Partha Sarathi Guru

Sorption on eggshell waste--a review on ultrastructure, biomineralization and other applications.

The structure, adsorption behavior and applications of eggshell waste materials have been reviewed. The ultrastructure of eggshell particles has been discussed to understand the pore structure as well as the surface geometry of the materials leading to its multifarious applicability. Besides, the ultrastructure studies give full information regarding the chemical constituents of egghell particles as well as eggshell membranes. The process of biomineralization in living organisms, their consequent effect of controlling the formation of inorganic-organic composites propelling their application in biomimetic designing of advanced composites with optimized novel properties leading to advances in materials design have been discussed. Utilization of eggshell waste materials for the removal of organic dyes and heavy inorganic ions has been reviewed with suitable models for understanding their adsorption quality and capacity. The applications of these materials in various fields of research have been extensively discussed.

Eggshell Particles (ESP) as Potential Adsorbent for Styryl Pyridinium Dyes—A Kinetic and Thermodynamic Study

Eggshell particles (ESP) of a definite mesh size have been prepared and characterized through infrared and scanning electron microscopy. Adsorption of some styryl pyridinium dyes (SP-1 and SP-2) has been studied on ESP surface from water-ESP interface and the effects of adsorbate concentration, adsorbent dosage, temperature, salts, and the contact time have been examined. A first time study of the effect of water-structure making salt (kosmotroph) such as NaCl and structure breaking salt (chaotroph) such as KCl and NH4SCN on the adsorption process on ESP has been reported. Both types of salts have opposing effects on the adsorption of SP-1 dye; however, in case of SP-2 dye both of them show similar effects. The adsorption process is found to follow a second order kinetics. Thermodynamic studies show the occurrence of a physical adsorption with exothermic energetic. The adsorption follows Langmuir isotherm model and the area of coverage has been calculated to show the impact of hydrogen bonding on the adsorption phenomenon.

Adsorption of Some Tailor-Made Styrylpyridinium Dyes on Sodium Dodecylsulphate-Treated Eggshell Particles (SDS-ESP): Impact of Dye Chain-Length and Substituent

Eggshell particles (ESP), a solid bio-waste, treated with sodium dodecylsulfate (SDS) have been examined for the adsorption of some tailor-made cationic styrylpyridinium dyes. The adsorbent is characterized through Fourier transform infrared spectroscopy and scanning electron microscopy. The anionic headgroups of the surfactant bilayer on the SDS-treated ESP (SDS-ESP) provide avenue for binding with the dye molecules. Dependence of equilibrium adsorption capacity on various adsorption parameters and effects of substituent and hydrophobic tail of the adsorbate on adsorption are enumerated. Physical adsorption obeying pseudo-second order kinetics has been proposed. (Supplemental materials are available for this article. Go to the publishers online edition of Journal of Dispersion Science and Technology to view the free supplemental file.)

Tween-80–n-Butanol–Diesel–Water Microemulsion System—A Class of Alternative Diesel Fuel

Tween-80–n–butanol–diesel–water microemulsion systems with various surfactant:cosurfactant (S:C) ratio have been reported as a class of alternative diesel fuel from their phase behavior, clouding phenomena, conductivity, turbidity, and inflammation studies. Temperature induced clouding of microemulsion containing 2% brine at an S:C ratio of 1:1 from a suitable turbid zone has been examined to see the stability of the diesel–water microemulsion systems. Regression models have been proposed to understand the impact of various components of the microemulsion on their cloud point (CP) values. Conductivity of the microemulsions at various S:C ratio increases with the volume of brine having two cut points depicting the presence of three microheterogenous phases within the system, whereas turbidity shows a linear increase. Dye-probed investigation of water-rich and oil-rich zones of the microemulsions indicates the involvement of a dynamic mass transfer process within the various zones. The intensities of flames produced during burning of the microemulsions with various O:E:W weight percentages selected from the isotropic regions of the phase diagrams have been estimated using MATLAB image processing method and the impacts of various components on the fuel use of the microemulsions have been analyzed.

