Aleksandra R. Nesic

Characterization of chitosan/montmorillonite membranes as adsorbents for Bezactiv Orange V-3R dye

The synthesis, characterization and environmental application of chitosan/montmorillonite membrane for adsorption Bezactiv Orange V-3R were investigated. Chitosan/montmorillonite membranes were synthesized in different ratios, containing 10-50% of montmorillonite (MMT) in membrane. These membranes were characterized by using Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TG) and scanning electron microscopy (SEM). The adsorption kinetics were investigated using three different concentrations of Bezactiv Orange dye (30, 50 and 80 mg/L). The adsorption capacity increases with increasing amount of MMT in membranes. These membranes show the highest adsorption capacity when the initial dye concentration was 80 mg/L. The results show that the optimum condition for adsorption of Bezactiv Orange is pH 6. A comparison of kinetic models was evaluated for the pseudo-first and pseudo-second order and intra-particle diffusion. The experimental data were fitted to the pseudo-second order kinetic model, and also followed by intra-particle diffusion. Intra-particle diffusion is not the only rate-controlling step. The Langmuir and Freundlich adsorption isotherms were applied to experimental equilibrium data at different concentration of dye solution. The results indicated the competency of chitosan/MMT membranes adsorbent for Bezactiv Orange adsorption.

Design of pectin-sodium alginate based films for potential healthcare application: Study of chemico-physical interactions between the components of films and assessment of their antimicrobial activity

In this study, pectin based films including different amounts of sodium alginate were prepared by casting method. All the films, with and without polyglycerol as plasticizer, were crosslinked with zinc ions in order to extend their potential functionality. The development of junction points, occurring during the crosslinking process with zinc ions, induced the increasing of free volume with following changing in chemico-physical properties of films. The inclusion of alginate in pectin based formulations improved the strength of zinc ions crosslinking network, whereas the addition of polyglycerol significantly improved mechanical performance. Finally, zinc-crosslinked films evidenced antimicrobial activity against the most common exploited pathogens: Staphylococcus Aureus, Escherichia Coli and Candida Albicans. These results suggest that zinc-crosslinked based films can be exploitable as novel bio-active biomaterials for protection and disinfection of medical devices.

Novel composite films based on amidated pectin for cationic dye adsorption.

Pectin, with its tendency to gel in the presence of metal ions has become a widely used material for capturing the metal ions from wastewaters. Its dye-capturing properties have been much less investigated, and this paper is the first to show how films based on amidated pectin can be used for cationic dye adsorption. In the present study amidated pectin/montmorillonite composite films were synthesized by membrane casting, and they are stable in aqueous solution both below and above pectin pKa. FTIR, thermogravimetry and SEM-EDAX have confirmed the presence of montmorillonite in the cast films and the interactions between the two constituents. In order to evaluate the cationic dye adsorption of these films Basic Yellow 28 was used, showing that the films have higher adsorption capacity compared to the others reported in the literature. The results were fitted into Langmuir, Freundlich and Temkin isotherms indicating an exothermic process and setting the optimum amount of montmorillonite in the films to 30% of pectin mass. According to the Langmuir isotherm the maximum adsorption capacity is 571.4 mg/g.

Complexation of amidated pectin with poly(itaconic acid) as a polycarboxylic polymer model compound

Complexes based on amidated pectin (AP) and poly(itaconic acid) (PIA) were prepared by casting films from solutions of AP and PIA in different ratios with the pectin amount ranging from 10% to 90% by mass. The complexes were investigated by elemental analysis, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetry (TG). In all investigated ratios of AP/PIA glassy transparent films with a uniform structure were obtained. The results of elemental analysis confirmed the composition of the complexes, and FTIR spectroscopy has shown carboxylic and amide peak shifting, indicating complex formation between AP and PIA. Comparison of thermograms of AP/PIA films with different ratios of AP indicated that the increase of the amount of AP increases the thermal stability of the films by retarding the onset of the main degradation processes.

Mineralized agar-based nanocomposite films: Potential food packaging materials with antimicrobial properties

New mineralized, agar-based nanocomposite films (Zn-carbonate and Zn-phosphate/agar) were produced by a combination of in situ precipitation and a casting method. The presence of minerals significantly influenced the morphology, properties and functionality of the obtained nanocomposites. Reinforcement with the Zn-mineral phase improved the mechanical properties of the carbonate-mineralized films, but had a negligible effect on the phosphate-mineralized samples. Both nanocomposites showed improved optical and thermal properties, better Zn(II) release potential in a slightly acidic environment and exhibited antimicrobial activity against S. aureus. These results suggest that Zn-mineralized agar nanocomposite films could be potentially used as affordable, eco-friendly and active food packaging materials.

