Mahadevappa Y. Kariduraganavar

Pervaporation separation of water–isopropanol mixtures using ZSM‐5 zeolite incorporated poly(vinyl alcohol) membranes

A solution technique was employed to prepare ZSM-5 zeolite incorporated poly(vinyl alcohol) (PVA) membranes for the pervaporation separation of water-isopropanol mixtures. The membranes were characterized by Fourier transform infrared spectroscopy and differential scanning calorimeter. Glass transition temperatures of the membranes varied from 102 to 110°C, with increasing zeolite content of the membrane. The effect of zeolite loading and feed composition on pervaporation performance of the membranes was analyzed. The membrane containing 6 mass% of zeolite gave the highest separation selectivity of 216 for 10 mass % of water containing feed mixture at 30°C. Increase in water selectivity of the membrane was explained as due to a reduction in free volume by increasing zeolite content of the membrane. Separation selectivity and permeation flux data are dependent on water composition of the feed mixture, but are comparatively less dependent on temperature. The hindrance of water permeation at higher composition of water in the feed mixture was explained as due to the formation of clusters of water molecules. The overall activation energy and preexponential factors were calculated using Arrhenius equation. Pervaporation data have also been explained on the basis of thermodynamic parameters calculated by using Arrhenius equation as well as relationship proposed by Ping et al.

Development of novel composite membranes using quaternized chitosan and Na+-MMT clay for the pervaporation dehydration of isopropanol

Novel polymer-clay-based composite membranes were prepared by incorporating sodium montmorillonite (Na(+)-MMT) clay into quaternized chitosan. The resulting membranes were characterized by Fourier transform infrared spectroscopy (FTIR), wide-angle X-ray diffraction (WXAD), and thermogravimetric analysis (TGA). The effect of membrane swelling was studied by varying the water concentration in the feed. The membranes were employed for the pervaporation dehydration of isopropanol in terms of feed composition and Na(+)-MMT clay loading. The experimental results demonstrated that membrane containing 10 mass% of Na(+)-MMT clay showed the highest separation selectivity of 14,992 with a flux of 14.23x10(-2) kg/m(2) h at 30 degrees C for 10 mass% of water in the feed. The total flux and flux of water are found to be overlapping each other particularly for clay-incorporated membranes, signifying that the composite membranes developed in the present study involving quaternized chitosan and Na(+)-MMT clay are highly selective toward water. From the temperature-dependent diffusion and permeation values, the Arrhenius activation parameters were estimated. The resulting activation energy values obtained for water permeation (E(pw)) are much lower than those of isopropanol permeation (E(pIPA)), suggesting that the developed composite membranes have higher separation efficiency for the water-isopropanol system. The estimated E(p) and E(D) values ranged between 8.97 and 11.89, and 7.56 and 9.88 kJ/mol, respectively. The positive heat of sorption (DeltaH(s)) values were obtained for all the membranes, suggesting that Henrys mode of sorption is predominant in the process.

Synthesis, characterization and in vitro anticancer evaluation of novel 1,2,4-triazolin-3-one derivatives

A series of novel 2-(4-chlorophenyl)-5-methyl-4-(2-amine/oxy-ethyl)-2,4-dihydro-[1,2,4]triazol-3-one (5a-t) were synthesized and in vitro anticancerous action of the resulting compounds was studied against NCI-60 Human Tumor Cell Line at a single high dose (10(-5) M) concentration for primary cytotoxicity assay. Among the tested compounds (5a-e, 5g-h, 5k, 5p), the compound 5g (NSC: 761736/1) was further evaluated for five dose criteria at five different minimal concentrations against the full panel of 60 human tumor cell lines which exhibited activity against Leukemia (GI50: 1.10 μM), Non-Small Cell Lung Cancer (GI50: 1.00 μM), Renal Cancer (GI50: 1.00 μM), Colon Cancer (GI50: 1.66 μM), CNS Cancer (GI50: 1.36 μM), Melanoma (GI50: 1.82 μM), Ovarian Cancer (GI50: 1.64 μM) and Breast Cancer (GI50: 1.69 μM).

