Lignin as Renewable and Superior Asphalt Binder Modifier - ACS

Mar 20, 2017 - The work was supported by the U.S. DOE (Department of Energy) EERE (Energy Efficiency and Renewable Energy) BETO (Bioenergy Technology ...
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Lignin as Renewable and Superior Asphalt Binder Modifier Shangxian Xie, Qiang Li, Pravat Karki, Fujie Zhou, and Joshua S. Yuan ACS Sustainable Chem. Eng., Just Accepted Manuscript • DOI: 10.1021/ acssuschemeng.6b03064 • Publication Date (Web): 20 Mar 2017 Downloaded from http://pubs.acs.org on March 21, 2017

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Lignin as Renewable and Superior Asphalt Binder Modifier

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Shangxian Xieabc*, Qiang Liabc*, Pravat Karkid, Fujie Zhoue$, and Joshua S. Yuanabc$

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a

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77843, USA

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b

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77843, USA

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c

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77843, USA

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d

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e

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*These authors contributed equally.

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$

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Complete Address: 2123 TAMU, College Station, TX 77843, USA.

Synthetic and Systems Biology Innovation Hub, Texas A&M University, College Station, TX

Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX

Institute for Plant Genomics and Biotechnology, Texas A&M University, College Station, TX

Texas A&M Transportation Institute, Texas A&M University, College Station, TX 77843, USA

College of Transportation Engineering, Tongji University, Shanghai, 201804, China

For correspondence: [email protected], [email protected]; Phone: +1-979-845-3016;

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Abstract

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The utilization of lignin for fungible products remains a major challenge for biofuel, pulp and

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paper industries. We hereby demonstrated the potential of lignin to be used as the asphalt binder

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modifier, and addressed the challenges in producing high-performance asphalt binder modifiers

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from lignin. We first demonstrated that Kraft lignin could improve the high temperature

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performance of asphalt binder, yet compromise the low temperature performance. To address the

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challenge, we developed both enzyme-mediator-based biological processing and formic acid-

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based chemical processing to derive lignin fractions to improve the high temperature

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performance of asphalt binder without compromising its low temperature performance.

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Moreover, the soluble fraction of biologically processed lignin could improve both high

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temperature and low temperature performance of asphalt binder, which enabled lignin to serve as

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a modifier with unique features. We also carried out a thorough characterization of different

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lignin fractions, and revealed the potential mechanisms for lignin to improve the asphalt binder

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performance. Overall, the study opened the new avenues for lignin to serve as an exceptional

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modifier and renewable substitute to improve both high and low temperature performance of

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asphalt binder. The novel application also transformed lignin waste into a valuable by-product

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with market size compatible to biorefinery, pulp and paper industries.

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Keywords: Asphalt binder modifier; Lignin; Temperature performance

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Lignin utilization for fungible products remains a major challenge for lignocellulosic

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biorefinery, pulp and paper industries.1-3 Even though lignin is the second most abundant

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biopolymer on earth, very little of it has been transformed into value-added bioproducts.2 More

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than 50 million tons of lignin are generated from pulp and paper industry annually, whereas only

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2% of this waste lignin has been utilized for bioproducts.4 Likewise, essentially all biomass

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conversion platforms result in the formation of a major lignin-containing waste stream, which

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needs to be upgraded into fungible products.2 The utilization of this excess lignin as feedstock

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for renewable products offers a significant opportunity to enhance the operational efficiency,

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reduce the cost, minimize carbon emissions, and maximize sustainability of lignocellulosic

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biorefinery. Despite the imminent needs, bioproduct development from lignin is highly

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challenging due to its recalcitrance nature.1-3 The technologies pursued by the industry included

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bioconversion, thermoconversion, specialty chemicals and materials from lignin, whereas each

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of the technologies has its limitations. These limitations include the low titer for bioconversion,

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corrosive products from thermoconversion, small market size and low cost-effectiveness for

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specialty chemicals. In particular, for bioproduct to enable biorefinery, it needs to be compatible

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with the scale of the industries like biorefinery, pulp and paper industry.

