Concentration Of Surface-active Substances Research Articles

Characterization of adsorbed microlayer thickness on an oceanic glass plate sampler

The thickness of solution layers adsorbed onto rotating glass plates designed for use on an oceanic glass plate sampler was investigated in laboratory experiments using optical techniques. Using the Beer‐Lambert Law, light attenuation measurements were used to calculate the thickness of adsorbed solution layers on a rotating glass disk with and without salt and surfactants. The observations have shown that the adsorbed film thickness can vary between 80 and 40 µm for glass rotation speeds between 4 and 16 cm s−1, depending on salinity and surfactant concentrations. For example, the thickness of a film of water with 40 ppt of salt and 5 cm s−1 rotation speed was in the range of 80 µm. The adsorbed layer thickness increases with increasing salt concentration and with increasing concentrations of surface active substances. These results are comparable to results obtained by vertically dipping a glass plate and determining film thickness from the collected volume of water. Because the glass disk rotational speed significantly influences the thickness of the adsorbed solution layer, it is important that the speed is maintained at a value for which the adsorbed thickness has been calibrated. At typical oceanic salinities, the dependence of the adsorbed film thickness on rotation speed was limited. However, even small changes in surface active substances resulted in significant thickness changes.

The Influence of Surface Active Substances Various Concentrations on Goethite Nanoparticles Magnetic Properties

Goethite nanopowder was prepared in the process of chemical precipitation of iron salt (FCl3) and alkali (NaOH) with addition of various surface active substances (SAS): cation-active cetylpyridinium chloride (CPC), anion-active sodium dodecyl sulphate (SDS) and complexon EDTA. The concentrations of SAS were 0.3% and 1%. It could be deduced from TEM data that these SASes unambiguously influence sizes of prepared goethite particles, compared with samples, obtained without SAS: in case of adding 1% SDS and EDTA significant crystal growth takes place. To explain this situation the study of magnetic characteristics and phase composition of obtained nanoparticles was carried out using Mossbauer spectroscopy and thermomagnetic analysis (TMA). It was suggested, that different organic Fe3+- complexes formed on goethite surface under SAS influence take part in the goethite crystallization process.

INFLUENCE OF ORGANIC ACIDS ON THE SYNTHESIS OF SURFACE-ACTIVE SUBSTANCES UNDER THE CONDITIONS OF GROWTH OF NOCARDIA VACCINII K-8 ON GLYCEROL

It was investigated the possibility of intensification of the synthesis of surface-active substances (SAS) of Nocardia vaccinii K-8 on glycerol in the presence of citrate (the lipid synthesis regulator) and С4 -bicarbonic acids (fumarate – the precursor of gluconeogenesis). The simultaneous addition of organic acids in concentration of 0.1% at the beginning of stationary growth phase led to 40–45% increase of the SAS quantity in comparison to the growth on the medium without citrate and fumarate. The addition of organic acids both into the medium appointed for preparing of the inoculum and for biosynthesis of SAS didn’t result in increase of SAS concentration.

Decreased production of surface-active organic substances as a consequence of the oligotrophication in the northern Adriatic Sea

The dynamics of surface-active substances (SAS) in the northern Adriatic Sea were studied based on monthly sampling from 1998 to 2010. The data from two stations on the eastern and the western part of the northern Adriatic basin, differing significantly in terms of their trophic status, are presented and discussed. As a consequence of oligotrophication the concentration of SAS, primarily produced by phytoplankton, decreased lately (period 2005–2010) in the upper water column. A higher decrease was observed at a site further away from the influence of freshwater, implying that oligotrophic regions are much more sensible to the environmental changes. Besides the change in SAS concentration, the changes in its distribution between the dissolved and the particulate fraction and their acidity characteristics along the water column have been also observed in the recent period. We suggest that production of SAS shifted to deeper layers. This probably due to the phytoplankton depth increasing in response to the changed vertical distribution of nutrients. This implies increased importance of regenerated nutrients near the bottom for the phytoplankton blooming lately. In the period 2005–2010 pico- and nano-phytoplankton might significantly contribute to new SAS production near the bottom during summer. The observed changes of SAS may result in the changes of biogeochemical cycling of macro- and microconstituents of sea.

