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Zinc chloride aqueous solution as a solvent for starch
Meiying Lin1, Xiaoqin Shang1, Peng Liu1
1School of Chemistry and Chemical Engineering, Guangzhou University, Guangzhou 510006, China.
Carbohydrate Polymers
|November 18, 2015
Summary
A zinc chloride (ZnCl2) aqueous solution effectively dissolves starch granules at 50°C, forming a homogeneous system without chemical modification. This finding is crucial for developing cost-effective starch modification processes.
Area of Science:
- Materials Science
- Polymer Chemistry
- Biochemistry
Background:
- Starch modification requires homogeneous systems, necessitating efficient and safe solvents.
- Current methods often involve expensive or toxic solvents, limiting applications.
Purpose of the Study:
- To identify a cost-effective, low-toxicity solvent for complete starch dissolution.
- To investigate the mechanism and conditions for starch dissolution in aqueous zinc chloride.
Main Methods:
- Starch dissolution experiments using aqueous zinc chloride (ZnCl2) solutions.
- Characterization using polarized light microscopy, turbidity measurements, FTIR, NMR, XRD, intrinsic viscosity, and TGA.
- Optimization of ZnCl2 concentration and temperature.
Main Results:
- Aqueous ZnCl2 solution (29.6 wt.%) at 50°C completely dissolved starch granules within 4 hours.
- Dissolution involves weakening hydrogen bonds and converting crystalline starch to amorphous regions, possibly via a zinc-starch complex.
- ZnCl2 caused starch macromolecule degradation, increasing with higher concentrations, but did not chemically alter starch glucosides.
Conclusions:
- Aqueous ZnCl2 is a viable non-derivatizing solvent for starch, enabling homogeneous systems for modification.
- The optimal conditions for dissolution were determined, balancing complete dissolution with minimal degradation.
- This offers a potentially economical and safer alternative for starch processing.
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