Biopolymer−Clay Nanocomposites Based on Chitosan Intercalated in Montmorillonite

Abstract

The objective of this work is the intercalation of the cationic biopolymer chitosan in Na +montmorillonite, providing compact and robust three-dimensional nanocomposites with interesting functional properties. CHN chemical analysis, X-ray diffraction, Fourier transform infrared spectroscopy, scanning transmission electron microscopy, energy-dispersion X-ray analysis, and thermal analysis have been employed in the characterization of the nanocomposites, confirming the adsorption in mono-or bilayers of chitosan chains depending on the relative amount of chitosan with respect to the cationic exchange capacity of the clay. The first chitosan layer is adsorbed through a cationic exchange procedure, while the second layer is adsorbed in the acetate salt form. Because the deintercalation of the biopolymer is very difficult, the -NH 3 + Acspecies belonging to the chitosan second layer act as anionic exchange sites and, in this way, such nanocomposites become suitable systems for the detection of anions. These materials have been successfully used in the development of bulkmodified electrodes exhibiting numerous advantages as easy surface renewal, ruggedness, and long-time stability. The resulting sensors are applied in the potentiometric determination of several anions, showing a higher selectivity toward monovalent anions. This selectivity behavior could be explained by the special arrangement of the polymer as a nanostructured bidimensional system.

Production, characterization and biological features of bacterial cellulose from scum obtained during preparation of sugarcane jaggery (gur)

“…Although the dried BC samples are used for TGA analysis, due to hydrophilic nature it absorb some moisture. Besides, the interlayer coordinated water molecules also contribute in this observed initial weight loss (Darder et al 2003;Li et al 2010). The second degradation phase starts above 220°C and remains till complete degradation of cellulose chains above 350°C.…”

Synthesis, Characterization and Studies of PANI-MMT Nanocompoisites

“…Scanning electron micrograph (SEM) revealed some interesting morphological d ifferences between the pure bentonite clay and Pani-clay co mposites. The surface of pure clay was flaky texture reflect ing its layered structure [26] as shown in figure. Pani has a rod like network texture and Pani Clay composite has flo wer petals like appearance. It can be clearly seen in micrographs of all clay co mposites that the textures of both pani-clay are retained in the co mposites which are of different grain sizes.…”

“…free pani-clay do mains) play an important role in the electrical conductivity of the composites. It is evident that the improvement in the conductivity of the pani-clay composite could be attributed to more ordered and dense structure enhancing inter-chain electron hopping [26].…”

Characterization of Clay/Chitosan Nanocomposites and their Use for Adsorption On Mn(ΙΙ) from Aqueous Solution

“…The Al-Al-OH deformation vibrational mode is found at 928 cm -1 , while for Al-Fe-OH and Al-Mg-OH deformation mode are at 886 and 849 cm -1 respectively [17] . The observed band at 797.4 cm -1 is due to Si-O stretching vibration of quartz and silica as well as the Si-O stretching only of quartz at 774 i.e.…”

“…The bands near 1080 to 1021 are attributed to ʋco of the ring COH, COC and CH2OH. The small peak at 894 cm -1 is corresponding to the wagging (C-H) of the saccharide structure of Chitosan [17,18,19] . [20] .…”