The effects of γ-irradiation dose and process time on the structure and properties of alkali lignin have been quantitatively evaluated. According to the 13C CP/MAS NMR FTIR analyses, the γ-irradiation dose, D, and process time, t, on lignin structure have been known to break the side-chains of lignin, e.g. the C-β structure within the β-O-4, to enhance the C=O and C=C structure. By taking the NMR peak intensity of C=O structure, IC=O, and IR peak intensity of C=C structure, IC=C, as two measures, we obtained quantitatively relationships between D or t and those two lignin structures, respectively. Thermogravimetric analyses indicated that the lignin has an original thermal stability and its degradation was started since the applied dose at 300 kGy or the time up to 24 h at 100 kGy condition. The γ-irradiated lignin presented enhanced liquid adsorption due to the adsorbed water amount, Qt, increased with the D increase to follow a non-linear relationship.
DongJQ, ShenQ.2009. Enhancement in solubility and conductivity of polyaniline with lignosulfonate modified carbon nanotube. J. Polym Sci B. 47:2036. doi: 10.1002/polb.21802
8.
DziedzielaWM, KotynskaDJ.1984. Some aspects of radiation-induced transformations of cellulose. Radiat Phys Chem. 23:723.
9.
FernandesDM, HechenleitnerAAW, JobAE, RadovanocicE, Gomez-PinedaEA.2006. Thermal and photochemical stability of poly(vinylalcohol)/modified lignin blends. Polym Degrad Stab91:1192. doi: 10.1016/j.polymdegradstab.2005.05.024
10.
FrazierCE, NiJ, SchmidtRG.1999. Application of NMR spectroscopy to the analysis of wood/adhesive bondlines. In: ArgyropoulosD S, editor. Advances in Lignocellulosics Characterization. Atlanta, USA: TAPPI Press; p. 145–156.
11.
HatfieldGR, MacielGE, ErbaturO, ErbaturG.1987. Qualitative and quantitative analysis of solid lignin samples by carbon-13 nuclear magnetic resonance spectrometry. Anal Chem. 59:172. doi: 10.1021/ac00128a036
12.
HawkesGE, SmithCZ, UtleyJHP, VargasRR, ViertlerH.1993. A comparison of solution and solid state 13C NMR spectra of lignins and lignin model compounds. Holzforschung. 47:302. doi: 10.1515/hfsg.1993.47.4.302
13.
KhanF, AhmadS, KronfliR.2006. γ-Radiation induced changes in the physical and chemical properties of lignocellulose. Biomacromolecules. 7:2303. doi: 10.1021/bm060168y
14.
KuzinaSI, ShilovaIA, MikhailovAI.2011. Chemical and radiation-chemical radical reactions in lignocellulose materials. Radiat Phys Chem. 80:937. doi: 10.1016/j.radphyschem.2011.04.005
LiB, AsikkalaJ, FilpponenI, ArgyropoulosDS.2010. Factors affecting wood dissolution and regeneration of ionic liquids. Ind Eng Chem Res. 49:2477. doi: 10.1021/ie901560p
17.
LiC, ZhaoX, WangA, HuberGW, ZhangT.2015. Catalytic transformation of lignin for the production of chemicals and fuels. Chem Rev. 115:11559. doi: 10.1021/acs.chemrev.5b00155
18.
LiuE, LiM, DasL, PuY, FrazierT, ZhaoB, CrockerM, RagauskasAJ, ShiJ.2018. Understanding lignin fractionation and characterization from engineered switchgrass treated by an aqueous ionic liquid. ACS Sustainable Chem Eng. 6:6612. doi: 10.1021/acssuschemeng.8b00384
19.
LuoH, ShenQ, YeF, ChengYF, MezgebeM, QingRJ.2012. Structure and properties of layer-by-layer self-assembled chitosan/lignosulfonate multilayer films. Mater Sci Eng C. 32:2001. doi: 10.1016/j.msec.2012.05.023
20.
MaR, HaoW, MaX, TianY, LiY.2014. Catalytic ethanolysis of kraft lignin into high-value small-molecular chemicals over a nanostructured a-molybdenum carbide catalyst. Angew Chem Int Ed. 53:7310. doi: 10.1002/anie.201402752
21.
