NFC /MFC Porous Structures

Development of microfibrillated cellulose-based porous materials in consideration of industrial relevant processes (CelPorMat)
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Picture: The light-weight material absorbs the oil spill, remains floating on the water surface and can then be recovered.

The objective of this project is to engineer cellulose-based porous materials, which can be used for various sorption applications for liquids. By tailoring the porosity and surface chemistry of these novel three-dimensional cellulosic structures, the hydrophilicity and oleophilicity of the final product will be tuned and optimized. The development and engineering of the sorbents take place with regard to industrial relevant processes and scalability.

 

Contact:  / Dr. Carlo Antonini

 

Partner:

Weidmann Fiber Technology (Wicor Holding AG)

Dr. Wolfgang Exner

Otto Nylén / Stefan Truniger

 

ETH Zurich, Laboratory of Food Process Engineering 

Prof. Erich Windhab

Judith Wemmer

 

Funding: Commission for Technology and Innovation CTI

Functional nanocellulose filters for water purification

Future technologies for water purification should call for chemically, energetically and operationally straightforward processes having a minimum impact on the environment. In this context water purification by filters comprising functional cellulose nanofibers (CNF) seems to represent an efficient strategy to enhance the quality and supply of water without intensive chemical treatment. Here we aim to understand the CNF filter processing-structure-performance relationship as well as the molecular-scale interactions occurring at the aqueous interface between constituents in water and the filter. The goal is to develop CNF filters with enhanced fluxes, improved contaminant retention with higher selectivity, low fouling and good resistance to a given chemical environment. The low carbon footprint of the CNF filter technology is also our challenge. Hence, we are exploiting waste raw materials (residues from wood pulp and crab shell) for filter development. Targeted contaminants include heavy metal ions, natural organic matter (humic acid) and nitrates.

Poster: Adsorption of natural organic matter onto cationic cellulose nanofibers for water purification

Publications:

  • Liu, P., Sehaqui, H., Tingaut, P., Wichser, A., Oksman, K., Mathew, A.P. Cellulose and chitin nanomaterials for capturing silver ions (Ag+) from water via surface adsorption (2014) Cellulose, 21 (1), pp. 449-461.

  • Sehaqui, H.; de Larraya, U. P.; Liu, P.; Pfenninger, N.; Mathew, A. P.; Zimmermann, T.; Tingaut, P., Enhancing adsorption of heavy metal ions onto biobased nanofibers from waste pulp residues for application in wastewater treatment (2014) Cellulose, pp. 1-14.

  • Sehaqui, H.; de Larraya, U. P.; Zimmermann, T.; Tingaut, P., Humic acid adsorption onto cationic cellulose nanofibers for bioinspired removal of copper (II) and a positively charged dye (2015) Soft Matter, 11 (26), pp. 5294-5300

  • Mautner, A., Maples, H.A., Sehaqui, H., Zimmermann, T., Perez U., Mathew, A.P, Lai, C.Y., Li, K., Bismarck, A. Nitrate removal from water using a nanopaper ion-exchanger (2015) Environmental Science: Water Research & Technology

  • Sehaqui, H., Mautner, A., Perez U., Pfenninger, N., Tingaut, P.,  Zimmermann, T., Cationic cellulose nanofibers from waste pulp residues and their nitrate, fluoride, sulphate and phosphate adsorption properties (2015)  Carbohydrate polymers 135, 334-340

Contact: Dr. Tanja Zimmermann

Partner:
Lulea University of Technology / VTT / Imperial College of London / Maribor University / Cemitec / Processum / Acondaqua / Alfa Laval

Funding: European project NanoSelect FP7 collaborative project

Functional dense and porous substrates for environmental remediation and water purification

This PhD project deals with the development of dense and porous substrates based on nanofibrillated cellulose (NFC). NFC serves as building block for the realization of different products targeting environmental remediation applications. By changing the drying procedure the self-assembly process of nanofibers can be tuned generationg highly packed structure with porosity below 5% or extremely porous architecture with porosity close to 90%. Classical paper-making approaches (membranes), freeze-drying (foams) and supercritical drying (aerogels) were employed to produce membranes for purification of water and foams for oil-spills absorption. 

In a first step a systematic study of porosity based on readily available porometric techniques has been carried out to evaluate the limits for characterization of membranes in dry and wet state (Orsolini et al. 2015). In a second study we developed high-permeance NFC membranes based on a templating approach to achieve water permeances competitive with industrial products. In parallel chemical modification strategies were envisaged to tune the amphiphilicity of nanocellulose based on chlorosilane chemistry. Chlorosilanes can impart new functionality to the cellulosic materials surfaces mastering water repellency and oil affinity. 

Contact: Dr. Tanja Zimmermann

Partner:


ETH Zurich, Multifunctional Materials Laboratory


ETH Zurich, Multifunctional Materials Laboratory

Publication:

P. Orsolini / B. Michen / A. Huch / P. Tingaut / W.R. Caseri / T. Zimmermann
Characterization of pores in dense nanopapers and nanofibrillated cellulose membranes: a critical assessment of established methods. ACS Appl. Mater. Interfaces 7 (2015) 25884-25897

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Figure 2 and 3: Cellulose pulp fibers are converted first into a NFC water-suspension and processed by fitration to form a dense NFC membrane. This was investigated by means of SEM microscopy, nitrogen adsorption, mercury intrusion and thermoporometry
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Figure 4: Superhydrophobic NFC membrane modified with chlorosilane showing water repellence behaviour.
ALD coating of highly porous cellulose materials
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Figure 1: schematic representation of a typical ALD cycle for the deposition of alumina using trimethylaluminium (TMA) and water as precursors

The main goal of this study is to understand the evolution of the pore size distribution and porosity of complex porous structure like cellulose foam or aerogel during ALD (figure 1). This will eventually result in a new method to characterize these materials by growing a conformal coating on the substrate surface and by measuring the pressure drop change. In fact in the home-made design of a flow through ALD reactor (figure 2) a pressure gauge allows to measure the pressure drop across the sample with a different volume of argon. This measure is related to characteristics of the membrane like pores size distribution, porosity, tortuosity and thickness. During the ALD process the conformal coating of the porous substrate changes in a very specific manner its characteristics: for example, the shifting of the pore size distribution to smaller pores or the reduction of porosity. All these modifications are appreciable by measuring the pressure drop during an ALD process revealing an interesting alteration of the structure that will be described. 

Contact:  / Dr. Tanja Zimmermann

Partner:
, Empa Thun, Mechanics of Materials and Nanostructures / Dr. Markus Rüggeberg, ETHZH

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Figure 2: representation of a designed flow through ALD reactor