NanoPlasma: Nanofibril production using plasma

In the NanoPlasma project, we have developed a plasma reactor that enables the fibrillation of cellulose using high voltage. Today cellulose nanofibrils (CNFs) can be produced, for instance by homogenization. Multiple passes of cellulose fibres through a homogenizer require high energy consumption. There are ways to reduce the high energy consumption substantially, but these include either complicated biological (enzymatic) pretreatment or chemical pretreatment. The main goal of the NanoPlasma project was to develop a plasma reactor that allows the fibrillation of cellulose in an energy-efficient manner. Development of a plasma reactor The main focus of the project was to develop a plasma reactor that could withstand high voltage over an extended period of time to produce nanofibrillated cellulose. In order to apply plasma discharges to a material, high voltages are required. How high this voltage is, depends on the electrode distance, geometry and the material between them. In this project several electrode materials, geometries and power generators have been tested to find the optimal setup design. The use of 3D printed objects and custom made equipment has been paramount to build the final setup design, which can produce high energy discharges at a relatively high frequency, as well as increase the efficiency of the setup so that lower energy is required to fibrillate cellulose pulp. Testing with cellulose pulp Tests with chemically treated cellulose pulp have been performed throughout the project period to assess the performance of the plasma reactor and improve the equipment accordingly. In the NanoPlasma project we have observed two different phenomena when cellulose pulp is treated with cold plasma: first, the cellulose fibres were cut by the high energy discharges, and after some time the fibrillation process starts. A high degree of fibrillation of cellulose fibres can be obtained after a high number of high voltage discharges, which is a very promising result.

The principal outcome from this project is the development of a plasma setup that can be used for fibrillation of cellulose. So far, partial fibrillation of chemically treated cellulose fibres has been obtained with this setup, as well as shortening of the fibre length. If complete fibrillation of the fibres could be achieved with the current setup, this would provide a new method to produce nanocelluloses that could be more energy efficient than the existing technologies. Nanocelluloses are used in many applications such as wound healing or as a viscosity modifier (eg. in the food industry) and is a high-value product. Cheaper production of nanocelluloses could result in cheaper products for the consumers. Additionally, this technology may benefit industry in the wood value chain by providing a nanocellulose production process with low energy expenditure and without toxic residues.

Today cellulose nanofibrils (CNF) can be produced, for instance by homogenization. Multiple passes of non-pretreated cellulose fibres through a homogenizer requires a high energy consumption. There are ways to reduce the high energy consumption substantially, but these include either complicated biological (enzymatic) pretreatment or chemical pretreatment. In the NanoPlasma project we will address these challenges and produce cellulose nanofibrils using plasma at low specific energy consumption. The NanoPlasma project will combine knowledge from plasma physics and nanocellulose/nanolignocellulose for effective production of cellulose nanofibrils. In this project RISE PFI will cooperate with Chalmers University of Technology