β-CD assisted dissolution of quaternary ammonium permanganates in aqueous medium

The non-polar internal cavity of β-cyclodextrin (β-CD) has been exploited for the entrapment of the hydrophobic tails of two water insoluble quaternary ammonium permanganates (QAPs): cetyltrimethylammonium permanganate (CTAP) and tetrabutylammonium permanganate (TBAP), for solubilization in aqueous medium. The solubilization and organizational behavior of the QAPs in aqueous β-CD solution have been determined from the comparison of their rates of self-oxidation in presence and in absence of β-CD. Effect of QAP concentration on their observed rate constants (k(obs)) at a fixed β-CD concentration, phase solubility analysis in varying β-CD concentration, impact of quaternary ammonium bromides (QABs) on the kobs values of CTAP and TBAP at fixed QAP and β-CD concentrations, and the temperature effect have been reported. A scheme to explain the solvation of QAPs in aqueous β-CD has been proposed based on dynamic light scattering (DLS) analysis of the samples.

Solvatochromic behavior of some α-styrylpyridinium dyes

The influences of solvent polarity and substituent on the electronic transition of six different N-butyl-α-styrylpyridinium dyes have been investigated in 21 solvents. Reichardts E(T)(30) scale has been used to propose a quantitative approach towards the relative stability of the electronic ground and excited state species. The solvents have been classified into three types and the dyes have been classified into four groups based on the contribution of field and inductive effects of the substituents towards the change in their absorption maxima values. Instead of a steady solvatochromism, all the dyes except p-nitro substituted one, suffer reversals in solvatochromism at E(T)(30) values of ~37 and ~48. The extents of contribution of non-polar and polar protic solvents towards the solvation of the excited states of the dye molecules have been determined to be 30-40% more than that towards the stability of their ground states by the dipolar aprotic solvents. The ortho effect shown by this class of dyes in contrast to their corresponding γ-isomers might have been responsible for their better solvent polarity sensing capability.

UV-Vis spectrophotometric studies of self-oxidation/dissociation of quaternary ammonium permanganates (QAP) - impact of solvent polarity.

Self-oxidation/dissociation of some quaternary ammonium permanganates (QAPs), such as cetyltrimethylammonium permanganate (CTAP) and tetrabutylammonium permanganate (TBAP), have been studied spectrophotometrically in six different organic solvent media of different polarities wherein the compounds show good solubility and stability. The optical densities of the substrates at zero time (ODo) and first-order rate constants of dissociation (k1) have been determined from their successive scanning for 40min. At comparable experimental conditions, absorption capabilities of the substrates are compared from the ODo values in various organic media; the stability of the solutions is compared from the successive scan spectra in those media. The ODo values and the k1 values have been plotted against some solvent parameters to understand their effects on the absorbance and reactivity of the QAPs. These data are also subjected to multiple regression analysis to explain the influence of various solvent parameters on the ion-pairing properties of the substrates, thus elucidating their effects on the process of self-oxidation/dissociation of the substrates.

β-CD assisted aqueous dissolution of cetylpicolinium dichromates (CPDC)—Evolution of a class of green water compatible lipopathic Cr(VI) oxidants

Water-insoluble lipopathic dichromates have been successfully solubilized in aqueous phase by the entrapment of their hydrophobic tails in β-cyclodextrin (β-CD) non-polar cavity. Aqueous solubility of α-, β-, and γ- cetylpicolinium dichromate (CPDC) molecules, synthesized in our lab, has been studied to find their suitability for Cr(VI) oxidation purposes in water medium. The analysis of phase solubility shows the existence of a Bs type curve and its significance has been fully deciphered through dynamic light scattering (DLS) analysis. The limiting concentration of β-CD up to which it can induce 1:1 host-guest complexation with the CPDC entities, has been determined and the stoichiometry has been confirmed from Jobs plot. The binding constant and complexation efficiency of the β-CD-CPDC complexes have been determined and temperature effect on these parameters has been discussed through thermodynamic calculations. Analyses of viscosity variation of the aqueous solutions of the complexes have been done and correlated with the solubilization phenomenon.