Beneficiation of zinc from electric arc furnace dust using hydrometallurgical approach

Zinc bearing wastes such as electric arc furnace dust (EAFD) obtained from steel making constitute an important resource for zinc extraction. Inclusion of heavy metals such as Pb, Cd, Cu, Cr, Ni, etc., in these wastes makes them hazardous to use and/or dispose. In the present research work, leaching kinetics of EAFD with sulfuric acid has been investigated and various experimental parameters such as concentration of lixiviant, stirring rate, sample particle size, liquid/solid proportion, and temperature of the reaction have been optimized. It has been found that the dissolution rate of EAFD increases with rise in temperature, acidic strength, rate of stirring, liquid to solid proportion and with reduction in EAFD particle size. From the analysis of leaching kinetic data by means of graphical and statistical methods, it has been evaluated that the leaching kinetics of EAFD is dictated by surface diffusion reaction. Apparent energy of activation for the leaching reaction of EAFD with sulfuric acid is found to be 13.1 kJ mol^–1 within the temperature range of 308 to 358 K.     

Bioinspired NC Coated BM-ZIF for Electrochemical Monitoring of Adrenaline from Blood and Pharmaceutical Samples

Herein, we have developed highly sensitive and selective non-enzymatic bioinspired polydopamine derived nitrogen rich carbon (NC) coated bimetallic zeolitic imidazolate framework (BM-ZIF) electrochemical sensor via simple hydrothermal approach for monitoring adrenaline (AD) from COVID-19 quarantined person blood and pharmaceutical sample. The designed NC-BM-ZIF electrode shows excellent sensitive and selective performance towards AD monitoring with detection limit (LOD) of 0.01 nM and 0.1931 μA/nM/cm² sensitivity over a wide linear range of 50–1625 nM. To the best of our knowledge, this is the first study of using of NC-BM-ZIF electrode for the electrochemical sensing of AD from quarantined person blood and pharmaceutical sample.     

Mössbauer and electronic spectral characterization of homo-bimetallic Fe(III) complexes of unsymmetrical [N10] and [N12] macrocyclic ligands

The homo-bimetallic complexes of stoichiometry Fe2(L)ClO4(ClO4)2 where L are novel unsymmetrical [N10] (L1.2HClO4) and [N12] (L2.2HClO4) macrocyclic ligands, have been prepared. The ligands were obtained from an in situ capping reaction of the reactive substrate, N,N'-bis(N-ethylaniline)hydrazine-1,2-diimine with a mixture of aniline or 1,3-diaminopropane and HCHO in presence of HClO4. The compounds have been characterized by elemental analyses, conductometric, IR, FAB-mass and electronic spectral studies. IR data of complexes suggest coordination from unsymmetrical aza sites as a tridentate (N,N,N) or tetradentate (N,N,N,N) ligand. mu(eff) values of the complexes suggest presence of antiferromagnetically coupled (Fe3+-Fe3+=S5/2-S5/2) spin exchange. M?ssbauer parameters of the complexes support (+/-3/2)-->(+/-1/2) nuclear transition in high-spin configurations of Fe(III) nuclei of the homo-bimetallic complexes with the presence of Kramer's double degeneracy.     

On the formation of spin dependent double layer structure in astrophysical plasmas

Double layers (DLs) are nonlinear structures, and are thought to be responsible for particle acceleration in laboratory plasmas and astrophysical plasmas. In this paper, the existence of spin dependent DLs structure is explored using separate spin evolution quantum hydrodynamic model. Based on reductive perturbation method, we derived an extended Korteweg–de Vries (eKdV) equation to demonstrate the existence and nature of DLs. We found that spin polarization significantly enhanced the amplitude of the electrostatic potential associated with DLs. Further, spin polarization also increases the depth and width of the Sagdeev potential. It is noted that the contribution of Bohm potential effect is essential for the formation of DLs structure. Our results may be helpful to explain the phenomenon of particle acceleration in dense astrophysical environments specifically in a white dwarf.     

Random matrix model for disordered conductors

We present a random matrix ensemble where real, positive semi-definite matrix elements, x, are log-normal distributed, exp[−log²(x)]. We show that the level density varies with energy, E, as 2/(1+E) for large E, in the unitary family, consistent with the expectation for disordered conductors. The two-level correlation function is studied for the unitary family and found to be largely of the universal form despite the fact that the level density has a non-compact support. The results are based on the method of orthogonal polynomials (the Stieltjes-Wigert polynomials here). An interesting random walk problem associated with the joint probability distribution of the ensuing ensemble is discussed and its connection with level dynamics is brought out. It is further proved that Dyson’s Coulomb gas analogy breaks down whenever the confining potential is given by a transcendental function for which there exist orthogonal polynomials.     

