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Herein, dodecyl sulfate chain-anchored mercerized lignocellulosic (SMPS) agro-waste biomass was developed through hydrophobic interaction to enhance negatively charged surface sites concentration, consequently increasing SMPS potential to adsorb highly toxic cationic heavy metal ions viz. Pb(II), Cd(II), and Zn(II) from an aqueous phase. Spectrophotometric and elemental analyses confirmed successful modification and heavy metal ions adsorption over mesoporous SMPS surface. Experimental parameters viz. pH, concentration, temperature, and adsorbent dose have a profound influence on heavy metal ions adsorption. Lead [Pb(II)] had the lowest hydrolyzing tendency and the strongest binding potential among the studied metals; therefore, it showed the highest adsorption, followed by Cd(II) and Zn(II). Extremely rapid adsorption kinetics was observed, accomplishing 90–97% heavy metal ions adsorption within 15 min. Isotherm and kinetics studies showed Freundlich and pseudo-second-order models applicability, respectively. The process was endothermic and spontaneous. Breakthrough capacities for Pb(II), Cd(II), and Zn(II) were 0.01, 0.05, and 0.05 mmol/g, respectively. The maximum amounts of metal ions were eluted with acids. © 2017 American Institute of Chemical Engineers Environ Prog, 36: 1676–1684, 2017

This is the peer reviewed version of the following article published in final form at https://doi.org/10.1002/app.50338. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.

A sipholane triterpenoid, named sipholenone A, with anti-cancer properties was isolated from the Red Sea sponge Siphonochalina siphonella and characterized by proton and carbon-13 nuclear magnetic resonance (1 H NMR and 13 C NMR) spectroscopies. The goal of this study was to visualize the binding of this triterpenoid with human serum albumin (HSA) and to determine its binding site on the biomacromolecule. The interaction was visualized using fluorescence quenching, synchronous fluorescence, far- and near-UV circular dichroism (CD), UV-visible and Fourier transform-infrared (FT-IR) spectroscopies. UV-visible spectroscopy indicated the formation of a ground-state complex as a result of the interaction. Sipholenone A quenches the fluorescence of HSA via a static quenching mechanism. A small blue shift in the fluorescence quenching profiles suggested the involvement of hydrophobic forces in the interaction. Sipholenone A binding takes place at site I of subdomain II A with a 1:1 binding ratio, as revealed by displacement binding studies using warfarin, ibuprofen and digitoxin. Far-UV CD and FT-IR studies showed that the binding of sipholenone A to HSA also had a small effect on the protein's secondary structure with a slight decrease in the α-helical content. Several thermodynamic parameters were calculated, along with Forster's radiative energy transfer analysis.

Rosin as a natural product has become a source for production of less toxic bio-surfactants to produce emulsions which are widely used in various agriculture and food products, cosmetic, and pharmaceutical industries. In this respect, a nonionic surfactant was prepared from reaction of rosin acids and rosin maleic anhydride adduct with poly(ethylene glycol) monomethyl ether 750 (MPEG 750) to produce a rosin ester (RMPEG 750). The surface activity parameters of the prepared surfactants, such as surface excess concentration (Γ max), the area per molecule at interface (A min), and the effectiveness of surface tension reduction, were measured to determine the micellization and adsorption characteristics of the prepared surfactants at the water/air interface. The adsorption of the prepared surfactants on the surface of either hydrophilic or hydrophobic silica particles was determined using a spectrophotometric method. Interfacial tension between water and toluene were measured to select the best condition to obtain toluene/water emulsion in the presence of modified solid silica particles. The effects of silica particle hydrophilicity and the surfactant concentrations on the surface, interfacial activity, and on the emulsion drop size were also investigated.

