The applications of colloids and interfaces are ubiquitous in human civilization. Beginning with edibles and personal hygiene care products, the applications of colloid and interface science are visible in large-scale industrial undertakings such as petroleum recovery, manufacture of heavy chemicals and coating processes. Soft colloids are materials such as micelles, vesicles, liposomes, microemulsions, emulsions and foams. They are common in foodstuffs, cosmetics, pharmaceuticals and petroleum industries.
Our research on soft colloids focuses around the formation and stability of these materials and the mathematical modeling of the interfacial phenomena. This research area embodies a major portion of Colloid and Interface Science.
1. Ghosh, Pallab, Colloid and Interface Science (PHI Learning Private Limited, New Delhi, 2009; ISBN: 978-81-203-3857-9; 520 pages).
2. Suryanarayana, G. and Ghosh, P., "Adsorption and coalescence in mixed surfactant systems: air water interface", Ind. Eng. Chem. Res., 49, 1711-1724 (2010).
3. Reddy, S. M. and Ghosh, P., "Adsorption and coalescence in mixed surfactant systems: water hydrocarbon interface", Chem. Eng. Sci., 65, 4141-4153 (2010).
2. Aromatic nitration
Nitration of aromatic compounds by mixed acid is the most general process for the preparation of aromatic nitro compounds. Many large-volume chemicals are prepared by these methods such as, nitrobenzene (used as a solvent and in the manufacture of aniline), nitrochlorobenzenes (used as intermediates for dyes, pharmaceuticals and perfumes) and nitrotoluenes (which are converted into toluene diisocyanates for the manufacture of polyurethanes). Acid catalyzed nitration is used in the manufacture of high explosives such as trinitrotoluene (TNT), glycerol trinitrate (nitroglycerin), cellulose nitrate, cyclo-1,3,5-trimethylenetrinitramine (RDX) and cyclo-1,3,5,7-tetramethylenetetranitramine (HMX). Overall, nitration is a ubiquitous reaction in pharmaceuticals (bulk drug and intermediates), agrochemical, specialty and fine chemicals, dyes and dye intermediates, and explosives.
Our research is based on mass transfer and kinetic aspects of nitration in concentrated sulfuric acid. We have found that high yield of nitro products can be achieved even for deactivated aromatic compounds (e.g., nitrobenzene and chlorobenzene) at moderate temperatures and low stirring speeds in concentrated sulfuric acid.
1. Rahaman, M., Mandal, B. P., and Ghosh, Ghosh, P., "Nitration of nitrobenzene at high-concentrations of sulfuric acid", AIChE J., 53, 2476-2480 (2007).
2. Rahaman, M., Mandal, B., and Ghosh, P., "Nitration of nitrobenzene at high-concentrations of sulfuric acid", AIChE J., 56, 737-748 (2010).
3. Design of chemical process equipment networks
In a chemical plant, heat and mass transfer equipment (e.g., heat exchangers and distillation columns) and reactors are arranged in a network of several units. The design of the optimum network configuration is a challenging task for a chemical engineer. Although this optimization problem was first proposed more than three decades ago, new methods are still emerging with new and better solutions of old benchmark problems.
We have developed a stochastic optimization method based on randomized algorithms. This algorithm has been able to detect better networks in many small and medium heat exchanger networks.
1. Pariyani, A., Gupta, A., and Ghosh, P., "Design of heat exchanger networks using randomized algorithm", Comput. Chem. Eng., 30, 1046-1053 (2006).
2. Gupta, A. and Ghosh, P., "A randomized algorithm for the efficient synthesis of heat exchanger networks", Comput. Chem. Eng., 34, 1632-1639 (2010).
4. Water treatment using microbubbles
Microbubble-based methods, in recent times, have been widely used for purification of water and wastewater. Microbubbles have several physicochemical properties, which make them eminently suitable for wastewater treatment.
Our research involves ozone microbubbles. Hydroxyl radicals are generated from these microbubbles which have higher (standard) redox potential than ozone. These microbubbles effectively oxidize the impurities present in water such as, ammonia, pesticides, dye stuffs and pathogens.
1. Khuntia, S., Majumdar, S. K., and Ghosh, P., "Microbubble-aided water and wastewater purification: a review", Rev. Chem. Eng., 28, 191-221 (2012).
2. Khuntia, S., Majumdar, S. K., and Ghosh, P., "Removal of ammonia from water by ozone microbubbles", Ind. Eng. Chem. Res., 52, 318-326 (2013).