Alkyl Polyglycoside Surfactants Research Articles

The effects of SDS, APG, and DTAB surfactants on the morphology of micro-nano RDX particles prepared in a microfluidic reactor

Abstract The effects of different surfactants on the morphology of 1,3,5-trinitro-1,3,5-triazinane (RDX) micro-nanoparticles prepared by solvent/non-solvent method in a microfluidic reactor were investigated. Alkyl polyglycoside (APG), sodium dodecyl sulphate (SDS) and dodecyltrimethylammonium bromide (DTAB) were selected as non-solvents. The surface tension and interfacial tension (IFT) properties of SDS, APG and DTAB were investigated. Compared to DTAB and SDS, the APG could effectively reduce the interfacial tension to 10−2 mN/m and exhibited better surface tension. The RDX prepared with different surfactants were analysed by scanning electron microscopy (SEM), X-ray diffractometry (XRD) and Fourier transform infrared spectrometry (FTIR). The results showed that the different surfactants could significantly improve the dispersion effect of RDX and the crystal morphology was uniform and stable.

Toward Sustainable Production of Sugar-Based Alkyl Polyglycoside Surfactant─A Comprehensive Review on Synthesis Route and Downstream Processing

This review aims to identify the challenges and opportunities in sustainable production of sugar-based alkyl polyglycoside, s-APG, by first assessing and subsequently comparing the production route and downstream processing for both the chemically and biologically catalyzed synthesis process, from the perspective of critical operating parameters, type of reactor technologies, and downstream processing strategies. From a sustainability point-view, the acidic homogeneous catalyst in chemically catalyzed s-APG production should be substituted by a practically active, stable, and recyclable heterogeneous catalyst. Alternatively, the green solvent could be used to increase the interaction between sugar and fatty alcohol, resulting in high yield s-APG without using a catalyst. To make the process employing biocatalyst more economically competitive, the free enzyme must be reused through the immobilization method, reactor intensified with membrane or other appropriate downstream processes. A less energy-intensive extraction process to replace the existing evaporative method to separate fatty alcohol from s-APG also deserves an intensive investigation.

Polymer enhanced foam for improving oil recovery in oil-wet carbonate reservoirs: A proof of concept and insights into the polymer-surfactant interactions

The feasibility of polymer enhanced foam (PEF) for enhanced oil recovery (EOR) in a strongly oil-wet and heterogeneous carbonate reservoir with medium temperature (131 °F) and high salinity was experimentally investigated. An Alkyl Poly-Glycoside (APG) surfactant was firstly selected because of its prominent foam behavior in oil-wet carbonates. The effect of polymer type, flow rate and brine composition on foam strength and stability were systematically investigated, aiming to understand how the interactions between polymer and surfactant could influence the transport behavior and performance of PEF in porous media. It was found that, with either an associative polymer or a nonionic polymer (PAM), the foam strength and foam stability could be largely enhanced, both in the absence and in the presence of oil. A significant improvement in oil recovery efficiency was obtained for PEF with an associative polymer, approximately 5% higher than that achieved for conventional polymer-free foam. The PEF behavior is intimately dependent on the interactions between the polymer and the surfactant. It is hypothesized that the increased foam strength by adding polymer at oil-wet conditions may be resulted from an increase of aqueous phase viscosity, the wettability alteration from oil-wet to less oil-wet, the generation of a highly viscoelastic film and (or) the creation of a more stable pseudo-emulsion film. This study provides a robust approach for PEF mobility control and reservoir conformance in oil-wet and heterogeneous carbonate reservoir under analogous reservoir conditions.

