Surface characterization of okra hydrocolloid extract by inverse gas chromatography (IGC)

Analysis of natural okra extracts as corrosion inhibitors for mild steel in acidic medium

Plant extracts have been shown to effectively inhibit metal corrosion. Using the Box-Behnken design, gravimetric, and electrochemical techniques, analyses were designed to investigate the anti-corrosion potential of okra in a 1M HCl medium. The inhibition performances derived from the various methods were in good agreement, demonstrating that physio-chemisorption was effective and adhered to the Langmuir isotherm model. The efficiency of okra mucilage extract was 96% at a much lower concentration compared to 91.2% and 88.4% for the unsieved extract and gelly-okra filtrate, respectively. FTIR results showed the presence of several functional groups in the okra mucilage extract that are associated with adsorption, and TGA analysis revealed that the extract has high thermal stability. FESEM analysis also supported evidence of adsorption. It was determined that corrosion inhibition by okra mucilage extract was primarily influenced by temperature, followed by extract concentration, with immersion time having the least effect. From the model optimization, it was observed that okra mucilage extract at 200 ppm, 60°C, and 24 h gave an inhibition efficiency of 89.98% and high desirability. These results demonstrate the high capacity of natural okra as an efficient biodegradable corrosion inhibitor.

Biodegradable and hemocompatible alginate/okra hydrogel films with promising stability and biological attributes

Currently, combinations of natural polymers and semi-synthetic biomolecules have gained attention for food-packaging, drug delivery, coatings, and biomedical applications. In this work, cross-linking property of two biopolymers was employed for the fabrication of hydrogel films. Sodium alginate (SAlg) and Okra gel (OkG) were used in different ratios (95:05, 75:25 and 85:15) to synthesize hydrogel films by solvent-casting method. Formation of the films was confirmed by FTIR and Raman techniques which specified the interaction between biomolecules of SAlg and OkG. XRD pattern has shown the presence of both amorphous and micro-crystalline phases in the hydrogel films and SEM studies have shown porosity, amorphousness and agglomerated morphology. TGA and DSC analyses revealed degradation of the film at 420 °C and stability studies using PBS buffer indicated stability and hydrophilic nature of hydrogel films. In-vitro degradation test was also performed for 10 weeks through the incubation of hydrogel-films in simulated body fluid and the effect of pH and temperature was also studied. Results have shown worth-some influence of okra gel on the fabricated films. Hemolytic and antioxidant activities of the gels were also determined and being non-toxic, all these ratios were found suitable for biomedical applications; especially 85:15 have shown maximum potential.

A comparative study of surface properties of Urtica dioica (nettle) leaves, roots, and seeds and examination of their ability to separate xylene isomers

INTRODUCTION

Urtica dioica (nettle) is a plant species of the Urticaceae family that grows in various parts of the world and exerts antioxidant, antibacterial, antiulcer, antiviral, and anti-inflammatory effects. Their leaves, roots, and seeds are used in various fields such as food, medicine, and cosmetics.

OBJECTIVES

Inverse gas chromatography (IGC) was used to evaluate the surface characteristics and separation ability of U. dioica leaves, roots, and seeds. Characterization of these biomasses was performed by Fourier transform infrared spectroscopy (FTIR) analyses.

METHODOLOGY

The surface properties of the biomasses including dispersive surface energy, adsorption enthalpy, Gibbs free energy, and acidity-basicity constants were determined at infinite dilution using various organic solvents. These properties were compared with each other. Dispersive surface energies were calculated using the Dorris-Gray, Donnet-Park, and Schultz methods. The accuracy of these methods and their applicability were evaluated. In the last stage of this study, the separation of xylene isomers was investigated by using U. dioica biomasses as stationary phases.

RESULTS

The surface functional groups were determined by FTIR analysis. As a result of the IGC studies, it was found that the adsorption of polar solvents on biomasses occurred exothermically and spontaneously. Besides, it was found that the surfaces of biomasses were basic. From the retention diagrams and selectivity coefficients, it was determined that xylene isomers were effectively separated.

CONCLUSION

IGC is a promising, low-cost, easy-to-apply, and high-accuracy technique for the investigation of the surface properties of biomasses and their ability to separate isomers.

Surface Characterization of Carbonaceous Materials Using Inverse Gas Chromatography: A Review

It is essential to understand the adsorption of guest molecules on carbon-based materials for both theoretical and practical reasons. It is crucial to analyze the surface properties of carbon-based materials with a wide range of applications (e.g., catalyst supports, hydrogen storage, sensors, adsorbents, separation media, etc.). Inverse gas chromatography (IGC) as a powerful and sensitive technique can be used to characterize the surface physicochemical properties (i.e., Brunauer-Emmett-Teller (BET) surface area, surface energy heterogeneity, heat of adsorption, specific interaction of adsorption, work of cohesion, glass transition temperatures, solubility, and so forth) of various types of materials such as powders, films, and fibers. In this review, the principles, common methods, and application of IGC are discussed. In addition, the examples of various experiments developed for the IGC to characterize the carbonaceous materials (such as carbon nanotubes, graphite, and activated carbon) are discussed.

Quantitative Analysis of Relationship between Hansen Solubility Parameters and Properties of Alkali Lignin/Acrylonitrile-Butadiene-Styrene Blends

Blends of alkali lignin and acrylonitrile-butadiene-styrene (ABS) resin are physically mixed and injected into the injection molding system. Although the components of the blend are bound together by intermolecular forces, noticeable phase separation still occurs. In the present study, inverse gas chromatography technology was used to characterize the Hansen solubility parameters of alkali lignin/ABS blends. The relationship between the Hansen solubility parameters and thermodynamic properties was then determined. Hansen solubility parameters, at room temperature, of alkali lignin/ABS blends containing 0, 10, 20, and 30 wt % alkali lignin were 17.40, 19.20, 18.98, and 17.37 (J/cm³)^0.5, respectively. Hansen solubility parameters of the blends were shown, both experimentally and theoretically, to be related to their mechanical and thermal properties.

Correlation between Solubility Parameters and Properties of Alkali Lignin/PVA Composites

Although lignin blending with thermoplastic polymers has been widely studied, the usefulness of the lignin⁻polymer composites is limited by the poor compatibility of the two components. In the present study, alkali lignin/PVA composite membranes were prepared by incorporating 10%, 15%, 20% and 25% alkali lignin into the composites. The thermodynamic parameters of the composites were measured using inverse gas chromatography (IGC). Composite membranes with 10%, 15%, 20%, and 25% alkali lignin had solubility parameters of 17.51, 18.70, 16.64 and 16.38 (J/cm³)0.5, respectively, indicating that the solubility parameter firstly increased, and then decreased, with increasing proportions of alkali lignin. When the alkali lignin content was 15%, the composites had the largest solubility parameters. The composite membrane with an alkali lignin content of 15% had a tensile strength of 18.86 MPa and a hydrophilic contact angle of 89°. We have shown that the solubility parameters of blends were related to mechanical and hydrophilic properties of the composites and the relationships have been verified experimentally and theoretically.

Physicochemical aspects of mucosa surface

An insight into adsorption thermodynamics of molecular probes onto the mucin surface of porcine intestinal is given by the aid of IGC based on chromatographic retention time.

Thermodynamics of a food macromolecular assembly: the case of okra mucilage

Isolation steps of okra hydrocolloid and its thermodynamic parameters.