A FOSS XDS NIR device. It has a solid content module that can allow for samples of a heterogenous particle to be analysed.
A Nabertherm furnace is used for the determination of the ash content of samples and also in the analytical protocol for determining Klason lignin content.
An autoclave is used in the protocols for the determination of the lignin and structural sugars (cellulosic and hemicellulosic) contents of samples.
Analytical data and quantitative near infrared (NIR) spectroscopy models for various lignocellulosic components (including Klason lignin and the constituent sugars glucose, xylose, mannose, arabinose, galactose, and rhamnose), ash, and ethanol-soluble extractives, were obtained for 53 samples of paper and cardboard. These samples were mostly the type of materials typically found in domestic wastes (e.g. newspapers, printing paper, glossy papers, food packaging). A number of the samples (48) were obtained by separating a sample, after milling, into two particle size fractions. It was found that the fractions containing the smaller particles typically had higher ash and Klason lignin contents and lower glucose and xylose contents that the larger particle size fractions. Nevertheless, all of the sample types had attractive total sugars contents (>50%) indicating that these could be suitable feedstocks for the production of biofuels and chemicals in hydrolysis-based biorefining technologies. NIR models of a high predictive accuracy (R2 of > 0.9 for the independent validation set) were obtained for total sugars, glucose, xylose, Klason lignin, and ash and with values for the Root Mean Square Error of Prediction (RMSEP) of 2.36%, 2.64%, 0.56%, 1.98%, and 4.87%, respectively. Good NIR models (R2 of > 0.8) were also obtained for mannose, arabinose, and galactose. These results suggest that NIR is a suitable method for the rapid, low-cost, analysis of the major lignocellulosic components of waste paper/cardboard samples.
Miscanthus samples were scanned over the visible and near infrared wavelengths at several stages of processing (wet-chopped, air-dried, dried and ground, and dried and sieved). Models were developed to predict lignocellulosic and elemental constituents based on these spectra. The dry and sieved scans gave the most accurate models; however the wet-chopped models for glucose, xylose, and Klason lignin provided excellent accuracies with root mean square error of predictions of 1.27%, 0.54%, and 0.93%, respectively. These models can be suitable for most applications. The wet models for arabinose, Klason lignin, acid soluble lignin, ash, extractives, rhamnose, acid insoluble residue, and nitrogen tended to have lower R(2) values (0.80+) for the validation sets and the wet models for galactose, mannose, and acid insoluble ash were less accurate, only having value for rough sample screening. This research shows the potential for online analysis at biorefineries for the major lignocellulosic constituents of interest.
The processing of lignocellulosic materials in modern biorefineries will allow for the
production of transport fuels and platform chemicals that could replace petroleum-derived
products. However, there is a critical lack of relevant detailed compositional information
regarding feedstocks relevant to Ireland and Irish conditions. This research has involved the
collection, preparation, and the analysis, with a high level of precision and accuracy, of a
large number of biomass samples from the waste and agricultural sectors. Not all of the
waste materials analysed are considered suitable for biorefining; for example the total sugar
contents of spent mushroom composts are too low. However, the waste paper/cardboard
that is currently exported from Ireland has a chemical composition that could result in high
biorefinery yields and so could make a significant contribution to Irelandís biofuel demands.