Search

A new HPLC method was optimized and validated for the determination of asparagine in Asparagus lycicus plant, an endemic specie found in Turkey, and the phytochemical analysis of this plant was carried out. For asparagine analysis, optimum separation was obtained with water:methanol mixture (95:5, v/v) in the presence of formic acid (FA):ammonium formate (AF) buffer as mobile phase by using a C18 reversed phase column. In this new method, retention time (0.61 min) of asparagine was very short. The linearity, accuracy, precision, limit of detection (LOD), limit of quantification (LOQ), and selectivity parameters were studied for the validation of optimized method. By this method, satisfactory recovery (100.10 ± 2.86%) was obtained for asparagine analysis and LOD and LOQ values were determined to be 0.28 mg L−1 and 0.92 mg L−1, respectively. Freeze-thaw stability of the method is quite high. The results of matrix effect experiments showed that the matrix of Asparagus lycicus plant does not significantly affect the quantification analysis of asparagine. In the phytochemical characterization of endemic Asparagus lycicus plant, asparagine content (6.14 mg g-1 plant), total phenolic (13.22 mg GAE g-1 plant) and flavonoid (3.24 mg CE g-1 plant) contents, phenolic and flavonoid components (28.8 mg rosmarinic acid, 109.2 mg ferulic acid, 531.2 mg chlorogenic acid, 2.8 mg o-coumaric acid, 17.6 mg p-coumaric acid and 6.0 mg sinapic acid per kg plant), total antioxidant activity (13.2 mg mg-1 DPPH), vitamin C content (234.6 mg kg-1 plant), organic acid content as malic acid (2.9 mg kg-1 plant), sugar components (25.15 g fructose and 18.25 g glucose per kg plant), total anthocyanin content (5.15 mg kg-1 plant), total oil content (9.65%) and fatty acid components (oleic acid (55.36%), and linoleic acid (32.01%) and palmitic acid (7.61%)) were determined. The results of this study exhibited that endemic Asparagus lycicus plant might be considered as a promising natural source with antioxidant and bioactive constituents in the potential applications of pharmaceutical and food industries.

The development of thermosensitive smart hydrogels with suitable thermosensitivity is of great importance for various biomedical and pharmaceutical applications. In this study, thermosensitive chitosan/carboxymethylcellulose/scleroglucan/montmorillonite (CHT/CMC/SGL/MMT) nanocomposite hydrogels were prepared for biomedical and pharmaceutical usages and characterized by using rheology, FTIR, SEM, EDX, TEM, XRD, TGA and swelling measurements. Exfoliated distribution of MMT in the network structure of hydrogels proved by XRD and TEM analyses caused a decrease in the pore size of hydrogels. Phase transition temperature of thermosensitive hydrogels was determined precisely by rheological measurements. In the presence of 5% MMT within hydrogel matrix, the gelling temperature of Sample 9 exhibited a decrease from 32.0 °C to 25.3 °C. It was found from TGA that among the CHT/CMC/SGL/MMT hydrogel materials the hydrogel system containing 5% MMT showed the highest decomposition temperature (175 °C). Furthermore, all hydrogel materials exhibited non-Fickian swelling behavior in distilled water and basic medium. The addition of MMT into the hydrogel matrix caused a significant decrease in the swelling amount of thermosensitive hydrogels. The results of this study indicate that thermosensitive CHT/CMC/SGL/MMT hydrogel materials may have potential applications in drug delivery, wound dressing and tissue engineering.

Water pollution caused by dyes is a significant global problem. Adsorption technique is successfully applied for the removal of dyes from water. In this technique, the use of effective adsorbents is very important. Here, agar/κ-carrageenan composite hydrogel adsorbent prepared through free radical cross-linking reaction in the presence of tri (ethylene glycol) divinyl ether as a cross-linker and characterized by using FTIR, SEM and TGA measurements was used to remove Methylene Blue from water. FTIR results exhibited that electrostatic interaction and hydrogen bonding formation were the main interactions in the adsorptive removal of Methylene Blue by agar/κ-carrageenan hydrogel. Pseudo second order and Langmuir models were found to be the most suitable kinetic and isotherm models, respectively. Maximum dye adsorption capacity of 242.3 mg·g−1 was obtained at 35 °C and pH 7. Thermodynamic parameters were calculated to understand the nature of adsorption process. Different solvents were applied for the regeneration of dye adsorbed-agar/κ-carrageenan hydrogel and the most suitable solvent was determined as ethyl alcohol. The results demonstrated that agar/κ-carrageenan hydrogel is a promising adsorbent for the removal of cationic dyes from water.

In this study, carbon nanotube-based adsorbents, oxidized multi-walled carbon nanotube (OMWCNT) with non-magnetic property and OMWCNT-Fe3O4 and OMWCNT-κ-carrageenan-Fe3O4 nanocomposites with magnetic property, having different structural and surface properties were prepared and their adsorptive properties for the removal of toxic diquat dibromide (DQ) herbicide from water by adsorption were determined in detail. For each adsorption system, the effects of initial DQ concentration, contact time and temperature on the adsorption processes were determined. Equilibrium time was found to be 300 min for DQ solutions. OMWCNT showed faster adsorption and higher maximum adsorption capacity value than magnetic adsorbents. With increasing initial herbicide concentration from 5.43 mg.L−1 to 16.3 mg.L−1, the values of initial sorption rate exhibited a decrease from 29.1 mg.g−1.min−1 to 4.28 mg.g−1.min−1 for OMWCNT-DQ system, from 1.21 mg.g−1.min−1 to 0.823 mg.g−1.min−1 for OMWCNT-Fe3O4-DQ system and from 0.674 mg.g−1.min−1 to 0.612 mg.g−1.min−1 OMWCNT-κ-carrageenan-Fe3O4 system. Maximum adsorption capacity value of OMWCNT was approximately 2.8-fold higher than magnetic OMWCNT-Fe3O4 and 5.4-fold higher than magnetic OMWCNT-κ-carrageenan-Fe3O4 at 25 °C. Adsorption kinetic and isotherm data obtained for all adsorption systems were well-fitted by pseudo second-order and Langmuir models, respectively. Thermodynamic parameters indicated that the adsorption of DQ onto carbon nanotube-based adsorbents was spontaneous and endothermic process. Furthermore, OMWCNT having the highest herbicide adsorption capacity could be regenerated and reused at least five times. This study showed that carbon nanotube-based adsorbents with magnetic and non-magnetic property were of high adsorption performance for the removal of DQ from water and could be promising adsorbent materials for the efficient removal of herbicides from wastewaters.

