Synthesis and Adsorption Study of some Chitosan Acid Derivatives as Dispersants for Ceramic Alumina Powders

Abstract

The different functionality nature of Chitosan adds to its application as a preferable natural polymer not only for the recovery, separation, and concentration of metal ions, but for the fabrication of a wide spectrum of efficient materials, and opens a new window to act as a dispersant for ceramic particles in an aqueous medium; this is why the current study focused on getting Chitosan from chitin extracted from shrimp shells by known and modified chemical methods to obtain a high Degree of Deacetylation (DD) reached 93% to increase its solubility in dilute acidic aqueous medium. Three acid Chitosan derivatives were synthesized by grafting Chitosan chains with Glutaric, Pimelic, and Sebacic acids. The grafting process was checked by FTIR, which confirmed the compositions of the acid derivatives prepared as well as Chitosan... The ability of Chitosan and its derivatives to act as a dispersant for alumina ceramics powder was assessed by sedimentation and rheological techniques. The results showed that they have good power for deflocculating alumina particles, this implies that they may be good dispersant for ceramic processing in aqueous media which is the priority for ceramic manufacturers. The quantity of adsorbed dispersants, qe (mg/g), was determined by thermal gravimetric analysis, and hence the remaining concentration in equilibrium Ce (mg/L), four different types of adsorption isotherm models were determined and evaluated by calculating the variables and constants for each type and studying the behavior of polymers prepared toward each model. The S-shape curve was obtained from plotting qe vs Ce referring to that the adsorption follows BET isotherm of multi-layer where each layer obeys Langmuir-Freundlich isotherm.