In vitro release study of verapamil hydrochloride through sodium alginate interpenetrating monolithic membranes.

Polymeric sodium alginate interpenetrating network membranes containing verapamil hydrochloride were fabricated for transdermal application. The membranes were evaluated for their physical properties, weight and thickness uniformity, water vapor transmission, as well as drug content uniformity. All the thin patches were transparent, smooth, and flexible. The drug-loaded membranes were analyzed by X-ray diffraction to understand the drug polymorphism inside the membrane. The transdermal patches were permeable to water vapor, indicating the permeability characteristics of the polymers. The in vitro drug release was performed in distilled water using a Keshary-Chien diffusion cell. The release data were analyzed to understand the mechanism of drug release.

Development of pervaporation membranes using chitosan and titanium glycine-N,N-dimethylphosphonate for dehydration of isopropanol

Titanium glycine-N,N-dimethylphosphonate, Ti[(O3PCH2)2NCH2COOH] (TGDMP), was synthesized and incorporated into chitosan in different weight ratios to obtain nanocomposite membranes. TGDMP acts as an electronegative nanofiller owing to the large number of –COOH groups and thereby establishes an electrostatic interaction between the nanofiller and chitosan. The structure, morphology, and thermal properties of the resulting membranes were studied using different techniques such as Fourier transform infrared (FTIR) spectroscopy, wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The membranes were subjected to pervaporation dehydration of isopropanol at different temperatures. The effect of TGDMP on the pervaporation performance was investigated systematically. The separation factor and permeation flux of the resulting nanocomposite membranes are much higher than those of the pure chitosan membrane. The membrane containing 1.2 mass% of TGDMP demonstrated the highest separation factor of 1050 with a permeation flux of 7.37 × 10−2 kg m−2 h−1 at 30 °C for 10 mass% of water in the feed. The total flux and flux of water are found to be overlapping particularly for TGDMP incorporated membranes, illustrating that the developed nanocomposite membranes could be used effectively to break the azeotropic point of water–isopropanol mixtures. From the temperature dependent diffusion and permeation values, the Arrhenius activation parameters were estimated. The activation energy values obtained for water permeation (Epw) are significantly lower than those of isopropanol permeation (EpIPA), suggesting that the developed membranes have a higher separation ability for the water–isopropanol system. The estimated Ep and ED values ranged between 20.00 and 2.52, and 19.72 and 2.48 kJ mol−1, respectively. Positive heat of sorption (ΔHs) values were obtained for all the membranes, suggesting that Henrys mode of sorption was predominant.

Preparation of zeolite-incorporated PDMS membranes for pervaporation separation of isopropanol-water mixtures

ZSM-5 zeolite-incorporated poly(dimethyl siloxane) membranes were prepared and molecular dispersion of zeolite in the membrane matrix was confirmed by scanning electron microscopy. After studying the behavior of membrane swelling at 30°C, the membranes were subjected to pervaporation separation of isopropanol-water mixtures at 30, 40 and 50°C. The effects of zeolite loading and feed composition on the pervaporation performances of the membranes were analyzed. Both permeation flux and selectivity increased simultaneously with increasing zeolite content in the membrane matrix. This was discussed on the basis of the enhancement of hydrophobicity, selective adsorption, and the establishment of molecular sieving action. The membrane containing the highest zeolite loading (30 mass%) exhibits the highest separation selectivity of 80.84 and flux of 6.78 × 10−2kg/m2h at 30°C for 5 mass% of isopropanol in the feed. From the temperature dependency of diffusion and permeation values, the Arrhenius activation parameters were estimated. A pure membrane (M) exhibits higher Ep and ED values compared to zeolite-incorporated membranes, signifying that permeation and diffusion require more energy for transport through a pure membrane, owing to its dense nature. Obviously, zeolite-incorporated membranes require less energy due to their molecular sieving action attributed to the presence of straight and sinusoidal channels in the framework of zeolite. All the zeolite-incorporated membranes exhibit positive ΔHs values, suggesting that the heat of sorption is dominated by the Henrys mode of sorption.

