Diwakar Z. Shende

Extractive Deep Desulfurization of Liquid Fuels Using Lewis-Based Ionic Liquids

A new class of green solvents, known as ionic liquids (ILs), has recently been the subject of intensive research on the extractive desulfurization of liquid fuels because of the limitation of traditional hydrodesulfurization method. In present work, eleven Lewis acid ionic liquids were synthesized and employed as promising extractants for deep desulfurization of the liquid fuel containing dibenzothiophene (DBT) to test the desulfurization efficiency. [Bmim]Cl/FeCl3 was the most promising ionic liquid and performed the best among studied ionic liquids under the same operating conditions. It can remove dibenzothiophene from the model liquid fuel in the single-stage extraction process with the maximum desulfurization efficiency of 75.6%. It was also found that [Bmim]Cl/FeCl3 may be reused without regeneration with considerable extraction efficiency of 47.3%. Huge saving on energy can be achieved if we make use of this ionic liquids behavior in process design, instead of regenerating ionic liquids after every time of extraction.

Reactive extraction of gallic acid with tri-n-caprylylamine

This paper presents an optimization study of reactive extraction of gallic acid from aqueous solution with tri-n-caprylylamine in hexanol. Extraction efficiency was optimized as a function of process variables: initial gallic acid concentration in the aqueous phase (CGA), tri-n-caprylylamine concentration (CTNCA) used as an extractant, and extraction temperature (T). Response surface methodology in conjunction with central composite design containing sixteen experimental runs was statistically employed for the reactive extraction of gallic acid. A statistical model predicted an extraction efficiency of 80.2% at the optimal values of process parameters as follows: CGA = 0.0147 mol L−1, CTNCA = 0.234 mol L−1, and T = 25 °C. Using these optimal parameters under experimental conditions in three independent replicates an extraction efficiency of 81.2% was obtained which was in close agreement with the predicted one.

Separation of phenylacetic acid using tri-n-butyl phosphate in hexanol: Equilibrium and kinetics

ABSTRACT Equilibrium and kinetics studies are required to design the continuous extraction process for the acid-extraction system. In the present study, an attempt has been made to investigate the equilibrium and kinetics parameters for the reactive extraction of phenylacetic acid (PAA) with tri-n-butyl phosphate (TBP) in hexanol. The equilibrium results show that the formation of the (1:1) PAA–TBP complex in the organic phase with an overall equilibrium complexation constant (Ke) was 78.74 and 29.15 m3.kmol−1 for TBP concentrations of 0.734 and 1.464 kmol.m−3, respectively. The mass transfer coefficients (kL) for PAA were found to be in the range of 3.7 × 10–5–6.2 × 10–5 m.s−1. Based on the Hatta number (Ha = 8.48), the reaction was found to be fast chemical reaction (regime 3) with the order of reaction as 0.77 and 0.36 with respect to PAA and TBP, respectively. The rate constant of the reaction was obtained as 0.017 kmol.m−3.s−1.

Modeling and Optimization of Reactive Extraction of Gallic Acid Using RSM

Reactive extraction was experimentally investigated for recovery of gallic acid (GA) from the aqueous solution using tri-n-octylamine (TOA) as extractant in hexanol. All experiments were carried out according to statistical design in order to develop a regression model used to optimize the extraction of GA. Two independent variables were selected as: initial concentration of GA (CGA0) in aqueous phase and concentration of TOA (CTOA) in organic phase. The statistical analysis showed that both the independent variables had significant effect on response value, followed by the quadratic and interactive effect on response. A five-level central composite rotatable design (CCRD) was employed. Analysis of variance (ANOVA) showed a high coefficient of determination (R2 = 99.0%). The optimal extraction conditions of GA were determined as: CGA0 = 2.01 g/L, CTOA = 6.8% v/v. At the optimum conditions, the experimental yield of GA was 91.9%, which was in close agreement with the predicted value of 93.2%.

Optimization of Process Parameters for Reactive Separation of Gallic Acid

Abstract Reactive extraction of gallic acid (GA) from aqueous solution was studied using extractant TOA and Aliquat 336 in hexanol and a comparative analysis were made for optimum extractant-diluent system with two factor central composite design. The model equations were developed using 13 experimentations, each with TOA and Aliquat 336. TOA and Aliquat 336 gave antagonistic and synergistic effects respectively for extraction of GA. The optimum conditions were observed as CTOA = 8.6 %, CGA0 = 2.9 g/L and CALQ = 33.2 %, CGA0 = 3 g/L with experimental extraction of 92.2 % and 96.5 % respectively. Lesser TOA and its non-toxicity for extraction of GA as compared to Aliquat 336 suggest TOA as better candidate in the prevailing conditions.

