DEVELOPING MINI FLUIDIC REACTOR EXPERIMENTAL SYSTEM
In this work, The LLE experiments were performed with raw FO ethyl esters using concentrated aqueous silver nitrate solution under conditions for which slug flow was expected. In the solvent-based extraction of co-3 PUFA, freshly prepared concentrated aqueous silver nitrate solution is used. The chemical used is silver nitrate (ACS grade-99% Purity), sodium nitrate (Assay-99%) from Fisher Scientific, 95% ethyl alcohol, deionized water, semi-refined 18/12 FO ethyl esters from DSM Ocean Nutrition, Dartmouth, NS, Canada, and Nitrogen gas which is used to blanket and prevent the oxidation of FO and AgNO,. Semi-refined FO ethyl ester was provided from DSM, derived from anchovy (Engraulis ringens) and Sardine (Sardinopssagax ssp. sagax) on 29th June 2013.
- 1. Preparation of Silver Nitrate Solution: Prior to each experiment, a fresh batch of the silver nitrate solution with 50 wt.% of AgN03 and 5 wt.% NaNOj was prepared to avoid long-term oxidation of the non-stabilized silver nitrate solution (Kamio et al., 2010, 2011). Similar to the silver nitrate solution, the 18/12EE FO was also nitrogen purged before and after transfer to the reservoir to avoid the oxidation of the co-3 PUFA.
- 2. Winterization of Fish Oil (FO): The 18/12 FO ethyl ester contains some solid matter and extraction at lower temperatures fonns some gelation in the FO ethyl esters. As a consequence, it may block flow in mini-channel. In order to avoid this problem, the FO ethyl ester was winterized. Winterization is the process of fractional crystallization of oils and fats followed by the separation of solids, and are often used to make high-quality food oils. On heating the FO ethyl ester to 60°C and cooling down to 10°C, gel forms within the solution and settles in the container. Subsequent analysis of non-winterized and winterized feedstock oils used in this process by Gas Chromatography confirmed that the overall DFLA, EPA, and total co-3 PUFA was not significantly modified by the winterization process.
DEVELOPMENT OF MINIFLUIDIC FLOW REACTOR
The slug flow mini-fluidic flow reactor was constructed for LLE of EPA and DHA ethyl esters from semi-refined 18/12EE FO ethyl esters. The simplified mini-fluidic experimental setup is shown in Figure 6.4 and the components of this experimental set up are shown in Figure 6.5, consisting of a 1/16" ID Tygon mini-fluidic channel submerged in a cooling reservoir controlled to 10°C using an external refrigerated circulating bath. The solutions from the reservoir were pumped using a double syringe pump (2
FIGURE 6.4 Slug flow mini-fluidic extraction experimental set up. The 1.58 mm ID minifluidic channel is immersed in subcooled water (10°C) in the bath which is circulated by a submersible pump.
FIGURE 6.5 Dual syringe pump from longer instruments used to control flow into the minifluidic system, immersion vessel for cooling the mini-fluidic channels, tygon mini-fluidic channel, sample port.
NE 4000), whereby a 60CC syringe was used for the silver nitrate solution, and a 10CC syringe was used for the 18/12EE FO. Keeping the dispense rate of 5 ml/min for 60CC syringe, the flow rate of silver salt solution and oil was set at 5 ml/min and 1.47 ml/min, respectively,thus maintaining an approximate salt to oil solution flow ratio of ~3.4:1 (Kamio et al., 2010, 2011).
The ethyl esters of FO and AgN03 solution are pre-cooled in a 1.5 m length of the tubing prior to being contacted together in a “Y” junction, after which the immiscible fluids were allowed to contact for a set residence time before being sampled via syringe. Sampling ports were fitted into the immersion vessel by the creation of holes through the side, minimizing the time which the fluids spent outside of the refrigerated environments. The holes in the vessel walls were below the water line inside the vessel and were sealed with silicon caulking. The water inside the cooler was circulated using a submersible pump, with a copper line run through from the refrigerated bath recirculation loop. In the LLE experiments, 50 wt.% concentrated silver nitrate solution was used as an extraction solvent for extraction of co-3 PUFA from FO EE. Silver nitrate is toxic and corrosive; necessitating minimum exposure to avoid immediately or any significant side effects other than the purple skin stains, but with more exposure, noticeable side effects or bums may result. In Figure 6.4(B), the flow patterns produced also depends on the contactor (mixing system) in the experimental systems. So that the various flow patterns will be anticipated like slug flow/droplet flow/stratified flow. The experimental set up has been designed for the slug flow pattern.
The focus of this investigation was to determine the practical performance characteristics of a liquid-liquid based concentration method employing mini-fluidic slug-flow reactor technology. To do so, a system was constructed at Multiphase Process Engineering Research Laboratory, Dalhousie University to contact 18/12EE with AgN03 (aq) silver-salt solutions in a controlled mamier and determine the extraction performance for a variety of contact tunes. The system utilized a large immersion vessel to enable extraction performance tests at sub-ambient conditions, specifically 10°C for this preliminary.