasma as a protein with a three polypeptide chain structure. Lately a single-chain form of C4 has been purified from human plasma by sequential steps of immunoadsorbent chromatography, gel filtration in 6 M guanidine hydrochloride, and gel filtration in 6 M guanidine hydrochloride and 0.015 M dithiothreitol. Single-chain C4, referred to as pro-C4, behaved as a protein of approximately 200,000 daltons upon gel filtration, and was separated from the three chains of C4 on the basis of molecular size. Pro-C4 could be isolated from each of five human plasmas examined and was found to constitute approximately 2% of total, immunoreactive C4. Replicate amino acid analyses of pro-C4 and C4 agreed within 0.5 mol % for all residues except glycine and threonine, which agreed within 0.7 mol percent. Polyacrylamide gel electrophoresis of pro-C4 in the presence of sodium dodecyl sufate in 5% gels under reducing conditions indicated an approximate molecular weight of 202,000. The sum of the molecular weights of the alpha-, beta-, and gamma-chain of C4 is 205,000. After gel electrophoresis, pro-C4 stained positively with periodic acid-Schiff reagent, suggesting the presence of covalently-bound carbohydrate. Competitive inhibition radioimmune assays with pro-C4, purified alpha-, beta-, or gamma-chain, and chain-specific antisera demonstrated the existence of antigenic sites on pro-C4 that are assignable to common determinants on each of the alpha-, beta-, and gamma-chains of C4.

Translation of albumin messenger RNA in a cell-free protein-synthesizing system derived from wheat germ.

Purified rat liver albumin mRNA directed the synthesis of albumin in a mRNA-dependent cell-free protein-synthesizing system derived from wheat germ extracts. The [3H]leucine-labeled in vitro translation product reacted with antibodies specific for albumin and co-migrated with authentic 14C-labeled serum albumin during gel electrophoresis in the presence or absence of sodium dodecyl sufate. Higher concentrations of potassium and magnesium ions were required for the translation of albumin mRNA than for total liver mRNAs. These requirements were consistent for the purified albumin as well as when it was a component in the liver mRNA mixture. At the higher potassium or magnesium concentrations, only intact albumin molecules were synthesized, whereas lower concentrations of these ions caused the production of antibody-reactive fragments. These fragments were apparently the result of premature termination of peptide synthesis and not due to endogenous proteolytic activity.

Purification and partial characterization of two genetic variants of placental alkaline phosphatase

The two most common variants of placental alkaline phosphatase, the F and S variants, were purified to homogeneity and characterized. Their molecular weights were determined by equilibrium ultracentrifugation and sodium dodecylsufate polyacrylamide gel electrophoresis, which gave almost identical values for the two variants, 118,000 (F) and 119,000 (S). The amino acid compositions of F and S variants presented here are found to be very similar. Differences between the two variants were found in specific activity (160 U/mg for F and 250 U/mg for S), isoelectric point (IP - 4.5 for F and 4.7 for S), sedimentation coefficient (6.5 X 10(-13) sec for F and 6.4 X 10(-13) sec for S). Thus the structural differences observed for these enzyme variants seem to affect both the active site and the protein conformation.