Rheological and wall-slip behaviour of composite propellant suspension containing Al-nanopowder

ABSTRACT Hydroxyl terminated polybutadiene composite propellant suspension mainly containing ammonium perchlorate (70%) and aluminium nanoparticles (ANP) (0–6%) was evaluated rheologically to determine the effect of wall slip occurring due to the formation of an apparent slip layer. True rheological properties have been obtained from gap-dependent steady-shear data using Tikhonov regularization method for the composite suspension. The advantage of this method is that it converts the gap-dependent steady-shear data into true rheological properties. The two-stage method can successfully establish both the true shear stress vs. shear rate behaviour and wall-slip parameters. The errors during rheological experimentation are analysed by determining the slip velocities and slip layer thickness. Slip velocity is observed to increase linearly with shear stress. Also, the slip layer thickness decreases with the increase in ANP content in the composite suspension. The maximum slip layer thickness of 2.13 µm is obtained for composition in which ANP is absent, and the same decreased to 0.24 µm for the composition containing 6% ANP. The rheological measurements show least deviation from gap-independent values as the amount of ANP in the propellant increases. Finally, a correlation of apparent slip layer thickness with normalized filler fraction is investigated to check the effect on wall-slip behaviour. Graphical Abstract

Potassium Hydroxide Activated Hydrogen Generation Using Aluminum in Water Splitting Reaction

Abstract The water splitting reaction using aluminum represents one of the best methods for on-demand hydrogen requirements. The present paper describes the hydrogen generation in water splitting reaction using aluminum in presence of potassium hydroxide as an alkaline activator. The effect of concentration of KOH, temperature, and shape of aluminum particles on the hydrogen generation in water splitting reaction was experimentally studied using various concentrations of aqueous KOH viz. 0.25 N, 0.50 N, 0.75 N and 1.0 N, at different temperatures of 30 °C, 40 °C, and 50 °C for Al powder (diameter: 200 mesh) and Al foil (thickness: 11 microns). The complete conversion of Al was recorded for all the experimental runs. The average hydrogen generation rate was found to vary between 3.40 ml/min to 21 ml/min per 0.1 g aluminum under considered concentrations and temperatures. The shrinking core model was applied to the experimental data for predicting the rate controlling mechanism.

Hydrogen Generation in Water Splitting Reaction Using Aluminum: Effect of NaOH Concentration and Reaction Modelling Using SCM

Abstract The kinetics of the heterogeneous reaction of metal aluminum with water was studied in presence of NaOH as an activator for generating the hydrogen. Aluminum (Al) powder of average size of 100 µm and foil of thickness of 11 µm were utilized to study the effect of the shape of particles of aluminum on hydrogen generation. The hydrogen generation was reported at various concentrations of NaOH, ranging from 0.12 N to 0.67 N. The fractional conversion of Al was found to be 0.66 at 0.12 N and 1.0 at 0.185 N, 0.37 N, 0.54 N, 0.65 N NaOH concentration. The activation energy of the reaction has been determined at the stoichiometric concentration of 0.185 N NaOH at the temperature ranging from 298 to 323 K. An attempt was made to model the reaction using Shrinking Core Model (SCM) for determining the rate controlling mechanism for the heterogeneous reaction. The reaction was observed to follow the first order kinetics and the average value of reaction rate constant using Al power and foil was found to be 27.322 x 10-4 cm/min and 2.125 x 10-4 cm/min respectively.

Hydrogen Generation in an Annular Micro-Reactor: an Experimental Investigation of Water Splitting Reaction Using Aluminum in Presence of Potassium Hydroxide

Abstract Hydrogen is one of the important non-conventional energy sources because of its high energy content and non-polluting nature of combustions. The water splitting reaction is one of the significant methods for hydrogen generation from non-fossil feeds. In the present paper, the hydrogen generation has been experimentally investigated with water splitting reaction using metal aluminum in presence of potassium hydroxide as an activator under flow conditions. The rate of hydrogen generation was reported in the annular micro- reactor of 1 mm annulus using various flow rates of aqueous 0.5 N KOH ranging from 1 ml/min to 10 ml/min. The complete conversion of aluminum was observed at all the flow rates of aqueous KOH. The hydrogen generation rate was observed to depend on the flow rate of liquid reactant flowing through the reactor. At 1 ml/min of 0.5 N KOH, hydrogen generates at an average rate of 3.36 ml/min which increases to 10.70 ml/min at 10 ml/min of aqueous KOH. The Shrinking Core Model was modified for predicting the controlling mechanism. The rate of hydrogen generation was observed to follow different controlling mechanisms on various time intervals at low flow rates of aqueous KOH. It was observed that chemical reaction controls the overall rate of hydrogen generation at higher flow rates of aqueous KOH.

Hydrogen Generation in an Annular Micro-Reactor: An Experimental Investigation and Reaction Modelling by Shrinking Core Model (SCM)

Abstract Hydrogen can be one of the key elements as source of future energy requirement. Water splitting reaction is an important route for generation of hydrogen as maximum fraction of hydrogen constitute in water. The present work describes the experimental investigation for generation of hydrogen through water splitting reaction in flow conditions with the aid of metal aluminum and sodium hydroxide as an activator. The hydrogen generation through water splitting reaction at various concentrations of NaOH, viz. 0.5 N and 1 N and the flow rates ranging from 0.2 to 10 ml/min was studied. The yield of hydrogen generated is reported for each NaOH concentration and flow rate. The yield of hydrogen generated at all the considered concentrations and flow rates was found to be greater than 98 %. The shrinking core model has been modified and developed for predicting the conversion of aluminum in the reaction system as per the prevailing conditions and rate controlling mechanism. The RMSE value of predicted conversion of Al was found to be 0.0351 which signify that the model agrees well with the experimental data.