An experimental investigation of the foam enhanced oil recovery process for a dual porosity and heterogeneous carbonate reservoir under strongly oil-wet condition

In this study, we investigate the feasibility of foam enhanced oil recovery (EOR) for a dual porosity and heterogeneous carbonate reservoir in the Middle East with medium temperature (55 °C) and high formation salinity (16% TDS). An Alkyl Poly-Glycoside (APG) surfactant was firstly selected based on the solubility tests and bulk foam tests. Afterwards, a series of core flooding experiments both in the absence and in the presence of crude oil were performed on Estaillades limestone, a dual-porosity and heterogeneous carbonate presenting reasonable similarities with the actual formation. In these foam tests, the influence of surfactant concentration, foam quality, injection velocity, brine composition, injection mode and permeability on foam strength and incremental oil recovery were systematically investigated. The optimal foam quality is found to be around 60–70% from foam quality scan tests in the absence of crude oil. Moreover, foam can still be generated in Estaillades under strongly oil-wet conditions, and the foam strength in the high-quality regime is largely dependent on surfactant concentration. More than 10% original oil in place (OOIP) of the water flooded residual oil was recovered after co-injecting 2.0 total pore volume (TPV) of nitrogen and 0.5 wt% APG surfactant (in synthetic seawater brine) at 65% foam quality and 4 ft./d. Interestingly, it was observed that the presence of lauryl betaine (LB) can significantly enhance the stability of APG foam in the presence of crude oil, though LB surfactant itself is not a good foamer. At last, the three phase co-injection tests proved the presence of foam at approximately 70% oil saturation. The results of this study may provide insights into the foam transport behavior in a dual porosity and heterogeneous porous media under strongly oil-wet condition.

Preparation of Microemulsion from an Alkyl Polyglycoside Surfactant and Tea Tree Oil.

Preparation and characterization of microemulsions consisting of a plant-derived alkyl polyglycoside (APG) surfactant and the essential oil of Melaleuca alternifolia (tea tree) was studied. This nonionic APG surfactant used was Triton CG-110 with a CMC at 1748 ppm at 25 °C. Tea tree oil (TTO) was extracted from tea tree leaves by Triton CG-110-assisted hydrodistillation method. The preparation of the microemulsion was aided by the construction of pseudo-ternary phase diagrams, which were investigated at the different weight ratios of surfactant mixtures (Smix = Triton CG-110/PPG) as 0.6:1, 1.8:1, 1:0 with hydrodistilled and commercial TTO by water titration method at room temperature. Particularly, structure of microemulsion was identified by electrical conductivity and viscosity. Moreover, shelf stability of some microemulsion made of 1% TTO with various concentration of Triton CG-110/PPG (1.8:1 w/w) were monitored for over a two-month period with dynamic light scattering. These results showed that microemulsion made of 1% TTO, 9% Triton CG-110/PPG (1.8:1 w/w) was insensitive with time and temperature of storage.

The impact of alkyl polyglycoside surfactant on oil yields and its potential effect on the biogenic souring during enhanced oil recovery (EOR)

The aim of this work is to quantify the effect of using alkyl polyglycoside (APG) surfactant as the main agent for oil recovery and to quantify its potential impact on biogenic souring. Sand-pack column replicates were subjected to two surfactant concentration injection events both in the presence and absence of oil. The activity of sulphate-reducing bacteria (SRB) was tested using the distinct resultant produced waters (PWs) or with surfactant solutions as the additional carbon source. The results suggested that a surfactant concentration of 2% (w/v) can recover 7.7 fold more oil than 0.1% (w/v). The PWs SRB-activity testing identified that surfactant concentrations below 1% (w/v) can significatively increase microbial activity (256μgSO4/L/h) - which enhances biogenic souring. PWs with higher surfactant concentrations inhibited SRB-activity in the presence of oil. SRB-microbes can utilize surfactant as the sole carbon source (concentrations below 2% w/v). Thus, the mixture of surfactant and oil increased or decreased SRB-activity depending on their concentration (low/high, respectively). Surfactant can not only assist in enhancing biogenic souring but, at a higher concentration, may control it without the need of employing significant amounts of biocide.