Polymer Synthesis and Processing

Polymer scientists have made an extensive research in the development of biodegradable polymers, which could find enormous applications in the area of medical science. Today, various biopolymers have been prepared and utilized in different biomedical applications. Despite the apparent proliferation of biopolymers in medical science, the science and technology of biopolymers is still in its early stages of development. Tremendous opportunities exist and will continue to exist for the penetration of biopolymers in every facet of medical science through intensive research and development. Therefore, this chapter addresses different polymerization methods and techniques employed for the preparation of biopolymers. The emphasis is on the general properties of biopolymers, synthetic protocols, and their biomedical applications. In order to make the useful biomedical devices from the polymers to meet the demands of medical science, various processing techniques employed for the development of devices have been discussed. Further, perspectives in this field have been highlighted and conclusions arrived at. The relevant literature was collected from different sources, including Google sites, books, and reviews.

Ion Exchange Membranes: Preparation, Properties, and Applications

Membrane science is a relatively new area of applied chemistry and chemical engineering and plays a vital role in the field of alternative energy and separation applications. The field of membrane science is therefore an emerging area with enormous industrial and public health significance. Today, various kinds of separation membranes have been studied and utilized industrially in different processes including reverse osmosis, nanofiltration, ultrafiltration, microfiltration, electrodialysis, and pervaporation. Technical feasibility of all these processes largely depends on membrane and its properties. Among the separation membranes, ion exchange membranes are one of the advanced separation membranes. Therefore, this chapter addresses on different types of ion exchange membranes with reference to their preparation, properties, as well as their industrial applications. Although ion exchange membranes are broadly classified into homogeneous and heterogeneous membranes, this chapter also covers other types of ion exchange membranes such as amphoteric, mosaic, bipolar, interpolymer, and graft and block copolymer membranes. At the end, prospectives and conclusions on the ion exchange membranes have also been highlighted. The relevant literature was collected from different sources including Google sites, books, reviews, and research articles.

Development of composite anion-exchange membranes using poly(vinyl alcohol) and silica precursor for pervaporation separation of water–isopropanol mixtures

Composite anion-exchange membranes were prepared using sol–gel techniques with poly(vinyl alcohol) (PVA) and anion-exchange silica precursor (AESP). Ammonium functionality was created on the AESP through a ring opening reaction between 2-(3-aminoethylamino)propyltrimethoxysilane and glycidyltrimethylammonium chloride under mild heating conditions. The resulting membranes were subjected to physico-chemical investigations using various techniques. The pervaporation performance of the membranes was systematically investigated based on the effects of feed composition and the mass% of AESP. Among the membranes studied, the membranes containing 4 mass% of AESP exhibited the highest separation factor of 2991 with a flux of 10.76 × 10−2 kg m−2 h−1 at 30 °C for 10 mass% of water in the feed. The trade-off phenomenon which exists between the flux and the separation factors was overcome by the incorporation of AESP in PVA matrix. We find that the overlap between the total flux and flux of water, suggests that these membranes could be used effectively to break the azeotropic point of water–isopropanol mixtures. From the temperature dependent diffusion and permeation values, the Arrhenius activation parameters were estimated. The Ep and ED values ranged between 18.36 and 7.94, and 18.68 and 8.09 kJ mol−1, respectively. The negative heat of sorption (ΔHs) values was obtained for all the membranes, indicating that Langmuirs mode of sorption is predominant in the transport process.

An expeditious synthesis of 1,2,4-triazolinones appended to 1,3-thiazoles using zinc triflate as catalyst

A convenient and high yielding method was developed for the ring transformation of 1,3,4-oxadiazolinones (2a-e) from 3-arylsydnones (1a-e) to 1,2,4-triazolinones (3a-e) using zinc triflate as catalyst and then appended to 1,3-thiazoles via an imino bridge in one-pot reaction with excellent yields. The novel compounds were further scored for c logP values, drug likeliness, drug score and toxicity rates using molecular OSIRIS property explorer. Selective compounds were also screened for antimicrobial studies.