Enzymatic Hydrolysis of Pretreated Newspaper Having High Lignin Content for Bioethanol Production

Abstract

Recovered papers are suitable biomass sources for conversion into sugars that can be used in bioethanol production. However, paper materials with a high lignin content have been found to be recalcitrant to enzymatic hydrolysis. To address this issue, several biomass pretreatment methods were employed to evaluate their efficiency on the conversion of newspaper with high lignin content to sugar. Autohydrolysis, a hot water treatment, was identified to adversely affect sugar conversion, presumably as a result of pore collapse under high-temperature pretreatment. Flexo ink, used in newspaper printing, had no effect on the enzymatic hydrolysis, with or without autohydrolysis. The ink was still detachable after autohydrolysis, as measured by hyperwashing. Compared to untreated newspaper, separate treatments of either mechanical refining or a non-ionic surfactant (sorbitan polyoxyethylene monooleate) improved the sugar conversion by 10% at enzyme dosages of 2 and 8 FPU/g substrate. The combination of both refining and surfactant resulted in the highest sugar conversions, i.e., 46.3%, 56.7%, and 64.1% at 2, 4, and 8 FPU/g enzyme dosages, respectively. Oxidative pretreatment (oxygen, 100 °C) marginally increased the sugar conversion, whereas alkaline and green liquor (NaCO3 and Na2S) pretreatments (at 160 °C) had either no effect or decreased the sugar conversion. Based on the results of the pretreatments, higher pretreatment temperatures of newsprint negatively impacted subsequent enzyme hydrolysis.

Optimization of Pilot Scale Mechanical Disk Refining for Improvements in Enzymatic Digestibility of Pretreated Hardwood Lignocellulosics

“…To further understand this effect, the surface lignin content of the lignocellulosic biomass was evaluated using a method adapted by Gray et al (2010) and Chen et al (2015a). X-ray photoelectron spectroscopy (XPS) measurement of carbon and oxygen signals of handsheets made from the unrefined and refined biomass (Table 2) indicated that there was a slight decrease in the calculated surface lignin in the 150 °C refined biomass compared with the ambient temperature refining and the unrefined control.…”

Valorization of sawdust biomass for biopolymer extraction via green method: Comparison with conventional process

“…The used method can be justified if the composition of different processed products with commercial cellulose is examined. For example, it can be observed that they have some percentage, in some cases significant, of hemicellulose and lignin, such as the case of either writing and printing paper 122 or newspaper, which typically have 40.0–55.0% of cellulose, 25.0–40.0% of hemicellulose and 18.0–30.0% of lignin, respectively 123 . In fact, as a part of this study and to confirm the composition of comercial products, the evaluation of CC of single‐use cups made of cellulose, was carried out.…”

“…For example, it can be observed that they have some percentage, in some cases significant, of hemicellulose and lignin, such as the case of either writing and printing paper 122 or newspaper, which typically have 40.0-55.0% of cellulose, 25.0-40.0% of hemicellulose and 18.0-30.0% of lignin, respectively. 123 In fact, as a part of this study and to confirm the composition of comercial products, the evaluation of CC of single-use cups made of cellulose, was carried out. Results confirmed that these compounds contains 66.0% of cellulose and 34.0% of a combination of hemicelulose and lignin.…”

Enzymatic degradation of lignin extracted from oil palm empty fruit bunch using laccase and cutinase

“…Through chemical or bioprocessing technology, lignin and cellulose from OPEFB can be separated (Hassan et al 2013). This material can be used as a renewable feedstock for the production of bio-products, ethanol, and industrial chemicals (Chen et al 2015). Since lignin is a complicated aromatic polymer with high molecular weight and is rather resistant to microorganisms, its utilization is quite limited (Wang et al 2011;Luo et al 2013).…”