a b s t r a c tThe influence of temperature and spouted bed geometry in drying chitosan with relation to powder quality (molecular weight, deacetylation degree, particle size, color) and operation characteristics (product recovery and mass accumulated) were investigated. Chitosan paste was obtained from shrimp wastes and dried in a spouted bed (slot-rectangular and conical-cylindrical geometries) with different inlet air temperatures (90, 100 and 110 C). Thermogravimetric curves, infra-red analysis and scanning electron microscopy were carried out in order to verify powder quality. Chitosan paste used in drying experiments showed solid content 4%, molecular weight 140 kDa and deacetylation degree 85%. In all drying experiments deacetylation degree was not modified and final moisture content was in the commercial range (10%). Temperature increase caused an increase in molecular weight, powder darkening and increased particle size. The best powder quality was obtained in slot-rectangular spouted bed at 90 C. In this condition product recovery was 65%, accumulated mass was 20% and the powder presented faint yellow coloration, high thermal stability and porous heterogeneous surface.

-In relation to some inorganic membranes, polymeric membranes have relatively low separation performance. However, the processing flexibility and low cost of polymers still make them highly attractive for many industrial separation applications. Polymer-inorganic hybrid membranes constitute an emerging research field and have been recently developed to improve the separation properties of polymer membranes because they possess properties of both organic and inorganic membranes such as good hydrophilicity, selectivity, permeability, mechanical strength, and thermal and chemical stability. The structures and processing of polymer-inorganic nanocomposite hybrid membranes, as well as their use in the fields of ultrafiltration, nanofiltration, pervaporation, gas separation and separation mechanism are reviewed.

No abstract

Films formed from polysaccharides, as chitosan, present a high permeability in water vapour. In order to increase resistance to water vapour for chitosan-based films, different lipid fractions were incorporated into a filmogenic matrix: fish and vegetable oils, stearic and oleic acids. The chitosan showed a molecular weight of 150 kDa and a deacetylation degree of 86 ± 1%. Results showed that incorporation of different lipid fractions decreased the water vapour permeability (WVP) (1.3-1.8 g mm m )2 day )1 kPa )1 ) as compared with pure chitosan film (3.8 g mm m )2 day )1 kPa )1 ). A higher reduction in WVP (65%) was found with the addition of refined fish oil to the continuous matrix of the films than with the addition of refined rice oil, oleic or stearic acid (50-60%). However, pure chitosan films showed better tensile strength (TS = 33 MPa) and elongation percentage (E = 18%) than lipids fraction-chitosan films (7-19 MPa and 7-13%, respectively).

No abstract

No abstract

Summary The effect of carp oil incorporation on properties of chitosan films was evaluated. Chitosan and carp oil were obtained from shrimp wastes and viscera respectively. Tests were performed with different values of chitosan: oil ratios, agitation rates, homogenisation times and pH. The optimum conditions for stability of the film–forming dispersions were of 20,000 rpm at 10 min, and 10:1 ratio of chitosan:oil. The highest values of tensile strength and elongation percentage (%E) of films were obtained at pH 3.5. The addition of carp oil in the chitosan films (10:1 ratio) showed an increase in the resistance to diffusion of water vapour (1.7 g mm m−2 day−1 kPa−1) in relation to pure chitosan films (4.1 g mm m−2 day−1 kPa−1). However, pure chitosan films showed better mechanical properties (38 MPa and%E 18%) and transparency than films of chitosan:oil (20.4 MPa and 8.8%).

No abstract