Pectin-based nanocomposite aerogels for potential insulated food packaging application

Environmental-friendly pectin-TiO2 nanocomposite aerogels were prepared via sol-gel process and subsequent drying under supercritical conditions. The first step includes dissolution of pectin in water, addition of proper amount of TiO2 colloid and crosslinking reaction induced in the presence of tert-butanol and zinc ions. Then, the gels are subjected to the solvent exchange and supercritical CO2 drying. The influence of TiO2 nanoparticles on the textural, mechanical, thermal and antibacterial properties of aerogels was investigated. Results indicate that in the presence of TiO2 nanoparticles (NPs) mechanical, thermal and antimicrobial properties of pectin-based aerogels are improved in comparison to the control pectin aerogels. It should be emphasized that the thermal conductivity of pectin-based aerogels (0.022-0.025 W m-1 K-1) is lower than the thermal conductivity of air. Generally, the results propose that the pectin-TiO2 nanocomposite aerogels, as bio-based material, might have potential application for the storage of temperature-sensitive food.

Response surface methodology for optimisation of edible coatings based on dextran from Leuconostoc mesenteroides T3

The aim of this study was to develop dextran-based edible films plasticized by sorbitol. In order to optimise the film-forming formulation, response surface methodology was used. The influence of dextran and sorbitol concentration on the mechanical and water vapour barrier properties of obtained films was investigated. The results showed that both parameters exhibited significant effect on the water vapour permeability of a film. Both dextran and sorbitol concentration had significant influence on tensile strength and elongation at break, whereas only sorbitol concentration had significant effect on Youngs modulus. After optimisation by desirability approach, it was found that a film made of 3.40 wt% of dextran and 20.43 wt% of sorbitol showed the lowest water vapour permeability and the highest tensile strength and elasticity.

The influence of nanofillers on physical–chemical properties of polysaccharide-based film intended for food packaging

Abstract Food packaging is an important part of the food industry wherein preservation and protection of all types of foods and their raw materials presents an imperative. Depending on water activity and temperature of storage, food material can be easily perishable and therefore needs appropriate protection against external influences in order to preserve it longer. Petrochemical based materials such as polyolefins, polyesters, and polyamides have been increasingly used as packaging materials, because of their availability in large quantities at low cost and satisfying functional characteristics. Despite all the advantages, these materials are totally nonbiodegradable and cause the problems in waste disposal. Therefore, the demands of the consumers have been shifted to ecofriendly biodegradable and biobased materials, obtained from renewable resources. Nonetheless, the usage of biopolymers has been limited due to the poor mechanical and barrier properties. The addition of nanofillers significantly improves the barrier, mechanical, and thermal properties of biobased materials, as well as petroleum-based materials. This chapter provides a review of implementation potentials and development of the nanocomposites materials based on polysaccharides (thermoplastic starch, chitosan, cellulose, alginate, pectin) in combination with various nanofillers with emphasis on mechanical, thermochemical, and barrier properties.

Preparation and Characterisation of Novel Biodegradable Material Based on Chitosan and Poly(Itaconic Acid) as Adsorbent for Removal of Reactive Orange 16 Dye from Wastewater

Environmental protection has been a topic of great interest in recent years. Discharging azo dyes in aquatic systems contaminates water and causes serious ecological problems. Azo dyes are bio-accumulative, and, due to allergenic, carcinogenic and mutagenic properties, are a grave threat to people and the environment. Because of economic feasibility, simplicity and a high efficiency, adsorption is the most suitable process for treatment of wastewater. The increasingly interesting bio-degradable adsorbents are those that stem from ecologically and economically sustainable sources. The aim of the study is preparation and characterisation of polymer complexes based on naturally occurring polysaccharide-chitosan and poly(itaconic acid), as an adsorbent for removal of Reactive Orange 16 dye from wastewater. The complexes are characterised by Fourier-Transform Infrared Spectroscopy and Scanning electron microscopy. The effect of initial dye concentration, temperature and pH value of the solution on the adsorption capacities is investigated. Comparison of the obtained results with reported data shows the studied complex being an efficiently replacement for conventional adsorbents removing Reactive Orange 16 from wastewater.