Plots Of Absorbance Research Articles

Biogenic synthesis of CeO2 nanoparticles via moringa oleifera seed extract: Photocatalytic and biological activity for textile dye degradation

This article presents a study on synthesizing cerium oxide nanoparticles utilizing cerium nitrate and Moringa oleifera seed extract as stabilizing and reducing agents. The XRD pattern of cerium oxide was a cubic structure with an average crystalline size of 11.92 nm. The surface feature of ceria nanoparticles has a foam-like nanostructure, type IV isotherms-mesoporous, with a 56.845 m2/g specific surface area. The UV–Vis absorbance and Tauc plot showed that the direct and indirect energy bandgap was 2.51 and 2.79 eV, respectively. TGA/DTA has established structural phase stability with corresponding mass changes by influencing bioactive molecules of seed extract in cerium nanoparticles. These nanoparticles exhibited effective antibacterial properties against S. aureus and E. coli pathogens, and the turbidimetry antioxidant properties were evaluated. Dye degradation through the photocatalyst was investigated, with the optimum degradation efficiency of 99.71 and 99.83 %, pseudo-first-order kinetics 4.62 × 10−2 and 5.07 × 10−2, respectively, for anionic-Congo red and cationic-Malachite green dye. The observed results concluded that green-mediated nanostructured ceria particles might effectively be used for antibacterial and photocatalytic purposes.

Structural and dielectric properties of CaCu3Ti4O12 synthesized by sol–gel method

CaCu3Ti4O12 (CCTO) nanomaterials were synthesized using the low-cost facile sol-gel technique. X-ray diffraction (XRD) patterns confirmed the cubic structure of the prepared sample. Scherrer’s formula and the W-H (Williamson-Hall) plot was used to calculated the average crystallite size of the prepared sample and it was found to be 27 nm and 31.3 nm, respectively, while the strain created in the lattice is 5.008 × 10−4. Based on the absorbance plot, the band-gap (Eg ) of the sample was determined using Tauc’s plot and it was found out to be 2.74 eV. The frequency dependence of dielectric permittivity (ε) and tangent loss (tan δ) of CCTO was analyzed at different temperature range from 300 K to 663 K over a frequency range from 10 Hz to 1 MHz. ε and tan δ decrease monotonically in entire frequency range and an anomalous frequency-dependent behavior was observed at different temperatures. High ε (in the range of 104) was found out at lower frequency range. Electrical conductivity was also analyzed in range of frequencies and temperature, it was found out that in higher region of frequency conductivity slightly increases. The room temperature values of ε, tanδ and conductivity was 7.5 × 103, 1.5 and 0.4 × 10−5 Ω−1 m−1, respectively. The reduction in Eg is achieved which was the major concern in this work. Furthermore, we have extensively studied the ε along with tan δ and ac conductivity for electronic application usage. According to these observations, CCTO is particularly prepared so that it could be suitable for microelectronic applications due to its high ε and low tan δ.

