Chiranjib Bhattacharya

Effect of drop size distribution on mass transfer analysis of the extraction of nickel(II) by emulsion liquid membrane

In the separation process using emulsion liquid membranes, the polydispersity affects mass transport of metal ions from the external phase because under steady operating conditions, drop size and size distribution are proportional to the interfacial area. The present study aims to assess the importance of polydisperse character of the emulsion globules. An advancing reaction front model considering emulsion globules of various sizes with same sauter mean diameter has been proposed for this purpose. In this paper, the important variables affecting sauter mean diameter of the emulsion drops, including injection method of emulsion, stirring speed, oil phase viscosity, composition of inner water phase and solute permeation rate are also systematically investigated.

Chapter 4 – Emulsion Liquid Membranes: Definitions and Classification, Theories, Module Design, Applications, New Directions and Perspectives

Publisher Summary The objective of this chapter is to provide comprehensive knowledge-based information by critical analysis, classification, model description, and applications of a variety of emulsion liquid membrane (ELM) separation processes. It also discusses new perspectives and directions of development in these fields. Liquid membrane separations have been extensively examined for potential application in many fields such as metal recovery, gas separation, organic compound removal, pollutant removal, and bioseparations. The difficulties in the application of these processes did not consist in sophisticated equipment or installation but in the adequate choice of reagent to allow the selective extraction of solute in required quantity. The widespread use of the ELM process has been limited due to the instability of emulsion globules against fluid shear. Numerous studies have attempted to enhance the stability of ELMs. Examples include adding more surfactants into the membrane phase and increasing the membrane viscosity. However, in most reported attempts increased stability has been unfortunately accompanied by loss in extraction efficiency and rate. A unique contacting device, a Taylor-Couette column, provides a relatively low and uniform fluid shear that helps maintain the stability of emulsion without compromising the extraction efficiency of a target compound. Current research has also been directed to minimizing membrane leakage or rupture through the use of bifunctional surfactants, which act as both emulsifier and extractant, and on additives (e.g., polymer) to impact elasticity of membrane.

Study of the Stability of W/O/W-Type Emulsion During the Extraction of Nickel via Emulsion Liquid Membrane

ABSTRACT Considerable effort has been directed toward describing the analysis of mass-transfer resistance for solute diffusion and reaction in an emulsion liquid membrane (ELM) system but very little attention has been paid to the loss of extraction efficiency often encountered in these systems due to rupture of the emulsion globules. In the present work, batch extraction of nickel(II) with ELM from a dilute sulfate solution by using di-(2-ethylhexyl) phosphoric acid (D2EHPA) as an extractant and hydrochloric acid as a stripping agent is reported. However, separation efficiency significantly decreases with breakage of the liquid membrane. Important variables affecting the stability of the emulsion, such as pH of the feed phase, speed of agitation, emulsion drops size per unit specific interfacial area, surfactant concentration, pH in inner aqueous phase, and the presence of different tracers, are systematically investigated during the extraction of nickel(II) ions.

Process intensification : Extraction of chromium(VI) by emulsion liquid membrane

Abstract Electroplating is one of the important processes involved in surface finishing and metal deposition for better life of articles and for decoration. Chromium(VI) is the most commonly used metal for electroplating. Thus, the waste water of such industries contains Chromium(VI) ions. Emulsion Liquid Membrane (ELM) separation technique provides a potentially powerful technique for the removal of Chromium(VI) ions from the waste water. In the present study, the effect of different parameters such as pH, different carriers concentration, synergistic effect caused by a mixture of two appropriate carriers concentration, effect of electrostatic surface potential and effects of composition of a dilute polymer solution; which will intensify the extraction efficiency of Chromium(VI); are systematically investigated using Aliquat 336 and tri‐n‐octyl amine as extractant, sorbitan mono‐oleate (span 80) as surfactant, kerosene as membrane phase and sodium hydroxide as stripping solution.

Mathematical Modeling of Simultaneous Copper(II) and Nickel(II) Extraction from Wastewater by Emulsion Liquid Membranes

In the present work, a mathematical model for batch extraction of copper(II) and nickel(II) with emulsion liquid membrane from a dilute sulfate solution containing equal amounts of both metal ions using di-(2-ethylhexyl) phosphoric acid (D2EHPA) as extractant and hydrochloric acid as stripping agent is reported. In this research, an effective technique was developed to recover copper(II) as a target metal. The model considers a reaction front to exist within the emulsion globule and assumes an instantaneous and irreversible reaction between the solute and the internal reagent at the membrane–internal droplet interface. Batch experiments were performed for the separation of copper(II) and nickel(II) from an aqueous sulfate solution of initial concentration in the range of 100 to 75 mg/L. It was established that at pH 3.5, recovery of copper(II) and nickel(II) is 90% and 46%, respectively. The influence of copper(II) and nickel(II) concentration on the distribution coefficient at pH 3.5 are fitted by a semiempirical model, which has been used for simulation of the extraction process. The simulated curves are found to be in good agreement with the experimental data.