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We hereby demonstrated that lignin can be fractionated and modified to enable the

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utilization as effective modifiers to improve asphalt binder performance. More than 90% of US

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road are paved with asphalt mixes. The annual production of asphalt mixes for highway

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pavement in United States is 360 million tons. 18 million tons of asphalt binders with good

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performance at both high- and low- temperatures are needed annually for maintaining a safe and

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smooth highway system.5 Asphalt binder is a mixed petroleum-derived material composed of

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asphaltenes, resins, saturates, and aromatics, where the more polar components including

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asphaltenes and resins render the asphalt binder modulus and high temperature properties, and

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the less polar components including saturates and aromatics promote asphalt flexibility and low

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temperature properties.6-9 A superior binder should have a higher performance grade (the higher,

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the better) to prevent melting and associated pavement distress (such as rutting) at high

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temperature. Meanwhile, it should also have a lower performance grade (the lower, the better) to

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reduce cracking potential at low temperature. As a renewable aromatic polymer, lignin consists

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of monoligonol precursors of ρ-hydroxycinnamyl alcohols including ρ-coummaryl alcohol,

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coniferyl alcohol, and sinapyl alcohol, which are further connected with different types of

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interunitery covalent linkages.10-11 Considering the structural similarity to the fossil fuel-based

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asphalt binder, lignin could serve as a renewable substitute and potentially modifier for asphalt

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binder. Even though previous studies have explored the possible antioxidant activity of lignin12,

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very limited amount of lignin is needed for the antioxidant function and the application does not

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create a market size-compatible utilization of lignin. Furthermore, it is not clear how adding

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lignin into asphalt binders will impact the most important characteristics of asphalt binder:

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permanent deformation (or rutting) resistance at high temperature and cracking resistance at low

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temperature.12-13 The impact on the high and low temperature performance will determine the

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capacity of lignin to serve as modifier of asphalt binder.

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Asphalt binder modifier could enhance the properties of asphalt binder to confer better

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high or low temperature performances of millions of miles of pavements. Few studies have

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explored how lignin can serve as asphalt binder modifier. The high heterogeneity and complexity

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of lignin make it difficult to predict how the lignin addition will change the high and low

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temperature performance of asphalt binder. Neither do we understand how to develop lignin

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products to enhance high temperature performance without compromising the low temperature

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performance of asphalt binder, and vice versa. In this study, we have first established that lignin

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can modify asphalt binder performance and has the potential to serve as asphalt binder modifier.

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More importantly, we have developed various biological and chemical processes to fractionate

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lignin into fractions with various molecular weights and chemical properties, which can in turn

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serve as elite modifiers to significantly improve both high temperature and low temperature

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performance. The study further reveals the potential mechanisms for processed lignin to serve as

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effective asphalt binder modifier, and opens new avenues for lignin-based value-adding products

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and renewable substitute for road materials.

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Lignin Can Change the Performance of Asphalt Binder

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We first evaluated how raw Kraft lignin could impact asphalt binder performance. The

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study suggested that the addition of raw Kraft lignin at different concentrations (5-20%) could

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improve the high temperature performance (rutting resistance) of the asphalt binder, indicating

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that the lignin modified binder can stand hotter summer temperatures without rutting problem.

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The result opens the opportunity for lignin to serve as renewable asphalt binder modifiers (Figure

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1). Despite the potential, the addition of raw Kraft lignin led to significantly compromised low

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temperature cracking property of the asphalt binder, when more than 5% of the lignin was added

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into the asphalt binder. Specifically, the low temperature performance was increased by 7 oC

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when 20% Kraft lignin was added into asphalt binder. In other words, the asphalt binder with

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raw Kraft lignin might crack at -17oC vs. at -24oC without lignin. The results indicated the

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improvement of high temperature performance came with a cost of compromised low

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temperature performance of asphalt binder. Therefore, raw Kraft lignin would not be a suitable

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modifier for asphalt binder.