Spectral characterization of fouled railroad ballast using hyperspectral imaging

The presence of fouling contamination in railroad ballast is a growing concern that causes deterioration, poor drainage functionality, and early failure of railroad components. Evaluation and characterization of fouled ballast are crucial for determining and monitoring fouling content (FC) and moisture content (MC) in ballast. However, human inspection, destructive testing, field sampling, and most available nondestructive evaluation methods (NDE) for inspection purposes pose safety risks, undermine the stability of the railroad substructure, or provide limited information about the condition of the ballast. This study presents the results of the spectral characterization of laboratory ballast samples using hyperspectral imaging (HSI) sensor. Nineteen (19) clean, dry-fouled, and wet-fouled samples were prepared and evaluated using HSI. The reflectance of ballast samples with different levels of MC and FC was determined in Visible-Near infrared (VNIR) and Near-infrared (NIR) wavelength range from 400 nm to 1700 nm. Results showed that; the presence of trapped water in ballast pores and free water in ballast voids reduced the reflectance; an increase in the dry fouling content increased the reflectance, and MC in wet-fouled ballast showed a nonlinear relationship with the reflectance or absorbance property. The presence of water was prominent in wavelengths of 1350 nm to 1550 nm. A second-order polynomial fit was adopted for the absorbance and reflectance features plotted against the MC, and the coefficient of determination (R2) values were determined. The R2 for the absorbance and reflectance plots between 900 nm and 1700 nm were 0.7747 and 0.8336 in the sample with 5% FC and 0.8790 and 0.9278 with 15% FC, respectively. For the 1350 nm to 1500 nm wavelength range, the R2 increased by 27% and 13%, respectively, for 5% FC and then 5% and 0%, respectively, for 15% FC. This study shows that absorbance features are more prominent than the reflectance features for determining MC in fouled ballast, with high prospects of detecting, monitoring, and quantifying MC and FC contamination using the HSI method.

Hydrothermal synthesis and characterization of TiO2-silica composites for dye-sensitized solar cell electrode

The current world energy crisis and increase in global temperature has further necessitated the need to conduct more research on solar cells. Dye sensitized solar cells (DSSCs) remain one of the cheapest solar cell technologies, but it has inherent challenges. Titanium dioxide (TiO2) remains one of the suitable electrode materials, but it requires modification to withstand the current solar cells technology problems. In this paper, silica was produced from rice husk and incorporated into TiO2 to tailor its wide band gap. Hydrothermal method was used to synthesizeTiO2-silica composites at 150°C. The energy band gap of virgin TiO2, TiO2-4.8 wt% silica and 20 wt% silica was found to be 3.73 eV, 2.91 eV and 2.85 eV respectively. The addition of 4.8 wt% silica resulted in good stability of anatase TiO2 compared to the 20 wt% silica judging from the absorbance plots.

Schiff Base Ligand 3-(-(2-Hydroxyphenylimino) Methyl)-4H-Chromen-4-One as Colorimetric Sensor for Detection of Cu2+, Fe3+, and V5+ in Aqueous Solutions.

The ligand 3-(-(2-hydroxyphenylimino) methyl)-4H-chromen-4-one (SL) has been synthesized and examined as a chemosensor for some metal ions in aqueous solutions based on colorimetric analysis. Color changes were monitored using UV-visible spectroscopy. Binding stoichiometry and limit of detection (LOD) were estimated using titration experimentation based on UV-visible absorbance and Job's plot. The synthesized ligand was tested for selectivity in the presence of several cations and was examined for possible utility as a chemosensor in real water samples. The results indicated sensing ability and selectivity for Cu2+, Fe3+, and V5+. Stable complexes were formed between SL and Cu2+, Fe3+, and V5+, and the ligand-to-metal binding stoichiometry was found 2 : 1 in the SL-Cu2+ and SL-Fe3+ complexes, and 1 : 1 in the SL-V5+ complex. The results of LOD and bending constant were (7.03 μM, 1.37 × 104 M-1), (5.16 μM, 2.01 × 104 M-1), and (5.94 μM, 1.82 × 104 M-1) for Cu2+, Fe3+, and V5+, respectively.

A Distinctive Pattern for Substituent Effects on Transition Metal Centers: Enhanced Electron-Donating Capacity of Cationic Palladium Species

A Distinctive Pattern for Substituent Effects on Transition Metal Centers: Enhanced Electron-Donating Capacity of Cationic Palladium Species

Effect of Cetyltrimethylammonium Bromide and Sodium Dodecyl Sulphate on Oxidation of Indigo Carmine with Potassium Peroxy Diphosphate: A Kinetic and Mechanistic Study