MartınezAT, AlmendrosG, Conzalez-VilaFJ, FrundR.1999. Solid-state spectroscopic analysis of lignins from several Austral hardwoods. Solid State NMR. 15:41. doi: 10.1016/S0926-2040(99)00045-4
22.
MezgebeM, ShenQ, ZhangJY, ZhaoYW.2012. Liquid adsorption behavior and surface properties of carbon black. Colloids Surf A. 453:25. doi: 10.1016/j.colsurfa.2012.03.045
23.
PhillipsGO, ArthurJC.1985. Photochemistry and radiation chemistry of cellulose. In: NevellTP, ZeronianSH, editors. Cellulose chemistry and its applications. Chichester: Ellis Horwood Ltd. Publishers; p. 291.
24.
RojasOJ, BullónJ, YsamberttF, ForgiariniA, SalagerJL, ArgyropoulosDS.2007. Lignins as emulsion stabilizers. In: Materials, chemicals, and energy from forest biomass, Chapter 12, p. 182–199.
25.
ShaoY, XiaQ, DongL, LiuX, HanX, ParkerSF, ChengY, DaemenLL, Ramirez-CuestaAJ, YangS, WangY.2017. Selective production of arenes via direct lignin upgrading over a niobium-based catalyst. Nat Commun. 8:16104. doi: 10.1038/ncomms16104
26.
ShenQ, MezgebeM, LiF, DongJQ.2011. Liquid adsorption behavior and surface properties of PANI doped by lignosulfonated modified carbon nanotubes. Colloids Surf A. 390:212. doi: 10.1016/j.colsurfa.2011.09.030
27.
ShenQ, MuD, YuLW, ChenL.2004. A simplified approach for evaluation of the polarity parameters for polymer using the K coefficient of the Mark-Houwink-Sakurada equation. J Colloid Interface Sci. 275(1):30. doi: 10.1016/j.jcis.2004.01.041
28.
ShenQ, RosenholmJB.1998. Kraft black liquors properties in relation to delignification. Nordic Pulp Paper Res J. 13(3):206. doi: 10.3183/NPPRJ-1998-13-03-p206-210
ShenQ, ZhangT, ZhuMF.2008. A comparison of the surface properties of lignin and sulfonated lignins by FTIR spectroscopy and wicking technique. Colloids Surf A. 320:57. doi: 10.1016/j.colsurfa.2008.01.012
31.
ShenQ, ZhongL.2007. Lignin-based carbon films and controllable pore size and properties. Mater Sci Eng A. 445:731. doi: 10.1016/j.msea.2006.09.066
32.
TakacsE, WojnarovitsL, BorsaJ, FoldvaryC, HargittaiP, ZoldO.1999. Effect of γ-irradiation on cotton-cellulose. Radiat Phys Chem55:663. doi: 10.1016/S0969-806X(99)00245-5
33.
TakacsE, WojnarovitsL, FoldvaryC, HargittaiP, BorsaJ, SajoI.2000. Effect of combined gamma-irradiation and alkali treatment on cotton–cellulose. Radiat Phys Chem. 57:399. doi: 10.1016/S0969-806X(99)00409-0
34.
WilliamsJL, StannettV, RoldanLG, SelloSB, StevensCV.1975. Graft copolymers as elastomeric fibers-II, mechanical properties and morphology of grafted copolymers. Int J Appl Radiat Isotopes. 26:169. doi: 10.1016/0020-708X(75)90113-1
35.
YoussefSK, OsirisWG, HashadAM.1996. Radiation induced effects on the physical properties of bioequivalent membrane cellulose acetate. Radiat Phys Chem. 47:321. doi: 10.1016/0969-806X(94)00185-M
36.
ZakzeskiJ, BruijnincxPC, JongeriusAL, WeckhuysenBM.2010. The catalytic valorization of lignin for the production of renewable chemicals. Chem Rev. 110:3552. doi: 10.1021/cr900354u
37.
ZhouHF, ZhouTW, ShenQ.2010. Rheological properties of lignin and lignosulfonates. Chin J Cellulose Sci Technol. 18(1):29. (In Chinese).