Membrane-less and mediator-free enzymatic biofuel cell using carbon nanotube/porous silicon electrodes

Membrane-less and mediator-free direct electron transfer enzymatic biofuel cells (BFCs) with bioelectrodes comprised of single wall carbon nanotubes (SWNTs) deposited by two methods on porous silicon (pSi) substrates, are reported. In one method the SWNTs were grown by chemical vapor deposition (CVD) and then functionalized with carboxylic groups, and in the second method, pre-synthesized carboxylated SWNTs (c-SWNTs) were electrophoretically deposited on gold-coated pSi. Anodic glucose oxidase (GOx) and cathodic laccase (Lac) were immobilized on the pSi/SWNT substrates to form BFCs in pH 7 phosphate buffer solution. A peak power density of 1.38 μW/cm² (with a lifetime of 24 h) down to 0.3 μW/cm² was obtained for a BFC comprised of c-SWNT/enzyme electrodes in 4 mM glucose solution as fuel, corresponding to normal blood sugar concentration, and air as oxidant. BFCs of this relatively simple architecture have the potential for further optimization of power output and lifetime.     

Spectral studies of Fe(III) complexes of dipodal tridentate chelating agents

The dipodal ligands (Im) and (BIm) as well as complexes [FeLCl₃] [L = Im (1) and BIm (2)] have been prepared and studied using spectroscopic techniques. The magnetic moment, IR, electronic (ligand field), FAB-mass and NMR spectral data indicate a hexa-coordinate geometry around high-spin state Fe³⁺ where the ligands coordinate as a tridentate [N,N,N] chelating agent. ⁵⁷Fe-Mössbauer spectral data confirmed the presence of a ligand asymmetry around Fe³⁺ in a high-spin state electronic configuration (t_2g³,e_g², S = 5/2) with nuclear transition Fe(±3/2 → ±1/2) exhibiting Kramer's double degeneracy. The molecular computations provided the optimum energy perspective plots for the molecular geometries giving the important structural data.     

Simultaneous Determination of the Endogenous Free ��-Lipoic Acid and Dihydrolipoic Acid in Human Plasma and Erythrocytes by RP-HPLC with Electrochemical Detection

A highly sensitive, precise, and accurate reversed-phase high-performance liquid-chromatography/electrochemical detection method for simultaneous determination of the endogenous free ??-lipoic acid and dihydrolipoic acid in biological matrices was developed and validated. The two analytes were extracted from the samples with acetonitrile/10% metaphosphoric acid solution_(aqueous) (50/50 v/v). To determine the total lipoic acid, samples were treated with tris(2-carboxyethyl)phosphine solution in phosphate buffer, pH 2.5 with 85% orthophosphoric acid prior to deproteination. The two analytes were separated on a C₁₈ (150 × 4.6 mm, 5 ??m) analytical column using acetonitrile-50 mM phosphate buffer, pH 2.5 with 85% orthophosphoric acid (35/65 v/v) as the isocratic mobile phase pumped at a flow rate of 2.0 mL min^?1 at the column oven temperature of 35 °C. The column eluents were monitored at a potential of 0.9 V. These analytes were efficiently resolved in <7 min. The present method was sufficiently robust and specific for simultaneous determination of the two analytes and demonstrated acceptable values for linearity (r ² = 0.999 in the range of 0.1?C500 and 0.25?C1,000 ng mL^?1 for ??-lipoic acid and dihydrolipoic acid, respectively), recovery (>97%), precision (RSD% <2), and sensitivity (on column limit of detection, 150 and 375 fg for ??-lipoic acid and dihydrolipoic acid, respectively and limit of quantification: 0.5 and 1.25 pg for ??-lipoic acid and dihydrolipoic acid, respectively), indicating that the proposed method was more sensitive, precise, economical, and versatile, and has higher throughput than the previously reported methods for simultaneous determination of the two analytes.     

Piperidines: a new class of urease inhibitors

A variety of piperidines (2-12, 14-26) with variable substituents at N-atoms have been synthesized and evaluated as urease inhibitors. The synthesized compounds showed varying degree of urease inhibitory activity ranging from 31.97 to 254 microM. The size and electron-donating or -withdrawing effects of substituents influence the activity, which lead to the formation of urease inhibitors.