Synergisms between siloxane-polyoxyethylene and alkyl polyglycoside surfactants in foam stability and pool fire extinction

Fluorocarbon surfactants in firefighting foams must be replaced with environmentally friendly surfactants without loss of fire suppression performance. Aqueous foams generated from commercial siloxane-polyoxyethylene and alkyl polyglycoside surfactants were characterized individually and as mixtures in a formulation by measuring the solution and foam properties, foam degradation and fuel transport rates through a foam layer on a hot heptane pool, and foam’s ability to suppress a heptane pool fire rapidly using minimum amount of foam. The results showed significantly smaller fire extinction times for the surfactant mixtures than for either of the individual components exhibiting a synergistic fire extinction rather than following the law of averages; 5 times enhancement in extinction performance. The measured foam degradation rate with the foam exposed to a hot heptane pool also showed a similar synergism. The reduced foam degradation rate resulted in a reduced fuel vapor transport for longer times and a more rapid fire extinction for the siloxane-glycoside mixture. By increasing the hydrophilicity with increased size of the polyglycoside head, the synergistic effect was enhanced. Both benchtop (19 cm diameter) and large scale (6 ft diameter) heptane pool fire extinction with the siloxane-glycoside surfactant mixture showed that the extinction time was 1.5 times (60% effectiveness of AFFF) that of an equivalent AFFF formulation containing a fluorosurfactant in place of the siloxane surfactant at a fixed foam application rate (22 L m−2 min−1). An understanding of the molecular interactions at the interface causing the synergistic effects may lead to improved siloxane-glycoside systems and other novel surfactant systems with performance matching that of fluorocarbon surfactants.

Nanocrystals for dermal penetration enhancement – Effect of concentration and underlying mechanisms using curcumin as model

Nanocrystals have received considerable attention in dermal application due to their ability to enhance delivery to the skin and overcome bioavailability issues caused by poor water and oil drug solubility. The objective of this study was to investigate the effect of nanocrystals on the mechanism of penetration behavior of curcumin as a model drug. Curcumin nanocrystals were produced by the smartCrystals® process, i.e. bead milling followed by high pressure homogenization. The mean particle size of the curcumin crystals was about 200nm. Stabilization was performed with alkyl polyglycoside surfactants. The distribution of curcumin within the skin was determined in vitro on cross-sections of porcine skin and visualized by fluorescent microscopy. The skin penetration profile was analyzed for the curcumin nanosuspension with decreasing concentrations (2%, 0.2%, 0.02% and 0.002% by weight) and compared to nanocrystals in a viscous hydroxypropylcellulose (HPC) gel. This study demonstrated there was minor difference between low viscous nanosuspension and the gel, but low viscosity seemed to favor skin penetration. Localization of curcumin was observed in the hair follicles, also contributing to skin uptake. Looking at the penetration of curcumin from formulations with decreasing nanocrystal concentration, formulations with 2%, 0.2% and 0.02% showed a similar penetration profile, whereas a significantly weaker fluorescence was observed in the case of a formulation containing 0.002% of curcumin nanocrystals. In this study we have shown that curcumin nanocrystals prepared by the smartCrystal® process are promising carriers in dermal application and furthermore, we identified the ideal concentration of 0.02% nanocrystals in dermal formulations. The comprehensive study of decreasing curcumin concentration in formulations revealed that the saturation solubility (Cs) is not the only determining factor for the penetration. A new mechanism based also on the concentration of the nanocrystals on skin surface was proposed.

Application of alkyl polyglycoside surfactant in ultrasonic-assisted extraction followed by macroporous resin enrichment for the separation of vitexin-2″-O-rhamnoside and vitexin from Crataegus pinnatifida leaves.

