Pulping and Papermaking of Nonwood Plant Fibers

By S. M. Sapuan

Pulping and Papermaking of Non-wood Plant Fibres presents the latest technologies associated with the papermaking process. With chapters specific to each non-wood species, the book provides step-by-step guidance on processes such as pulping, bleaching, blending and beating. Non-wood fibers are practical for pulp and paper production due to their chemical content of cellulose, hemicellulose and lignin percentages. Beginning with a general overview of non-wood fibers in the papermaking process, chapters then take a deep dive into different raw materials and their processes, including bamboo, corn stalk, pineapple leaves and sugarcane. This book is an essential resource for researchers, scientists and industry specialists.

• Provides comprehensive coverage of the processes involved in pulp and papermaking technology for each species of non-wood raw materials
• Written by the leading research and industrial experts in the field of pulping, bleaching, blending, beating and papermaking processes
• Includes step-by-step processes and methodologies

• Language: English
• Publisher: Academic Press
• Release date: Apr 1, 2023
• ISBN: 9780323984867

Book preview

Preface

Pulping and Papermaking of Nonwood Plant Fibers explains the meaning of nonwood fibers that are practical for pulp and paper production due to their chemical content of cellulose, hemicellulose, and lignin percentages. The nonwood fibers can be derived from many types of raw materials provided they are lignocellulosic-based materials. This book covers various types of raw materials from plant or agricultural waste that have proved their scientifical findings suitable for pulp and paper throughout many years worldwide. In pulp and paper technology, the processes involved are listed as plantation, harvesting, chipping, pretreatment, pulping, bleaching, stock preparation, papermaking, finishing, and paper testing as well. Hundreds of approaches are applied since centuries ago comprising mechanical, chemical, thermal, or combination methods in obtaining the pulp. End product of paper should be first identified before determining the pulp process methods. This is very crucial to optimize the performance of fibers produced via different techniques. Pulp properties need to be characterized before entering the papermaking process. This book also exhibits the differences of pulp properties derived from different types of nonwood fibers as well as paper properties. Once the paper is produced, paper testing needs to be carried out in terms of many aspects such as physical, mechanical, thermal, morphological, chemical, and more that are described in this book.

Z.M.A. Ainun, S.M. Sapuan and R.A. Ilyas

Chapter 1

Introduction to nonwood plant fibers for pulp and papermaking production

S.M. Sapuan¹, Z.M.A Ainun², S. Zakiah¹, A. Nazrin¹ and R.A. Ilyas³,    ¹Advanced Engineering Materials and Composites Research Centre (AEMC), Department of Mechanical and Manufacturing Engineering, Universiti Putra Malaysia, Serdang, Selangor, Malaysia,    ²Program of Pulp and Paper & Pollution Control, Institute of Tropical Forestry and Forest Products (INTROP), Universiti Putra Malaysia, Serdang, Selangor, Malaysia,    ³Department of Chemical Engineering, Faculty of Chemical and Energy Engineering, Universiti Teknologi Malaysia, Johor Bahru, Malaysia

Abstract

Paper was invented in CE 105 by a Chinese that used the mixture of mulberry bark, hemp, and shredded cloth rags as raw materials. In the early days, paper was produced using nonwood materials before humans discovered the technique to process wood. Moving from handmade paper into automation, humans can produce paper from several pieces up to hundreds of tons per day. Days passed and the usage of paper nowadays is not only for writing and printing but the functions becoming wider due to the paper’s capability to be folded or formed into various designs and in fact its biodegradability aspects. This chapter discusses the history of paper, reasons of selecting nonwood plant as raw material, and its challenge and future of nonwoody plant fibers in pulp and paper manufacture.

Keywords

Nonwood fibers; pulp; papermaking

1.1 History of pulp and papermaking

Based on reports, the Chinese papermakers started the papermaking by using nonwood material called hemp. This was followed by other nonwoody plants like mulberry in the early second century CE, rattan, bamboo and then rice and wheat straw, and bark of sandalwood (Tsien, 1973). Paper has been applied by humans that began with the use of nonwood materials. At this moment, humans reached for substances that are situated close to them to be processed like nonwoody plants. Papermaking from the nonwood pulp of mulberry trees was reported as early as CE 105 in China (Kamoga Omar Lwako et al., 2013). Mulberry trees or papyrus are some plants that are easily accessible materials. They can be easily cut down and importantly easy to handle for the manufacture of paper pieces. To thin the tree trunk into slices or pieces, humans practice cooking, beating, screening, washing, and drying the sheets from the trunk until human can write on them. At first, this type of paper was a bit rough but the paper from nonwood material was very useful for the purpose of storing information. As time passed until the Industrial Revolution, paper production became more advanced as humans already had the technology of logging wood. Wood logging allowed humans to explore more on the usage of wood in papermaking to be better in paper quality in terms of strength because wood has a good fiber anatomy structure. The work on modern papermaking from wood pulps started in 1844 in Canada by Charles Fenerty, where he developed papers from woods, replacing traditional papers made from rags and cotton (John Crane, 2019). To date, humans have been relying on the use of wood in producing all categories of paper. However, in the last 30 years, the world is experiencing a decline in timber due to the growth of timber that takes 10–20 years to be logged causing humans to start turning back to nonwood trees. Thus many studies were carried out, and the appearance of industries that began to seriously use nonwood materials to be used as pulp for papermaking.

