Contribution to the preparation of chitins and chitosans with controlled physico-chemical properties

International audienc

Interaction of chitosan with metallic ions.applications on the metallic depollution of waste water from Marrakech

International audienc

Valorization of waste products from fishing industry by production of chitin and chitosan

International audienc

Investigation of different natural sources of chitin: influence of the source and deacetylation process on the physicochemical characteristics of chitosan

International audienc

On the influence of deacetylation process on the physicochemical characteristics of chitosan from squid chitin

cited By 191International audienceChitin was extracted from squid pens and the used conditions allow to obtain a completely N-acetylated β-chitin with a molecular weight large enough for the obtention of chitosans of high molecular weight. Deacetylation, leading to the obtention of chitosan, was performed according to two processes (Kurita and Broussignac conditions) and the physicochemical characteristics (degree of acetylation and molecular weight) of the obtained chitosans were compared. The influence of the reaction conditions (temperature, repetition of alkaline steps, etc.) is discussed in relation with the physicochemical characteristics of the chitosan. This will allow one to choose the best process for preparing chitosan so that it is suitable for its end use. Chitin was extracted from squid pens and the used conditions allow to obtain a completely N-acetylated β-chitin with a molecular weight large enough for the obtention of chitosans of high molecular weight. Deacetylation, leading to the obtention of chitosan, was performed according to two processes (Kurita and Broussignac conditions) and the physicochemical characteristics (degree of acetylation and molecular weight) of the obtained chitosans were compared. The influence of the reaction conditions (temperature, repetition of alkaline steps, etc.) is discussed in relation with the physicochemical characteristics of the chitosan. This will allow one to choose the best process for preparing chitosan so that it is suitable for its end use

Chitin and chitosan: Study of the possibilities of their production by valorization of the waste of crustaceans and cephalopods rejected in Essaouira

cited By 0International audienceIn this paper, we study the possibility of valorization of the waste of crustaceans and cephalopods, rejected by the seafood restaurants in Essaouira, by the production of chitin and chitosan. It is part of the continuity of previous works which have been interested in the exploration of the chitinous sources of the Moroccan coast and in the preparation of chitins and chitosan with controlled physico-chemical characteristics. We realized an investigation about fishing activity in Essaouira and the quantities of waste from marine sources that could be valorized, Sources chosen further to this investigation were the object of reactions of extraction and of N-deacetylation to prepare the chitin and the chitosan. The followed processes are chosen to obtain products of good quality; in particular chitosan of varied molar weight but highly deacetylated (low degree of acetylation DA) were targetted. An estimation of the annual quantities of chitin and chitosan can be produced only from the waste of restaurants in this small coastal city will be presented

Contribution to the study of the complexation of copper by chitosan and oligomers

cited By 110International audienceThe complexation of copper ions by chitosan and its oligomers is investigated using potentiometric and spectrophotometric methods to study the nature of the complexes involved and the role of the degree of polymerisation. Two complexes are demonstrated. Their structure is proposed, the pH range in which they are respectively stable is determined and their stability constants calculated. Finally a degree of polymerisation of 6 appeared as the threshold value for an efficient complexation of copper ions by chitosan oligomers. © 2001 Elsevier Science Ltd. All rights reserved

Radio frequency high voltage power supplies

Originally published in March 1948. Revised by S.J. Buchsbaum in 1952NRC publication: Ye

Extraction of chitin from prawn shells and conversion to low molecular mass chitosan

Extraction and depolymerisation of chitin and chitosan from prawn shells was carried out using various chemical procedures. Sodium hydroxide and hydrochloric acid solutions were used for deproteination and demineralisation, respectively, while acetone was used for decolourisation. The amount of chitin and subsequently chitosan obtained was ∼35% and 25% respectively of the dry weight of the shells. The chitin was deacetylated using sodium hydroxide at 100 °C and the influence of the concentration of the reagent and duration of the reaction was investigated. The degree of deacetylation (DD) of the chitosan was evaluated by FTIR and NMR spectroscopy and the molecular mass distribution was determined by Gel Permeation Chromatography. It was found that the final DD was significantly higher using 50% sodium hydroxide solution (73% ± 9%) compared to 25% sodium hydroxide solution (40% ± 5%). It was noted also that the deacetylation reaction was more than 80% completed after 2 h but the chitosan produced had higher molecular mass while chitosan produced after 10 h had lower molecular mass and higher degree of deacetylation. The molecular mass distribution was bimodal for all the samples and consisted of a broad high molecular mass peak (peak 1) and a sharp low molecular mass peak (peak 2). The Mw of peak 1 decreased from ∼1.3 × 106 after 2 h reaction with sodium hydroxide to 3.1 × 105 after 10 h reaction indicating that depolymerisation and deacetylation occurred simultaneously. Peak 2 had a Mw of ∼2.4–9.9 × 103