In this study, low-cost, environmentally friendly and porous agar/PVA aerogel sorbent materials with highly hydrophobic property were fabricated for the selective separation of oily substances and organic solvents from water by (i) the cross-linking reaction, (ii) freeze drying process and (iii) surface coating treatment. The characterization of agar/PVA aerogels was performed by water solubility, contact angle, SEM, EDX, mapping and XPS measurements. SEM and porosity results revealed that the increase of PVA amount within aerogel matrix led to a decrease in the pore structure of aerogel material. Agar/PVA (100:0) aerogel had good absorption capacity values (19.0-48.1 g·g

This review (including 127 refs) summarizes applications of nanosorbent-based solid phase microextraction (SPME) for the cleanup, extraction, and quantification of Emerging Organic Contaminants (EOCs). SPME is the most widely used technique for the analysis of EOCs from water samples. The selection of sorbent material plays a key role in SPME applications. Here, we have collected information about recent developments in the application of nanosorbents in the SPME technique used for the extraction of EOCs from water and wastewater samples. In this review, the preparation, properties, advantages, and limitations of nanosorbents used in SPME applications are evaluated and discussed. Besides, the applications of these nanosorbents in SPME-based extraction techniques and their analytical characteristics for the determination of EOCs are reviewed. Graphical abstract.

In this study, agar/κ-carrageenan/montmorillonite (MMT) hydrogels were prepared to examine their usability as wound dressing materials and to see the effect of MMT amount on some properties of agar/κ-carrageenan hydrogel materials. Hydrogels were characterized by SEM-EDX, TEM and DSC analyses. By increasing the MMT content within hydrogel matrix from 0% to 5%, the decomposition temperature of the hydrogel material was increased from 256.6 °C to 262.1 °C. Swelling amount of hydrogels in d -glucose solution (2682%) was found to be much higher compared with other physiological solutions such as physiological saline solution (937%), synthetic urine solution (746%) and simulated wound fluid (563%). The release studies of analgesic lidocaine hydrochloride (LDC) and antibiotic chloramphenicol (CLP) drugs from hydrogel systems demonstrated that the release amount of LDC and CLP from hydrogels could be controlled by MMT amount within hydrogel matrix. The concentrations of drugs within hydrogel sample stored at 4 °C for 6 months did not exhibit a significant change. Hydrogel materials containing CLP exhibited good antibacterial activity against E. coli and S. aureus. Cytotoxicity test results indicated that hydrogels were biocompatible with MG-63 cells. The ultimate compressive stress of agar/κ-carrageenan hydrogel with LDC and CLP and agar/κ-carrageenan/MMT hydrogel including 5% MMT with LDC and CLP was measured as 38.30 kPa and 47.70 kPa, respectively. The experimental results revealed that prepared agar/κ-carrageenan and agar/κ-carrageenan/MMT hydrogels have great potential for wound care applications.

Carvedilol is a drug used in the treatment of serious cardiovascular diseases. Therefore, the development of a new method for analyzing the therapeutic and toxic concentrations of carvedilol in hum...

The effective use and control of maritime routes in the commercial/military area is an increasing and important need for states. There are some motivations for this purpose: Safe traffic of the ships in narrow canals, avoiding illegal usage of anchoring areas of ships, monitoring fishing activities to avoid illegal fishing or protect fish population, detection of lost ships, boats or debris in the ocean, detection and identification of warships (intelligence, defense, offensive, etc.). This paper proposed an open source, fast running ship detection system from optical satellite images with the deep learning algorithm. The system does not need any comprehensive hardware, even can work on an average laptop. Tensorflow Object Detection Application Programming Interface (API)is trained by optical satellite images with ships and used as object detection API.

The removal of various oils, petroleum products and organic solvents from water has a great importance for environmental protection. In this study, highly hydrophobic and superoleophilic fluoro organothiol-coated carbonized melamine sponge/rGO composite absorbent material (CMS/rGO/PFDT) material was prepared as a new absorbent for the cleanup of oil spills and selective separation of oil-water mixtures. The results of contact angle, scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and Raman measurements proved that the preparation of new absorbent material was successfully performed. CMS/rGO/PFDT displayed excellent hydrophobicity with a high-water contact angle of 143.2°. and superoleophilicity with an oil-contact angle of 0°. This absorbent was unsinkable in water and could absorb the hydrophobic organic contaminants up to 55 times of its own weight. CMS/rGO/PFDT could effectively and selectively absorb the oily substances from olive oil-water and gasoline-water emulsions and achieved the continuous oil-water separation with the assistance of a vacuum pump. The developed CMS/rGO/PFDT material may be a potential absorbent in the absorptive removal of oily substances and organic solvents from oily wastewater and in the separation of oil-water mixture.

In this study, oxiconazole nitrate (OXI)-loaded antifungal thermosensitive chitosan/carboxymethylcellulose/scleroglucan/montmorillonite (CHT/CMC/SGL/MMT) nanocomposite hydrogels were developed for onychomycosis treatment. The presence of 5% (w/w) MMT within hydrogel matrix increased the glass transition temperature of CHT/CMC/SGL material from 63.72 °C to 76.75 °C and the compressive stress value from 126.45 ± 8.83 kPa to 266.99 ± 6.60 kPa. For the use of hydrogel materials in the treatment of onychomycosis, antifungal OXI drug was loaded into the network of thermosensitive CHT/CMC/SGL and CHT/CMC/SGL/MMT hydrogels and the release of OXI from these materials was monitored spectrophotometrically. At the end of 420 min, for hydrogel systems containing 0, 1, 3 and 5 % (w/w) MMT, OXI release amounts were determined as 70.33 ± 1.74 %, 63.92 ± 0.31 %, 58.78 ± 1.45 % and 52.89 ± 0.21 %, respectively. This means that the drug release depends on the MMT amount within hydrogel matrix and can be controlled by changing the amount of clay mineral in hydrogel material. OXI-loaded new hydrogels showed high antifungal activity against Trichophyton mentagrophytes and Trichophyton rubrum dermatophytes. This study suggests that new antifungal thermosensitive CHT/CMC/SGL/MMT nanocomposite hydrogels could be promising materials for onychomycosis treatment.

