title: Optimization of carboxymethyl chitosan synthesis using response surface methodology and desirability function.
abstract: In this paper, chitosan was reacted with monochloroacetic acid under alkaline conditions to prepare carboxymethyl chitosan. A 2(3) full-factorial central composite design was applied to evaluate the effect of molar ratio sodium hydroxide (NaOH)/Chitosan (Ch), time and molar ratio monochloroacetic acid (MCA)/Chitosan (Ch) on the reaction yield and on the characteristics of carboxymethyl chitosan such as average degree of substitution (DS¯) and solubility. An optimization strategy based on response surface methodology was used together with the desirability function approach to optimize this process. The occurrence of carboxymethylation was evidenced by FTIR and (1)H NMR spectroscopy. The optimum conditions for carboxymethylation process were found to be 12.4, 10.6h and 5 for molar ratio sodium hydroxide (NaOH)/Chitosan (Ch), time and molar ratio monochloroacetic acid (MCA)/Chitosan (Ch), respectively. Under these optimal conditions, it was possible to obtain carboxymethyl chitosan with DS¯ of 1.86 and solubility of 99.6%. X-ray diffraction and thermogravimetry analysis showed that crystallinity and thermal stability of derivatives was lower than chitosan and decreased with increase of DS¯.
authors.affiliation: Campus de Anápolis de Ciências Exatas e Tecnológicas Henrique Santillo, Universidade Estadual de Goiás (UEG), Br 153 no 3.105-Fazenda Barreiro do Meio, P.O. Box 459, Anápolis, GO 75132-903, Brazil. Electronic address: andrea_bukzem@hotmail.com.
authors.forename: Andrea L
authors.initials: AL
authors.lastname: Bukzem
authors.affiliation: Campus de Anápolis de Ciências Exatas e Tecnológicas Henrique Santillo, Universidade Estadual de Goiás (UEG), Br 153 no 3.105-Fazenda Barreiro do Meio, P.O. Box 459, Anápolis, GO 75132-903, Brazil. Electronic address: roberta.signini@ueg.br.
authors.forename: Roberta
authors.initials: R
authors.lastname: Signini
authors.affiliation: Campus de Anápolis de Ciências Exatas e Tecnológicas Henrique Santillo, Universidade Estadual de Goiás (UEG), Br 153 no 3.105-Fazenda Barreiro do Meio, P.O. Box 459, Anápolis, GO 75132-903, Brazil. Electronic address: danilomartins_1@hotmail.com.
authors.forename: Danilo M
authors.initials: DM
authors.lastname: Dos Santos
authors.affiliation: Instituto de Química, Universidade Federal de Goiás, Campus Samambaia, P.O. Box 131, Goiânia, GO 74001-970, Brazil. Electronic address: luciano@quimica.ufg.br.
authors.forename: Luciano M
authors.initials: LM
authors.lastname: Lião
authors.affiliation: Campus de Anápolis de Ciências Exatas e Tecnológicas Henrique Santillo, Universidade Estadual de Goiás (UEG), Br 153 no 3.105-Fazenda Barreiro do Meio, P.O. Box 459, Anápolis, GO 75132-903, Brazil. Electronic address: ascheridpr@gmail.com.
authors.forename: Diego Palmiro R
authors.initials: DP
authors.lastname: Ascheri
mesh_terms: D000704:Analysis of Variance; D060326:Chemistry Techniques, Synthetic; D048271:Chitosan / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D066244:Proton Magnetic Resonance Spectroscopy; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared; D013818:Thermogravimetry; D014961:X-Ray Diffraction
chemical_list: C514968:carboxymethyl-chitosan; D048271:Chitosan
keywords: Carboxymethylation of chitosan; Desirability function; Response surface methodology