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Even though the direct use of raw Kraft lignin as asphalt binder modifier is challenging, it

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is possible to process lignin to tailor the molecular weight and functional groups through

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different biological and chemical fractionation.14-15 We hypothesized that different lignin

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functional groups and molecular weight could impact the high and low temperature performance

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of asphalt binders. Based on this hypothesis, we developed two different types of lignin

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processing and investigated their effects on the performance of asphalt binder as shown in Figure

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1.

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Development of Biological Process to Improve Lignin Property as Asphalt Binder Modifier

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We firstly developed a new biological process to fractionate lignin into portions with

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different molecular weights and functional groups. In particular, the processing exploited the

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laccase-mediator system that was previously used in delignification in pulp and paper industries.

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The laccase-mediator system has not been used to fractionate commercial lignin toward different

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applications. However, from a fundamental scientific perspective, the laccase-mediator system

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has potential to enhance the electron transfer in redox reactions for better linkage cleavage

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during depolymerization processes, and thus has potential to be used for efficient fractionation of

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lignin toward broad usage. In particular, electron mediator could both facilitate more rapid

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electron transfer and allow better penetration of redox reactions into lignin molecular structure,

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both of which will result in better linkage cleavage, broader modification of functional group,

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and fractionation of lignin into portions with altered molecular weights.

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We have established an efficient laccase-mediator system using 1-hydroxybenzotriazole

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(HBT) to fractionate lignin for asphalt binder modifier usage. The laccase-HBT system could

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fragmentize and solubilize over 35% of Kraft lignin as a water-soluble fraction. Both the water-

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soluble and insoluble lignin fractions were investigated for their performance as asphalt binder

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modifiers. The asphalt binder blended with different lignin fractions and concentrations were

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characterized for both high temperature and low temperature performance. The analysis showed

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that the addition of both soluble and insoluble lignin fractions could significantly improve the

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high temperature performance of asphalt binder, in a way similar to the raw Kraft lignin (Figure

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2A). However, unlike the raw Kraft lignin, the addition of water-soluble lignin fraction could

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slight improve the low temperature performance of the asphalt binder when added at 10 to 20%

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(Figure 2B). The water-insoluble lignin fraction also had little effects on the low temperature

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performance when added as 5%-10% modifier, whilst it reduced the low temperature

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performance of asphalt binder when added at 20% (Figure 2B). The results highlighted that the

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laccase-HBT fractionated lignin could serve as a good asphalt binder modifier to enhance the

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high temperature performance of asphalt binder without compromising the low temperature

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performance. The detailed structural analysis of fractionated lignin was subsequently carried out

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to elucidate the potential mechanisms for altering asphalt binder performance by lignin.

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The molecular weight and structural characteristics for the biologically fractionated lignin 13

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were characterized using gel permeation chromatography (GPC) and

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resonance (13C-NMR), respectively. The GPC analysis revealed that the molecular weight of

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insoluble lignin fraction was increased 1.6 times as compared to that of the raw Kraft lignin,

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whilst the soluble fraction had significantly decreased molecular weight (Figure 2 C). NMR

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analysis revealed the changes of functional groups in fractionated lignin, which could contribute

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to the performance of lignin as asphalt binder modifier. The amount of aliphatic hydroxyl (172-

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168.6 ppm), phenolic hydroxyl (168.6-166 ppm), and aliphatic carboxylic (173-171 ppm)

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functional groups in the insoluble fraction were slightly increased as compared to that of the raw

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Kraft lignin (Figure 2 D), indicating that biological fractionation has led to lignin degradation.

