Sustainable valorization of paper mill sludge into cellulose nanofibrils and cellulose nanopaper

Haishun Du; Mahesh Parit; Meiyan Wu; Xinpeng Che; Yifan Wang; Miaomiao Zhang; Ruigang Wang; Xinyu Zhang; Zhihua Jiang; Bin Li

doi:10.1016/j.jhazmat.2020.123106

Sustainable valorization of paper mill sludge into cellulose nanofibrils and cellulose nanopaper

J Hazard Mater. 2020 Dec 5:400:123106. doi: 10.1016/j.jhazmat.2020.123106. Epub 2020 Jun 12.

Authors

Haishun Du¹, Mahesh Parit¹, Meiyan Wu², Xinpeng Che², Yifan Wang³, Miaomiao Zhang¹, Ruigang Wang³, Xinyu Zhang⁴, Zhihua Jiang⁵, Bin Li⁶

Affiliations

¹ Department of Chemical Engineering, Auburn University, Auburn, AL, 36849, USA.
² CAS Key Laboratory of Biofuels, Dalian National Laboratory for Clean Energy, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong, 266101, China.
³ Department of Metallurgical and Materials Engineering, The University of Alabama, AL, 35487, USA.
⁴ Department of Chemical Engineering, Auburn University, Auburn, AL, 36849, USA. Electronic address: xzz0004@auburn.edu.
⁵ Department of Chemical Engineering, Auburn University, Auburn, AL, 36849, USA. Electronic address: zzj0012@auburn.edu.
⁶ CAS Key Laboratory of Biofuels, Dalian National Laboratory for Clean Energy, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong, 266101, China. Electronic address: libin@qibebt.ac.cn.

PMID: 32580093
DOI: 10.1016/j.jhazmat.2020.123106

Abstract

As a kind of agro-industrial wastes, paper mill sludge (PMS) has posed serious environmental and economic challenges for disposal due to the more stringent regulations and diminishing land availability in recent years. The present study is aimed at providing a sustainable approach to efficiently convert PMS to cellulose nanofibrils (CNFs) and cellulose nanopaper (CNP) by formic acid (FA) hydrolysis pretreatment and the followed microfluidization. It is found that FA hydrolysis (4-6 h) could swell and shorten PMS fibers, and only two-pass microfluidization is sufficient to get uniform CNFs from the collected cellulose residual. Results indicate that the obtained CNFs show high thermal stability and crystallinity index, surface functionality (ester groups), as well as a high yield of over 75 wt.%. Notably, more than 90 % FA can be recovered and the hydrolyzed sugars could be potentially used to produce platform chemicals (e.g. lactic acid, furfural). Finally, transparent CNP is prepared from the CNFs suspension via a simple vacuum filtration technique. The resultant CNP shows good mechanical properties with the maximum tensile strength and toughness of 106.4 MPa and 6.62 MJ/m³, respectively. Therefore, the current work provides a green and sustainable method to valorize PMS for the production of valuable CNFs and CNP.

Keywords: Cellulose nanofibrils; Cellulose nanopaper; Formic acid hydrolysis; Mechanical fibrillation; Paper mill sludge.

Publication types

Research Support, Non-U.S. Gov't