Optimizing the Experimental Conditions and determining the Bound Water Associated with Commercially available suspensions of Milk of Magnesia

摘要

The present study was performed to develop a standard set of protocols for thermal studies of suspensions. Magnesium hydroxide suspension (Milk of magnesia) was chosen as the test suspension. Its bound water content was also determined. Thermogravimetry (TG) was performed under different experimental conditions that included: heating rates of 5 and 10℃/min, atmospheres of nitrogen and air, crimped crucibles with and without pinhole, and sample sizes ranging from 15-20 mg to 20-30 mg. The results established that the ideal conditions minimizing heat and mass transfer effects were a small sample size (between 15-20 mg), a heating rate of 5℃/min, and an atmosphere of nitrogen. Crimped crucibles without pinholes allowed maximum resolution and gave relatively well-defined mass losses. It estimated the bound water content of the system to be 35%. DSC studies characterized the presence of 19-22% non-freezing water.