(400f) Towards 'factory in a Box' for Tailored Emulsions

Emulsions are used as delivery vehicles for many active and functional chemical ingredients so that they perform specific functions in various industry sectors [1-3] such as healthcare (drugs, active pharmaceutical ingredients), personal care (cosmetics, fragrances, beauty care), home care (paints, room fresheners), food and nutrition (milk products, ice creams, salad dressings), agrochemicals (insecticides, fungicides, pesticides). In all these sectors, there is an increasing trend towards customised and personalised products [1]. The primary focus of this is to bring customisation and personalisation to the consumer in a decentralised manner, which will shorten the number of steps for producing a finished product that is consumer ready. On-demand emulsification technology can lead to additive free and fresher products.

In recent years, there is an increasing interest in using hydrodynamic cavitation devices for generating emulsions [2, 4]. Recently Thaker and Ranade [5] and Upadhyay et al. [6] have reported effective use of vortex-based hydrodynamic cavitation devices for producing oil in water emulsions up to 60% oil volume fraction. Such compact devices offer an excellent potential for applications towards on-demand manufacturing of customised emulsions. In this work, we present a critical review of performance and characteristics of oil in water emulsions using vortex-based cavitation devices with an objective of developing a ‘factory in a box’ platform for truly distributed manufacturing of emulsions. The focus is on clearly defining desired attributes needed for ‘factory in a box’ platform and providing critical evaluation in terms of:

• Continuous production of emulsions for obtaining desired droplet size distribution (DSD)
• Minimising energy consumption per unit weight of emulsion (enhancing droplet breakage efficiency)
• Compact designs of cavitation devices and auxiliary equipment like pumps etc.
• In-line sensors for characterising DSD (soft sensors based on turbidity measurements)

Based on this work, a proof of concept of ‘factory in a box’ producing emulsions is established (see Figure 1a) for producing emulsions at ~100 ml/min capacity. Vortex-based hydrodynamic cavitation devices at three different scales were used. Schematic of devices used in this work are shown in Figure 1b. The device dimensions are same as that disclosed by Ranade et al. [4]. The rape seed oil-in-water emulsions were produced. The continuous phase was water with 2 % (w/v) of TWEEN 20 (MP Biomedicals, LLC, France) surfactant. The quantity of surfactant was adequate to stabilise these emulsions up to 60% volume fraction of oil [6]. The cavitation device was operated with pressure drop of 200 kPa. A sample of emulsions produced in the factory in a box is shown in Figure 1c (as an image from microscope) and in Figure 1d (full DSD as measured by Malvern master sizer - 3000). An in-line turbidity sensor was used to characterise DSD. The performance of ‘factory in a box’ was evaluated for a range of oil volume fractions and flow rates of emulsions. The presented data will be useful for evaluating computational models of simulating droplet breakage in vortex-based cavitation devices. The devices used in this work show an excellent potential for applications towards on-demand manufacturing of customised emulsions. The presented results and critically analysis of emulsion producing devices will provide a sound basis for further work towards realising ‘Factory in a Box’ platforms for customised and personalised emulsions.

References:

1. Calvo, J.M. G´omez, O. Alvarez, L. Ricardez-Sandoval, Trends and perspectives on emulsified product design. Curr. Opin. Chem. Eng. 35 (2022) 100745.https://doi.org/10.1016/j.coche.2021.100745.

2. J. Carpenter, D.V. Pinjari, V.K. Saharan, and A.B. Pandit, Critical Review on Hydrodynamic Cavitation as an Intensifying Homogenizing Technique for Oil-in-Water Emulsification: Theoretical Insight, Current Status, and Future Perspectives, Industrial & Engineering Chemistry Research 61 (30), (2022) 10587-10602. https://doi.org/10.1021/acs.iecr.2c00754.

3. M. Sherman, A. Mounika, D. Srikanth, A. Shanmugam, M. Ashokkumar, Leveraging new opportunities and advances in high-pressure homogenization to design non-dairy foods. Comprehensive Reviews in Food Science and Food Safety, 23 (2024) e13282. https://doi.org/10.1111/1541-4337.13282.
4. V. Ranade, V.M. Bhandari, S. Nagarajan, A. Simpson, V. Sarovothaman, Hydrodynamic Cavitation: Devices, Design and Applications; Wiley-VCH: Beijing. 2022.
5. H. Thaker, V.V. Ranade, Emulsions Using a Vortex-Based Cavitation Device: Influence of Number of Passes, Pressure Drop, and Device Scale on Droplet Size Distributions, Ind. Eng. Chem. Res. 62 (45), 2023, 18837–18851.
6. Upadhyay, A. Ravi, and V.V. Ranade, Dense Oil in Water Emulsions using Vortex-based Hydrodynamic Cavitation: Effective viscosity, Sauter mean diameter and droplet size distribution, Ind. Eng. Chem. Res. (2024).