Scalable Preparation of Cellulose Nanofibers from Office Waste Paper by an Environment-Friendly Method.

Deyuan Huang,Haiyan Zhang,Weilong Huang,Xiaobin Hong,Haoqun Hong

doi:10.3390/polym13183119

Deyuan Huang, Haiyan Zhang + Show 3 more

Open Access

https://doi.org/10.3390/polym13183119

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Abstract

Waste paper is often underutilized as a low-value recyclable resource and can be a potential source of cellulose nanofibers (CNFs) due to its rich cellulose content. Three different processes, low acid treatment, alkali treatment and bleaching treatment, were used to pretreat the waste paper in order to investigate the effect of different pretreatments on the prepared CNFs, and CNFs obtained from bleached pulp boards were used as control. All sample fibers were successfully prepared into CNFs by 2,2,6,6-tetramethyl-piperidine-1-oxyl (TEMPO) oxidation. It was quite obvious that the bleached CNFs samples showed dense fibrous structures on a scanning electron microscopy (SEM), while needle-like fibers with width less than 20 nm were observed on a transmission electron microscopy (TEM). Meanwhile, the bleaching treatment resulted in a 13.5% increase in crystallinity and a higher TEMPO yield (e.g., BCNF, 60.88%), but a decrease in thermal stability. All pretreated CNFs samples showed narrow particle size distribution, good dispersion stability (zeta potential less than −29.58 mV), good light transmission (higher than 86.5%) and low haze parameters (lower than 3.92%). This provides a good process option and pathway for scalable production of CNFs from waste papers.

Highlights

With the increasing calls for environmental protection and resource depletion, sustainable green development has become an everlasting international topic and our pursuit of sustainable green materials has never stopped
The fiber morphology of all TEMPO-oxidized cellulose nanofibers (CNFs) samples was observed by scanning electron microscopy (SEM)
In the partial enlarged image on the right, there are many nanopore structures on the leaf surface due to cellulose accumulation, which indicates that office waste paper containing high cellulose content can be prepared into CNFs without any pretreatment

Summary

Introduction

With the increasing calls for environmental protection and resource depletion, sustainable green development has become an everlasting international topic and our pursuit of sustainable green materials has never stopped. The use of natural biodegradable materials such as cellulose [1], chitin [2] and starch [3] has been greatly promoted. As a potential and neglected source of nanocellulose [11], requires no excessive physical and chemical treatment to remove lignin and hemicellulose because most of the lignin and hemicellulose in lignocellulosic biomass is already removed by the papermaking process [12,13,14]. Lignin and hemicellulose are removed using sodium hydroxide and sodium sulfite at 80–90 ◦ C, followed by bleaching by sodium hypochlorite to further remove lignin. Waste paper contains a high cellulose content (60–70%) because of the debinding and bleaching process, while the total amount of hemicellulose and lignin

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