Enhanced leaching from sugar beet cossettes by pulsed electric field

Abstract

The impact of moderate electric field pulses (MEFP) (160-780 V/cm) on the performance of a laboratory scale solid-liquid extractor, has been investigated. The experimental set-up allowed the simultaneous measurements of soluble matter concentrations and electrical conductivity of the solid-liquid mixture during the extraction process. The use of MEFP after 50 min of extraction, thus showed that the transfer of soluble substances into the liquid can be significantly intensified. On the basis of these two measurements, the ratio of diffusion coefficients before and after treatment (RD = Dat/Dbt) and that of the electrical conductivity just before and just after the treatment (Rσ = σat/σbt) were used to study the efficiency (ξ = (R - 1)/(Rmax - 1)) of an MEFP treatment. It has been found that a minimal value of E = 150 V/cm is required to detect a significant enhancement of soluble transfer, and that a significantly large increase in the efficiency is obtained up to E = 500 V/cm before reaching a stable value. In addition, both efficiencies showed a good agreement and are best correlated using an Archie type model (ξσ = ξDm). This study illustrated well the benefits of using an MEFP treatment in solid-liquid leaching and the possibility of using continuous electrical conductivity measurements to monitor the extraction process. © 2003 Elsevier Science Ltd. All rights reserved.