In this study, magnetic oxidized multiwalled carbon nanotube (OMWCNT)-κ-carrageenan-Fe3O4 nanocomposite was prepared as a new adsorbent and characterized by specific surface area, Fourier transform infrared (FTIR), X-ray diffraction (XRD), vibrating sample magnetometry (VSM), thermal gravimetric analysis (TGA), scanning electron microscope (SEM) and transmission electron microscope (TEM) measurements. Magnetic adsorbent displayed a super-paramagnetic property. Cationic Crystal Violet (CV) and anionic Reactive Black 5 (RB5) dyes were used to evaluate the adsorption ability of magnetic OMWCNT-κ-carrageenan-Fe3O4 nanocomposite. The effect of contact time, initial dye concentration, pH and temperature on the adsorption process was investigated. The equilibrium time was determined to be 300 min. An increase in the initial dye concentrations and the temperature of dye solutions led to an increase in the adsorption amounts of magnetic adsorbents. A decrease in the adsorption amount of CV dye was observed at low pH values, on the contrary to RB5 dye. For the adsorption of CV and RB5 dyes onto magnetic adsorbent, the adsorption kinetics followed the pseudo second-order model. Langmuir isotherm model exhibited the best fitting with the experimental isotherm data obtained at 25, 35 and 45 °C. Thermodynamic parameters showed that adsorption processes are spontaneous and endothermic. On the contrary to anionic RB5 dye, the adsorption capacity of magnetic OMWCNT-κ-carrageenan-Fe3O4 nanocomposite for cationic CV dye is higher than that of magnetic OMWCNT-Fe3O4 nanocomposite. Therefore, magnetic OMWCNT-κ-carrageenan-Fe3O4 nanocomposite may be used as a potential adsorbent to remove the cationic dyes from aqueous solution.

In the present study, for the first time, agar/κ-carrageenan and agar/κ-carrageenan/montmorillonite hydrogel materials were prepared by the free-radical crosslinking reaction of agar and κ-carrageenan in the presence of triethylene glycol divinyl ether (TEGDE) as the crosslinker agent. Here, montmorillonite (MMT) modified with phenylalanine was used as additive agent. Agar/κ-carrageenan hydrogel materials with and without MMT were characterized by FTIR, SEM and XRD analyses. The effect of free radical initiator (ammonium persulfate, APS) concentration, crosslinking agent (TEGDE) concentration, reaction temperature, polysaccharide ratio and MMT concentration on the swelling performance and surface property of hydrogel material was investigated and optimum reaction conditions were determined. Maximum equilibrium swelling capacity of the agar/κ-carrageenan hydrogel was found to be 2523 % under the optimum conditions ([APS] = 5 × 10−4 M, [TEGDE] = 5 × 10−4 M, T = 70 °C and magar:mκ-carrageenan = 1:4). An increase of the MMT content within hyrogel matrix led to a decrease in the swelling values of hydrogels. All of the hydrogels prepared in various formulations exhibited non-Fickian swelling behavior. New hydrogel materials obtained from this study could be potential candidates for biomedical applications.

Glucosamine sulphate can be taken orally from the dietary supplement tablets for the treatment of osteoarthritis. In these tablets, the determination of glucosamine sulphate concentration is very important for the identification of fraudulent products and quality-control studies. In this study, a simple, rapid, accurate and sensitive method was developed for the determination of glucosamine sulphate in the dietary supplement tablets by using isocratic reversed-phase high-performance liquid chromatography with diode array detector (RP-HPLC-DAD). The separation process was performed by Prodigy™ C18 reversed-phase column using an acetonitrile:H2O mixture (50:50 (v/v), pH 4.0) as mobile phase. The method developed was optimized and subsequently validated. Method validation was performed to illustrate the reliability of new analytical method through various validation parameters including linearity, precision, accuracy, limit of detection (LOD), limit of quantification (LOQ), selectivity and stability. Relative standard deviation (%) values for the intra-day and inter-day precision studies were low. The calibration curve was linear in the glucosamine sulphate concentration range of 0.05-2.5 mg.L-1. In this method, recovery values were obtained in the range between 85.15% and 118.86% and LOD and LOQ values were determined to be 0.014 mg.L-1 and 0.046 mg.L-1, respectively. Furthermore, all results confirmed that the new method is suitable for the determination of glucosamine sulphate in dietary supplement tablets.

In this article, we have critically overviewed some interesting articles published in 2015–2019 about the use of the nanosorbents for the extraction of emerging organic contaminants (EOCs) from various environmental samples. Properties, advantages, disadvantages, and the applicability of different categories of nanosorbents used for the extraction of EOCs are evaluated and discussed. The potential applications of these nanomaterials as adsorptive phase in solid-phase extraction (SPE) based techniques are reviewed.

In this study, carbon nanotube-based adsorbents, oxidized multi-walled carbon nanotube (OMWCNT) with non-magnetic property and OMWCNT-Fe

In this study, the adsorption of Basic Red 9 (BR9) from aqueous solution onto sepiolite was investigated. Batch experiments were carried out to determine the effects of various parameters including contact time, initial dye concentration, temperature and pH on the adsorptive removal of BR9 by sepiolite. Both kinetic and isotherm data were obtained. The kinetic and isotherm data fitted very well with the pseudo second-order kinetic model and Freundlich isotherm model, respectively. The calculated thermodynamic parameters indicated that the adsorption process was spontaneous, favorable, and exothermic. The pH of dye solution and electrostatic interaction do not play an important role on the adsorption process. The increase in the adsorption amount of BR9 led to a decrease in the zeta potential of sepiolite. The interaction between sepiolite and BR9 was investigated by Fourier transform infrared (FTIR) spectroscopy. Desorption of BR9 from spent adsorbent was studied in water, ethyl alcohol and benzyl alcohol. The highest desorption amount was obtained by benzyl alcohol. This study revealed that sepiolite could be used as effective and low-cost adsorbent in the treatment of wastewater contaminated with triarylmethane dyes.

The adsorption characteristics of toxic Basic Red 9 (BR9) onto expanded vermiculite were determined. The effect of contact time, initial dye concentration, pH and temperature on the adsorption process was investigated. The adsorption amount of BR9 onto expanded vermiculite increased with increasing initial dye concentration and pH, but it displayed a decrease with increasing temperature. The adsorption kinetics of BR9 followed the pseudo second-order model. Freundlich model provided the best fitting with the experimental adsorption isotherm data obtained at 25, 35 and 45 °C. Thermodynamic parameters indicated that the adsorption process was exothermic, occurred spontaneously and led to an increase in the randomness at the solid/solution interface. The desorption of dye from spent adsorbent was investigated in water, ethyl alcohol and benzyl alcohol. The sign of the zeta potential value of clay changed from negative to positive due to the adsorption of BR9 onto expanded vermiculite. The adsorption of BR9 led to some changes in the FTIR spectrum of adsorbent material. The maximum adsorption capacity of expanded vermiculite for BR9 adsorption is comparable with other adsorbents reported in the literature. Therefore, expanded vermiculite as an efficient and economical adsorbent may be used for the removal of dyes from wastewaters.

