Effect Of Organic Surfactants Research Articles

Efficient maximization of coloration by modification in morphology of electrodeposited NiO thin films prepared with different surfactants

In this paper, we report on the nickel oxide (NiO) thin films potentiostatically electrodeposited onto indium-doped tin oxide-coated glass substrates by using two types of organic surfactants: (1) non-ionic: polyethylene glycol (PEG), polyvinylpyrrolidone (PVP) and (2) anionic: sodium dodecyl sulfate (SDS). An aqueous solution containing nickel sulfate precursor and potassium hydroxide buffer was used to grow the samples. The effect of organic surfactants on its structural, morphological, wettability, optical, electrochromic, and in situ colorimetry were studied using X-ray diffraction, scanning electron microscopy, contact angle, FT-IR spectroscopy, optical transmittance, cyclic voltammetry, and CIE system of colorimetry. X-ray diffraction patterns show that the films are polycrystalline, consisting of NiO cubic phase. A nanoporous structure with pore diameter of about 150–200 nm was observed for pure NiO. The films deposited with the aid of organic surfactants exhibits various surface morphological feature. PVP-mediated NiO thin film shows noodle-like morphology with well-defined surface area whereas, an ordered pore structure composed of channels of uniform diameter of about 60–80 nm was observed for PEG. A compact and smooth surface with nanoporous structure stem from SDS helps for improved electrochromic performance compared with that of NiO deposits from surfactant-free solution. Wetting behavior shows, transformation from hydrophilic to superhydrophilic nature of NiO thin films deposited with organic surfactant, which helps for much more paths for electrolyte access. The surfactant-mediated NiO produce high color/bleach transmittance difference up to 57% at 630 nm. On oxidation of NiO/SDS, the CIELAB 1931 2° color space coordinates show the transition from colorless to the deep brown state (L* = 84.41, a* = −0.33, b* = 4.41, and L* = 43.78, a* = 7.15, b* = 13.69), with steady decrease in relative luminance. The highest coloration efficiency of 54 cm2 C−1 with an excellent reversibility of 97% was observed for NiO/SDS thin films.

Stripping Voltammetric Determination of Uranium Traces in Sea Water Samples: Effect of Surfactants on the Measurements

The variables affecting determination of ultra trace levels of uranium (VI) in aqueous samples by differential pulse cathodic stripping voltammetry using chloranilic acid as the complexing agent have been examined in detail. Effect of organic surfactants on the voltammetric behavior has been studied. Electrochemical impedance measurements reveal the effect of adsorption of different surfactants on the adsorption pre-concentration step of uranium-chloranilic acid complex. Additionally, to better understand the analytical feature of the method, physicochemical aspects of the preconcentration process has been studied. Adsorption of uranium-chloranilic acid complex follows the Langmuir adsorption isotherm. Analysis results on sea water samples from India are reported.

Organized Nanostructured Complexes of Polyoxometalates and Surfactants that Exhibit Photoluminescence and Electrochromism

AbstractA variety of functional nanostructured organic/inorganic hybrid materials from the europium‐exchanged derivative of a Preyssler‐type polyoxometalate (POM), [EuP5W30O110]12−, and functional organic surfactants were prepared by the ionic self‐assembly (ISA) route. The effect of organic surfactants on the structure, photoluminescent, electrochemical and electrochromic properties of the POM anions was investigated in detail. All obtained hybrid materials are amphotropic, i.e., exhibit both thermotropic and lyotropic liquid‐crystalline phase behaviour. Investigations of their photophysical properties have shown that the interactions of the various surfactants with the polyanions influence the coordination environments and site symmetry of Eu3+ in different ways. The functional groups in the organic surfactants significantly influence the electrochromic properties and photoluminescence of POMs. Different from normal and pyridine‐containing complexes, no photoluminescence and no electrochromism were observed from the ferrocene‐containing complexes. This may be explained in view of charge transfer between the POM anion and the ferrocenyl group.