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However, the aforementioned aliphatic hydroxyl group, phenolic hydroxyl group, and methoxyl

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group (57-54 ppm) in the soluble fraction had 13, 4.3, and 2.5 folds of increases, respectively

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(Figure 2 D), suggesting that lignin had been depolymerized and/or decyclized. In particular, the

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significant increase in aliphatic region for soluble fraction of laccase-HBT processed lignin

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indicated that the benzene ring of lignin had undergone ring-opened reaction. The potential ring-

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opening reactions could also be supported by the reduction in aromatic region at 160-102 ppm in

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Figure S1. The results thus indicated that the soluble fraction of laccase-HBT processed lignin

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was a mixture of lignin-derived small molecule aromatic compounds, and non-aromatic

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compounds derived from lignin benzene ring opening reaction.

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The structural features well correlated with the performance of lignin as asphalt binder.

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Asphaltenes is generally considered as a highly polar aromatic material with the highest

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molecular weight in asphalt,8, 16 and lignin is polyphenylpropanoid macromolecule with aromatic

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monomers.2, 14 The similarity in molecular structures makes it possible for lignin to interact with

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asphaltene in asphalt binder. The results suggested that lignin could act as a cross linker to

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modify asphalt binder performances. First, lignin as a branched aromatic macromolecule could

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cross link with polar asphaltenes through dipolar-dipolar intermolecular forces to create a closely

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interacted macromolecular structure. Such cross-linking could generate macromolecular

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structure in a similar way as in plant cell wall. The cross-linked macromolecular structure may

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allow the asphalt to be more stable at high temperature, and thus prevent the melting (or rutting)

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at high temperature. However, such macromolecular structure could also lead to less molecular

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flexibility and thus higher viscosity of asphalt, which in turn could make asphalt binder more

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brittle and prone to cracking at low temperature. An increase in the molecular weight of

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insoluble lignin fraction (Figure 2C) would increase the asphalt binder stability at high

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temperature (Figure 2A) due to the enhanced dipolar-dipolar intramolecular forces between

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lignin and asphalt. On the other hand, the soluble lignin derived from laccase-mediator

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processing with lower molecular weight led to less extent of enhancement for high temperature

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performance (KL-L/H-Sol. in Figure 2A).

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Second, the differences in low temperature performance could be explained by the

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various functional groups in different lignin fractions. The improvement of asphalt binder’s low

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temperature performance by adding soluble lignin fraction could be due to the increase in

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hydroxyl groups in lignin structure. The soluble lignin with lower molecular weight (Figure 2C)

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had much more hydroxyl groups (Figure 2D), which could form intermolecular hydrogen bonds

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between this lignin and asphalt. The increased hydrogen bonding could enhance the flexibility of

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asphalt binder, thus improve the asphalt binder’s low temperature performance. The aliphatic and

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phenolic moieties could also increase the saturate and aromatic components of asphalt binder,

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and thus enhance the flexibility of asphalt binder. The significantly improved hydroxyl groups in

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soluble lignin fraction could balance off the effects on cross-linkage of lignin with asphaltene,

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and thus overall prevents the cracking of asphalt at a lower temperature. Overall, lignin could

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cross link with asphaltenes through dipolar-dipolar interactions to improve the high temperature

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performance of asphalt binder. In addition, the increased hydroxyl groups in biological processed

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lignin could also form intermolecular hydrogen bond to prevent the cracking of asphalt at a

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lower temperature.

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Development of Chemical Processes to Improve Lignin Property as Asphalt Binder

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Modifier

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Besides the biological lignin processing, we further developed a chemical process, where

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formic acid and Fenton reagent (iron ions and H2O2) were used to derive both soluble and

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insoluble lignin fractions. The combination of formic acid, iron ions, and H2O2 might synergize

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the formic acid and Fenton reactions to achieve maximized fractionization of Kraft lignin into

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formic acid-soluble and -insoluble fractions. These fractions were then evaluated for their

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capacity to serve as renewable asphalt binder modifiers. The results showed that the addition of

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the insoluble lignin fraction at 5% to 20% could significantly improve the high temperature

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performance of asphalt binder (Figure 3A). Meanwhile, the addition of the insoluble lignin had

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no significant impact on the low temperature properties (Figure 3B). The results highlighted the

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insoluble fraction from the chemical fractionation could serve as a quality asphalt binder

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modifier. However, the soluble fraction had a drastic different effect on asphalt performance as

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compared to all other type of lignin fractions. Basically, the high temperature performance was

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significantly reduced when >5% of soluble lignin fraction from chemical fractionation was added

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(Figure 3A), whilst the addition of 20% of the fraction could improve the low temperature

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performance of the asphalt binder.