The motivation of the current work has stemmed from the fact that the selection of suitable stabilizers for nonaqueous emulsions is still challenging because of lack of general knowledge about the underlying stabilization mechanisms. The preparation and surface activity of new amphiphilic gel nanoparticles in organic solvents were investigated. A new bifunctional surfmer was prepared by reacting polyoxyethylene 4-nonyl-2-propylene-phenol nonionic reactive surfactant with maleic anhydride followed by esterification with poly(ethylene glycol). This surfmer was used as stabilizer to prepare amphiphilic crosslinked N-isopropylacrylamide (NIPAm) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) copolymer nanogel on the basis of nonaqueous radical copolymerization temperature modified method in the presence of toluene and formamide (FA) as solvents and N, N-methylene bisacrylamide as a crosslinker. The chemical structure of the prepared nanogels was determined by Fourier transform infrared spectroscopy analyses. The morphologies of the prepared nanogels were detected by transmission electron microscopy and scanning electron microscopy techniques. The surface tension of colloidal NIPAm/AMPS dispersions was measured in FA as functions of surface age (time), temperature, and the morphology of the NIPAm/AMPS nanogels. The NIPAm/AMPS nanogels reduced the surface tension of FA from 58.2 to about 30.2 mN/m at 25°C, and a little increase in the surface tension was observed at 40°C. The prepared nanogels show great reduction in interfacial tension values between FA and styrene. The NIPAm/AMPS dispersions exhibited high surface activity and used as stabilizers to prepare crosslinked styrene-co-AMPS microgel in the presence of divinylbenzene and FA as organic solvents based on nonaqueous emulsion crosslinking polymerization technique. Copyright © 2013 John Wiley & Sons, Ltd.

The kinetics of alkaline hydrolysis of procaine under the pseudo–first-order condition ([OH−] ≫ [procaine]) has been carried out. N,N-Diethylaminoethanol and p-aminobenzoate anion were obtained as the hydrolysis product. The rate of hydrolysis was found to be linearly dependent upon [NaOH]. The addition of cationic cetyltrimethylammonium bromide (CTAB), dodecyltrimethylammonium bromide (DDTAB) and tetradecyltrimethylammonium bromide, and anionic sodium dodecyl sulfate (SDS) micelles inhibited the rate of hydrolysis. The maximum inhibitive effect on the reaction rate was observed for SDS micelles, whereas among the cationic surfactants, CTAB inhibited most. The variation in the rate of hydrolysis of procaine in the micellar media is attributed to the orientation of a reactive molecule to the surfactant and the binding constant of procaine with micelles. The rate of hydrolysis of procaine is negligible in DDTAB micelles. The observed results in the presence of cationic micelles were treated on the basis of the pseudophase ion exchange model. The results obtained in the presence of anionic micelles were treated by the pseudophase model, and the various kinetic parameters were determined. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 45: 1–9, 2013

The synthesis and characterization of a series of polymerizable surfactants based on alkyl phenol ethoxylate backbone and carboxylic or anhydride chain ends were investigated. Surface activities of these polymerizable surfactants were investigated to correlate their structure and their performances. The new bifunctional surfmers were prepared by reacting polyoxyethylene 4-nonyl-2-propylene-phenol nonionic reactive surfactants with maleic anhydride. The chemical structure of the prepared surfactants was characterized by 13C and 1H NMR analyses. The surface activities of the modified polymerizable surfactants were measured from the adsorption isotherm measurements which were determined from the relationship between the concentrations and surface tension of surfactants in aqueous medium at different temperatures. Critical micelle concentration (CMC) values were determined for water soluble surfactants. It was found that CMC decreases with the incorporation of the anhydride and acid groups in the chemical structure of polyoxyethylene 4-nonyl -2-propylene-phenol nonionic surfactant. surface-active parameters such as area per molecule at the interface (A min), surface excess concentration (Γmax) and the effectiveness of surface tension reduction (πCMC) were measured from the adsorption isotherms of the modified surfactants. Some thermodynamic data for the adsorption process were calculated and discussed. The data indicated that the new surfmers are more reactive than the simple polyoxyethylene 4-nonyl-2-propylene-phenol and more adsorbed at interfaces. We have performed a preliminary experiment to explore the emulsification efficiency of the newly synthesized reactive surfactants in equal volume oil–water emulsions. Different emulsion types and stabilities were obtained.