The oxidative kinetic study of Indigo carmine (IC) with potassium peroxydiphosphate (PDP) in absence and presence of cationic cetyl-trimethylammonium bromide (CTAB) and anionic sodium dodecyl sulphate (SDS) micelles was studied in an aqueous sulphuric acid medium by maintaining the ionic strength at 3.0 mol dm-3 using sodium sulphate. The pseudo-zero-order constant was determined from the linear plots of absorbance versus time under the conditions [IC] < [PDP]. The reaction obeys zero-order kinetics with respect to varying [IC], first order kinetics with respect to varying [H+] and [PDP] in the absence and in presence of micelles. The reaction rate was accelerated with varying [CTAB] and [SDS] and reached a limiting value. The [surfactant] rate profile has limited nature since the reaction is unimolecular on the micelle surface. The binding constant of peroxy diphosphate was also determined with CTAB and SDS micelles by applying Berezin equation for the kinetic pattern.

Mid-infrared spectroscopy of liquids by using a modified button sample holder

A new approach for mid-infrared spectroscopy measurements of liquids is described. Thin layers of liquid samples are analyzed by using a modified button sample holder that incorporates a reservoir. To obtain spectra, buttons containing liquid samples are placed at the infrared beam focus of a praying mantis diffuse reflection optical system. Infrared radiation absorption path lengths can be adjusted by changing the quantity of liquid added to the reservoir. Thin film transflection spectra are similar to those obtained by transmission measurements. Transflection spectra of thicker layer liquids also resemble transmission measurements, but with increased relative intensities for low absorptivity peaks. Unlike transmission measurements, transflection spectra retain overlapping peak profiles for highly absorbing vibration bands due to multiple path length dynamic range effects. For a fixed effective path length (i.e. constant liquid volume), linear calibration plots of absorbance or integrated absorbance versus concentration are obtained. The button sample holder provides a methodology that is complementary to the transmission cell and attenuated total reflection (ATR) techniques for infrared analyses of neat solids and liquids, and is especially useful for characterizing thick samples and high absorptivity bands.

Fabrication of stable electrospun blended chitosan-poly(vinyl alcohol) nanofibers for designing naked-eye colorimetric glucose biosensor based on GOx/HRP

In this study, designing of a stable electrospun blended chitosan (CS)-poly(vinyl alcohol) (PVA) nanofibers for colorimetric glucose biosensing in an aqueous medium was investigated. CS and PVA solutions were blended to acquire an optimum content (CS/PVA:1/4) and electrospunned to obtain uniform and bead-free CS/PVA nanofiber structures following the optimization of the electrospinning parameters (33 kV, 20 cm, and 1.2 ml.h−1). Crosslinking process applied subsequently provided mechanically and chemically stable nanofibers with an average diameter of 378 nm. The morphological homogeneity, high fluid absorption ability (>%50), thermal (<230 °C) and morphological stability, surface hydrophilicity and degrability properties of cross-linked CS/PVA nanofiber demonstrated their great potential to be developed as an eye-readable strip for biosensing applications. The glucose oxidase (GOx) and horseradish peroxidase (HRP) was immobilized by physical adsorption on the cross-linked CS/PVA nanofiber. The glucose assay analysis by ultraviolet-visible (UV–Vis) spectrophotometry using the same enzymatic system of the proposed glucose strips in form of absorbance versus concentration plot was found to be linear over a glucose concentration range of 2.7 to 13.8 mM. The prepared naked eye colorimetric glucose detection strips, with lower detection limit of 2.7 mM, demonstrated dramatic color change from white (0 mM) to brownish-orange (13.8 mM). The developed cross-linked CS/PVA nanofiber strips, prepared by electrospinnig procedure, could be easily adapted to a color map, as an alternative material for glucose sensing. Design of a practical, low-cost, and environmental-friendly bio-based CS/PVA testing strips for eye readable detection were presented and suggested as an applicable medium for a wide range of glucose concentrations.

