Monohar Hossain Mondal

Modernization of surfactant chemistry in the age of gemini and bio-surfactants: a review

Modern surfactant science demands chemistry which is benign by design. Efficient green chemicals like gemini surfactants along with natural resource derived bio-surfactants are thus most dependable in this case. In the search for less pollution and more ecologically beneficial solvents, more and more environmentally accepted trends are emerging every day into the market; species related to properties such as lower toxicity, higher biodegradability, chemical stability, environmental safety, efficient solubilization and of course, ease of recycling, can be vital tools. Bio-surfactants along with geminis are of great interest for their very efficient working ability, lower CMC and other up to date features that modern science desires for the betterment of mother nature. This review contains elaborate discussions on the efficiencies of gemini and bio-surfactants as modern generation green chemicals in various fields viz. in laboratory based kinetic experiments, electron transfer reactions, emulsification, solubilization, and agro-industrial and bio-medicinal fields which provides us with the hope of an amazing future prospect with these types of green chemicals.

A halotolerant Enterobacter sp. displaying ACC deaminase activity promotes rice seedling growth under salt stress

Agricultural productivity is proven to be hampered by the synthesis of reactive oxygen species (ROS) and production of stress-induced ethylene under salinity stress. One-aminocyclopropane-1-carboxylic acid (ACC) is the direct precursor of ethylene synthesized by plants. Bacteria possessing ACC deaminase activity can use ACC as a nitrogen source preventing ethylene production. Several salt-tolerant bacterial strains displaying ACC deaminase activity were isolated from rice fields, and their plant growth-promoting (PGP) properties were determined. Among them, strain P23, identified as an Enterobacter sp. based on phenotypic characteristics, matrix-assisted laser desorption ionization-time of flight mass spectrometry data and the 16S rDNA sequence, was selected as the best-performing isolate for several PGP traits, including phosphate solubilization, IAA production, siderophore production, HCN production, etc. Enterobacter sp. P23 was shown to promote rice seedling growth under salt stress, and this effect was correlated with a decrease in antioxidant enzymes and stress-induced ethylene. Isolation of an acdS mutant strain enabled concluding that the reduction in stress-induced ethylene content after inoculation of strain P23 was linked to ACC deaminase activity.

Review on chemically bonded geminis with cationic heads: second-generation interfactants

Cationic gemini surfactants are a special class of second-generation smart surfactants. Since Menger first named them, gemini surfactants have drawn a wide and immense attraction from scientists throughout the whole world. These dimeric surfactants possess two or more hydrophilic with two or more hydrophobic head groups, chemically bonded with a linker, called the spacer group. These kinds of surfactants are used mainly in homogeneous catalytic reactions, as well as for solubilisation, emulsification, and many more technical applications. They are used in industries for electro-decoating, stabilization of adhesive polymer latex, anti-friction agents, mining, paper manufacturing, preparation of surfactants including softeners, cosmetics, and most importantly, recent advancement in drug designing, synthesis, and application in medicine. The aim of this paper is to bring attention to the high performance second generation interfactants, with a focus on their synthesis, structure, types, and greener industrial application with high possibility of future prospect.

Employment of different spectroscopic tools for the investigation of chromium(VI) oxidation of acetaldehyde in aqueous micellar medium

Different spectroscopic methods have been applied to investigate the chromic acid oxidation of acetaldehyde in aqueous media, catalysed by surfactants. Three representative heteroaromatic nitrogen base promoters, 2-picolinic acid (PA), 2,2’-bipyridine (bpy) and 1,10-phenanthroline (phen), have been associated along with surfactants as promoters to the kinetic study. Comparative studies of unpromoted and promoted reactions invoked that 2,2’-bipyridine produced maximum rate enhancement. The mechanism of the reaction path has been proposed with the help of kinetic results and spectroscopic studies. The observed net enhancement of rate effects has been explained with scientific manipulations and data obtained. The combination of TX-100 and1,10-phenanthroline is found to be most effective for acetaldehyde oxidation.Graphical AbstractChromium(VI) oxidation of acetaldehyde in aqueous micellar media has been carried out. Micellar catalysis by TX-100 in association with a ‘phen’ promoter increases the rate of the reaction almost 60 fold. The combination of TX-100 and ‘phen’ is the most suitable one for chromic acid oxidation of acetaldehyde to acetic acid in aqueous media.

Characterization of Pyrene Solubilization in Selective Micellar Media of Novel Bio-degradable Natural Surfactant Saponin (Extracted from Soap Nut) and Conventional Surfactant SDBS in Presence and Absence of Common Salt NaCl

Abstract Solubilisation of pyrene (PAHs) in aqueous micellar solutions of natural surfactant saponin and conventional surfactant sodium dodecylbenzene sulfonate (SDBS) has been examined by UV-Vis and steady state fluorescence spectrometry at 30°C. The effect of addition of common salt NaCl on the I1/I3 of fluorescence has also been determined. The experiment concludes that the pyrene molecules were incorporated in the palisade layers of both micelles because of their hydrophobic character. The interaction of pyrene with a neutral saponin micelle resulted in a red shift of UV absorption spectra, while the negative headed surfactant SDBS showed no such phenomena. The resulting thermodynamic parameters proved the better efficiency of the bio-surfactant saponin for the solubilization of pyrene with respect to that of the conventional surfactant SDBS. With increasing ionic strength (on addition of NaCl) the solubilization of pyrene was found to be better and effective in both the surfactant mediums.

Extraction of Natural Surfactant Saponin from Soapnut (Sapindus mukorossi) and its Utilization in the Remediation of Hexavalent Chromium from Contaminated Water

Abstract In this study optimization of extraction conditions for saponin from soapnut (Sapindus mukorossi) has been investigated. This investigation showed that a better extraction of saponin can be achieved with increasing the dielectric constant of solvent employed. The best yield was attained in a 50% v/v aqueous ethanol medium. Another objective of the present study is to assess the thermodynamics of the uptake-reduction of hexavalent chromium in contaminated water samples using saponin. Pyrene has been employed to determine the critical micellar concentration (CMC) (in the UV-vis method of determination) of saponin as a spectroscopic probe. Thus, the effectiveness of the bio-surfactant as a self-motivated adsorbent for hexavalent chromium is investigated. Several physico-chemical parameters like contact time, sorbate concentration, pH and temperature have been determined. The findings of the investigation invoked a very efficient uptake of 213.48 mg g−1 of hexavalent chromium from the contaminated water sample at a lower value of pH 2 and temperature 35°C. It is observed that the method followed a pseudo-first order kinetics, where the evaluated ΔG0 has supported the sorption as a feasible and spontaneous process. The HR-MS, FTIR, steady state Fluorescence spectroscopy, HR-TEM and UV-Vis spectroscopy have been employed for the current scientific studies.

A study on the synthesis of alkaline copper(III)-periodate (DPC) complex with an overview of its redox behavior in aqueous micellar media

In the present study the copper(III)-periodate (DPC) has been synthesized in an alkaline medium. The stability of this complex is significantly dependent on the pH of the medium; studies reported its stability in alkaline media. The stability of DPC was investigated in different surfactant media for the first time. The + 3 oxidation state of copper is very useful for its high potential value and thus a representative electron transfer reaction between long chain alcohol (1-pentanol) and Cu(III) complex was monitored.