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The distinct performance as asphalt binder modifier for chemically processed lignin 13

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fractions could be due to the unique pattern of functional groups. GPC and

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were carried out to understand the potential mechanisms for asphalt binder performance when

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adding different lignin fractions. Besides the molecular weight considerations, one of the key

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features is that carboxylate peaks were detected as C4 in Ar-COOH (163-161 ppm) for both

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insoluble and soluble fractions out of chemical fractionation (Figure S1). These carboxylate

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moieties could be derived from the oxidation of aliphatic hydroxyl group by formic acid.17 In

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addition, the semi-quantitative

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C-NMR analyses

C NMR showed that the insoluble fraction had a two-fold

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increase in aliphatic hydroxyl group, yet almost no phenolic hydroxyl groups were detected

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(Figure 3D). Meanwhile, aliphatic hydroxyl group in formic acid/water-soluble fraction was

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similar to that of Kraft lignin, whilst the content of phenolic hydroxyl groups was increased by

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three times (Figure 3D). The differences in functional groups between the two fractions could be

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that most of the phenolic hydroxyl groups were removed in the insoluble fraction, whilst the

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benzene ring was slight degraded in the soluble portion, leading to an increase in the phenolic

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hydroxyl group per aromatic ring. The functional groups, in particular, the Ar-COOH group

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might have a significant impact on the asphalt binder performance. As a strong polar and more

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oxidized group, the Ar-COOH group could have prevented the better crosslinking of lignin with

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asphaltenes and thus reduced the melting temperature at high temperature. For the insoluble

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fraction, the lignin fraction with much higher molecular weight would enhance the dipolar-

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dipolar intermolecular forces between lignin and asphaltene to form an interacted

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macromolecular structure as aforementioned. The Ar-COOH group might interfere with the

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formation of macromolecular structure, yet the combinatory effects still led to the enhancement

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of high temperature performance. However, for the soluble fraction, the effects of Ar-COOH

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group could be more predominant considering the low molecular weight of lignin molecules. The

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increase of concentrations for soluble lignin fraction led to a decrease in high temperature

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performance of asphalt binder.

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Processed Lignin Improved Aging Resistance, Mechanical and Rheological properties

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To further evaluate the potential of fractionated lignin as renewable asphalt binder

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modifier, we investigated the aging resistance, mechanical and rheological properties of the

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asphalt binder when mixed with fractionated lignin. One of the key considerations of the asphalt

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binder performance is the aging resistance. To study the effects of lignin on binder aging

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resistance, we compared the G*/sinδ ratio of aged to unaged among the base asphalt binder and

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modified binders with different lignin fractions. Smaller G*/sinδ ratio means better aging

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resistance. The results showed that G*/sinδ ratio of the modified asphalt binders with the

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biologically processed lignin fractions and the chemically processed insoluble lignin fraction

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were significantly low than that of the base binder (Figure S2). Thus, these modified lignin

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fractions significantly improved the aging resistance property of asphalt binder. However, the

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asphalt binder modified with chemically processed soluble lignin fraction has lower aging

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resistance. This observation suggested that the method used for lignin fractionation would have

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significant impact on the aging resistance. The results also indicated that three out of four

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fractions from processed lignin could improve aging resistance of asphalt binder. In combination

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with temperature performance (Figures 2A, 2B, 3A, and 3B), the results highlighted that these

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fractions could serve as quality asphalt binder modifiers.

