Babulal Rebary

Colorimetric and fluorogenic recognition of Hg2+ and Cr3+ in acetonitrile and their test paper recognition in aqueous media with the aid of rhodamine based sensors.

Two new rhodamine derivatives (L1 and L2) were synthesized, characterized and their ion recognition property has been investigated. Both of the ionophores exhibit colorimetric and fluorogenic response for Hg2+ and Cr3+ ions among large number of alkali, alkaline earth and transition metal ions tested in acetonitrile. Detail studies on determination of binding constant, binding mode, reversibility of binding, lower detection limit have been carried out. Detection of metal ions in aqueous media has also been demonstrated by preparation of simple, convenient and disposable test paper sensors with two approaches viz. filter paper and membrane filter loaded with these ionophores. Both of these methods responded sharply to both the metal ions (Hg2+ and Cr3+) in aqueous solution, detectable by bared-eye. For better sensing at low concentration of metal ions, reprecipitation followed by filtration enrichment of ligands on membrane filter was employed.

Fluorescence characteristics of carbon nanoemitters derived from sucrose by green hydrothermal and microwave methods.

In this work, fluorescent carbon nanoparticles (CNPs) were prepared through two green methods i.e. microwave and hydrothermal, using sucrose as carbon precursor. Both of these methods have offered fluorescent CNPs as characterized by TEM, FTIR, zeta potential, absorbance and emission techniques. Excitation dependent emission spectra were exhibited by aqueous dispersion of these CNPs when they were subjected to different excitation wavelengths. The luminous characteristics of CNPs obtained from both of these methods were studied and compared. Their fluorescence stability in water and buffer was monitored for about three months. Influence of pH and various metal ions on emission spectra were investigated.

Preparation of Thin Film Polymer Composite Membranes for Optical Resolution of Racemic Mixture of α-Amino Acids

Thin film polymer composite membranes capable of resolving racemate of α-amino acids were prepared by coating a chiral selective layer on micro-porous polysulfone membrane in situ through interfacial polymerization of trans-1, 4-diaminocyclohexane (T-1, 4-DCH) with trimesoyl chloride (TMC). The chiral selective layer of membranes was extensively characterized by FTIR spectroscopy (ATR), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), and Transmission Electron Microscopy (TEM). The membranes prepared from monomer solutions of low concentrations (T-1, 4-DCH, 2%, and TMC, 1%) rejected more solute with low enantioselectivity whereas the membranes prepared from monomer solutions of high concentrations (T-1, 4-DCH, 4% and 6% and TMC, 2%) rejected less solute with high enantioselectivity. The membrane prepared from 6% T-1, 4-DCH, and 1% TMC solutions exhibited maximum enantioselectivity (>92% ee). The membranes prepared from monomer solutions of low concentrations had very thin coating layer (<0.5 µm) whereas membranes prepared from concentrated monomer solutions had comparatively thick coating layer (>0.5 µm). The rejection of arginine increased marginally with permeation time but the enantioselectivity remained constant.

Mapping of iodine, lithium and strontium in oilfield water of Cambay basin, Gujarat

The major oil and gas producing fields in Gujarat are found in Cambay basin. It is known that a huge amount of water is produced with oil and gas production which is called produced oilfield water. Some useful elements (iodine, lithium and strontium) are present with this oilfield water which may be extracted in case of their abundance. The investigation of iodine, lithium and strontium concentrations in produced oilfield water was accomplished by Ion chromatography while for other cations ICP instrument was used. In oilfield water, iodine content ranges from 0.08 to 1.89 mg/l, lithium content ranges from 0.06 to 2.90 mg/l and strontium content ranges from 0.24 to 73.5 mg/l. In addition to above element, Na, Mg, K, Ca, Al, Ba, Fe, Se, Cu, Zn, As, Cd and Hg were also analyzed. The pH and TDS of all the samples were also measured. There is considerable variation in iodine, lithium and strontium in oilfield water samples collected from oil and gas producing fields of Gujarat. There is no definite pattern of variation in iodine, lithium and strontium content.

