Self-Assembled TEMPO Cellulose Nanofibers: Graphene Oxide

May 30, 2017 - The porous biohybrid structure, studied using advanced microscopy techniques, revealed a unique networking and self-assembling of TOCNF...
3 downloads 13 Views 7MB Size
Subscriber access provided by AUSTRALIAN NATIONAL UNIV

Article

Self-assembled TEMPO Cellulose Nanofibers – Graphene Oxide based Biohybrids for Water Purification Chuantao Zhu, Peng Liu, and Aji P Mathew ACS Appl. Mater. Interfaces, Just Accepted Manuscript • Publication Date (Web): 30 May 2017 Downloaded from http://pubs.acs.org on May 31, 2017

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

ACS Applied Materials & Interfaces is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 38

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Applied Materials & Interfaces

Self-assembled TEMPO Cellulose Nanofibers – Graphene Oxide based Biohybrids for Water Purification Chuantao Zhu, Peng Liu and Aji P Mathew* Division of Materials and Environmental Chemistry, Stockholm University, Stockholm, 10691, Sweden

ABSTRACT: Nanocellulose, graphene oxide and its combinations there off, have triggered great attention for the application of water purification recently, due to the unique adsorption capacity, mechanical characteristics, coordination with transition metal ions, surface charge density etc.

In the current work TEMPO (2,2,6,6-tetramethylpiperidine-1-oxylradical) -

mediated oxidation nanofibers (TOCNF) and graphene oxide sheets (GO) or graphene oxide nanocolloids (nanoGO) biohybrids were prepared by vacuum filtration method to obtain selfassembled adsorbents and membranes for water purification. The porous biohybrid structure, studied using advanced microscopy techniques, revealed a unique networking and selfassembling of TOCNF, GO and nanoGO, driven by the morphology of the GO phase and stabilized by the inter molecular H- bonding between carboxyl groups and hydroxyl groups. The biohybrids exhibited promising adsorption capacity towards Cu(II) mainly contributed by TOCNF and formed a unique ‘arrested state’

in water due to ionic crosslinking between

adsorbed Cu(II) and the negatively charged TOCNF and GO phase. The mechanical performance of the freestanding biohybrid

membranes investigated using PeakForce Quantative

NanoMechanics (PF-QNM) characterization confirmed the enhanced modulus of the hybrid membrane compared with TOCNF membrane. Besides, the TOCNF+nanoGO membrane shows

ACS Paragon Plus Environment

1

ACS Applied Materials & Interfaces

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 2 of 38

unique hydrolytic stability and recyclability even under several circles of adsorption and desorption and strong sonication. The study shows that TOCNF and nanoGO hybrids can generate a new generation of water cleaning membranes with synergistic properties with respect to high adsorption capacity, flexibility, hydrolytic stability and mechanical robustness. KEYWORDS: TEMPO cellulose nanofibers, graphene oxide nanocolloids, biohybrid, water purification, Peak Force QNM

1. INTRODUCTION A tremendous amount of research are in progress to identify new robust materials and methods to address one of the most pervasive worldwide problems - Water pollution. 1,2 Nanocellulose, prepared by a top-down approach from abundantly available wood biomass and in particular the 3-7

TEMPO (2,2,6,6-tetramethylpiperidine-1-oxylradical) - mediated oxidised nanofibers

(TOCNF), modified by the position - selective catalytic oxidation of C6 primary hydroxyls from nanocellulose, have shown high efficiency for the removal of water contaminants and has been studied extensively in recent years. 8, 9 TOCNF have unique and characteristic properties in terms of high aspect ratios (>100), high crystallinity (65-95%), low ζ-potential in water (~-75 mV), high tensile strengths (200-300 MPa) and elastic moduli (6–7 GPa). 8, 10 The carboxyl and hydroxyl groups on the surface of TOCNF is found to co-ordinate effectively and capture heavy metallic cations (Cu(II), Co(II), Ni(II), Cd(II), Ag(I))

11-13

or different organic pollutants (p-

nitrophenol, 2,4,5-trichlorophenol, and amoxicillin) etc 14-16 Our recent studies showed that the adsorption capacity could even reach to 374 mg/g toward Cu(II) by in-situ TEMPO modified membranes 17 which is much higher than many other bio-based adsorbents (