Non-paper products from wood or the papermaking process
Trees of all kinds have provided mankind with fuel, food, fibre and medicine from their fruit, flowers, roots, wood, leaves and branches since time immemorial.
Today, many things we use are also connected to trees – sustainably farmed trees. Items like printer paper, chewing gum, planks, viscose fabric, vitamins, pallets, toilet tissue, toothpaste, and detergents have a link back to wood in some form or another.
The most abundant organic compound and polymer on earth – is the major component of wood and the starting point for various reactions.
- Dissolving woodpulp, a purified form of cellulose, is suitable for subsequent chemical conversion into a range of products. It is spun into viscose and lyocell textile fibres for use in fashion and decorating textiles, cast into a film or regenerated into a sponge.
- Hydroxyethyl cellulose (HEC) is added to paint to help prevent splatter. HEC is also a common ingredient in cosmetics, adhesives and detergents.
- Cellulose triacetate is used in the manufacture of laptop LCD screens as a polarising film that provides exceptional optical clarity.
- Carboxymethyl cellulose is extremely versatile. It can bind active medicinal ingredients or vitamins into palatable tablets, stabilise emulsions or increase viscosity – which is why cellulose is added to low-fat yoghurt, and lipstick! It also acts as an abrasive or exfoliant in cosmetics and toothpaste, or an anti-caking agent in washing powders and foods.
Lignin is the glue that holds wood and plant fibres together. It is removed during the pulping process when manufacturing fine paper to prevent yellowing with age, with some 50 million tonnes being produced worldwide each year. Depending on the pulping process used, lignin can be recovered from spent pulping liquors in different forms, for example., lignin and lignosulphonates, or used as pellets for fuel.
Lignosulphonates are used in mining and road maintenance as a dust suppressant while their addition to ready-mix concrete improves the flow of concrete as well as reducing the water required, without compromising on strength. Lignin also shows promise as a multifunctional and renewable alternative to petroleum-derived styrene plastics and foams.
Bio-oils, Bio-ethanol, and Furfural
Bio-oils are obtained by heating wood in an oxygen-free environment, in a process known as pyrolysis. The solid product generated (bio-char) can be used as an enriched growing medium for seedlings or converted into high-grade activated carbon.
Bio-ethanol is produced when wood waste is broken down by enzymes and fermentation.
Furfural, dubbed ‘the sleeping beauty of bio-renewable chemicals’, was one of the first bio-chemicals made from biomass. As a worthy competitor to oil-based chemicals, new interest has been sparked in furfural for the production of bio-fuels and bio-chemicals. Furfural and its derivatives have been extensively used in the plastics, pharmaceutical and agrochemical industries. As a natural precursor to a range of chemicals and solvents, it is widely applied in fungicides and nematicides, transportation fuels, lubricants, resins, a rapid all-weather repair system for potholes and also for wood modification and book preservation. And that’s just the short list.
Xylitol is a natural sugar substitute that can be made from xylose, the sugar molecule in hemicellulose. It also has oral health benefits due to its acid neutralising and antibacterial properties and is commonly used in chewing gum.
Sawdust and bark
Sawdust and bark can yield high-value speciality chemicals and composites.
Paper sludge, a reject material from the paper recycling process, can potentially be converted into NCC, bio-polymers and bio-gas.