Obtaining lignin nanoparticles by sonication

Abstract

a b s t r a c tLignin, the main natural aromatic polymer was always aroused researchers interest. Currently around 90% of this biomaterial is burned for energy. It has a very complex and complicated structure which depends on the separation method and plant species, what determine difficulties to use as a raw material widely. This research presents a physical method to modify lignin by ultrasonic irradiation in order to obtain nanoparticles. The nanoparticles synthesized were dimensionally and morphologically characterized. At the same time the preoccupations were to determine the structural and compositional changes that occurred after sonication. To achieve this, two types of commercial lignins (wheat straw and Sarkanda grass) were used and the modifications were analyzed by FTIR-spectroscopy, GPC-chromatography, 31 P-NMR-spectroscopy and HSQC0. The results confirm that the compositional and structural changes of nanoparticles obtained are not significantly modified at the intensity applied but depend on the nature of lignin.

Characterization of technical lignins by NMR spectroscopy: optimization of functional group analysis by 31P NMR spectroscopy

“…However, a dramatic increase of aliphatic OH groups ( Figure 5 ) was observed, from 1.91 mmol g -1 (not sonicated) to 5.45 mmol g -1 (sonicated for 1 h; see Figure 4b), and this is an indication of splitting of ether or ester bonds releasing OH groups. Gilca et al (2015) reported similar results. More over, peak sharpening for several groups is indicative of depolymerization.…”

Lignin from Micro- to Nanosize: Production Methods

“…The nanolignin dispersions were very stable in pure water because no specific aggregation occurred within 60 days, which was explained by the relatively high negative ζ-potential of about −60 mV in pure water at pH values from around 5 to 11. This work yielded more spherical nanoparticles compared to other methods [16,35,36], which represents an important advantage for advanced applications. Particles could be dried and dispersed using sonication.…”

“…Gilca et al [36] used sonication for the size reduction of wheat straw and Sarkanda grass lignin. In contrast to the sonication carried out by Tortora et al [20], which caused crosslinking and an increase in molecular weight, this sonication process resulted in decreasing molecular weight and is roughly considered as mechanical treatment.…”

Lignin coating to quench photocatalytic activity of titanium dioxide nanoparticles for potential skin care applications

“…To achieve a good mixing and to reduce the particles size of the composite material, vortex homogenization was used, followed by ultrasonic treatment (20 kHz). 59 Phase separation was never observed, even after ultracentrifugation.…”