An alkyl polyglycoside (APG) surfactant was used in ultrasonic-assisted extraction to effectively extract vitexin-2″-O-rhamnoside (VOR) and vitexin (VIT) from Crataegus pinnatifida leaves. APG0810 was selected as the surfactant. The extraction process was optimized for ultrasonic power, the APG concentration, ultrasonic time, soaking time, and liquid-solid ratio. The proposed approach showed good recovery (99.80-102.50% for VOR and 98.83-103.19% for VIT) and reproducibility (relative standard deviation, n=5; 3.7% for VOR and 4.2% for VIT) for both components. The proposed sample preparation method is both simple and effective. The use of APG for extraction of key herbal ingredients shows great potential. Ten widely used commercial macroporous resins were evaluated in a screening study to identify a suitable resin for the separation and purification of VOR and VIT. After comparing static and dynamic adsorption and desorption processes, HPD100B was selected as the most suitable resin. After column adsorption and desorption on this resin, the target compounds VOR and VIT can be effectively separated from the APG0810 extraction solution. Recoveries of VOR and VIT were 89.27%±0.42% and 85.29%±0.36%, respectively. The purity of VOR increased from 35.0% to 58.3% and the purity of VIT increased from 12.5% to 19.9%.

Analysis of the Photophysical Behavior and Rotational-Relaxation Dynamics of Coumarin 6 in Nonionic Micellar Environments: The Effect of Temperature.

The photodynamics of Coumarin 6 have been investigated in three nonionic micellar assemblies, i.e., n-dodecyl-β-d-maltoside (β-C12G2), p-tert-octyl-phenoxy polyethylene (9.5) ether (Triton X-100 or TX100) and n-dodecyl-hexaethylene-glycol (C12E6), to assess their potential use as encapsulation vehicles for hydrophobic drugs. To evaluate the effect of the micellar size and hydration, the study used a broad temperature range (293.15–323.15 K). The data presented here include steady-state absorption and emission spectra of the probe, dynamic light scattering, together with fluorescence lifetimes and both steady-state, as well as time-resolved fluorescence anisotropies. The time-resolved fluorescence anisotropy data were analyzed on the basis of the well-established two-step model. Our data reveal that the molecular probe in all of the cases is solubilized in the hydration layer of micelles, where it would sense a relatively polar environment. However, the probe was found to undergo a slower rotational reorientation when solubilized in the alkylpolyglycoside surfactant, as a result of a more compact microenvironment around the probe. The behavior of the parameters of the reorientation dynamics with temperature was analyzed on the basis of both micellar hydration and the head-group flexibility of the surfactants.

Toxicity of Cúspide 480SL® spray mixture formulation of glyphosate to aquatic organisms.

In 2011, an alternative formulation of glyphosate (Cúspide 480SL®) was chosen to replace Roundup-SL®, Fuete-SL®, and Gly-41® for the control of Erythroxylum coca, the source of cocaine, in Colombia. Cúspide 480SL contains the active ingredient glyphosate isopropylamine (IPA) salt, which is the same active ingredient used in previous formulations. However, Cúspide 480SL contains an alkyl polyglycoside surfactant rather than the polyethoxylated tallow amine (POEA) surfactant used in other formulations and known to be more toxic to nonprimary producing aquatic organisms than glyphosate itself. An adjuvant, Cosmo-Flux F411, and water also are added to the spray mixture before application. Aquatic ecosystems adjacent to the target coca fields might be exposed to the spray mix, placing aquatic organisms at risk. Because no toxicity data were available for spray mixture on aquatic organisms, acute toxicity tests were conducted on aquatic plants, invertebrates, and fish, by using the Cúspide 480SL spray mix as described on the label. Based on the median effective concentration (EC50) values for similar organisms, the spray mixture was less toxic to aquatic organisms than formulations previously used for the control of coca (i.e., Roundup-SL, Fuete-SL, and Gly-41). A physical effect induced by Cosmo-Flux F411 was observed in Daphnia magna, Ceriodaphnia dubia, and Hyalella azteca, causing the invertebrates to be trapped in an oily film that was present at the surface of the water. However, a hazard assessment for the Cúspide 480SL spray mix, using estimated worst-case exposure scenario concentrations and EC50 values from the toxicity tests, indicated de minimis hazard for the tested aquatic animals, with hazard quotients all <<1.

