Monday, April 30, 2012
Napoleon Ballroom C-D, 3rd fl (Sheraton New Orleans)
There is a need to develop a high-throughput method for measurement of lignin in pretreated feed stocks, especially in pretreatments that involve removal of lignin. The
E-AFEXTM process has been designed to remove lignin from biomass with the help of various organic solvents. Hence, high throughput and reliable measurement of percent delignification is necessary for a deeper understanding of the process. The acetyl bromide assay method for lignin determination has the potential to be applied as a high throughput analytical method. However, interferences from degraded xylans and presence of extractives lead to an overestimation of lignin content. In this study, the acetyl bromide assay method is systematically studied and then compared to the standard gravimetric NREL protocol for determination of lignin. The effect of reaction temperature, digestion time, extractives and xylan degradation is studied using pretreated and untreated corn stover. Extinction coefficient calculations are performed on pretreated and untreated corn stover by utilizing extracted and purified lignin standard from the source. The results show that there is a significant variation in the estimated lignin value using acetyl bromide digestion when compared to the standard NREL protocol, especially for pretreated samples. The application of feed stock and pretreatment specific extinction coefficients is effective in making the two protocols comparable.
E-AFEXTM process has been designed to remove lignin from biomass with the help of various organic solvents. Hence, high throughput and reliable measurement of percent delignification is necessary for a deeper understanding of the process. The acetyl bromide assay method for lignin determination has the potential to be applied as a high throughput analytical method. However, interferences from degraded xylans and presence of extractives lead to an overestimation of lignin content. In this study, the acetyl bromide assay method is systematically studied and then compared to the standard gravimetric NREL protocol for determination of lignin. The effect of reaction temperature, digestion time, extractives and xylan degradation is studied using pretreated and untreated corn stover. Extinction coefficient calculations are performed on pretreated and untreated corn stover by utilizing extracted and purified lignin standard from the source. The results show that there is a significant variation in the estimated lignin value using acetyl bromide digestion when compared to the standard NREL protocol, especially for pretreated samples. The application of feed stock and pretreatment specific extinction coefficients is effective in making the two protocols comparable.