Dissolution behaviours of structured particles

The work presented in this thesis aims at the fundamental understanding and investigation of dissolution behaviors of structured particles. This topic is relevant to numerous industrial applications including detergent, pharmaceutical, agrochemical and energy products. Both experimental works and theoretical analyses were carried out in this work. The particles of several different materials including sodium carbonate and polymers with specific characteristic and structure were used into the experimental works in this thesis. Polymers used in this thesis included carboxymethyl celluslose, croscarmellose sodium and crospovidone. The studies on characteristics of these particles included the determination of particle size, shape and structure with several measurement techniques.
The dissolution process was measured with experimental methods under different solution conditions including temperature, stirring speed and pH. Based on these measured data, the dissolution kinetics such as dissolution rate constant were quantified with mathematical models and analyzed with theoretical studies. In this way, the dissolution behaviors of different structured particles could be finally identified and analyzed with the quantified data of dissolution process and dissolution kinetics. Additionally according to the quantification process, the effects of these solution conditions on dissolution kinetics could also be determined and identified that how these conditions impact dissolution kinetics. Main conclusions of my work on dissolution experiments in this thesis were simply summarized as the following that:
• An increasing in the temperature and stirring speed leads to the increases of dissolution rate and dissolution rate constant of sodium carbonate particles in all cases.
• The dissolution rate and the rate constant decreases with the increasing of pH value of solution.
• Carboxymethyl cellulose and crospovidone show a clear effect to enhance the dissolution rate and the rate constant of sodium carbonate-polymer composite tablets.
• Cropovidone also has a stronger effect to enhance the dissolution process and kinetics than carboxymethyl cellulose
• Croscarmellose sodium shows a clear effect to weaken the dissolution rate and the rate constant of sodium carbonate-polymer composite tablet.