Formulation of solid lipid nanoparticles (SLN): The value of different alkyl polyglucoside surfactants

Alkyl polyglycosides (APGs) represent a group of nonionic tensides with excellent skin compatibility. Thus they seem to be excellent stabilizers for lipid nanoparticles for dermal application. To investigate this, different APGs were selected to evaluate their influence on the formation and characteristics of solid lipid nanoparticles (SLN). Contact angle analysis of the aqueous solutions/dispersions of the APGs on cetyl palmitate films revealed good wettability for all APG surfactants. Cetyl palmitate based SLN were prepared by hot high pressure homogenization and subjected to particle size, charge and inner structure analysis. 1% of each APG was sufficient to obtain SLN with a mean size between 150nm and 175nm and a narrow size distribution. The zeta potential in water was ∼ −50mV; the values in the original medium were distinctly lower, but still sufficient high to provide good physical stability. Physical stability at different temperatures (5°C, 25°C and 40°C) was confirmed by a constant particle size over an observation period of 90 days in all dispersions. In comparison to SLN stabilized with classical surfactants, e.g., Polysorbate, APG stabilized SLN possess a smaller size, improved physical stability and contain less surfactant. Therefore, the use of APGs for the stabilization of lipid nanoparticles is superior in comparison to classical stabilizers. Further, the results indicate that the length of the alkyl chain of the APG influences the diminution efficacy, the final particle size and the crystallinity of the particles. APGs with short alkyl chain led to a faster reduction in size during high pressure homogenization, to a smaller particle size of the SLN and to a lower recrystallization index, i.e., to a lower crystallinity of the SLN. The crystallinity of the SLN increased with an increase in the alkyl chain length of APGs. Therefore, by using the tested APGs differing in the alkyl chain length, not only small sized and physically stable but also SLN with different sizes and crystallinity can be obtained. An optimized selection of these stabilizers might therefore enable the production of lipid nanoparticles with “tailor-made” properties.

Application of Green Commercial Surfactant in Preparing Purely Acrylic Latex via Semi‐continuous Seeded Emulsion Polymerization

AbstractNonylphenol ethoxylates (NPEOs) are widely used as surfactants for emulsion polymerization and for post adding stabilization for latex applications in formulations with high filler content. However, NPEOs are bioaccumulative and persistent in the environment while nonylphenol, the breakdown product of NPEs, is an endrocrine disruptor. Therefore, it has been recommended to ban technical processes using NPEOs as surfactants. The acrylic polymer latex was prepared via semi‐continuous seeded emulsion polymerization of butyl acrylate and methyl methacrylate in water phase initiated with potassium persulfate when nonylphenol ethoxylates are replaced with alkyl polyglycoside (APG) surfactants. The structure of the resultant acrylic polymer latex is confirmed with Fourier transform infrared spectroscopy spectrum. Differential scanning calorimetry confirms that the resultant latex is a kind of random copolymer and the consistency among the chain segment is fairly good. Influences of amount of APG on the properties of the resultant latex and its film were investigated. Results show that the particle size of the latex is decreased with the increase of the amount of APG. And the ionic stability of latex is also improved with the increase of the amount of APG. However, the water‐resistance of the film of the latex is decreased with the increase of the amount of APG.

Analysis of the Influence of Alkyl Polyglycoside Surfactant and Cosolvent Structure on Interfacial Tension in Aqueous Formulations versus n-Octane

Abstract We studied the influence of molecular structural elements of alkyl polyglycoside (APG) surfactants on the interfacial tension (IFT) in aqueous formulations against n-octane. This included the analysis of alkyl and aryl chain length, type and number of sugar-ring head, anomers, addition of cosolvents and effect of salt addition. We found that longer alkyl or aryl chains lead to lower IFT, consistent with data recorded for commercial (mixed) APGs. APGs with only one sugar-ring head had lower IFT than their analog maltose derivates (two-ring head). Intriguingly the stereochemistry of the sugar head (i.e. galactose versus glucose) and the type of anomer showed a significant influence on IFT. The n-octyl-α-D-glucopyranoside anomer had a lower IFT than the corresponding β-anomer. 1-octanol and 1-hexanol were efficient cosolvents consistent with the datasets observed for commercial APGs. Salt addition reduced IFT. Functional groups (aldehyde, amide-methoxy) integrated into the molecular architecture of the APG skeleton were efficient in terms of significantly reducing IFT, suggesting a strategy for the molecular design of advanced APG surfactants. We discuss the results in the context of the hydrophilic-lipophilic deviation (HLD) concept, which we modified so that IFT values are discussed instead of phase behavior.

