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1563072 
Journal Article 
Intercalation of the Microbial Biopolymers Welan Gum and EPS I into Layered Double Hydroxides 
Plank, J; Ng, S; Foraita, S 
2012 
1 
Zeitschrift für Naturforschung B
ISSN: 0932-0776 
67 
5 
479-487 
WOS:000307482900013 
Three microbial polysaccharides, namely welan gum,
scleroglucan, and EPS I, a novel polysaccharide obtained from a newly isolated bacillus species
with structural similarities to xanthan gum, were employed in the fabrication of bio-
nanocomposites based on layered double hydroxides (LDH). Synthesis was performed by direct co-
precipitation of Zn(NO3)(2) and Al(NO3)(3) in the polysaccharide solutions at pH similar to 8.5.
The reaction products were characterized by powder X-ray diffraction (XRD), elemental and
thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and scanning and
transmission electron microscopy (SEM and TEM). It was found that welan gum is successfully
intercalated into the Zn-Al-LDH structure, giving a d-spacing of 2.38 nm for the interlayer
distance, while neutral scleroglucan failed to be intercalated. Instead, this biopolymer was only
surface-adsorbed on inorganic CaAl-OH-LDH platelets, as was evidenced by de-washing experiments.
These results indicate that the anionic functionality of the polysaccharides presents a main
driving force behind their intercalation. In contrast to regular xanthan gum, EPS I was
intercalated into the LDH structure to give a sharp X-ray reflection representing a d-spacing of
2.77 nm. This behavior proves that slight modifications of the polysaccharide can greatly improve
its intercalation ability. 
Polysaccharide; Layered Double Hydroxide; Intercalation; Welan Gum; Scleroglucan