Biosciences Center, National Renewable Energy Laboratory, Golden, CO 80401, USA.
National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO 80401, USA.
Molecules. 2020 Mar 20;25(6):1427. doi: 10.3390/molecules25061427.
Ferrous ion co-catalyst enhancement of dilute-acid (DA) pretreatment of biomass is a promising technology for increasing the release of sugars from recalcitrant lignocellulosic biomass. However, due to the reductive status of ferrous ion and its susceptibility to oxidation with exposure to atmosphere, its effective application presumably requires anaerobic aqueous conditions created by nitrogen gas-purging, which adds extra costs. The objective of this study was to assess the effectiveness of oxidative iron ion, (i.e., ferric ion) as a co-catalyst in DA pretreatment of biomass, using an anaerobic chamber to strictly control exposure to oxygen during setup and post-pretreatment analyses. Remarkably, the ferric ions were found to be as efficient as ferrous ions in enhancing sugar release during DA pretreatment of biomass, which may be attributed to the observation that a major portion of the initial ferric ions were converted to ferrous during pretreatment. Furthermore, the detection of hydrogen peroxide in the liquors after DA/Fe ion pretreatment suggests that Fenton reaction chemistry was likely involved in DA/Fe ion pretreatments of biomass, contributing to the observed ferric and ferrous interchanges during pretreatment. These results help define the extent and specification requirements for applying iron ions as co-catalysts in DA pretreatments of biomass.
亚铁离子共催化剂增强稀酸（DA）预处理生物质是一种很有前途的技术，可以提高木质纤维素生物质中糖的释放。然而，由于亚铁离子的还原状态及其在与大气接触时易被氧化，其有效应用可能需要通过氮气吹扫产生的厌氧水条件，这会增加额外的成本。本研究的目的是评估氧化态铁离子（即三价铁离子）作为共催化剂在生物质 DA 预处理中的有效性，使用厌氧室在设置和预处理后分析过程中严格控制氧气的暴露。值得注意的是，三价铁离子在 DA 预处理生物质过程中提高糖释放的效果与亚铁离子相当，这可能是因为预处理过程中观察到大部分初始三价铁离子转化为亚铁离子。此外，在 DA/Fe 离子预处理后的液体中检测到过氧化氢表明，Fenton 反应化学可能参与了生物质的 DA/Fe 离子预处理，这有助于解释预处理过程中观察到的三价铁和亚铁离子的相互转化。这些结果有助于确定在 DA 预处理中应用铁离子作为共催化剂的程度和规范要求。