The hydrolysis of 2-chloro-3,5-dinitropyridine by sodium hydroxide in the presence of micelles of cetyltrimethylammonium bromide (CTABr), cetyltrimethylammonium chloride (CTACl) and sodium dodecyl sulfate (SDS) has been studied. The reaction follows a consecutive reaction path involving the formation of a long-lived intermediate 3 and finally giving the product, 3,5-dinitro 2-pyridone 2. The mechanism follows an addition of the nucleophile, ring opening and ring closure (ANRORC) reaction path. The rate constant was observed to be first-order dependent on [OH−]. The rate of reaction increased on increasing [CTABr] and, after reaching to the maxima, it started decreasing. The anionic SDS micelles inhibited the rate of hydrolysis. The results of the kinetic experiments were treated with the help of the pseudophase ion exchange model and the Menger–Portnoy model. The added salts, viz. NaBr, Na-toluene-4-sulphonate, and (CH3)4NBr on varying [CTACl] and [SDS] inhibited the rate of reaction. The various kinetic parameters in the presence and absence of salts were determined and are reported herewith. Copyright © 2011 John Wiley & Sons, Ltd.

Corrosion behaviour of steel in acid solutions was followed in presence of cationic micelles of Cetyltrimethylammonium bromide (CTABr), n-tetradecyl-N,N,N-trimethylammoni um bromide (TDTABr), n-dodecyltrimethylammonium bromide (DDTABr) and n- decyltrimethylammonium bromide (DTABr) using gasometry and potentiodynamic techniques. Plots of adsorption isotherms produce S- shaped curves. Surfactants were found to act as corrosion inhibitors of mixed - type, i.e., affecting the dissolution of the metal and the cathodic reaction of hydrogen evolution. Inhibitive effect of the surfactants has been shown to increase with the alkyl chain length and at concentrations above their critical micelle concentration (cmc). Corrosion kinetic empirical equation describing the relationship between the surfactants structure and their activity is introduced. The number of active sites on the metal occupied by the surfactant molecule, binding constant and change in free energy of adsorption are calculated following Temkin adsorption isotherms. All results obtained are compared to the kinetic-thermodynamic model to certify its applicability. The mode of adsorption of the surfactant molecules according to their structure is also discussed.

Two quinoxaline derivatives, 1 and 2, were prepared via a bis-aza-Wittig reaction when the suitable aromatic diamine was treated with (MeO)3PBr2/Et3N followed by the addition of benzil. Also, two additional novel heterocyclic compounds, 4 and 6 were prepared via an intramolecular aza-Wittig reaction.

The reaction of N-alkyl-2-chloropyridinium ions (1a–f; alkyl = Me, n-hexyl, n-decyl, n-dodecyl, n-tetradecyl, n-hexadecyl) with N3– is affected by cationic micelles of cetyltrimethylammonium ion (CTAX, X = Cl–, Br–, N3–), which inhibit the reaction of ion (1a) at low [surfactant] but catalyse it at high [surfactant]. First-order rate constants, kψ, for the reaction of ion (1b) continue to increase with increasing [surfactant] but, for reaction of the hydrophobic substrates (1c–f) at a given [NaN3], kψ goes through maxima with increasing [surfactant]. Reaction in CTABr is always faster than in CTACl, but the difference decreases with increasing substrate hydrophobicity so the rate–surfactant profiles do not fit the pseudophase, ion-exchange model. For reactions of substrates (1c–f) with N3–, kψ increases with [substrate] in the absence of surfactant and it also increases with [CTAN3]. The rate enhancement for reaction of ion (1f) in water is greater than that of ion (1a) by a factor of ca. 1.2 × 104, and this is probably due to self-micellization of 2-chloro-N-hexadecylpyridinium ion. Second-order rate constants for reactions of ions (1a–f) with N3– in MeCN–water (1:1 w/w) are very similar.

The rates of spontaneous cis-trans isomerization of the complex cis-[PtCl2(PBu3)(PhCN)] have been measured in different solvents. Values of kobs decrease with the polarity of the solvent (benzene ∼ toluene $ CHCl3 ∼ DMF). 31P and 195Pt NMR spectroscopy provide (for the first time) strong evidence for dimer formation (sym. trans-[Pt2(μ- Cl)2(Cl)2(PBu3)2]) which are intermediates in spontaneous cis/trans isomerization.