In this study, the interaction of human serum albumin (HSA) with neohesperidin dihydrochalcone (NHD) was investigated by UV, fluorescence, synchronous fluorescence and circular dichroism spectroscopic methods. Experimental results confirmed the complex formation between HSA and NHD molecules under physiological conditions. NHD quenched the intrinsic fluorescence spectrum of HSA by static quenching mechanism. The binding constant of this system was calculated as 2.79×10 4 M −1 at 298.15 K. The stability of HSA–NHD complex illustrated a decrease with increasing temperature. The number of binding sites was found to be 1. Thermodynamic parameter values were calculated by using van’t Hoff equation. According to sign and magnitude of thermodynamic parameters (Δ H =−29.22 kJ mol −1 and Δ S =−12.91 J mol −1 K −1 ), hydrogen bonding and van der Waals forces were found as the effective interaction forces between HSA and NHD molecules. Synchronous fluorescence and circular dichroism spectroscopic methods proved the alteration of secondary structure of HSA in the presence of NHD. Site marker competitive experiments indicated that the binding of NHD to HSA took place in subdomain IIA region of protein.

In this study, various spectroscopic techniques including UV absorption, fluorescence and synchronous fluorescence spectroscopy were used to examine the interactions of carbofuran (CF) and amitrol (AMT) herbicides with human serum albumin (HSA). The results of spectroscopic experiments illustrated that CF was bound by HSA, on the other hand there was no interaction between HSA and AMT molecules. In HSA–CF system, static quenching mechanism was responsible for the fluorescence quenching of HSA. The Stern–Volmer constant and binding constant decreased with increasing temperature. This means that an increase in temperature reduces the stability of HSA–CF complex. In HSA–CF system, the number of binding site on protein was found to be one. From the thermodynamic parameters, enthalpy change (Δ H ) and entropy change (Δ S ) were calculated as −22.30 kJ mol −1 and −10.70 J mol −1 K −1 , respectively, which indicated that the interaction forces between HSA and CF molecules were mainly hydrogen bonding and van der Waals forces. The conformational change in the protein structure was investigated by synchronous fluorescence spectroscopy. According to the results of synchronous fluorescence analysis, there was a change in the protein structure owing to the interaction of CF with HSA.

In this study, gelatin-based conductive hydrogels doped with carbon nanotube (CNT), poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and silver (Ag) nanoparticle were prepared for use in biopotential measurements. Gelatin was modified by various concentrations of methacrylic anhydride (MA) to obtain photo-crosslinkable gelatin methacrylate (GelMA) polymer with low (21%), medium (44%) and high (78%) methacrylation degree. Chemical modification of gelatin was characterized by 1H-NMR spectroscopy. It was observed that mechanical properties of the GelMA hydrogels were highly dependent on methacrylation degree. Ultimate compressive stress of low, medium and high methacrylated gelatin hydrogel was measured to be 9.97 ± 0.14 kPa, 17.83 ± 1.73 kPa and 38.23 ± 2.96 kPa, respectively. Surface morphology of hydrogels was visualized by scanning electron microscope (SEM). The pore size of methacrylated gelatin hydrogel significantly reduced with the addition of CNT, PEDOT:PSS and Ag nanoparticle into the hydrogel matrix. The results of thermal gravimetric analysis showed that conductive hydrogels were of higher thermal stability than nonconductive GelMA hydrogel. The suitability of the prepared hydrogels for biopotential measurements was determined by equivalent impedance measurements. Impedance values of hydrogel samples were obtained in the frequency range of 20 Hz–500 Hz. The hydrogel materials prepared in this study exhibited high impedance at low frequencies and low impedance at high frequencies. The results of this study showed that the hydrogels produced with Ag nanoparticle are more suitable electrode materials for physiological measurement systems such as electrocardiography (ECG) and electroencephalography (EEG).

The interactions of chloroquine diphosphate (CQP) and phenelzine sulfate (PS) drugs with human serum albumin (HSA) and human hemoglobin (HMG) proteins were investigated by various spectroscopic methods. It was found that CQP caused the fluorescence quenching of protein molecules through a static quenching mechanism, but PS did not. The values of Stern–Volmer quenching constant, bimolecular quenching constant, binding constant and number of binding site on the protein molecules were calculated for HSA–CQP and HMG–CQP systems at pH 7.4 and different temperatures. For CQP, there was only one binding site on HSA and HMG proteins and the binding affinity of HSA was higher than that of HMG. The binding constants decreased with increasing temperature. The values of negative enthalpy change and positive entropy change indicated that electrostatic interactions play an important role in the binding processes. In addition, the binding processes were spontaneous and carried out by exothermic reactions. According to Forster resonance energy transfer theory, the average binding distance between proteins and CQP was calculated as 3.72 nm for HSA–CQP system and 3.45 nm for HMG–CQP system. Circular dichroism analysis displayed that the addition of CQP led to a decrease in the α-helix amount of HSA and HMG proteins.

The interactions of tramadol hydrochloride (THC) and 5-azacytidine (AZA) drugs with human serum albumin (HSA) and human hemoglobin (HMG) proteins were investigated by fluorescence, UV absorption and circular dichroism (CD) spectroscopy at pH 7.4 and different temperatures. The UV absorption spectra and the fluorescence quenching of HSA and HMG proteins indicated the formation of HSA–THC and HMG–THC complexes via static quenching mechanism. AZA did not interact with HSA and HMG proteins. It was found that the formation of HMG–THC complex was stronger than that of HSA–THC complex. The stability of HSA–THC and HMG–THC complexes decreased with increasing temperature. The number of binding site was found as one for HSA–THC and HMG–THC systems. Negative enthalpy change (Δ H ) and Gibbs free energy change (Δ G ) and positive entropy change (Δ S ) values were obtained for these systems. The binding of THC–HSA and HMG proteins was spontaneous and exothermic. In addition, electrostatic interactions between protein and drug molecules played an important role in the binding processes. The results of CD analysis revealed that the addition of THC led to a significant conformational change in the secondary structure of HSA protein, on the contrary to HMG protein.

