Solid-liquid extraction of caffeine from tea waste using battery type extractor: Process optimization

This article deals with solid-liquid extraction of caffeine from tea waste containing 2% (w/w) caffeine using water and chloroform as effective solvents. The extraction has been performed at isothermal conditions of 370 K for water and 293 K for chloroform in the battery type extraction plant including both three and five extractors connected in series. An obvious difference in extraction behavior has been observed for two solvents, distinguishing the divergent interactions attributed to the different mechanism of solvent-caffeine aggregation. The high degree of separation of caffeine by chloroform is feasible with the efficiency ranging about two times larger than water in terms of the solvent flow rates tested. The optimum process parameters were estimated through the graphical interpretation of dependently changing variables, composition, flow rate and extraction degree. Details underlying some aspect of selection of an appropriate differential equation for fitting the data are discussed. (c) 2005 Elsevier Ltd. All rights reserved.