Surface-active substances in atmospheric aerosol: an electrochemical approach

ABSTRACTWe characterised surface-active substances (SASs) in aqueous extract of atmospheric aerosols by using phase sensitive alternating current voltammetry. The electrochemical method has mainly been used for the quantification of surfactants in sea water but has not been applied to atmospheric aerosols yet. The advantage of the method is its simplicity and sensitivity that enables direct analysis of aerosol extracts without the need for sample concentration. Aerosol samples were collected at Middle Adriatic Martinska station influenced by different air masses as well as from urban (Zagreb, Croatia) and rural (K-puszta, Hungary) areas from late spring to early autumn in 2010. The highest SAS concentrations, expressed in equivalents of T-X-100, ranging from 0.34 to 0.91 µg m−3 were detected in urban samples. The SAS concentrations obtained for marine, regional and continental samples ranged from 0.14 to 0.31, 0.18 to 0.42 and 0.07 to 0.28 µg m−3, respectively. The SAS concentrations in K-puszta aerosols ranged from 0.13 to 0.46 µg m−3. Investigation of humic-like substances isolated from K-puszta samples (2008) confirmed their significant surfactant nature. Different SAS chemistry was noticed for urban and non-urban samples. Investigations at different pH revealed anionic character of SASs in aerosol samples.

Direct Determination of Cadmium Traces in Natural Water by Adsorptive Stripping Voltammetry in the Presence of Cupferron as a Chelating Agent

AbstractA sensitive, simple and fast adsorptive stripping voltammetric procedure for trace determination of cadmium in natural samples containing high concentrations of surface active substances and humic substances has been developed. The method is based on adsorptive accumulation of the Cd(II)‐cupferron complex onto a hanging mercury drop electrode, followed by the reduction of the adsorbed species by a voltammetric scan using differential pulse modulation. The detection limit was 3×10−10 mol L−1 (33.6 ng L−1) with an accumulation time 30 s. The procedure was applied to the determination of Cd(II) in natural water samples without any pre‐treatment with satisfactory results.

Scaling of the process of biosynthesis of surfactants by Rhodococcus erythropolis EK-1 on hexadecane

Peculiarities of synthesis of surface-active substances (SAS) are studied at periodical cultivation of Rhodococcus erythropolis EK-1 in the AK-210 fermenter on medium containing n-hexadecane. Maximum indicators of SAS synthesis (concentration of extra cellular SAS is 7.2 g/l; factor of emulsification of the cultural liquid 50%; SAS yield from the substrate 50%) have been observed at 60-70% concentration of dissolved oxygen from the saturation level with aerial oxygen (pH 8.0) fractional supply of the substrate by portions each being 0.3-0.4% every 5-6 h to a final volume concentration of 2.4% and with the use of 10% inoculate grown until mid-exponential phase on the medium with 1.0 vol % of n-hexadecane. Implementation of the process of SAS biosynthesis with the fermentation equipment provided the possibility to increase almost two-fold the amount of the synthesized SAS and reduce 3.5-fold the time of cultivation of the producer strain compared with the growth in flasks at shake-flask propagator.

Surface active drugs significantly alter the drug output rate from medical nebulizers

Background Surface tension of aqueous solutions has a great impact on the resulting size of the produced aerosol droplets. Nevertheless, little attention has been drawn so far to the drug output of surface active substances during nebulization. Methods Six nebulizers with three different nebulization mechanisms were operated on the breath simulator and the dependence between the type of aerolisation mechanism, concentration of surface active substance and output rate was investigated. Results The results of this study confirm that surface active substances significantly affect nebulization. During ultrasonic nebulization of surface active substances a decrease of the residual drug concentration occurs. Simultaneously, higher amounts of aerosolized substance were observed in in vitro studies. These findings were dependent on the saturation of the liquid–air interface with molecules of a surface active substance. During jet nebulization, nevertheless, the process of an incorporation of substance molecules into aerosol droplets is associated with a strong solvent evaporation from the reservoir. In this case the resulting residual concentration and the aerosolized substance amount are dependent on the outbalancing of either an up-concentration of the surface active substance in the reservoir or rate of solvent evaporation. Vibrating membrane mechanism to nebulize solutions were observed to have minimal effects on the aerosolized substance quantity and residual concentration during nebulization. Conclusions Following conclusions for an efficient nebulization delivery of drugs with surface activity with respect to optimal delivery device can be made. Generally, ultrasonic devices produce higher drug output rates within shorter periods of time as compared to jet and vibrating membrane nebulizers. Accordingly, prescription instructions have to be adjusted to these findings. The study also emphasizes that aqueous nebulizer solutions should preferably be prescribed in conjunction with a specific nebulizer which has been tested in vitro and been used in in vivo studies, rather than to let patients choose their delivery device themselves.