The effect of montmorillonite and carvacrol (as an antimicrobial agent) on the wettability, mechanical, gas barrier, thermal and color properties of methyl cellulose-based nanocomposite films was investigated. To make a comparison among the film samples, methyl cellulose (MC) film and methyl cellulose/montmorillonite (MC/MMT) and methyl cellulose/carvacrol/montmorillonite (MC/CRV/MMT) nanocomposite films with different clay concentration were prepared. The interactions among MMT, CRV and film matrix were characterized by FTIR spectroscopy. The contact angle value of MC film showed an increase of 2.5 fold with the incorporation of 60 wt.% MMT into the film matrix. The addition of clay into the film matrix increased the melting point of MC film and improved the mechanical properties of film material. The tensile stress of pure MC film exhibited an increase of 9.2 MPa in the presence of 60 wt.% MMT. With the addition of MMT into the film matrixes, water vapor permeability values of MC film and MC/CRV film were decreased by 28% and 13%, respectively. The incorporation of 60 wt.% MMT into the film matrix caused to a decrease of 47 fold for MC film and 16 fold for MC/CRV film in the oxygen permeability of film sample. The addition of CRV into MC film and MC/MMT nanocomposite films with different clay concentration reduced the mechanical strengths of film materials. Oxygen permeability values of MC film and MC/MMT nanocomposite films decreased with the inclusion of CRV into the film matrix.

In this study, magnetic oxidized multiwalled carbon nanotube (OMWCNT)-Fe3O4 and OMWCNT-κ-carrageenan-Fe3O4 nanocomposites were synthesized and used as adsorbent for the removal of Methylene Blue (MB) from aqueous solution. Magnetic nanocomposites were characterized by using of specific surface area, Fourier transform infrared, X-ray diffraction, vibrating sample magnetometry, thermal gravimetric analysis, scanning electron microscope and transmission electron microscope measurements. The results of characterization analyses exhibited that OMWCNT was successfully modified with κ-carrageenan. Furthermore, OMWCNT-Fe3O4 and OMWCNT-κ-carrageenan-Fe3O4 nanocomposites were of a super-paramagnetic property. Adsorption studies revealed that the data of adsorption kinetics and isotherm were well fitted by the pseudo second-order kinetic model and Langmuir isotherm model, respectively. The adsorption amounts of magnetic adsorbents increased with contact time and initial dye concentration. Compared with magnetic OMWCNT-Fe3O4 nanocomposite, magnetic OMWCNT-κ-carrageenan-Fe3O4 nanocomposite showed a better adsorption performance for the removal of MB from aqueous solution. Therefore, OMWCNT-κ-carrageenan-Fe3O4 nanocomposite may be used as a magnetic adsorbent to remove the cationic dyes from wastewaters.

The interactions between C.I. Basic Yellow 2 (BY2) and sodium dioctylsulfosuccinate (NaDS) have been investigated in the premicellar and micellar region using spectrophotometric method at 288.15, 298.15, 308.15 and 318.15 K. Absorption spectra of dye–surfactant mixtures show that dye–surfactant aggregates occur in the premicellar region. The addition of excess NaDS to the BY2 solution enhances the solubility of dye molecules due to the micelle formation. Moreover, the presence of excess surfactant micelles in the dye solution causes an increase in the absorption intensity of BY2 and leads to a bathochromic shift in the maximum absorption wavelength of dye. The values of binding constants, partition coefficients between the micellar and the bulk water phases and thermodynamic parameters have been calculated for the BY2–NaDS system at different temperatures. The binding of BY2 to surfactant micelles decreases with increasing temperature. The binding and partition processes are exothermic and occur spontaneously.

The effects of cationic tetradecytrimethylammonium bromide (TDTMABr), anionic sodium tetradecyl sulfonate (NaTDS) and nonionic Brij 30 surfactants on the electrokinetic and rheological properties of Na-bentonite and sepiolite suspensions have been investigated. It has been found from the zeta potential measurements that the negative surface charge of Na-bentonite and sepiolite has become positive in the presence of 7.5 × 10−3 M and 1.0 × 10−3 M TDTMABr, respectively. As the concentration of NaTDS is increased in the suspension, the zeta potential value of Na-bentonite does not change significantly, but that of sepiolite decreases gradually. Na-bentonite–surfactant suspensions show a thixotropic behavior, on the other hand sepiolite–surfactant suspensions display a rheopexic or thixotropic behavior depending on the surfactant concentration. All clay–surfactant suspensions follow a Bingham type flow behavior. The surfactant concentration leads to significant changes in the plastic viscosity (ηpl) values of sepiolite–surfactant suspensions, on the contrary of Na-bentonite–surfactant systems. Some shifts in the peak positions have been observed in the FTIR spectra of samples, which have provided evidence about the interactions between clay particles and surfactant molecules. This study shows that the suspensions having the desired zeta potential and ηpl values and thixotropic or rheopexic behaviors can be obtained using different clay–surfactant mixtures.

The decolorization of two azo dyes including Acid Red 66 (AR66) and Direct Blue 71 (DB71) from aqueous solution has been investigated using Fenton process by on-line spectrophotometric method. The effects of different operational parameters such as H2O2, Fe2+ and dye concentrations, pH and temperature of solution and various salts on the decolorization process have been studied to determine the optimum conditions for Fenton process. The results have showed that the amounts of 2.94 × 10−5 M AR66 and DB71 decolorization are 99.6% and 99.8%, respectively, under the optimum conditions ([H2O2]/[Fe2+] = 30:1 for AR66 and 200:1 for DB71, pH = 3.5 and T = 45 °C) at the end of 180 min. The presence of NaCl exhibits a negative effect on the decolorization of azo dyes, on the contrary of Na2SO4. An increase in the reaction temperature gives rise to an increase in the decolorization rate of AR66 and DB71. The results of spectral analyses indicate that the destruction of azo linkages in the AR66 and DB71 during the Fenton process occurs quickly compared with the destruction of benzene and naphthalene rings in the dye molecules. The decolorization kinetics of azo dyes has also been investigated in the different reaction conditions. It has been found that experimental kinetic data are represented well by Behnajady–Modirshahla–Ghanbery model.

