• ASHOK KUMAR

Articles written in Journal of Chemical Sciences

• Abstracts

• Modern Trends in inorganic chemistry - Foreword

• N′, N″, N‴-tris(2-pyridyloxymethyl) ethane as ionophore in potentiometric sensor for Pb(II) ions

N′,N″,N‴ tris(2-pyridyloxymethyl) ethane (TPOME) has been used as an ionophore in a polyvinylchloride (PVC)-based membrane. Membrane electrode with a composition 30:5:62:3 (PVC:TPOME: o-NPOE:NaTPB) exhibits Nernstian response towards Pb(II) ions with a slope of 30mV/decade, over a concentration range of $1 \times 10^{−5}$ M to $1 \times 10^{−1}$ M. Potential response remains almost unchanged over pH range of 3.7-6.4. The electrode shows fast response time of $15 \pm 2$ s and a lifetime of four months. It shows good selectivity for Pb(II) ions over other mono-, di- and trivalent cations. Electrode response is satisfactory in mixed solvent media up to 30% (v/v) non-aqueous contents. Selectivity of the ionophore for Pb(II) ions was determined by spectrophotometric method. The electrode can also be used as an indicator electrode in potentiometric titration of Pb(II) ions with standard chromate solution and its determination in real-life samples. Surface morphology of membrane electrode at different stages of its development and use is also discussed.

• Construction of metal oxide decorated g-C3N3 materials with enhanced photocatalytic performance under visible light irradiation

Herein we report the synthesis and photocatalytic evaluation of heterostructure WO3/g-C3N4 (WMCN) and CeO2/g-C3N4(CMCN) materials for RhB degradation and photoelectrochemical studies. These materials were synthesized by varying the dosages of WO3 and CeO2 on g-C3N4 individually and were characterized with state-of-the-art techniques like XRD, BET surface area, FT-IR, UV–Vis DRS, TGA, SEM, TEM and XPS. A collection of combined structural and morphological studies manifested the formation of bare g-C3N4, WO3, CeO2, WO3/g-C3N4 and CeO2/g-C3N4 materials. From the degradation results, we found that the materialwith 10 wt% WO3 and 15 wt% CeO2 content on g-C3N4 showed the highest visible light activity. The first order rate constant for the photodegradation performance of WMCN10 and CMCN15 is found to be 5.5 and 2.5times, respectively, greater than that of g-C3N4. Photoelectrochemical studies were also carried out on the above materials. Interestingly, the photocurrent density of WMCN10 photoanode achieved 1.45 mA cm − 2 at 1.23 V (vs.) RHE and this is much larger than all the prepared materials. This enhanced photoactivity of WMCN10 is mainly due to the cooperative synergy of WO3 with g-C3N4, which enhanced the visible light absorption and suppresses the electron–hole recombination

• A ninhydrin–thiosemicarbazone based highly selective and sensitive chromogenic sensor for Hg2+ and F- ions

This study demonstrates the design, synthesis and sensing applications of a simple and efficient chemosensor, 2-(1,3-dioxo-1H-inden-2(3H)-ylidene)hydrazinecarbothioamide (R) for quick detection of Hg2+ and F- in aqueous media using a colorimetric test, UV–Vis spectral analysis, and silica gel support Sensor R showed the typical absorption peak at 305 nm for Hg2+ which is responsible for color change from yellow to colorless, while in the case of F-, R exhibits a major peak at 415 nm and a color change from yellow to red. The limit of detection (LOD) of R for the analysis of Hg2+ was calculated as 1x10-6 M while for F-, it was found to be 3.4x10-7 M. The binding modes of R with Hg2+ and F- have been investigated by the Job’s plot, Benesi–Hildebrand (BH) method, 1H NMR, FTIR and theoretical studies. The sensor R was reversible after treating it with reagents such as EDTA and calcium nitrate solution after contacting with Hg2+ and F-, respectively. The performance of R can be successfully applied for the analysis of F- contents present in toothpastes

• An improved protocol for the synthesis of 3,4-disubstituted isoxazol- 5(4H)-ones through L-valine-mediated domino three-component strategy

An expeditious, metal-free protocol has been demonstrated for the synthesis of isoxazolone derivatives using domino multi-component strategy. The envisaged methodology involves the L-valine promoted three-component cyclo-condensation reaction of alkylacetoacetates, hydroxylamine hydrochlorideand aldehydes in ethanol under reflux. The reaction proceeded to deliver the desired products in good to excellent yields (74–97%), exhibited good functional group tolerance and completed in less than 4 min with most of the substrates. High yields, short reaction time, noncorrosive organocatalyst, mild reaction conditions, clean reaction profiles and the absence of any tedious workup or purification are the beneficial features of this process. Moreover, quantum computational study has been performed at B3LYP/6-311G??(d, p) level toinvestigate the various DFT based molecular descriptors, HOMO–LUMO energy gap and electrostatic potential surface properties of the synthesized product

• Removal of Cr and Mn from aqueous medium using bentonites and their derivatives

Bentonite minerals of Rajmahal Hills and Hazaribagh district along with their derivatives have been used to remove hexavalent chromium and manganese from aqueous medium. Bentonites are smectite group of minerals having swelling power and cation exchange properties. Blue colour with benzidine solutionindicates the presence of montmorillonite unit having SiO2, Al2O3, K2O, Fe2O3, FeO and traces of TiO2 also. The adsorption isotherm and removal performance of hexavalent chromium and manganese have been examined by shaking 100 mL 2 ppm solution with 1 gram of bentonite and their derivatives up to differentintervals of time and also with varying amount of bentonite up to fixed time intervals. The percentage removal of chromium (VI) ranges from 12% to 67.7% whereas percentage removal of manganese (VII) varies from 09% to 92.5%. Experimental data showed that the removal of Cr (VI) and Mn (VII) represented both Freundlich and Langmuir adsorption isotherms. Adsorption of Cr (VI) and Mn (VII) on to bentonites and their derivatives follow first-order kinetics. It is concluded that locally available bentonites may be exploited as a low-cost feasible adsorbent for removal of Cr (VI) and Mn (VII) in the laboratory as well as industrial level too.

• # Journal of Chemical Sciences

Volume 132, 2020
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Continuous Article Publishing mode

• # Editorial Note on Continuous Article Publication

Posted on July 25, 2019