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Another important consideration for asphalt binder performance is the mechanical and

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rheological property.18-19 The shear modulus (or stiffness) of binders doped with different

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percentage of lignin were measured from the frequency sweep tests. The results showed that

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stiffness of either base asphalt binder or lignin modified asphalt binder increased with an

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increase in loading frequency – a typical response of viscoelastic material (Figure S3). The

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results also demonstrated that, at any given loading frequency, binder stiffness increases with an

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increase in the percentage of lignin (Figure S3). Our study also indicated that, under low lignin

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dosage, the binder modified with biologically processed insoluble fraction was stiffer than the

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binder modified with raw Kraft lignin and the soluble fraction (Figure S4), which is consistent

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with our aforementioned results on high- and low- temperature properties.

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Lignin Offers New Opportunities for Renewable Asphalt Binder Modifier

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Overall, the results highlighted the potential of modified lignin to serve as renewable

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asphalt binder modifier. First, we have established that raw Kraft lignin can improve high

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temperature performance of asphalt binder, yet decrease the low-temperature performance. The

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results highlighted the potential and limitation of lignin as a renewable asphalt binder modifier,

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and indicated the necessity of modifying lignin for the application. Second, we have developed

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two different methods to process lignin to produce quality asphalt binder modifiers. Even though

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lignin has been proposed to serve as asphalt antioxidant before, previous studies fall short in

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evaluating lignin as an asphalt binder modifier to enhance both high temperature and low

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temperature performance. We hereby established the concept that lignin can be properly

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processed to derived fractions to serve asphalt binder modifier to improve asphalt binder

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performance under different temperatures. In particular, two lignin processing strategies were

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developed, a biological process based on enzyme-mediator system, and a chemical process using

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formic acid, iron and H2O2. Both the soluble fraction of biologically processed lignin and the

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insoluble fraction of the chemically processed lignin can serve as quality asphalt binder modifier

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to enhance high temperature performance of asphalt mixtures without compromising the low

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temperature performance. Moreover, the soluble fraction of biologically processed lignin might

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even improve both high and low temperature performance of asphalt binder, offering unique

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features as modifier. Third, we have established that some lignin fractions not only improved

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temperature performance, but also enhanced aging resistance of asphalt binder. In particular,

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three out of four fractions of processed lignin could increase aging resistance, including the

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soluble fraction of biologically processed lignin. The fraction thus can serve as unique asphalt

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binder modifier for improving aging resistance along with the high and low temperature

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performance. Fourth, the study established potential mechanisms regarding how molecular

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weight and functional groups could impact the performance of asphalt binder. Extensive studies

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need to be carried out to further verify the hypothesis established in this study. Nevertheless, the

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results could provide practical guidance on how to fractionate lignin toward asphalt binder

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modifiers to suite different applications.

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Lignin is a major waste from biorefinery and paper-making industry. The study not only

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provides fundamental understanding on how to produce quality modifier from lignin to improve

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asphalt binder performance, but also enables the biological and chemical modification of

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industrial lignin for value-added material to benefit the entire biorefinery supply chain. Thus, the

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utilization of lignin as asphalt binder modifier renders practical solutions for both road pavement

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and biorefinery industry. The additional stream will enable a multi-stream biorefinery with better

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sustainability and cost-effectiveness. In particular, the soluble fraction of biologically processed

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lignin can actually improve both high temperature and low temperature performance of asphalt

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binder, which is a unique feature that most of petroleum-based asphalt binders lack. The study

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thus not only provided a new approach to utilize an industrial waste for valued products, but also

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enabled asphalt binders with unique features.

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Acknowledgement

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The work was supported by the U.S. DOE (Department of Energy) EERE (Energy

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Efficiency and Renewable Energy) BETO (Bioenergy Technology Office) (grant No. DE-

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EE0006112 and DE-EE0007104) to J.S.Y. The research was also supported by Texas A&M

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Agrilife Research's biofuel initiative to J.S.Y.

