Ajay Mandal

Synthesis, characterization, and physicochemical properties of a series of quaternary gemini surfactants with different spacer lengths

AbstractThe study deals with the synthesis and characterization, as well as the adsorption and micellization behavior (including thermodynamics) in aqueous solution of a series of gemini surfactants with different spacer lengths. The synthesized surfactants were characterized by FTIR, 1H-NMR, FESEM, EDX, and TGA analyses. DLS measurements showed that micelles formed at critical micelle concentration (CMC) transformed into an assemblage of micelles and micellar agglomerates at higher concentrations. Surface tension was found to decrease with temperature and spacer length. However, CMC values increased with spacer length, as confirmed by surface tension and conductivity results. Surface adsorption parameters such as surface excess, minimum area, surfactant effectiveness, and efficiency were also determined. Gibbs free energy of adsorption (ΔGads) value was found to be greater than Gibbs free energy of micellization (ΔGmic), showing that adsorption is more favored in aqueous gemini systems. Graphical abstractᅟ

Characterization and application of methylcellulose and potato starch blended films in controlled release of urea

Abstract Biodegradable blended films from methylcellulose (MC) and potato starch (PST) have been developed by the casting process. In the present work the influences of concentrations of MC and PST on rheological properties, swelling, mechanical properties such as tensile strength, percentage elongation at break and water vapor transmission rate (WVTR) of the prepared blended films have been studied. Fourier transform infrared (FTIR) analysis of pure MC, PST, their mixture and the mixture with glutaraldehyde and urea was performed to investigate the interactions in blended films. The blended films of MC and PST showed an increase in tensile strength due to the cross linking reactions of the amylopectin molecule of PST in the physical gel state. The change of percentage elongation at break increased with MC concentration and the opposite trend was found in the case of the WVTR due to the network structure of the blended films. The blended films showed a large improvement in the abovementioned properties compared with each single component, due to the interaction formed between hydroxyl groups of PST and the methoxy groups of MC. Experiments were also conducted to investigate the controlled urea release through blended films and the kinetics of the process. Interesting results were found with the prepared MC and PST blended films.

Synthesis, characterization, physical and thermodynamic properties of a novel anionic surfactant derived from Sapindus laurifolius

The present study deals with the synthesis, characterization, physical and thermodynamic properties of a novel anionic surfactant derived from Sapindus laurifolius for its potential application against conventional non-biodegradable surfactants. The synthesized surfactant was characterized by FTIR, GC-MS, EDX and FE-SEM analyses. The surfactant showed good thermal stability at different temperatures as obtained from TGA studies. Critical micelle concentration (CMC) values were obtained by surface tensiometry measurements. DLS studies revealed the micelle structures of the CMC aggregates at higher concentrations. Low interfacial tension values were obtained at the oil–aqueous interfaces for surfactant solutions. The effect of temperature on the interfacial behaviour was also investigated. Thermodynamic studies showed that adsorption was more favoured in comparison to micellization for all systems. Foam stability studies were performed as a function of time and concentration by the Bartsch method. The surfactant also formed stable emulsions at concentrations near the CMC value. A comprehensive assessment of the thermal, interfacial, foaming and emulsifying properties of the soap-nut-based surfactant provides grounds for potential application in a wide range of industries.

Synthesis of activated charcoal from saw-dust and characterization for adsorptive separation of oil from oil-in-water emulsion

ABSTRACT The paper represents the synthesis process of charcoal from saw dust by chemical activation with different chemical agents like phosphoric acid, zinc chloride, and ferrous sulfate heptahydrate. The synthesized charcoal samples were analyzed by scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and BET surface analyser. The adsorption capacity of different charcoal samples was tested to separate oil from the oil-in-water emulsion. Effects of different parameters like adsorbent dosage, contact time and temperature on adsorption of oil from oil-in-water emulsion by synthesized charcoals have been investigated. Under optimized condition, the oil separation efficiency is more than 98%, though it also depends on the initial concentration of oil in the emulsion. Isotherm and kinetic study on adsorption of oil from oil-in-water emulsion have also been studied. Three widely applied isotherm models viz., Langmuir, Freundlich, and Temkin were used to analyze the experimental adsorption data. Different adsorption kinetic models were considered to model the experimental data. Thermodynamics parameters were also evaluated for the adsorption of oil onto the charcoal samples.

Rheological modeling and drag reduction studies of Indian heavy crude oil in presence of novel surfactant

ABSTRACT Viscosity and rheology modeling of heavy crude oil were studied at different shear rate and temperature with and without naturally extracted surfactant Mahua. Drag reduction analysis was done in 2”-ID, 2.5 m horizontal pipeline at different temperatures and flow rates. Viscosity was reduced by 60.4% after addition of 1000 ppm Mahua at 50°C. Modeling analysis showed that crude oil-surfactant samples followed Power law model with high regression coefficients. Maximum drag reduction of 94.8% occurred after adding 2000 ppm Mahua to 85% heavy oil+15% water at 40°C and at a flow rate of 50 LPM.

Thermodynamic modeling of equilibrium conditions of CH4/CO2/N2 clathrate hydrate in presence of aqueous solution of sodium chloride inhibitor

ABSTRACT In this work, the effect of sodium chloride (NaCl) on thermodynamic properties of CH4+CO2+N2 hydrate formation and equilibrium condition has been studied. The three-phase (hydrate–liquid–gas) equilibrium calculation has been carried out using the Peng–Robinson equation of state (PR EoS) and Universal Quasi Chemical (UNIQUAC) activity coefficient models. The PR EoS coupled with classic mixing rule is applied for the vapor phase. The calculations of the gas hydrate formation pressures are performed in the absence and presence of sodium chloride inhibitor for the gas hydrate systems. The Chen–Guo model has been used for the hydrate phase and the UNIQUAC activity coefficient is applied for non-ideality of the liquid phase. To obtain higher accuracy, the solubility of the gases in the aqueous phase is also taken into account using pressure corrected Henrys law. Finally, the stepwise procedure has been followed to obtain the results and compared with the experimental results. The addition of 2% (by volume) sodium chloride to water results in large shifts in phase equilibrium boundary to increase pressure for the same temperature condition.

Effect of pour point depressant on wax deposition and drag reduction in horizontal pipelines

ABSTRACT A newly synthesized pour point depressant (PPD) was used to decrease the wax deposition thickness and drag force during a waxy crude oil flow in two horizontal pipes of length 2.5 m each and inner diameters 1 inch and 2 inches. The flow rates of 80–120 LPM were used. 1,000-ppm PPD reduced the thickness of wax deposited by 31% and 72% at 120 LPM and 30°C in 1-inch and 2-inch pipes, respectively. There was about 15% drag reduction in both the pipes at 30°C and 120-LPM flow rate after adding 1,000-ppm PPD.