Identification of the coupled fouling mechanism involved in microfiltration of tobacco extracts liquid by multistage Hermia model

Abstract

AbstractMicrofiltration (MF) is a promising technique widely applied in the separation of solid–liquid mixtures. However, the potential application of MF was not explored much in the purification of tobacco extracts liquid. To be efficient, it necessitates having an assessment of the fouling mechanisms involved in MF processing. In this work, a thorough design of experiments was carried out to investigate various operating conditions, while specifying their effects on permeate flux were studied. Both single‐stage and multistage Hermia models were used to elucidate the fouling mechanisms. The results of the single‐stage Hermia model showed that cake layer formation was the dominant model, yet with fitting accuracy lower than 0.9; the type of fouling mechanism does relate to the operating conditions. Subsequently, the multistage Hermia model was used for determining the fouling mechanism during different time stages. It was found that the determinant coefficients R2 were significantly increased and multiple fouling mechanisms could be coupled or occurred simultaneously. A ternary plot was established to visualize the contribution of each model and to bridge the relationship between the fouling mechanism and the operating conditions. Therefore, the proposed method is a valid, convenient tool when selecting optimal operating conditions with the lowest irreversible fouling. The flux recovery of fouled membranes exceeded 95% after successive cleaning with deionized water, a 1 wt% NaOH + 0.5 wt% SDS mixed solution, and a 0.5% (vol/vol) HNO3 solution.Practical ApplicationsCeramic microfiltration membrane could separate tiny particles and macromolecules from tobacco extracts liquid (TEL) while it can keep most of active ingredients. The present study aims to have a better understanding of the complex membrane fouling mechanism in the MF processing of TEL. The fouling mechanism involved in the MF of TEL was firstly reported and a new method to bridge operating conditions and the fouling mechanism was proposed. It demonstrated that it is feasible to reduce irreversible membrane fouling by changing operating conditions during the initial stage of the MF processing. Identification of fouling mechanisms in the present study could be used to postpone fouling of the membranes by optimizing the operating parameters, and reduce irreversible membrane fouling.