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Supplementary Information

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Methods and Materials

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Figure S1. 13C NMR spectra of lignin.

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Figure S2. G*/sinδ ratios of aged and unaged samples for unmodified base binder and modified

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binders doped with 10% different lignin fractions.

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Figure S3. Mechanical and rheological properties of base asphalt binder and asphalt binders

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modified with different dosage of Kraft lignin.

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Figure S4. Mechanical and rheological properties of asphalt binders modified with 3% different

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lignin.

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Table S1. Assignments and quantification of functional groups in 13C NMR spectra

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Reference

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1. Ragauskas, A. J.; Beckham, G. T.; Biddy, M. J.; Chandra, R.; Chen, F.; Davis, M. F.; Davison, B. H.; Dixon, R. A.; Gilna, P.; Keller, M.; Langan, P.; Naskar, A. K.; Saddler, J. N.; Tschaplinski, T. J.; Tuskan, G. A.; Wyman, C. E., Lignin Valorization: Improving Lignin Processing in the Biorefinery. Science 2014, 344 (6185). 2. Xie, S.; Ragauskas, A. J.; Yuan, J. S., Lignin Conversion: Opportunities and Challenges for the Integrated Biorefinery. Ind. Biotechnol. 2016, 12 (3), 161-167. 3. Xie, S.; Syrenne, R.; Sun, S.; Yuan, J. S., Exploration of Natural Biomass Utilization Systems (NBUS) for advanced biofuel--from systems biology to synthetic design. Curr. Opin. Biotechnol. 2014, 27 (0), 195-203. 4. Gargulak, J. D.; Lebo, S. E., Commercial Use of Lignin-Based Materials. In Lignin: Historical, Biological, and Materials Perspectives, American Chemical Society: 1999; Vol. 742, pp 304-320. 5. Association, N. A. P., The Asphalt Paving Industry, A Global Perspective. EAPA, Brussels: 2011.www.eapa.org/userfiles/2/Publications/GL101-2nd-Edition.pdf. 6. Wang, P.; Dong, Z.-j.; Tan, Y.-q.; Liu, Z.-y., Investigating the Interactions of the Saturate, Aromatic, Resin, and Asphaltene Four Fractions in Asphalt Binders by Molecular Simulations. Energ. Fuel. 2015, 29 (1), 112-121. 7. Strausz, O. P.; Mojelsky, T. W.; Faraji, F.; Lown, E. M.; Peng, P. a., Additional structural details on Athabasca asphaltene and their ramifications. Energ. Fuel. 1999, 13 (2), 207-227. 8. Wei, J. B.; Shull, J. C.; Lee, Y.-J.; Hawley, M. C., Characterization of asphalt binders based on chemical and physical properties. Int. J. Polym. Anal. Charact. 1996, 3 (1), 33-58. 9. 230, I. S. N., The Bitumen Industry-A Global Perspective: Production, Chemistry, Use, Specification and Occupational Exposure. 3rd Edition, a joint publication of Asphalt Institute and Eurobitume 2015, (ISBN 978-1-934154-73-1). 10. Xu, Z.; Zhang, D.; Hu, J.; Zhou, X.; Ye, X.; Reichel, K. L.; Stewart, N. R.; Syrenne, R. D.; Yang, X.; Gao, P.; Shi, W.; Doeppke, C.; Sykes, R. W.; Burris, J. N.; Bozell, J. J.; Cheng, M. Z.; Hayes, D. G.; Labbe, N.; Davis, M.; Stewart, C. N., Jr.; Yuan, J. S., Comparative genome analysis of lignin biosynthesis gene families across the plant kingdom. BMC Bioinformatics 2009, 8 (10), 1471-2105. 11. Li, Q.; Koda, K.; Yoshinaga, A.; Takabe, K.; Shimomura, M.; Hirai, Y.; Tamai, Y.; Uraki, Y., Dehydrogenative Polymerization of Coniferyl Alcohol in Artificial Polysaccharides Matrices: Effects of Xylan on the Polymerization. J. Agric. Food Chem. 2015, 63 (18), 4613-4620. 12. Mills-Beale, J.; You, Z.; Fini, E.; Zada, B.; Lee, C. H.; Yap, Y. K., Aging influence on rheology properties of petroleum-based asphalt modified with biobinder. J. Mater. Civ. Eng. 2012, 26 (2), 358-366. 13. Pan, T., A first-principles based chemophysical environment for studying lignins as an asphalt antioxidant. Constr. Build. Mater. 2012, 36, 654-664. 14. Zhao, C.; Xie, S.; Pu, Y.; Zhang, R.; Huang, F.; Ragauskas, A. J.; Yuan, J. S., Synergistic enzymatic and microbial lignin conversion. Green Chem. 2016, 18 (5), 1306-1312. 15. Pandey, M. P.; Kim, C. S., Lignin depolymerization and conversion: a review of thermochemical methods. Chem. Eng. Technol. 2011, 34 (1), 29-41. 16. Peramanu, S.; Pruden, B. B.; Rahimi, P., Molecular Weight and Specific Gravity Distributions for Athabasca and Cold Lake Bitumens and Their Saturate, Aromatic, Resin, and Asphaltene Fractions. Ind. Eng. Chem.Res. 1999, 38 (8), 3121-3130.