Surfactant-mediated growth of nanostructured zinc oxide thin films via electrodepositionand their photoelectrochemical performance

Zinc oxide (ZnO) thin films were electrodeposited from an aqueous zinc acetate solutiononto fluorine-doped thin oxide (FTO) coated conducting glass substrates. The effect oforganic surfactants like polyvinyl pyrrolidone (PVP), sodium dodecyl sulfate (SDS),polyethylene glycol (PEG), ethylene glycol (EG) and polyvinyl alcohol (PVA) on theirstructural, morphological, optical and photoelectrochemical properties was studied. Thex-ray diffraction patterns revealed the formation of phase-pure ZnO thin films. The filmsdeposited using organic surfactants exhibit different surface morphologies. It was observedthat the organic surfactants play important roles in modifying the surface morphology andsize of the crystallites. A compact granular morphology was observed for the ZnOsamples grown without organic surfactants. The films exhibit nanoparticles of size100–150 nm for PVP, EG and PVA mediated growth. The vertically aligned thin andcompact hexagonal crystallites stem from the SDS, whereas microporous corrugatedmorphology is observed for PEG-mediated growth. All the samples exhibit roomtemperature photoluminescence (PL). Oxygen vacancies contribute to the activeluminescent centers for the emission of green light in ZnO thin films. PL getsquenched for the SDS surfactant. All the samples were post-treated with ethanol toremove stray surfactant molecules. FTIR study was used to confirm the removalof adsorbed surfactant molecules from the samples. Moreover the samples arephotoelectrochemically (PEC) active and exhibit the highest photocurrent of231 µA, a photovoltage of 492 mV and 0.42 fill factor for the ZnO:SDS films.

Chemical and dynamical effects on cloud droplet number: Implications for estimates of the aerosol indirect effect

Most aerosol‐cloud‐climate assessment studies use empirical aerosol number/droplet number relationships, which are subject to large variability. Historically, this variability has been attributed to unresolved variations in updraft velocity. We revisit this postulation and assess the effects of both updraft velocity and chemical composition on this variability. In doing so we utilize an inverse modeling approach. Using a detailed numerical cloud parcel model and published aerosol characteristics, with published correlations of cloud droplet versus sulfate and cloud droplet versus aerosol number as constraints, we determine a most probable size distribution and updraft velocity for polluted and clean conditions of cloud formation. A sensitivity analysis is then performed to study the variation in cloud droplet number with changes in aerosol chemistry and updraft velocities. This addresses the need to estimate the importance of chemical effects on spatial scales relevant for global climate models. Our analysis suggests that the effect of organic surfactants can introduce as much variability in cloud droplet number as the effect of expected variations in updraft velocity. In addition, the presence of organics seems to further enhance the sensitivity of droplet concentration to vertical velocity variability. The variability from organic surfactants is seen to be insensitive to variations in aerosol number concentration, implying that such effects can affect cloud droplet number consistently over large spatial scales. Our findings suggest that organics can be as important to the aerosol indirect effect as the effect of unresolved cloud dynamics, and they illustrate the potential and complex role of chemical effects on aerosol‐cloud interactions.

Effect of Organic Surfactant on Femtosecond Solvation Dynamics at the Air−Water Interface

Effect of Organic Surfactant on Femtosecond Solvation Dynamics at the Air−Water Interface

Interaction of Organic Surfactants with Heterogeneous Ion-Exchange Membranes

The effect of organic surfactants (1,4-butynediol, benzoic and disulfonaphthalene acids) on electrochemical properties of heterogeneous ion-exchange membranes MK-40 and MA-40 is studied. The surfactants effect the membrane properties both under equilibrium conditions and, especially, in the electric field, suggesting that they are involved in both the exchange sorption and the electrotransport. The mechanism of their effect on the anionite membrane is considered. It is shown that bipolar boundaries can arise in the membrane, promoting water dissociation and transport of hydrogen and hydroxyl ions in the field direction.

Effect of Organic Surfactant on Femtosecond Solvation Dynamics at the Air-Water Interface

Solvation dynamics at an air−water interface covered with a Langmuir monolayer of a neutral surfactant stearic acid CH3(CH2)16COOH was measured using femtosecond pump−probe spectroscopy of a molecu...