|Author||Arjun, Kumar K. ♦ Mamata, Mukhopadhyay ♦ Madhu, Vinjamur ♦ Dalvi, Sameer V.|
|Subject Domain (in DDC)||Technology ♦ Chemical engineering|
|Subject Keyword||Gas Expanded ♦ Liquids ♦ Mathematical Modeling ♦ Supercritical fluid processes|
|Abstract||Supercritical fluid processes provide a good alternative to conventional nanoparticle production methods. However,use of high pressures (100-400 bar), high temperatures (up to 300 oC) and specially designed fine nozzles (50-70μm) are the main drawbacks of these processes as high pressures require pumps which increase the cost of operation, high temperatures cause loss of activity and thermal degradation of heat sensitive materials and fine nozzles can get clogged anytime leading to the operational difficulty. Therefore, a novel process “PPRGEL”(Precipitation by Pressure reduction of Gas-Expanded Liquids) has been developed for the production of ultra-fine particles using subcritical CO2, without using high pressure pumps and specially designed nozzles. A rapid, high, and uniform supersaturation is attained by a rapid pressure reduction over a CO2-expanded liquid solution from 40−70 to 1 bar at 303 K. This reduces the solution temperature by 30−80 K in a very short span of time (0.5−1.5min) and facilitates precipitation of ultrafine particles. The process has been optimized for the production of temperature drop using various gas (CO2)-expanded liquids (GEL) by systematic parametric studies on the effects of process parameters. This temperature drop was then used for particle production of cholesterol from 100 mL of its acetone and ethanol solutions (5−10 mg/mL) at 40–70 ba and 303 K using a 1 L high-pressure vessel. Particles with a size range of 200 nm to 7 μm and morphologies of near-spherical to needles were produced with a change in operating conditions. Thermodynamic analysis of the process has been carried out for the better understanding of the process. Total volume expansion (T-V-E) criteria have been used to find out the pressure at which the vessel gets completely filled, by calculating molar volumes of CO2-expanded liquids. A model has been developed for the prediction of number of moles of CO2 liberated from the solution after pressure reduction using total volume expansion (T-V-E) criteria, high pressure vapor-liquid equilibria (V-L-E) and low pressure gas-liquid-equilibria (GL-E) for binary CO2 (1)-solvent (2) system. The mathematical modeling of the PRGEL (Precipitation by Pressure Reduction of Gas-Expanded Liquids) process is also done to predict the temperature drop obtained by depressurization and the particle size distribution obtained after precipitation.|
|Spatial Coverage||California, US|
|Learning Resource Type||Article|
National Digital Library of India (NDLI) is a virtual repository of learning resources which is not just a repository with search/browse facilities but provides a host of services for the learner community. It is sponsored and mentored by Ministry of Education, Government of India, through its National Mission on Education through Information and Communication Technology (NMEICT). Filtered and federated searching is employed to facilitate focused searching so that learners can find the right resource with least effort and in minimum time. NDLI provides user group-specific services such as Examination Preparatory for School and College students and job aspirants. Services for Researchers and general learners are also provided. NDLI is designed to hold content of any language and provides interface support for 10 most widely used Indian languages. It is built to provide support for all academic levels including researchers and life-long learners, all disciplines, all popular forms of access devices and differently-abled learners. It is designed to enable people to learn and prepare from best practices from all over the world and to facilitate researchers to perform inter-linked exploration from multiple sources. It is developed, operated and maintained from Indian Institute of Technology Kharagpur.
NDLI is a conglomeration of freely available or institutionally contributed or donated or publisher managed contents. Almost all these contents are hosted and accessed from respective sources. The responsibility for authenticity, relevance, completeness, accuracy, reliability and suitability of these contents rests with the respective organization and NDLI has no responsibility or liability for these. Every effort is made to keep the NDLI portal up and running smoothly unless there are some unavoidable technical issues.
Ministry of Education, through its National Mission on Education through Information and Communication Technology (NMEICT), has sponsored and funded the National Digital Library of India (NDLI) project.
For any issue or feedback, please write to email@example.com