New surfactant classes for enhanced oil recovery and their tertiary oil recovery potential

We investigate four different types of surfactants for effectiveness in tertiary oil recovery (TOR). The selected surfactant formulations were tested for enhanced oil recovery using coreflood tests on Berea sandstones. In addition to the corefloods, one sandpack surfactant flood was performed. The porous media were conditioned to residual waterflood oil saturation prior to surfactant slug injection. This was followed by polymer drive slug injection, and incremental oil recovery was measured against time. The tested formulations were selected after an extensive research effort including measuring interfacial tensions (IFT) and adsorption behavior on kaolinite clay. Effective were low 1-naphthol concentrations dissolved in 1-butanol in alkyl polyglycoside surfactant formulations which led to significant additional incremental oil recovery (40% TOR) due to dramatic reductions in IFT. Three other types of surfactants in this study include: • a di-tridecyl sulfosuccinic acid ester, • coconut diethanolamide, and • alkylpropoxy sulfate sodium salts which led to TOR of 15%, 75% and 35–50%, respectively. These results indicate that a wide variety of surfactants can meet the technical requirements as enhanced oil recovery (EOR) agents.

Predictive synthesis of ordered mesoporous silica with maltoside and cationic surfactants based on aqueous lyotropic phase behavior

Self-assembled nonionic alkyl glycoside surfactants are of interest for creating functional adsorption and catalytic sites at the surface of mesoporous sol-gel-derived materials, but they typically impart poor long-range order when they are used as pore templates. Improved order and control over the functional site density can be achieved by mixing the alkyl polyglycoside surfactant with a cationic surfactant. Here, we investigate the rarely reported lyotropic liquid crystalline (LLC) phase behavior of aqueous solutions of a nonionic disaccharide surfactant, n-dodecyl-beta-d-maltoside (C(12)G(2)/DM), and cetyltrimethylammonium bromide (C(16)TAB) by low-angle powder X-ray diffraction (XRD) and polarized optical microscopy (POM). An approximate ternary phase diagram of the C(16)TAB-C(12)G(2)-water system is developed at 50 degrees C, which includes 2-D hexagonal (P6mm symmetry), bicontinuous cubic (Ia3 d symmetry), lamellar, and rectangular (cmm symmetry) LLC phases. By replacing the volume of water in the phase diagram with an equivalent volume of silica, ordered mesoporous materials are prepared by a nanocasting technique with variable C(12)G(2)/C(16)TAB ratios. For large regions of the phase diagram, this approach is predictive. However, silica materials synthesized with comparatively high C(12)G(2)/C(16)TAB ratios are only poorly ordered in a way that does not correspond to their lyotropic liquid crystalline phase behavior. Also, in contrast with our previous study of mixed C(16)TAB/n-octyl-b-d-glucopyranoside templating [37] the boundary between hexagonal and bicontinuous cubic materials is shifted towards higher surfactant content than in the aqueous LLC system.

Aqueous Solution Properties, Biodegradability, and Antimicrobial Activity of some Alkylpolyglycosides Surfactants

Abstract In the present investigation, a series of alkyl polyglycosides with alkyl chain length of C 8, 9, 10, 12 and 14 were synthesized using transacetalization method. Purity of the products was investigated using high performance liquid chromatography. Surface parameters particularly Effectiveness πcmc, Efficiency Pc20, maximum surface excess Γmax, minimum surface area Amin and HLB values are investigated, in addition to thermodynamic parameters (ΔGads and ΔGmic). Resistance to hydrolysis for the prepared compounds was investigated. The synthesized compounds were tested for their biodegradability in Nile river water according to Die-away test method and their antimicrobial activity against different strains of bacteria, yeast and fungi was investigated.

