Hydration Behavior of Sodium Tripolyphosphate in Detergent Slurries

Analysis of pentasodium triphosphate hydration kinetics

“…In the stage in which crystallization of the hexahydrate takes place, the formation of nuclei and, consequently, the global process of hydration of TPP may be favored if small nuclei are initially added to the product used (TPP-C). This can be deduced from the literature (6,7) and is supported by the experimental results represented in Figure 5. The reduction of the induction period with the addition of hexahydrate crystals supports the importance of hexahydrate crystallization in TPP hydration.…”

“…The literature (6,7,16) shows that TPP hydration in a detergent slurry involves a series of intermediate stages that include the solution and further crystallization of the hexahydrate when the solution is supersaturated. These irreversible at moderate temperatures.…”

“…Of the existing methods used to control TPP hydration, we selected the so-called "Test of Hydration". The experimental method is a simplification of the DTA (Differential Thermal Analysis) technique (6). Its use is justified by the advantages offered--it provides sufficient information on TPP hydration, the thermal changes produced during that process are clearly detected, and it is easy to carry out.…”

“…The use of TPP in detergents presents some technical problems in industrial plants where their slurries are processed because of hydration of TPP in the bulk suspension. Each molecule of TPP reacts with six molecules of water to form a product with low solubility, hexahydrated TPE This hydration, which has been extensively studied by several authors (6)(7)(8)(9), takes place during the mixing operation and causes a considerable increase in the consistency of the slurry. Moreover, control of this stage is important because it may influence both production efficiency and detergent properties.…”

Properties of detergent phosphates and their effects on detergent processing

“…R~"~_. at higher temperatures and in high solids detergent slurries (16); its presence also inhibits the hydration of STP. For this reason a thinner detergent slurry may be derived from TSPP or a mixture of TSPP and STP than from STP alone at the same phosphate content.…”