The zeta potential and viscosity values of kaolinite suspensions in cationic poly(diallyldimethylammonium chloride) (PDDACl), anionic poly(sodium 4-styrene sulfonate) (PSSS) and nonionic poly(vinyl alcohol) (PVA) solutions have been determined. The zeta potential value of kaolinite increases with the first addition of PDDACl and PVA solutions, on the contrary of PSSS. Kaolinite–water suspensions exhibit a thixotropic or rheopectic behavior depending on clay concentration. However, kaolinite–polymer suspensions display a thixotropic behavior. The flow type of kaolinite–water and kaolinite–polymer suspensions is Bingham, except kaolinite–PVA suspensions including 7.5 × 10−5 and 1.0 × 10−4 M PVA. It has been found from the relative plastic viscosity measurements that PDDACl and PVA are of a significant effect on the plastic viscosity values of kaolinite suspensions, unlike the PSSS. The interactions between kaolinite and polymer molecules have been investigated by FTIR spectroscopy. This study shows that the zeta potential and viscosity values of kaolinite suspensions can be adjusted using different polymers.

The effect of cationic surfactant, hexadecyltrimethylammonium bromide (HDTMABr), on the electrokinetic and rheological properties of sepiolite suspensions was investigated. The zeta potential measurements indicate that the addition of HDTMABr into the sepiolite suspensions causes the change of surface charge of clay particles from negative to positive. The concentration of sepiolite in the suspension affects differently the flow behavior of sepiolite–water suspensions. The sepiolite–water suspensions containing less than 2.0 wt.% of sepiolite show a thixotropic behavior and a hysteresis loop, whereas the suspensions containing more than 2.0 wt.% of sepiolite exhibit a rheopexic behavior and a hysteresis loop. The addition of 5.0 × 10 −4 M cationic surfactant into the clay suspensions containing 3.0 wt.% of sepiolite leads to a transition from rheopexic suspension to thixotropic suspension. The sepiolite–water and sepiolite–HDTMABr suspensions exhibit a Bingham type flow behavior. The plastic viscosity ( η pl ) values of suspensions decrease with the increase of temperature from 25 °C to 45 °C. The η pl values of sepiolite suspensions are affected differently depending on the surfactant concentration. It can be concluded from the rheological measurements that the flow behaviors and the η pl values of sepiolite suspensions can be controlled with the sepiolite and HDTMABr concentrations. The interactions between sepiolite and HDTMABr were also investigated by FTIR spectrometer.

Methyl cellulose (MC)/carvacrol (CRV)/montmorillonite (MMT) nanocomposite films were prepared to obtain active antimicrobial packaging materials. The characterization of film samples by X-ray diffraction and transmission electron microscopy showed that composite films were of nano structures. CRV addition to the MC film and MC/MMT nanocomposite films led to a decrease in the thickness and opacity values of them, whereas MMT addition to the film matrix caused an increase in these values. Thermal stability of films slightly increased with increasing MMT concentration in film matrix. CRV release from films was investigated at different temperatures for 30 days. An increase in the MMT concentration matrix caused a decrease in CRV release at 25.0 ± 0.5 °C and in 60 ± 4% relative humidity (RH). CRV release increased with temperature at a constant RH. The antimicrobial activities of films were tested against Escherichia coli ( E. coli ) and Staphylococcus aureus ( S. aureus ) by the microatmosphere method and these organisms were completely inhibited on the nutrient broth/bacteriological agar medium when film samples containing 11.1 ± 0.2 mg CRV were present. MC/CRV film and MC/CRV/MMT-60% nanocomposite films on sausage reduced E. coli and S. aureus counts by 0.9 and 0.7 log cfu/mL, respectively, compared to the control film. The amount of CRV release from developed antimicrobial films can be controlled by MMT concentration within the film matrix and by the storage temperature of film.

Interactions between cationic dye–cationic surfactant and anionic dye–cationic surfactant systems were investigated in aqueous solutions using spectrophotometric method at 288.15, 298.15, 308.15 and 318.15 K. C.I. Basic Red 9 (BR9) and C.I. Acid Blue 25 (AB25) were used as cationic and anionic dyes, respectively, and hexadecyltrimethylammonium bromide (HDTMABr) was selected as cationic surfactant in this study. Although there was an interaction between the AB25 and the HDTMABr molecules, an interaction between the BR9 and HDTMABr did not occur due to the electrostatic repulsion forces. Binding constants and partition coefficients between the micellar and the bulk water phases for the AB25–HDTMABr system were calculated from the changes in absorbance values and the critical micelle concentrations at different temperatures. It was found that the values of binding constant and partition coefficient decreased with increasing temperature. Thermodynamic parameters (Δ G 0 , Δ H 0 and Δ S 0 ) were determined for the binding and partition processes of AB25–HDTMABr system. It was concluded from Δ G 0 values that the binding of AB25 to HDTMABr occurred spontaneously. In addition, the binding and partition processes were exothermic.

Procedures for the preparation of methyl cellulose/montmorillonite (MC/MMT) nanocomposite films were optimized by testing 30 procedures including differences in type of mixing, speed of mixing and time of mixing. The characterization of films by XRD and TEM indicated that a procedure involving mixing by a homogenizator was the most suitable nanocomposite film preparation method. The effect of MMT concentration on some properties of MC/MMT nanocomposite films was also investigated. It was found that the increase in the MMT concentration caused an increase in the film thickness and opacity values of MC/MMT nanocomposite films, whereas the increase in MMT concentration led to a decrease in their water adsorption and water solubility.

Activated carbon cloth (ACC) was used as adsorbent for the removal of cationic surfactants such as benzyltrimethylammonium chloride (BTMACl), benzyltriethylammonium chloride (BTEACl), benzyltributylammonium chloride (BTBACl), benzyldimethyldecylammonium chloride (BDMDACl), benzyldimethyltetradecyl ammonium chloride (BDMTDACl), benzyldimethylhexadecylammonium chloride (BDMHDACl), N-dodecylpyridinium chloride (N-DPCl) and N-cetylpyridinium chloride (CPCl) from aqueous solutions. The adsorption efficiency of the ACC was evaluated for cationic surfactants. Adsorption process was followed by in situ UV spectroscopic technique. The kinetic data, so obtained, were treated according to the pseudo first-order, the pseudo second-order, the Elovich and the intraparticle diffusion models in order to understand the adsorption mechanism of cationic surfactants onto the ACC. The best fit was found with the pseudo second-order model. The experimental isotherm data were obtained at 30 °C and analyzed by the Freundlich and the Langmuir models. The parameters of isotherm equations were determined. The Freundlich model was found to represent the experimental data better than the Langmuir model. The observed adsorption behaviors are discussed in terms of the pH of the solution, the nature of cationic surfactants (e.g. functional groups, size, and hydrophobicity) and the nature of the ACC (e.g. surface charge, pore size). A fair linear correlation was found between some adsorption parameters and apparent molar volumes at infinite dilution for benzyltrialkylammonium chlorides.

