68
4 Effective Biomass Valorization Procedures Using Ultrasound …
biocide systems in wood protection. In this context, Gilca et al. (2015) have made use
of the effect of US on lignin aggregation processes to obtain new nanoparticles from
two different types of lignin (wheat straw and Sarkanda grass). Two main reaction
patterns were postulated for US-assisted lignin nanoparticle preparation; a side chain
cleavage/ depolymerization and an oxidative coupling/polymerization (Scheme 4.3).
The depolymerization process was prevalent under the applied reaction conditions
(20 kHz–600 W). Moreover, it was possible to tune the depolymerization process by
modulating US irradiation time and/or power. An increase in the number of condensed
units was observed in IR spectra and indirectly from QQ-HSQC analyses. Phenyl
coumaran and pinoresinol subunits were found to be completely degraded and aryl
glycerol aryl ether subunits (β–O–4) were found to be reduced in number. The results
confirm that the compositional and structural changes in the nanoparticles obtained
are not significantly modified at the intensity applied (20 kHz–600 W), but that they
rather depend on lignin nature.
The production of suitable and cost-effective biopolymers is still another significant challenge for biomass valorization. The commercial success of biopolymer
food packaging is somewhat limited at present, partially because of the high cost of
biopolymer materials. Food processing waste could be utilized to produce biodegradable packaging film and address these issues. In fact, Borah et al. (2017) have developed a protocol that is based on the use of potato peel and sweet lime pulp to prepare
composite films under US irradiation (40 kHz, 50 W). The biopolymers were prepared over 45–60 min by varying potato peel (PP) powder and sweet lime pomace
(SLP) proportions across a 0:1 to 1:0 ratio range.
4.5 Conclusion
Extensive research has been carried out in support of sustainable biomass valorization
using acoustic and hydrodynamic cavitation. Although it has not seen extensive use
yet, hydrodynamic cavitation is a promising biomass conversion technique. More
significant scientific breakthroughs in the field of biomass valorization are expected
to occur in this innovative field in the near future.
References
Ahmad S, Pathak VV, Kothari R, Singh RP (2017) Prospects for pretreatment methods of lignocellulosic waste biomass for biogas enhancement: opportunities and challenges. Biofuels. https://d
oi.org/10.1080/17597269.2017.1378991
Amidon TE, Wood CD, Shupe AM, Wang Y, Graves M, Liu SJ (2008) Biorefinery: conversion of
woody biomass to chemicals, energy and materials. J. Biobased Mater Bioenergy 2(2):100–120
Borah AJ, Agarwal M, Poudyal M, Goyal A, Moholkar VS (2016) Mechanistic investigation in US
induced enhancement of enzymatic hydrolysis of invasive biomass species. Bioresour Technol
213:342–349
4 Effective Biomass Valorization Procedures Using Ultrasound …
biocide systems in wood protection. In this context, Gilca et al. (2015) have made use
of the effect of US on lignin aggregation processes to obtain new nanoparticles from
two different types of lignin (wheat straw and Sarkanda grass). Two main reaction
patterns were postulated for US-assisted lignin nanoparticle preparation; a side chain
cleavage/ depolymerization and an oxidative coupling/polymerization (Scheme 4.3).
The depolymerization process was prevalent under the applied reaction conditions
(20 kHz–600 W). Moreover, it was possible to tune the depolymerization process by
modulating US irradiation time and/or power. An increase in the number of condensed
units was observed in IR spectra and indirectly from QQ-HSQC analyses. Phenyl
coumaran and pinoresinol subunits were found to be completely degraded and aryl
glycerol aryl ether subunits (β–O–4) were found to be reduced in number. The results
confirm that the compositional and structural changes in the nanoparticles obtained
are not significantly modified at the intensity applied (20 kHz–600 W), but that they
rather depend on lignin nature.
The production of suitable and cost-effective biopolymers is still another significant challenge for biomass valorization. The commercial success of biopolymer
food packaging is somewhat limited at present, partially because of the high cost of
biopolymer materials. Food processing waste could be utilized to produce biodegradable packaging film and address these issues. In fact, Borah et al. (2017) have developed a protocol that is based on the use of potato peel and sweet lime pulp to prepare
composite films under US irradiation (40 kHz, 50 W). The biopolymers were prepared over 45–60 min by varying potato peel (PP) powder and sweet lime pomace
(SLP) proportions across a 0:1 to 1:0 ratio range.
4.5 Conclusion
Extensive research has been carried out in support of sustainable biomass valorization
using acoustic and hydrodynamic cavitation. Although it has not seen extensive use
yet, hydrodynamic cavitation is a promising biomass conversion technique. More
significant scientific breakthroughs in the field of biomass valorization are expected
to occur in this innovative field in the near future.
References
Ahmad S, Pathak VV, Kothari R, Singh RP (2017) Prospects for pretreatment methods of lignocellulosic waste biomass for biogas enhancement: opportunities and challenges. Biofuels. https://d
oi.org/10.1080/17597269.2017.1378991
Amidon TE, Wood CD, Shupe AM, Wang Y, Graves M, Liu SJ (2008) Biorefinery: conversion of
woody biomass to chemicals, energy and materials. J. Biobased Mater Bioenergy 2(2):100–120
Borah AJ, Agarwal M, Poudyal M, Goyal A, Moholkar VS (2016) Mechanistic investigation in US
induced enhancement of enzymatic hydrolysis of invasive biomass species. Bioresour Technol
213:342–349