Characterization and seasonal variations of surface active substances in the natural sea surface micro-layers of the coastal Middle Adriatic stations

Surface micro-layer (ML) samples were collected in different seasons over a long time period in the coastal area of the Middle Adriatic Sea including the seawater Rogoznica lake location and the semi-enclosed estuarine Martinska station. Natural surface micro-layers were studied as original samples and as ex-situ reconstructed films after previous extraction by organic solvents of different polarities ( n-hexane and dichloromethane). Using alternating current (AC) voltammetry (out-of-phase mode) the concentration of surface active substances (SAS) in original ML of both locations was determined, and the enrichment factor (EF) in the ML was related to the underlayer water (ULW) samples collected at 0.5 m depth. Seasonal variability of SAS concentrations of the ML was observed at both locations. The ex-situ films were studied using a modified AC voltammetry method (out-of-phase mode) transferring an organic extract of natural micro-layers spread onto electrolyte from the air-water interface to the mercury electrode surface. The comparison of adsorption characteristics for model lipids of different polarities and those of transferred ex-situ reconstructed films has revealed that different types of lipid material were present in each ex-situ film of the same micro-layer. Additional characterization of the surface active material of natural MLs was carried out by AC voltammetry (in-phase mode) using cathodic reduction of cadmium ions as an indicator of permeability of different films adsorbed at the mercury electrode. The SAS of ML of both investigated locations induced an inhibition effect to the reduction of cadmium ions. Seasonal variations of inhibition have also been noticed. The electrochemical study contributed to the physicochemical characterization of the surface active matter of the surface micro-layer with the emphasis to the role of lipids which, although they represent a minor fraction of the total micro-layer organic material, contribute considerably to the micro-layer formation and stabilization at the air–water interface.

Copper complexing ligands and organic matter characterization in the northern Adriatic Sea

The study on dissolved organic ligands capable to complex copper ions (L T), surface-active substances (SAS) and dissolved organic carbon (DOC) in the Northern Adriatic Sea station (ST 101) under the influence of Po River was conducted in period from 2006–2008. The acidity of surface-active organic material (Ac r) was followed as well. The results are compared to temperature and salinity distributions. On that way, the contribution of the different pools of ligands capable to complex Cu ions could be determined as well as the influence of aging and transformation of the organic matter. The L T values in the investigated period were in the range of 40–300 nmol l −1. The range of DOC values for surface and bottom samples were 0.84–1.87 mg l −1 and 0.80–1.30 mg l −1, respectively. Total SAS concentrations in the bottom layer were 0.045–0.098 mg l −1 in equiv. of Triton-X-100 while those in the surface layer were 0.050–0.143 mg l −1 in equiv. of Triton-X-100. The majority of organic ligands responsible for Cu binding in surface water originate from new phytoplankton production promoted by river borne nutrients. Older, transformed organic matter, possessing higher relative acidity, is the main contributor to the pool of organic ligands that bind copper in the bottom samples. It was estimated that ∼9% of DOC in surface samples and ∼12% of DOC in the bottom samples are present as ligands capable to complex copper ions.