Rapid selective optical detection of sulfur containing agrochemicals and amino acid by functionalized cyclodextrin polymer derived gold nanoprobes

Rapid and accurate evaluation of sulfur-based pollutant contamination in an aqueous solution is one of the major tasks in environmental monitoring. A novel cyclodextrin phthalate ester polymer was used to synthesize gold and silver nanoparticles (NPs) with less than 15 nm size. The potential of the NPs solutions as chemosensor was assessed for the colourimetric detection of sulfur-based compounds. An agglomeration of only gold nanoparticles was induced selectively upon interaction with cysteine and sodium diethyldithiocarbamate (SDDC) leading to visual readout. The sensing, as well as quantification of cysteine (hydrophilic) and sodium diethyldithiocarbamate (SDDC) compounds (hydrophobic), occurred within seconds due to the dual binding ability of cyclodextrin. The limit of detection was determined using the linearity of absorbance plots. The proof of concept experiments demonstrates the rapid colourimetric determination in the range of 0.01–0.25 µM with a satisfactory limit of detection as 0.05 and 0.07 µM for SDDC and Cysteine respectively. The effect of pH and NaCl concentration on sensing was also investigated and optimized. 6 and 10 are the optimum pH values for the determination of cysteine and SDDC respectively. The optimum salt concentration was found to be 0.02 M for both the analytes. AuNPs nanosensor was much superior to AgNPs nanosensor as Au has an affinity for sulfur groups thus assisting a selective detection of cysteine and sulfur-containing pesticides in aqueous medium as well as allicin from onion and garlic extract.

Reactivity trends of cobalt(III) complexes towards various amino acids based on the properties of the amino acid alkyl chains.

The reactivity of the cobalt(III) complexes dichlorido[tris(2-aminoethyl)amine]cobalt(III) chloride, [CoCl2(tren)]Cl, and dichlorido(triethylenetetramine)cobalt(III) chloride, [CoCl2(trien)]Cl, towards different amino acids (L-proline, L-asparagine, L-histidine and L-aspartic acid) was explored in detail. This study presents the crystal structures of three amino acidate cobalt(III) complexes, namely, (L-prolinato-κ2N,O)[tris(2-aminoethyl)amine-κ4N,N',N'',N''']cobalt(III) diiodide monohydrate, [Co(C5H8NO2)(C6H18N4)]I2·H2O, I, (L-asparaginato-κ2N,O)[tris(2-aminoethyl)amine-κ4N,N',N'',N''']cobalt(III) chloride perchlorate, [Co(C4H7N2O3)(C6H18N4)](Cl)(ClO4), II, and (L-prolinato-κ2N,O)(triethylenetetramine-κ4N,N',N'',N''')cobalt(III) chloride perchlorate, [Co(C4H7N2O3)(C6H18N4)](Cl)(ClO4), V. The syntheses of the complexes were followed by characterization using UV-Vis spectroscopy of the reaction mixtures and the initial rates of reaction were obtained by calculating the slopes of absorbance versus time plots. The initial rates suggest a stronger reactivity and hence greater affinity of the cobalt(III) complexes towards basic amino acids. The biocompatibility of the complexes was also assessed by evaluating the cytotoxicity of the complexes on cultured normal human fibroblast cells (WS1) in vitro. The compounds were found to be nontoxic after 24 h of incubation at concentrations up to 25 mM.

The effects of concentration based on the absorbance form the ultraviolet–visible (UV-VIS) spectroscopy analysis

This experiment utilizes the material characterization technique known as UV-Vis spectroscopy. The aim of this research is to study the UV-Vis absorption spectroscopy readout in order to investigate the effect of concentration on absorbance for gold solution and to determine the value of band gap for powder sample (TiO2). The types of TiO2 specimens can be characterized on a solid form of powder, thin film and/or in a liquid form. The preparation of each state of specimen are varies. In this current research, Liquid samples of Au nanoparticles dispersed in different concentrations of ethanol were characterized using UV-Vis technique. The absorbance versus concentration plot of the Au-ethanol samples were found to obey Beer’s law. When examining the solid state in a form of TiO2 powder, the sample need to be packed before running the experiment. To calculate the band gap of each matter from the reflectance data of UV-Vis, the graph of energy (eV) versus is plotted. The J-curve is identified quickly, extrapolating the tangent to intersect the x-axis to obtain the band gap value.