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17. Rahimi, A.; Ulbrich, A.; Coon, J. J.; Stahl, S. S., Formic-acid-induced depolymerization of oxidized lignin to aromatics. Nature 2014, 515 (7526), 249-52. 18. Golestani, B.; Nam, B. H.; Nejad, F. M.; Fallah, S., Nanoclay application to asphalt concrete: Characterization of polymer and linear nanocomposite-modified asphalt binder and mixture. Constr. Build. Mater. 2015, 91, 32-38. 19. Golestani, B.; Nejad, F. M.; Galooyak, S. S., Performance evaluation of linear and nonlinear nanocomposite modified asphalts. Constr. Build. Mater. 2012, 35, 197-203.

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Figures and figure legends

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Figure 1.The limitation of raw Kraft lignin as asphalt binder modifier, and the strategies to

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process lignin toward effective asphalt binder modifier.

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Figure 2. The performance of laccase-HBT processed lignin fractions as asphalt binder modifiers.

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A. The high temperature performance grade of asphalt binder with different percentage of

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various lignin fractions. B. The low temperature performance grade of asphalt binder with

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different percentage of various lignin fractions. C. The GPC analysis of the different processed

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lignin fractions. D. The 13C NMR analysis of the different processed lignin fractions. KL, Kraft

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lignin without processing; KL-L/H-Insol, the insoluble fraction of the Kraft lignin after laccase-

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HBT processing; KL-L/H-Sol, the soluble fraction of the Kraft lignin after laccase-HBT

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processing.

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Figure 3. The performance of formic acid/Fenton-processed lignin. A. The high temperature

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performance grade of asphalt binder with the addition of different percentage of various lignin

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fractions. B. The low temperature performance grade of asphalt binder when adding various

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lignin fractions at different concentrations. C. The GPC analysis of the different lignin fractions

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after chemical processing. D. The

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processing. KL, Kraft lignin without processing; KL-FA-Insol, the insoluble fraction of the Kraft

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lignin after formic acid/Fenton processing; KL-FA-Sol, the soluble fraction of the Kraft lignin

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after formic acid/Fenton processing.

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C analysis of the different lignin fractions after chemical

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For Table of Contents Use Only

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Lignin as Renewable and Superior Asphalt Binder Modifier

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Shangxian Xie, Qiang Li, Pravat Karki, Fujie Zhou, and Joshua S. Yuan

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Abstract Graphic

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Synopsis The biologically and chemically processed lignin could serve as unique renewable modifier to improve both high and low temperature performance of asphalt binder.

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