Correlating growth mechanism and morphology in Cu-TCNQ organometallic complex: A microscopic study

The structure-property correlation in the Cu-TCNQ organometallic complex is very important for explaining its unusual electrical, optical and magnetic properties. Consequently several morphological studies and their correlation with the properties of these materials can be found in the literature, although no systematic study of various morphologies with growth conditions and their correlation has been reported to the best of our knowledge. Therefore in this manuscript the interconversion of various morphologies is reported using electron and probe microscopies. A conventional Cu TEM grid acted as the copper source to form a Cu-TCNQ complex and the complex, which formed at the surface of the TEM grid. The complex thus prepared was characterized by FTIR and Raman spectroscopic techniques. The shifting of ̵-CN from 2221 cm-1 (TCNQ) to 2201 cm-1 indicates formation of a complex and the identical nature of IR spectra in two phases indicates that they are polymorphs. The morphologies of Cu-TCNQ were followed through FE-SEM and TEM studies. Various morphologies such as needle, square tube, platelet etc. were observed as a function of time. A distinct transition from needle to platelet morphology was observed as the complex grew. The conductance of various morphologies in phase-I as well as phase-II were also measured and compared by Spreading Resistance Imaging (SRI) at different bias voltage i.e. 1 V, 3 V and 5 V.

An Adsorption Study of Sr2+ From Saline Sources by Coconut Shell Charcoal

ABSTRACT The adsorption potential of charcoal for the removal of heavy metal ions is well documented in the literature. However, its exploration for uptake of technologically valuable metal ions such as Sr2+ is poorly known. In this work, the batch adsorption study of Sr2+ ion from aqueous solution as well as from saline matrix (>3% of NaCl) onto charcoal has been carried out. The experiments were conducted with two charcoals, i.e., our prepared charcoal (coconut shell charcoal) and commercial charcoal. Strontium adsorption has been investigated as a function of its initial concentration, contact time, and varied mass of adsorbent. Equilibrium adsorption data were evaluated for Langmuir and Freundlich isotherm models. The adsorption capacities (mg/g) of Sr2+ present in the salt matrix onto coconut shell charcoal and commercial charcoal was found to be 18.4 and 22.2, respectively. Uptake of Sr2+ from subsoil brine onto coconut shell charcoal has been successfully demonstrated in this work. GRAPHICAL ABSTRACT

Fluorescent carbon nanoparticles obtained from charcoal via green methods and their application for sensing Fe3+ in an aqueous medium

Two green methods (microwave and hydrothermal) were employed for the preparation of water dispersible fluorescent carbon nanoparticles (CNPs) from activated charcoal. Microwave and hydrothermally synthesized carbon nanoparticles, (MW-CNPs) and (HT-CNPs), respectively were characterized by microscopic and spectroscopic techniques. A detailed study of their fluorescence characteristics was made. MW-CNPs and HT-CNPs were tested for metal ion selectivity in aqueous medium. MW-CNPs showed selectivity for Fe3+ among the tested metal ions and important studies such as for interference, linear range and limit of detection were carried out. The application of MW-CNPs for detection of Fe3+ in water was demonstrated.

Geological introduction to strontium-rich sub-soil brine with emphasis on the Little Rann of Kutch and Bhavnagar, Gujarat

The methodology for green mining operation, one that extracts minerals from waste brine water for eco-friendly products, is appealing. Little Rann of Kutch (LRK) and the sites near Bhavnagar associated with producing sub soil brine water which contain strontium up to 215 mg/L. This value is significant considering its value in sea water (~8 mg/L). The high-strontium brines also contain elevated lithium (up to 2.98 mg/L) and uranium (up to 0.1 mg/L). The occurrence of strontium in the India’s brine water is poorly understood and inadequately represented in the literature. The objectives of this report, therefore, are to illustrate where strontium-rich brine waters occur in Gujarat (India). The investigation of strontium, lithium and uranium in sub-soil brine was accomplished by the ICP-OES instrument. We have checked the pH, density, specific gravity and Degree Bowme (DB’) of the all samples. Alkali and alkaline earth metals like Na, K, Mg, Ca and Ba; metalloid B; transition element like Zn, Cr and Fe; heavy metals like Cd, Pb and Ni were also analysed for toxicity evaluation and anion Cl– and SO4–2 were analysed by classical methods. Field wise, there is considerable variation in strontium, lithium and uranium in sub-soil brine water.