New thiosemicarbazone Schiff base ligands: Synthesis, characterization, catecholase study and hemolytic activity

Two novel thiosemicarbazones ligands have been synthesized and characterized by FT-IR, ESI-MS, 1H NMR, and also by single-crystal X-ray diffraction for L1. The crystal structure shows that L1 molecules are planar and are connected via N-H----S and O-H----S interactions. The catecholase activity of is situ copper and cobalt complexes of this ligands has been investigated against 3,5-di-tert-butylcatechol. The progress of the oxidation reactions was closely monitored over time following the strong peak of 3,5-DTBC using UV–Vis. Oxidation rates were determined from the initial slope of absorbance vs. time plots, then analyzed by Michaelis-Menten equations. Catechol oxidation reactions were realized using different concentrations of copper and cobalt acetate and ligands (L/Cu: 1/1, 1/2, 2/1). The results show that all complexes were able to catalyze the oxidation of 3,5-DTBC. Acetate complexes have the highest activity. CuL1 and CoL1 complexes act as a catalyst and inhibitor. While copper and cobalt complexes obtained from ligand L2 illustrate concentration-independent oxidation activation. The hemolysis study performed by L1 increases as a function of its concentration. However, ligand L2 has no hemolytic effect.

Influence of the atmosphere on the decomposition of vegetable oils: study of the profiles of FTIR spectra and evolution of gaseous products

The thermal stability of vegetable oils may be one of important properties in their use in the food industry, cosmetics and agro-industry, especially for high-temperature applications and there are several methods available to evaluate its thermal stability. In order to investigate the thermal behavior of vegetable oils extracted from seeds of Bixa orellana L., of Caryodendron orinocense K., of Moringa oleifera L., of Chenopodium quinoa W., of Coffea robusta L., of Syzygium cumini and oil extracted from leaves and flowers of M. oleifera L., the following analyzes were performed: FTIR, thermogravimetric study and analysis of gases evolved in thermal decomposition. The spectra obtained through the FTIR showed that all oils have similar characteristics, changing the peak intensity between the samples, which can be used to characterize a sample lot, since the composition can vary from lot to lot. It can be observed that the atmosphere of thermal decomposition influences the profiles of the TG and DTG curves. The samples when submitted to the atmosphere of synthetic air exhibited three mass losses while in atmosphere of N2 they exhibited a single stage of decomposition. The FTIR spectra of the decomposition products of the vegetable oils obtained in the atmosphere of synthetic air and nitrogen are useful data for the characterization of vegetable oils. In relation to the evolution profiles of the decomposition products, in synthetic air and nitrogen, the intensity and the profile of the temperature absorbance plot are related to the composition of each sample.

Optimizing a detection method for estimating polyunsaturated fatty acid in human milk based on colorimetric sensors

Human milk is considered as a complete food since it constitutes all the major essential nutrients, minerals, and vitamins to sustain the life. Human milk is responsible for the evolution of an efficient immune system and organ development as well as acts as a protective barrier against inflammation and infection. In addition, it is known to be a good source for polyunsaturated fatty acids (PUFAs) which are indispensable for brain and retinal development as well as growth of a child. The amount of PUFAs in the human milk varies depending on several factors such as lactation stage, maternal diet, external environment, and maternal health. In this work, we demonstrate the optimization of a detection method for estimating PUFAs in the human milk using a UV–Visible spectrophotometer. For this purpose, fatty acids were extracted from the human milk using three different types of methods, namely Hara and Radin method (HR), Bligh and Dyer (BD) method, modified Bligh and Dyer (MBD) method. Further, we compared the efficacy of all three methods on the basis of the yield of fatty acids obtained and the solvents used for extraction. The outcomes indicated that modified BD method could be the best choice amongst the three methods tested for fatty acid extraction from the human milk. In addition, the study exploited docosahexaenoic acid (DHA) in its pure form as a standard candidate of PUFA and revealed its absorption spectrum using a spectrophotometer. A sharp absorbance peak at a wavelength of 205 nm was observed to be characteristic of DHA. Also, the height of the absorbance peak was found to be varying depending upon the concentration of DHA; revealing the linear relationship between absorbance and concentration. Therefore, we characterized the absorbance plot of fatty acids extracted from the various samples of human milk at 205 nm and noticed a trend similar and well correlated with that of DHA. Thus, we anticipate that the optimized method could be utilized as a preliminary routine test to examine the PUFA content in the human milk.

