SOLVENT REDUCTION IN AN INDUSTRIAL SOLID-LIQUID CONTACTOR
Sustainable process-product development & green chemistry
Selection & Use of Organic Solvents (T1-7)
Keywords: solid-liquid extraction, leaching, raw plant substrate, active principle,continuous industrial extractor
Solid-liquid extraction represents an important part of many industrial processes. Continuous counter-current extraction or leaching processes are widely used instead of mechanical pressing processes. It is based on the diffusive transfer of solutes from a solid to a surrounding solvent. The use of a solvent leads to a selective extraction. The extraction yield of compounds from plant materials is influenced by the conditions under which the process of liquid-solid extraction is carried out. The choice of solvent, of extraction temperature and of mechanical action (pressure, agitation…) is important. Moreover, the vegetable matrix has a complex microstructure formed by cells, intercellular spaces, capillaries and pores. The chemical characteristics of the solvent and the diverse structure and composition of the natural product ensure that each material-solvent system shows different behaviours, which cannot be easily predicted.
In an industrial context, this leads to the necessity of developing fast and reliable methods to implement this operation. In pharmaceutical industries this is of main importance because of the versatility of the raw material and the frequent changes of plants all along the year. The key point is to acquire in small batch experiments the minimum information necessary to optimize the operating policy and the operating parameters of the unit. This optimization must be done under the following constraints: minimize solvent use and decrease both solute and solvent recovery costs.
In the present work, the solid-liquid extraction is performed in a Pierre Fabre Company’s industrial unit using a continuous single-screw extractor. This extractor treats large solid loads, which have different potentials, in order to extract a weak solute amount. Advantages over the conventional batch extraction methods include a decrease in solvent consumption and shorter handling time. However, continuous extractor implementation at industrial level requires preliminary laboratory tests in order to ensure the feasibility of the process and get element to evaluate economic and environmental impact. This study has been integrated in a classical pharmaceutical industry methodology as the first step of the batch to continuous process transfer. In this perspective, the contactor global behaviour has been characterized. Tests of permeation in a compression cell have been carried out in order to study the solid-liquid behaviour. A methodology has been extracted from this study on leaves as raw material and is based essentially on batch tests.
See the full pdf manuscript of the abstract.
Presented Tuesday 18, 09:05 to 09:25, in session Selection & Use of Organic Solvents (T1-7).