The influence of conditions of Acinetobacter calcoaceticus K-4 strain cultivation on surface-active substances synthesis

It has been observed that the Acinetobacter calcoaceticus K-4 strain produces surface-active substances (SAS) while growing either on hydrophilic (ethanol) or on hydrophobic substrates (hexadecane). Maximal SAS synthesis (with a conditional SAS concentration of 3.6; emulsifying activity of culture liquid dissolved in 50 times equal to 96%) was detected with growth on an ethanol-containing medium with the addition of urea, yeast autolysate and microelements, C/N ratio 60:1 and 10% inoculate, cultivated on ethanol-containing medium by the end of the exponential phase of growth. With respect to its chemical nature, extracellular SAS synthesized by A. calcoaceticus K-4 growing on ethanol-containing medium under optimal cultivating conditions form a glycolipid-aminolipid complex.

Multivariate statistical analysis of the distribution patterns of carbohydrates and surface-active substances in the northern Adriatic Sea

Dissolved and particulate carbohydrates (DTCHO and PTCHO) as well as surface-active substances concentrations and relative acidities (SAS T and Ac r) were studied in the northern Adriatic Sea during the period between 1998 and 2005 with the aim to investigate their temporal and spatial dynamics in the basin and possible links with the mucilage events with help of comprehensive statistical data analysis. The investigated time period encompassed 3 years characterized by intensive appearance of mucilage aggregates (mucilage years) and 3 years without this phenomenon (non-mucilage years). In order to explore possible regularities in the distribution and covariation of investigated parameters, univariate and multivariate analyses of variance (MANOVA) were performed, considering effects of different parameters, including water column depth, geographic location, season, individual year, and mucilage appearance. The investigated organic matter parameters showed a significant complexity of their temporal (seasonal, interannual) and spatial (vertical and horizontal) distribution patterns. Although some characteristics of the distribution patterns, such as seasonality and differences between surface (0.5m) and deeper layers, were already described in the literature, this work provides the first rigorous statistical analysis performed on a larger data set, allowing quantitative assessment of the observed differences. It was shown that mucilage years in the northern Adriatic were characterized by different patterns of the investigated four organic matter parameters, compared to those of the non-mucilage years. Moreover, it was shown that carbohydrates substantially contribute to the overall surfactant activity of the present organic matter, especially in the surface layer of the most productive western part of the basin, indicating new production, triggered by river-born nutrients, as the predominant source. To the best of our knowledge, this is the first evidence for a possible coupling between CHO and surfactant-activity in environmentally relevant conditions.

Organic matter in the bulk precipitations in Zagreb and Šibenik, Croatia

Dissolved organic carbon (DOC), surface active substances (SAS) and copper complexing capacity (CuCC) were studied in bulk precipitations collected periodically from 2003 to 2007 in the continental city of Croatia (Zagreb: n = 27) and in the city at the Adriatic coast (Šibenik: n = 38). DOC concentrations (Zagreb: 0.67–4.03 mgC/L with average concentration of 1.93 ± 0.76 mgC/L; Šibenik: 0.44–4.13 mgC/L with average concentration of 1.83 ± 0.83 mgC/L) are similar to those measured in other samples of continental rainwater in the northern hemisphere. The concentrations of SAS in samples from Zagreb ranged from 0.055 to 0.45 eq. Triton-X-100 mg/L with average concentration of (0.14 ± 0.06) eq. Triton-X-100 mg/L. SAS fractions were of a similar range in Šibenik (0.02–0.60 eq. Triton-X-100 mg/L) with an average concentration of 0.11 ± 0.06 eq. Triton-X-100 mg/L. However, the lowest values of SAS (between 0.02 and 0.04 eq. Triton-X-100 mg/L) were observed only in Šibenik (27%). We have estimated that the higher pH values were responsible for lower surface activity of organic matter in bulk samples from Šibenik. DOC may form complexes that control the transport and solubility of heavy metals in natural water. CuCC measured in Šibenik in the range 0.066–1.4 μM Cu 2+ was in general higher, compared to the one in Zagreb (0.010–0.586 μM Cu 2+) which is the result of biogenically driven organic contribution to the precipitation, especially in the warmer period of the year.