Interactions of benzene and naphthalene sulfonates with activated carbon cloth (ACC) during adsorption from aqueous solutions were investigated. Systematically chosen sulfonates were sodium salt of benzene sulfonic acid (NaBS), disodium salt of 1,3-benzene disulfonic acid (Na 2 BDS), sodium salt of 1-naphthalene sulfonic acid (NaNS), disodium salt of 1,5-naphthalene disulfonic acid (Na 2 NDS) and trisodium salt of 1,3,(6 or 7)-naphthalene trisulfonic acid (Na 3 NTS). The adsorption behaviors of these adsorbates from solutions in water and in 0.01 M H 2 SO 4 onto the ACC were monitored by in-situ UV–visible spectroscopic technique. The order of rates and extents of adsorption of sulfonates were explained in terms of acidity of the medium and structural factors influencing the interactions between sulfonates and the ACC surface. Kinetic data of adsorption were treated according to pseudo first-order, pseudo second-order, Elovich and intra-particle diffusion models. The best model representing the experimental kinetic data was found to be the pseudo second-order model. Adsorption isotherms of the sulfonates onto the ACC were derived at 30 °C. Isotherm data were found to fit the Freundlich model better than the Langmuir model.

Densities and speeds of sound for aqueous solutions of sodium benzene sulfonate, sodium p-toluene sulfonate, disodium 1,3-benzene disulfonate, sodium 1-naphthalene sulfonate, and disodium 1,5-naphthalene disulfonate were accurately measured at various concentrations and at (293.15, 303.15, 313.15, 323.15, and 333.15) K. These data were utilized in determining apparent molar volumes, VΦ, and apparent molar isentropic compressibilities, KSΦ. VΦ and KSΦ values were plotted against concentration according to equations based on the Debye−Huckel theory, and the corresponding infinite dilution values (V0Φ and K0SΦ) were determined by extrapolation to zero concentration. Properties at infinite dilution were interpreted in terms of solute−water interactions. The temperature dependence of volumetric data provided the apparent molar isobaric expansivities of benzene and naphthalene sulfonates. A comparison of V0Φ and K0SΦ values for certain pairs of systematically chosen benzene and naphthalene sulfonates provided i...

Adsorptive removal of the dyes C.I. Basic Blue 9, C.I. Basic Red 2, and C.I. Acid Blue 74 from aqueous solution onto the activated carbon cloth (ACC) has been investigated. The removal of each dye has been followed by in-situ UV-visible spectroscopic method using the so-called scanning kinetics technique. Kinetic data obtained in this way were tested according to pseudo-first order, pseudo-second order, Elovich, and intraparticle diffusion models. Pseudo-second order model was found to be the best in representing the experimental kinetic data. Adsorption isotherms at 30°C were derived for each dye. Isotherm data were found to fit best to Freundlich isotherm model among the three isotherm models tested; Langmuir, Freundlich, and Redlich-Peterson. High specific surface area of the ACC allowed almost complete removal of each dye under the experimental conditions applied. Adsorption capacity of the ACC for the three dyes was correlated with the dimensions of dye molecules and pore sizes of the ACC.

Densities and ultrasound speeds of benzyltrialkylammonium chlorides (BTAACls) were measured accurately in aqueous solutions at five temperatures (293.15, 303.15, 313.15, 323.15, and 333.15) K. The data were utilized in determining apparent molar volumes, VΦ, and apparent molar isentropic compressibilities, KSΦ. Infinite dilution values of these apparent molar quantities, V Φ ∘ and K S Φ ∘ , were determined by extrapolation procedures. Contribution of CH2 groups, along the alkyl groups of BTAACls, to V Φ ∘ and K S Φ ∘ values were derived from plots of these quantities as a function of number of additional CH2 groups in going from benzyltrimethylammonium chloride to benzyltributylammonium chloride. The temperature dependencies of V Φ ∘ and K S Φ ∘ values were examined on the basis of isobaric expansivity. Apparent molar isobaric expansivities at infinite dilution, E Φ ∘ , were obtained from the slopes of V Φ ∘ versus temperature data. Concentration dependencies of VΦ and KSΦ were examined. A fair correlation was observed between V Φ ∘ and K S Φ ∘ values of the three BTAACls.

Zeta potential values of particles and their sign are very important in many applications. In this study, the zeta potential values of pumice were obtained in the presence of various monovalent (LiCl, NaCl, KCl, NaClO4, and NaNO3), divalent (MgCl2, CaCl2, SrCl2, BaCl2, CuCl2, MnCl2, NiCl2, Na2CO3, and Na2SO4) and trivalent (AlCl3 and Na3PO4) salts. The zeta potential measurements were performed as a function of pumice concentration, pH, ionic species and electrolyte concentration by electrophoresis technique. The pH profiles of pumice/water systems at different pH values were obtained to determine the stability of suspension pH. The results showed that the zeta potential values of pumice in water did not change significantly with pumice concentration, while they changed mostly with pH. The isoelectric point of pumice was at pH 2.70. It was found that monovalent cations and mono-, di-, and tri-valent anions were indifferent electrolytes for pumice particles, on the other hand, di- and tri-valent cations we...

Electrokinetic and rheological properties of Na-bentonite suspensions were investigated in the presence of various electrolyte solutions including LiCl, NaCl, KCl, NH4Cl, NaClO4, CH3COONa, NaNO3, Na2SO4, Na3PO4, CuCl2, MnCl2, CaCl2, BaCl2, NiCl2 and AlCl3. It was found that divalent cations (CU2+, Mn2+, Ca2+, Ba2+ and Ni2+) and trivalent cation (Al3+) were potential determining cations for the Na-bentonite suspensions. Trivalent cation, Al3+, changed the Surface charge of Na-bentonite from negative to positive. The zeta potential measurements showed that monovalent counter-cations and mono-, di- and tri-valent anions were indifferent ions for the Na-bentonite suspensions. The plastic viscosity and the Bingham yield stress values of the Na-bentonite suspensions were also determined in the presence of electrolyte solutions. (C) 2008 Elsevier Inc. All rights reserved.

