Update:
We have developed and refined a procedure that enables us to efficiently produce a large volume of M-SSM (Montmorillonite-coated Soybean Starch Microbeads). This process involves the blending and optimization of soybean starch and montmorillonite within a co-solvent comprising 90% water and 10% ethanol. The overall solute concentration was maintained at 10 wt.%. In this solution, we added a commercial epoxy-based glue (Norland®) to enhance the adhesion between the soybean starch and montmorillonite. Subsequently, the solution undergoes a 30-minute stirring at room temperature to ensure thorough homogenization.
To fabricate microbeads of M-SSM, we have employed a straightforward yet scalable spraying-based technique by using a readily available commercial sprayer. The droplets generated through this process undergo immediate cross-linking via a brief exposure to ultraviolet irradiation. This cross-linking mechanism enhances the adhesive properties of the epoxy-based glue, facilitating the steadfast attachment of montmorillonite onto the starch solution. Please note that the surface tension of water plays a pivotal role in shaping the starch into distinctive bead structures. Our investigations have pinpointed four key parameters that exert a direct influence on the size of the resultant M-SSM microbeads. These parameters encompass spray pressure, spray distance, temperature, and humidity. Generally, elevated spray pressure coupled with a reduced spray distance leads to the formation of smaller beads. The interplay between temperature and humidity jointly determines the bead size. Typically, a higher temperature and a lower humidity level results in the generation of smaller beads. At present, we are compiling data from our experimental measurements, seeking to establish a clear correlation between the size of the microbeads and these aforementioned parameters.
Challenges: The challenge of augmenting the dissolution of soybean starch within a co-solvent remains a pertinent consideration. Ordinarily, starch exhibits poor solubility in aqueous solutions. Such restricted solubility of starch within a water-ethanol co-solvent can significantly impact the overall yield of M-SSM production per operational unit. While certain commercial solvents, such as ionic liquids, possess the ability to enhance starch solubility in water, their adoption is hampered by either their high cost or their lack of environmental friendliness. At present, our focus persists on utilizing the water-ethanol co-solvent system in our ongoing investigations. While we acknowledge the potential advantages of alternative solvents, we have decided to retain this co-solvent approach for the foreseeable future as we delve deeper into further studies.
Please see the separately attached report.
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