Removal of Pb++ in presence of surfactants

PurposeThe object of the present work is to study the kinetics of removal of Pb++ on zinc rods in the presence and absence of three surface active substances (SAS) at different concentrations of SAS and different temperatures.Design/methodology/approachThe paper uses a range of recently published (1973‐2003) works, which aim to provide practical and theoretical information about lead, which is a very toxic metal.FindingsLead tends to accumulate a sediment, from which it can be released by various processes of remobilization and in many cases it enters the food chain and is concentrated in fish and other edible organisms. The reaction can be considered as taking place via six steps.Research limitations/implicationsThe work is a list of recent papers which have been published in different European journals and magazines.Practical implicationsThe determination of change of Pb++ concentrations was carried out using a Perkin‐Elmer atomic absorption Spectrophotometer.Originality/valueThe rate of PbII/Zn cementation reaction in the presence of surfactants as non‐ionic (Triton‐X‐100), anionic (SDS) and cationic (CTAB) decreased compared with the blank solution (lead nitrate solution). The order of decreasing rate was as follows: Triton‐X‐100 > CTAB > SDS. The rate of cementation was increased by temperature and the value of ΔE* ranged between 27 and 33 kJmol−1, which indicated that the reaction is a diffusion‐controlled process. The presence of two different SAS in the solution is more effective than the presence of one only.

Influence of the method of mixing of pigments with a polymer on the structure and properties of polyurethane compositions

The effect of the nature of pigments and the method of their addition on the properties of polyurethanes based on diphenylmethane diisocyanate and polyester is studied. Technical carbon black and titanium dioxide, which are added to a polyurethane composition in the presence of surfactants, are used as pigments. It is established that, upon the addition of pigments, the viscosity changes nonmonotonically, maximal values of viscosity being observed at a 20% concentration of technical carbon black. Optimal concentration of surface-active substances is found whose magnitude for technical carbon black is 0.25–0.5%. With an increase in surfactant concentration, they act as plasticizers abruptly lowering the intermolecular interaction. The effect of different surfactants on the rheological properties of polyurethane compositions is studied. It is shown that the addition of pigments makes it possible to enhance mechanical properties and to decrease internal stresses in films.

Surface active substances in the upper water column during a Southern Ocean Iron Fertilization Experiment (EIFEX)

Surface active substances (SAS) in the water column were measured by voltammetry using the electrochemical probe o‐nitrophenol (ONP) during EIFEX, a mesoscale open ocean iron enrichment experiment in the Southern Ocean. SAS levels were low throughout the experiment (<0.005 – 0.03 mg L−1 Triton X‐100 equivalents). Initially SAS was extremely low in the photic zone, but as the phytoplankton bloom developed concentrations markedly increased throughout the upper 100 m (∼0.02 mg L−1 Triton X‐100 equivalents). Highest concentrations of SAS (>0.02 mg L−1 Triton X‐100 equivalents) were found at the end of the bloom particularly at density discontinuities where organic material may accumulate. Exudates from diatoms appeared to be the major source of SAS during EIFEX, either from direct extracellular release or in the action of being grazed upon by zooplankton.

Investigation of wind-induced solitary waves in a circular aerohydrochannel

The mechanisms of initiation and interaction of wind-induced solitary waves in a circular aerohydrochannel are experimentally investigated. We study the influence of flotation (floating mass) and surface-active substances on the time of formation of a soliton and its parameters. It is shown that the increase in the concentration of surface-active substances and the amount of flotation leads to an increase in the time of initiation wind-induced solitary wave. It is shown that, in the case of small difference between the amplitudes of the interacting solitons, they behave as particles. In the case where the difference between the amplitudes is significant, the larger soliton passes through the smaller, which leads to the formation of a single soliton as a result of multiple interaction between the original solitons.

Organic matter characterization and fate in the sub-arctic Norwegian fjords during the late spring/summer period

