WasteWood2Paper: paper packaging from waste wood derived cellulose

Summary:

Currently, UK packaging producers use imported, virgin cellulose pulp for manufacturing their paper-based packaging materials and solutions. Meanwhile, industrial waste wood, such as wood pallets, wood chips and wooden off-cuts from the construction industry, is disposed of at a substantial cost due to the presence of metal preservatives and other contaminants.

Aims:

We will use our patented, zero waste process developed at Imperial College London for the conversion of biomass in the conversion of construction waste wood to produce purified cellulose for paper packaging applications. The purified cellulose will be used to produce paper and also converted into microfibrillated cellulose, used to optimise paper properties. Paper sheet prototypes will be produced and commercially evaluated, and the effects of changes in the cellulose production stages in the paper properties will be evaluated.

Outcomes:

Non treated Waste Wood (original species pine) from a construction site (roof trusses) was converted into a cellulose-rich pulp using a non-polluting process that employs cheap protic ionic liquids as pretreatment media. The pulps obtained were bleached using a chlorine-free method based on hydrogen peroxide. Analysis of the pulp properties, both before and after bleaching, was used to optimize pretreatment and bleaching conditions to ensure the highest possible pulp quality. Effects of initial particle size and bleaching conditions on pulp fibre length were examined and optimised. Bleaching was successful on several species and after optimization, a larger batch of bleached pulp (130 gr) was produced and used for fibrillation.

The project has been successful as a proof of the feasibility of producing paper packaging from construction waste wood. However, it has highlighted some shortcomings in the current conditions for pretreatment optimisation for pulp quality and bleachability. Further research is needed to optimize these areas.

Impact:

We have created a process to take unwanted and unvalorised waste wood and convert it into cellulose pulp that can be bleached and converted to microfibrillated cellulose (MFC). We used these MFCs to strengthen handsheets made from recycled paper fibres, extending the fibre lifetime.

Academic partners: Agnieszka Brandt-Talbot, Imperial College London

Industrial partners: Jon Phipps, Fiberlean; Paul Edmondson, James Cropper; Krisztina Kovacs-Schreiner, Lixea Limited

1 – Pine Waste Wood samples. Top right corner: cuts of 3 x 3 cmts cubes obtained from the original slabs to be grinded. In the plastic bags, from top to bottom: raw sieved biomass, pulp after 60 min of pretreatment at 150 °C, pulp after 90 min of pretreatment at 150 °C. Increasing particle size from left to right: fine (180 µm to 850 µm) to medium (850 µm to 1.80 mm) to coarse (1.80 mm to 3.15 mm).

2 – Comparison of Pulp obtained after pretreatment before bleaching (left) and after bleaching (right).