In this study, the zeta potential values of vermiculite and expanded vermiculite were measured to determine the effect of pH, clay concentration, and various mono- and multivalent electrolytes including NaCl, KCl, NH4Cl, NaNO3, NaClO4, Na2SO4, Na2CO3, Na3PO4·12H2O, MgCl2·6H2O, CaCl2·2H2O, BaCl2, SrCl2·6H2O, CuCl2·2H2O, CoCl2·6H2O, NiCl2, AlCl3, and CrCl3·6H2O on the electrokinetic properties of vermiculite samples. It was found that generally the measured zeta potential values of expanded vermiculite for the studied systems were slightly more negative than that of vermiculite. The pH profiles of vermiculite and expanded vermiculite at acidic, natural, and basic pH values were obtained to determine the effect of time on the pH values of clay suspensions. The zeta potential measurements showed that the surface charge of clay particles was negative in water. The isoelectric point of vermiculite and expanded vermiculite were determined as pH 2.30 and 2.57, respectively. Divalent cations (Mg2+, Ca2+, ...

In this study, the effect of monoethylene glycol (MEG) and different molecular weight of poly(ethylene glycol) (PEG) solutions (PEG200, PEG400, PEG600, PEG1000, PEG3350 and PEG8000) on the electrokinetic and rheological properties of Na-bentonite suspensions were investigated in the polymer concentration range of 1 × 10 −5 to 1 × 10 −1 M. The physicochemical properties of Na-bentonite such as chemical composition, cation exchange capacity, density, particle size distribution and specific surface area were determined to characterize the clay sample. Na-bentonite did not have an isoelectric point value in the pH ranges of 1.75–11.56 and it had a negative surface charge in studied pH ranges. The zeta potential values of clay–polymer suspensions were less negative at high concentrations (at 1 × 10 −1 M and 1 × 10 −2 M) and at higher molecular weights of polymer in the suspensions. The suspensions exhibited Bingham flow behavior. Some peak position variations were observed in the FTIR spectra of Na-bentonite interacted with PEG molecules when it was compared with purified Na-bentonite and pure polymer spectra.

The effects of the molecular weights and concentrations of three polymers, poly(acrylic acid sodium salt) (NaPA), polyacrylamide (PAA), and poly(ethylene glycol) (PEG), on the electrokinetic and rheological properties of sepiolite suspensions were investigated. The ζ-potential values of the sepiolite suspensions were measured at different pH values, and the isoelectric point of sepiolite was determined to be 3.27. The anionic NaPA polymers were much effective in reducing the ζ-potential values of sepiolite than the nonionic polymers PAA and PEG. PAA and PEG of higher molecular weights caused a significant increase in the ζ-potentials of the sepiolite suspensions as their concentrations and molecular weights increased. The suspensions exhibited Bingham flow behavior. The reason for the increase in the plastic viscosity values of the sepiolite/NaPA suspensions was the increase in the polymer concentration in the suspensions; on the other hand, for the sepiolite/PAA or PEG suspensions, the reasons were the increase in the polymer concentration in the suspensions and the sepiolite–polymer interactions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Moisture adsorption isotherms of fuzzy cottonseed, black cottonseed, whole cottonseed kernel, blended cottonseed kernel and its protein isolate were obtained using gravimetric static method at 15, 25, 35 and 45 °C. GAB, Halsey and Harkins–Jura equations gave the best fit to experimental data among 14 well-known equations tested. M 0 values of samples calculated by G.A.B. and B.E.T. equations decreased with increasing temperature. The moisture adsorption isotherms obtained were type II sigmoidal. Thermodynamic properties such as differential enthalpy and entropy were determined from moisture adsorption data, using Clausius–Clapeyron equation. The experimental data showed that enthalpy–entropy compensation theory was applicable for the moisture adsorption behaviours of cottonseed samples and the adsorption process of samples was enthalpy-controlled.

The interactions of cationic surfactants with anionic dyes were studied by conductometric method. Benzyltrimethylammonium chloride (BTMACl), benzyltriethylammonium chloride (BTEACl) and benzyltributylammonium chloride (BTBACl) were used as cationic surfactants and indigo carmine (IC) and amaranth (Amr) were chosen as anionic dyes. The specific conductance of dye–surfactant mixtures was measured at 25, 35 and 45 °C. A decrease in measured specific conductance values of dye–surfactant mixture was caused by the formation of non-conducting or less-conducting dye–surfactant complex. The equilibrium constants, K1, the standard free energy changes, Δ G 1 ° , the standard enthalpy changes, Δ H 1 ° and the standard entropy changes, Δ S 1 ° for the first association step of dye–surfactant complex formation were calculated by a theoretical model. The results showed that the equilibrium constants and the negative standard free energy change values for all systems decreased as temperature increased. Also these values decreased for all systems studied with increasing alkyl chains of surfactants due to the steric effect. When the equilibrium constant values, K1, for the first association step of IC–surfactant and Amr–surfactant systems with the same surfactant were compared, the values of K1 for IC–surfactant system were higher than that of Amr–surfactant system.

Adsorption of benzaldehyde (BA), sulphanilic acid (SA), and sodium salt of p‐phenolsulfonic acid (p‐PhS) from water, acid, or base solutions onto activated carbon cloth (ACC) was studied by in‐situ UV‐spectrophotometric method. Kinetics of adsorption was followed over 90 min and the data were fitted to first order rate law. The order of rate of adsorption was found to be BA>SA≈p‐PhS in water, BA>p‐PhS>SA in 1 M H2SO4 and BA>SA >> p‐PhS in 0.1 M NaOH. Competitive adsorptions of BA and SA from an equimolar mixture in 1 M H2SO4 and of BA and p‐PhS from an equimolar mixture in H2O were studied for exploring the possibilities of separation of binary mixtures. It was found that p‐PhS was not adsorbed at all from 0.1 M NaOH solution. Adsorption isotherms of BA, SA, and p‐PhS at 30°C were derived and the data were fitted to the Langmuir and Freundlich models. The Freundlich model was found to represent the experimental data better than the Langmuir model.

Moisture sorption isotherms of cowpea (Vigna unguiculata L. Walp), powdered cowpea and protein isolate of cowpea at 10, 20 and 30 °C were derived. The sorption data were treated according to many well-known sorption isotherm equations. The goodness of fit was evaluated on the basis of criteria such as the mean relative deviation modulus, coefficient of determination and standard errors of models. It was found that the GAB model was the most satisfactory model for representation of the sorption data. Monolayer moisture contents (M0) were determined from the GAB and the BET equations. The temperature dependence of M0 was examined. Heats of sorption data were evaluated using the Clausius–Clapeyron equation. An attempt was made to determine the moisture contribution of the protein component of cowpea to the total moisture content.