A facile solvothermal synthesis of 3D magnetic MoS2/Fe3O4 nanocomposites with enhanced peroxidase-mimicking activity and colorimetric detection of perfluorooctane sulfonate

Recently, two-dimensional (2D) layered structural MoS2 has emerged as novel inorganic nanomaterials with excellent characteristics especially of its tunable bandgap applicable to the field of catalysis. Owing to the inherent basal surface catalytic inertia and instability of 2D MoS2, methods of coupling with other functional materials or exploiting three-dimensional (3D) structure have been developed. Here, we report a facile preparation process of 3D MoS2-based nanomaterials with remarkably enhanced peroxidase-like catalytic activity, magnetic separation, cost-effective and high yield, which is of great significance for the construction of colorimetric sensors. All SEM and TEM images showed a 3D flower-shaped morphology of our prepared MoS2 with Fe3O4 nanoparticles (NPs) anchored on the “petals”, so called MoS2/Fe3O4 nanocomposites. The absorbance plots confirmed higher catalytic property of nanocomposites, taking MoS2, Fe3O4 NPs and a blend of the two by physical method as comparison. And this robust catalytic activity was utilized to achieve hypersensitive colorimetric sensing method for detecting perfluorooctane sulfonate (PFOS) with the linear relationship between absorbance and PFOS concentrations, ranging from 0.1 to 12.5 μM, and the limit of detection (LOD) was 8.6 nM (3σ/k).

Electrical and Optoelectronic Properties of Chemically Prepared PbS/MnS Heterojunction

Lead sulfide (PbS)/manganese sulfide (MnS) heterojunction is synthesized by a simple two-step chemical bath deposition technique. The as-synthesized heterojunction is studied based on the optical and electrical analyses. The optical absorbance spectrum of the test structure confirms dual peaks at two different wavelengths, which has prompted consideration of the two band gaps of the structure. The origin of dual peaks in the absorbance plot is attributed to the existence of the PbS base layer and the MnS window layer. The band gaps are estimated using the conventional Tauc’s method (Eg = 1.75 eV and 2.9 eV) and also by the absorbance spectrum fitting method (Eg = 1.82 eV and 2.97 eV). In the dc analyses, the PbS/MnS heterojunction possesses low dark current and high dynamic resistance. However, under illumination (400–700 nm) a distinct photo-response is observed, showing a substantial rise in device current with the reduction of dynamic resistance. The photo-response of the heterojunction is examined at 635–699 nm, 514–538 nm and 410–452 nm wavelengths by analyzing the photo-current and photo-resistance. The device is found to be more photosensitive at lower wavelength illuminations compared to the higher wavelength exposures.

