5.3 Biochemical Conversion of Biomass and Nanotechnology
55
5.3 Biochemical Conversion of Biomass
and Nanotechnology
Several studies have reported the use of wide-ranging nanomaterials for the fermentation of biomass for the production of hydrogen. In a study, hematite nanoparticles
were used for the fermentation of sucrose in order to generate hydrogen. The nanoparticles were prepared by using the solution of FeCl 3 . The solution was placed in the
oven at 100 °C for 72 h which resulted in the formation of red precipitates which
were separated by centrifugation. The obtained product was washed with ethanol and
water. Afterward, the synthesized nanoparticles were resuspended in aqueous media
via ultrasonication. The prepared nanoparticles were characterized with TEM and
XRD. The TEM analysis revealed that the hematite nanoparticles have the average
diameter of ~ 55 nm. The XRD studies indicated that the nanoparticles are in hexagonal form. Clostridium butyricum was used for the fermentation, and the microbe
was employed as inocula without additional pretreatments. The study reported that
the maximum 3.57 mol of H 2 were obtained per mole of sucrose when 200 mg/L of
the nanoparticles were used [27].
As mentioned earlier, water gas shift reaction is an important biochemical reaction for the generation of hydrogen from biomass. Different studies have employed
varying nanomaterials in the water gas shift reaction for obtaining better yield and
high-quality hydrogen. In a study, researchers have claimed the use of gold nanoparticles for the generation of hydrogen via water gas shift reaction. The study reported
that the method of preparation and the pretreatment of the catalysts is very critical
for the functioning of the catalyst in water gas shift reaction. In order to achieve the
catalytic activity of the Au nanoparticles in the reaction, the close contact between
oxide support and gold is crucial. The close contact is associated with the zerovalent atoms of Au which is necessary for the high catalytic activity. The abovementioned hypothesis is supported by the in situ extended X-ray absorption fine structure
(EXAFS) measurements [28].
An investigation has determined the effects of zerovalent Fe and Ni nanoparticles against the divalent Fe
2+ and Ni
2+ ions on the proficiency of dark fermentation mesophilic reaction from glucose on the pretreated anaerobic sludge for the
generation of hydrogen. The sludge was treated with heat-shock. For the fermentation experiment, glucose solution (5.5 pH) was taken in dark glass bottle and the
supplemented metal particles (separately) were added in the varied concentrations.
Afterward, the nutrient solution and inoculum were also added along with the particular amount of deionized water. The bottles were covered with butyl rubber cap.
Before the determination of the results the bottles were also incubated. The zerovalent Fe nanoparticles depicted 8% increase in the hydrogen yield, and this is probably
because of the fact that Fe
0 improved the activity of ferredoxin electron transfer and
hydrogenase; however, contrary to the Fe nanoparticles, Ni nanoparticles showed
insignificant improvement (~0.9%) in the generation of hydrogen [29].
In another study, nanoparticles of maghemite (magnetite + hematite) were used in
the fermentation of starch wastewater for the generation of hydrogen. The magnetite
55
5.3 Biochemical Conversion of Biomass
and Nanotechnology
Several studies have reported the use of wide-ranging nanomaterials for the fermentation of biomass for the production of hydrogen. In a study, hematite nanoparticles
were used for the fermentation of sucrose in order to generate hydrogen. The nanoparticles were prepared by using the solution of FeCl 3 . The solution was placed in the
oven at 100 °C for 72 h which resulted in the formation of red precipitates which
were separated by centrifugation. The obtained product was washed with ethanol and
water. Afterward, the synthesized nanoparticles were resuspended in aqueous media
via ultrasonication. The prepared nanoparticles were characterized with TEM and
XRD. The TEM analysis revealed that the hematite nanoparticles have the average
diameter of ~ 55 nm. The XRD studies indicated that the nanoparticles are in hexagonal form. Clostridium butyricum was used for the fermentation, and the microbe
was employed as inocula without additional pretreatments. The study reported that
the maximum 3.57 mol of H 2 were obtained per mole of sucrose when 200 mg/L of
the nanoparticles were used [27].
As mentioned earlier, water gas shift reaction is an important biochemical reaction for the generation of hydrogen from biomass. Different studies have employed
varying nanomaterials in the water gas shift reaction for obtaining better yield and
high-quality hydrogen. In a study, researchers have claimed the use of gold nanoparticles for the generation of hydrogen via water gas shift reaction. The study reported
that the method of preparation and the pretreatment of the catalysts is very critical
for the functioning of the catalyst in water gas shift reaction. In order to achieve the
catalytic activity of the Au nanoparticles in the reaction, the close contact between
oxide support and gold is crucial. The close contact is associated with the zerovalent atoms of Au which is necessary for the high catalytic activity. The abovementioned hypothesis is supported by the in situ extended X-ray absorption fine structure
(EXAFS) measurements [28].
An investigation has determined the effects of zerovalent Fe and Ni nanoparticles against the divalent Fe
2+ and Ni
2+ ions on the proficiency of dark fermentation mesophilic reaction from glucose on the pretreated anaerobic sludge for the
generation of hydrogen. The sludge was treated with heat-shock. For the fermentation experiment, glucose solution (5.5 pH) was taken in dark glass bottle and the
supplemented metal particles (separately) were added in the varied concentrations.
Afterward, the nutrient solution and inoculum were also added along with the particular amount of deionized water. The bottles were covered with butyl rubber cap.
Before the determination of the results the bottles were also incubated. The zerovalent Fe nanoparticles depicted 8% increase in the hydrogen yield, and this is probably
because of the fact that Fe
0 improved the activity of ferredoxin electron transfer and
hydrogenase; however, contrary to the Fe nanoparticles, Ni nanoparticles showed
insignificant improvement (~0.9%) in the generation of hydrogen [29].
In another study, nanoparticles of maghemite (magnetite + hematite) were used in
the fermentation of starch wastewater for the generation of hydrogen. The magnetite