Simultaneous Optimization of Deacetylation Degree and Molar Mass of Chitosan from Shrimp Waste

Abstract

Shrimp waste is a valuable source for chitin extraction and consequently for chitosan preparation. In the process of obtaining chitosan, a determining step is the chitin deacetylation. The main characteristic of chitosan is the degree of deacetylation, which must be as high as possible. The molar mass is another important parameter that defines its utilizations, and according to these, high or low molar masses are required. The present study is an attempt to optimize the deacetylation step to obtain chitosan with a high degree of deacetylation and high or low molar mass. The study was carried out based on experimental data obtained in the frame of a central composite design where three working parameters were considered: NaOH concentration, liquid:solid ratio, and process duration. The regression models defined for the degree of deacetylation (DD) and for the mean molar mass (MM) of chitosan powders were used in the formulation of optimization problems. The objectives considered were simultaneous maximum DD and maximum/minimum MM for the final chitosan samples. For these purposes, multiobjective optimization problems were formulated and solved using genetic algorithms implemented in Matlab®. The multiple optimal solutions represented by trade-offs between the two objectives are presented for each case.

α-Chitosan and β-Oligochitosan Mixtures-Based Formula for In Vitro Assessment of Melanocyte Cells Response

“…According to Dinculescu et al [ 83 ], chitosan powders (CHP1, CHP2, CHP3) were obtained by optimizing shrimp waste through a recovery process. The oligochitosan powder (COP4) was chemically extracted from Rapana venosa capsule waste, aligning with the previous study’s methodology [ 30 ].…”

“…The molar mass (MM) was determined by measuring the intrinsic viscosity of diluted acid solutions of chitosan prepared in 2% acetic acid with 0.1 M KCl [ 86 ] using an Ostwald-type capillary viscometer (model 518 10, SI Analytics GmbHTM, Mainz, Germany, capillary tube inner diameter Øi = 0.43 mm) [ 30 , 83 ]. The measurements were carried out at 25 ± 1 °C, in triplicate.…”

“…The measurements were carried out at 25 ± 1 °C, in triplicate. The approach employed in this study relies on the correlation between the viscosimetric-average molar mass, MM (g/mol), and the intrinsic viscosity, [η] (mL/g), as described by Mark–Houwink–Sakurada [ 30 , 83 ] and illustrated by Equation (5). …”

“…where C M is the molar concentration of the NaOH solution used for titration (mol/L); ∆V represents the difference volume between the two inflexion points (L); m is the mass of chitosan analyzed (g); 203 is a coefficient that represents the molar mass of chitin (g/mol); and 42 is a coefficient that represents the molar mass of acetyl group (g/mol). The molar mass (MM) was determined by measuring the intrinsic viscosity of diluted acid solutions of chitosan prepared in 2% acetic acid with 0.1 M KCl [86] using an Ostwaldtype capillary viscometer (model 518 10, SI Analytics GmbHTM, Mainz, Germany, capillary tube inner diameter Øi = 0.43 mm) [30,83]. The measurements were carried out at 25 ± 1 • C, in triplicate.…”