Alkyl polyglycoside surfactant–alcohol cosolvent formulations for improved oil recovery

We examine here the suitability of alkyl polyglycosides (APG) for improved oil recovery (IOR) applications. In recent years, these nonionic carbohydrate-based surfactants have become a significant commercial product (80,000 tons/year) with widespread use in household and agricultural products. Our laboratory study determined several characteristics of common APG surfactant formulations, in particular their capability to create low interfacial tensions (IFT) with n-alkane hydrocarbons. Our formulations included a wide range of alcohol cosurfactants with APG surfactants. We found APG–cosurfactant combinations that exhibit low IFT values of 0.01 mN/m or less versus n-octane. Our laboratory tests confirmed these APG formulations can provide useful IFT properties that are largely independent of both salinity and temperature. We report a coreflood test conducted on a Berea sandstone core using a selected formulation that exhibits oil recovery as high as 85% IOIP.

Synthesis and Characterization of some Alkyl Polyglycosides Surfactants

AbstractAlkyl polyglycosides (APGs) of different hydrocarbon chain lengths were prepared using an indirect method involving the condensation of fatty alcohol with dextrose. The chemical structures of the prepared compounds were confirmed using different spectroscopic techniques, primarily Fourier transform infrared spectroscopy, nuclear magnetic resonance and mass spectroscopy. The surface properties of the solutions containing different concentrations of the prepared APGs were determined at different temperatures. The results of the spectroscopic analysis demonstrate that these materials were prepared through the correct techniques, producing pure materials. The results of the critical micelle concentration (CMC) determination demonstrate that the surface properties of these compounds depend mainly on the nature of their hydrophobic component.

The effects of foliar applied CaCl 2·2H 2O, Ca(OH) 2 and K 2CO 3 combined with the surfactants Glucopon and Plantacare on gas exchange of 1 year old apple ( Malus domestica BORKH.) and broad bean ( Vicia faba L.) leaves

Calcium chloride, calcium hydroxide, potassium carbonate and the alkylpolyglycoside surfactants Glucopon 215 CSUP and Plantacare 12 UP are salts applied to leaves as foliar nutrients and fungicides. These chemicals were sprayed on apple ( Malus domestica BORKH.) and broad bean ( Vicia faba L.) leaves. Stomatal conductance and rates of net photosynthesis were measured continuously in the light and in the dark using a Portable Photosynthesis System CIRAS-1. All compounds with the exception of Ca(OH) 2 affected stomatal conductance and net photosynthesis, albeit to different degrees. In light, Plantacare either alone (0.2 g l −1) or in combination with CaCl 2·2H 2O (5 g l −1) or K 2CO 3 (5 g l −1) caused a rapid initial increase in stomatal conductance during the first 1–3 h after spraying on the leaves, maximum conductances were observed about 6 h after application. A rather high stomatal conductance was observed during the dark period when Glucopon (0.2 g l −1) was applied either alone or in combination with Ca(OH) 2. The combination CaCl 2·2H 2O + Glucopon did not cause this elevated stomatal conductance during the dark. CaCl 2·2H 2O reduced stomatal conductance in combination with both Glucopon and Plantacare. The surfactant Plantacare reduced net photosynthesis during the first light period (12 h), if applied alone or in combination with CaCl 2·2H 2O. Treatment of broad bean leaves with K 2CO 3 + Plantacare resulted in a rapid decrease in net photosynthesis during the first hour, and then the rates of net photosynthesis increased rapidly and approached to those of the water control. The effects of surfactants and salts on net photosynthesis had nearly disappeared by the beginning of the second light period. Non-specific glycosidases presumably cleaved the glycosidic bond between the alkyl and the sugar moieties during the preceding night. Our data showed that foliar applications of CaCl 2·2H 2O and K 2CO 3 together with alkyl polyglycoside surfactants can affect gas exchange. However, the effects of the chemicals at the concentrations used in our study were not very large and were transient. They practically vanished within 24 h and a detrimental effect on growth and development of crops was not likely.