The organic matter (OM) pool has been studied in two sub-arctic north Norwegian fjords, Balsfjord and Ullsfjord, in July 2001 and June 2003. Besides general OM parameters such as dissolved organic carbon (DOC), particulate organic carbon and nitrogen (POC and PON), the distribution of specific compounds such as folic acid and surface active substances (SAS) was followed. The results are supported with data of salinity, temperature, and chlorophyll a (Chl a). This approach allowed assessment of the fate of the OM pool, and its distinct vertical, spatial, and seasonal variations. Fjord waters could be vertically divided into two layers: the upper mixed layer (UML), until 40 m depth, and the deep aphotic layer. Spatial variability between the two fjords is a consequence of different influences of shelf waters on the fjords. Significant enrichment of POC and PON concentrations (3–5 times), as well as those of particulate SAS and folic acid (up to 3.2 times) in the UML was recorded during the period of new production, in early June. Depletion of particulate OM in deep waters was ascribed to fast dissolution or remineralization in the UML or upper part of aphotic layer. OM in July 2001 was characterized with 15.9% higher DOC pool compared to June 2003, and had refractory properties, suggesting the fjords to be an important source of organic matter for the continental shelf ecosystem. The DOC pool in these subarctic fjords represents the major component of the OM pool. The DOC concentrations in fjords are lower than those in previously studied warmer seas (e.g. the Adriatic Sea), whereas the concentrations of folic acid and SAS are comparable to those in the Adriatic Sea.

Mucopolysaccharide transformation by sulfide in diatom cultures and natural mucilage

The role of sulfur species in the formation and stability of mucus aggregates in the Adriatic Sea was studied. Natural aggregates were compared with a mixed diatom culture. A sample from the sea bottom collected from the northern Adriatic Sea was cultivated and transferred to f/2 medium to isolate benthic diatoms. Diatom cultures were incubated at room temperature and irradiated with dim light (30 to 40 mmol m-2 s-1). Subcultured samples were incubated at room temperature under anaerobic conditions for up to 1 mo, with different concentrations of sulfide (10-4 and 10-3 mol l-1). In diatom cultures, interactions between sulfide and organic matter were investigated and followed for 10 d through: (1) formation of organosulfur species ; (2) changes in surfactant activity and (3) degradation of pennate diatoms followed by cell lysis and release of large amount of polysaccharides. A large increase in dissolved organic carbon (DOC) concentration was recorded in the ambient water of the sulfide-treated samples. A DOC concentration of 7.17 mg l-1 was determined in the ambient water of untreated diatom cultures increasing to 40 mg l-1 in sulfide-treated samples. Simultaneously, in the same sulfide-treated samples (both ambient water and aggregates of enriched diatom cultures), surfactant activity was observed to increase by 2 orders of magnitude. The concentration of surface-active substances (SAS, expressed as Triton-X-100 conc.) increased from 0.35 mg l-1 in the aggregate and 0.59 mg l-1 in the ambient water of the untreated diatom cultures to 20 mg l-1 in sulfide-incubated samples. Epifluorescence microscopy observations showed that diatoms decomposed under sulfide treatment and released a large amount of polysaccharides, as revealed by a specific molecular probe for glucose and mannose, i.e. Con-A lectin conjugated by fluorescein. These comparative experiments indicated that one of the factors triggering mucilage formation in the Adriatic Sea could be massive diatom lysis in bottom or anoxic microzones where, due to microbial activity, reduced sulfur species are prominent and have an important role in the formation and stability of mucilage development.

Distribution and Seasonal Variability of Organic Matter in a Small Eutrophicated Salt Lake

Distribution and seasonal variability of dissolved organic carbon (DOC) and surface active substances (SAS) were studied along the depth profile (15m) in a small eutrophicated and periodically anoxic sea lake (Rogoznica Lake, Eastern Adriatic coast) in 1996 and 1997. The range of DOC concentrations was characteristic for productive coastal marine ecosystems (60% of samples in the range of 1–2mgl−1and 40% between 2 and 3mgl−1). Distribution of SAS concentrations was uniform and shifted toward higher concentrations in comparison to other coastal areas in the Adriatic Sea. Eutrophication in the lake is generated by nutrient recycling under anaerobic conditions. Systematically higher concentrations of chlorophyll a, DOC and SAS were determined at the chemocline in the bottom layer (10–12m) than in the upper water layer (0·5–2m). Seasonal variability of organic matter was discussed regarding distributions of microphytoplankton (cells >20 μm) and photosynthetic pigments as well as oxygen and salinity changes along the depth profile. The dissolved oxygen saturation reaching up to 300% in the water layer between 8m and 10m depths in May and June 1996, was correlated with enhanced concentrations of phytoplankton biomass (reflected as chl a and b, fucoxanthin, peridinin, zeaxanthin) and increased concentrations of DOC and SAS.