Separation and Identification of Isomeric and Structurally Related Synthetic Cannabinoids Using 2D Liquid Chromatography and High Resolution Mass Spectrometry

Novel psychoactive substances (NPS) are emerging drugs of abuse that are variations of existing compounds intended to cause a CNS psychotropic effect. Some NPS are so comparable in structure and physicochemical properties that they co-elute using traditional single column chromatographic techniques and therefore will not be detected as individual compounds. 2D liquid chromatography (2D-LC) has demonstrated applicability in difficult separations of small molecules and compounds in complex mixtures. It was hypothesized that this technique could also be used to separate co-eluting isomeric and structurally related, non-isomeric NPS, including synthetic cannabinoids (SC). Initial studies assessed several parameters, including column type, mobile phase, analysis time, gradient and flow rate, to optimize a 2D-LC method for separation and analysis of SC. The final comprehensive on-line 2D-LC method employed a Bonus-RP column in the first dimension (1D) coupled with UV detection and a biphenyl column in the second dimension (2D) coupled with QTOF-MS detection in full scan positive mode. To test the utility of the method, three SC mixes were created, each containing five compounds that were unresolvable in a traditional, 1D-LC separation; one mix with isomeric compounds and two with structurally related but non-isomeric compounds. Contour plots of UV absorbance in 1D and MS ion intensity in 2D demonstrated that all components in each mixture were successfully resolved using the 2D-LC separation method. This research serves as proof-of-concept for the application of 2D-LC to the separation of isomeric and structurally related SC. With further optimization and validation, 2D-LC may be a generally useful tool for separation of complex mixtures of NPS.

Reduced-Dimensional α-CsPbX3 Perovskites for Efficient and Stable Photovoltaics

Summary Inorganic CsPbX3 perovskites have gained great attention owing to their excellent thermal stability and carrier transport properties. However, the power conversion efficiency (PCE) of solution-processed CsPbX3 perovskite solar cells is still far inferior to that of their hybrid analogues. Insufficient film thickness and undesirable phase transition are the two major obstacles limiting their device performance. Here, we show that by adopting a new precursor pair, cesium acetate (CsAc) and hydrogen lead trihalide (HPbX3), we were able to overcome the notorious solubility limitation for Cs precursors to fabricate high-quality CsPbX3 perovskite films with large film thickness (∼500 nm). We further introduced a judicious amount of phenylethylammonium iodide (PEAI) into the system to induce reduced-dimensional perovskite formation. Unprecedentedly, the resulting quasi-2D perovskites significantly suppressed undesirable phase transition and thus reduced the film's trap density. Following this approach, we reported a state-of-the-art PCE to date, 12.4%, for reduced-dimensional α-CsPbI3 perovskite photovoltaics with greatly improved performance longevity.

Determination of Critical Micelle Concentration and Thermodynamic Evaluations of Micellization of GMS

The uncontrolled distribution of surfactants which are commonly used as household and industrial products like soaps, lubricants and detergents in the global market have provoked this study. The determination of critical micelle concentration (CMC) of glycerol monostearate surfactant (GMS) was evaluated using Conductivity and UV-Visible Spectroscopic techniques respectively. The effect of solubility was quantified and the Krafft temperature was obtained. The thermodynamic feasibility parameters were evaluated using Erying and Vant Hoff’s equations. The CMC values were taken from the sharp breaks in the plots of absorbance versus surfactant concentrations and conductivity versus surfactant concentration respectively. The result showed that as the temperature increases, the CMC initially decreases and then followed by slight increase owing to the smaller probability of hydrogen bond formation at higher temperatures. The result showed that the critical micelle concentration of GMS obtained using Conductivity and UV-Visible techniques were 4.50 × 10-2 and 2.40 × 10-2 moldm-3 respectively and the Krafft temperature (KT) was obtained at 50°C. The Gibbs free energy change of micellization (ΔG° CMC) was found to decrease as temperature increases over the whole temperature range. The entropy change of micellization (ΔS° (CMC)) showed positive values throughout the temperature range tested while the large enthalpy change, ΔH° (CMC) means that in the micellization process, the attractive interaction among hydrophobic chains was opposed by the strong interaction of the oxyethylene chains of glycerol monostearate with water molecules. The study revealed that the use of UV-Visible Spectroscopy technique was a very good and easy way of determining the critical micelle concentration of GMS. This study is also a valuable industrial tool for the production of soap related products and its applications in domestic and industrial processes.