Multivariate statistical analysis of mid-infrared spectra for a G1 allyl-terminated carbosilane dendrimer

Analysis of alkali ultrasonication pretreatment in bioethanol production from cotton gin trash using FT-IR spectroscopy and principal component analysis

Background

Cotton gin trash (CGT) is a lignocellulosic residue that can be used in the production of cellulosic ethanol. In a previous research, the sequential use of ultrasonication, liquid hot water, and ligninolytic enzymes was selected as pretreatment for the production of ethanol from CGT. However, an increment in the ethanol production is necessary. To accomplish that, this research evaluated the effect of pretreating CGT using alkaline ultrasonication before a liquid hot water and ligninolytic enzymes pretreatments for ethanol production. Three NaOH concentrations (5%, 10%, and 15%) were employed for the alkaline ultrasonication. Additionally, this work is one of the first applications of Fourier transform infrared (FT-IR) spectrum and principal component analysis (PCA) as fast methodology to identify the differences in the biomass after different types of pretreatments.

Results

The three concentrations employed for the alkaline ultrasonication pretreatment produced ethanol yields and cellulose conversions higher than the experiment without NaOH. Furthermore, 15% NaOH concentration achieved twofold increment yield versus the treatment without NaOH. The FT-IR spectrum confirmed modifications in the CGT structure in the different pretreatments. PCA was helpful to determine differences between the pretreated and un-pretreated biomass and to evaluate how the CGT structure changed after each treatment.

Conclusions

The combination of alkali ultrasonication hydrolysis, liquid hot water, and ligninolytic enzymes using 15% of NaOH improved 35% the ethanol yield compared with the original treatment. Additionally, we demonstrated the use of PCA to identify the modifications in the biomass structure after different types of pretreatments and conditions.

A near infrared spectroscopic study of the structural modifications of lime (Tilia cordata Mill.) wood during hydro-thermal treatment

The modifications and/or degradation of lime (Tillia cordata) wood components during wood heat treatment under low temperature at about 140°C and 10% percentage of relative humidity were evaluated. The aim of this study was to obtain results by simple NIR coupled with second derivative, principal component analysis and two dimensional correlation spectroscopy in order to better understand how these techniques are able to evaluate structural differences resulted under hydro-thermal treatment of the wood over a period of 504h. The NIR spectra of treated samples were compared with the reference one. Due to the broad bands in the NIR spectra, the assignment and modifications occurring during treatment is difficult, therefore the second derivative principal component analysis were applied. Principal component analysis by first two components was able to differentiate the samples series, PC1 being considered as the time axis, and PC2 as the axis representing the structural modification of wood components. 2D NIR correlation spectroscopy was able to estimate the sequential order of the groups variations under the hydro-thermal treatment time as external perturbation, indicating as first moment changes the OH and CO groups from carbohydrates and lignin, followed by CarH, CH and CH2 groups from lignin, cellulose and hemicelluloses.