1.2 Why nonwood plant fibers for pulp and paper recently?

The reason for selecting nonwood plant fibers mainly due to the shortage of wood materials. Besides that, there are few other reasons as stated in Fig. 1.1.

Figure 1.1 Reasons of using nonwood plant.

1.2.1 Shortage of wood plant fibers

The world is facing a shortage of wood plant fibers due to the deforestation. The consumption of raw material sources comprises roundwood, chips and residues, and recovered paper. Virgin pulp from roundwood, chips, and residues is one of the important sources in imparting the strength of paper quality derived from wood plant. Most pulp and paper mills still need wood greatly to maintain the quality of paper products, besides blending with nonwood fibers or imparting with other additives. Looking at the high demand of wood, pulp and paper industry is an industry that gives high impact on the global forest and footprint to the environment. An amount of 400 million tonnes of paper and paperboard are produced each year worldwide, which involves 13%–15% of wood consumption. It is predicted that the world production will reach double by 2050 due to the high demand year by year (World Wide Fund For Nature, 2020) meaning that world is facing the declination of forest at about 13.0 million ha per year (Ashori, 2006). The rise of global population, the need for education, and industrialization are expected to increase the demand for paper. In other words, the products of pulp, paper, and packaging contributed to high impact on the social, economic, and infrastructure developments. In response to the concern of environmentalists, governmental, and nongovernmental administrations, new legislative regulations are enacted to supervise the logging activities to maintain the supply and price of the wood to the international market. Shortage of wood-based materials caused the need to seek for alternative materials, and the use of nonwood fibers seemed to be the obvious choice. The forest still must be sustainable, which can be achieved by the responsible management of plantations and reducing the usage of wood by replacing it with other lignocellulosic materials.

1.2.2 Abundance of nonwood plant fibers

The size of nonwood pulp market globally will increase year by year, which involved stalk, bast, leaf, cotton fiber, or more. The market from North America, Europe, Asia Pacific and South America, and the Middle East and Africa, which to date, 133 companies have applied nonwood pulps in their wood-based pulp slurries for commercial papermaking purposes as shown in Table 1.1.

Table 1.1

Based on the record by the Food and Agriculture Organization of the United Nations (2022), there are 43 countries that are contributing to pulp production of nonwood fibers as shown in Table 1.2. Two main countries that recently led the production are China and India with more than 5 million and 3 million tonnes, respectively.

Table 1.2

The substitution of wood with low-cost alternative raw materials was proposed to utilize nonwood fibers such as agro-wastes and annual plants for reliable resources as well as to compensate the lack of forest resources. Through 1900 years, paper was made from grass and other nonwood fibers instead of wood (Mohieldin, 2015). In comparison to wood, nonwood fibers are higher in hemicelluloses and lower in lignin. Most nonwood fibers were derived from agriculture by-products, which came at lower price, require less refining, have fast annual growth, make excellent filler, and have decent smoothness. The processing of nonwood fiber requires less energy and lower chemical expenses thus providing economically viable operation for the smaller millers. Furthermore, the exploitation of these agro-wastes potentially generates additional income to the smallholders without compromising the yield of the main products.

1.2.3 Speed growth of paper industry

Pulp and paper industry cannot be hindered from human life, although the world is drastically changing into digital era. Last 25 years, the world expected that the consumption of paper will tremendously drop due to the emergence of digital technology (Beckline et al., 2016); however, it is reported that the need is getting greater each year. Paper plays a vital role in the development of global social, economic, and environmental growth in many areas, such as packaging, communication, education, sanitation, security, and more (Ezeudu et al., 2019). In fact, the reality that is happening shows that the industry is thriving and exploding the worldwide industry with interesting trending, especially in packaging paper. It is known that one of the largest industries in the world is pulp and paper industry that is led by countries of the United States of America and China, followed by North American, Northern European, and East Asian. The world production of paper and paperboard is around 390 million tonnes and is expected to reach 490 million tonnes by 2022 (Linchpin et al., 2022). Per capita, paper consumption can be one of the good indicator or a measure of the growth of a country. More than 200 kg per capita consumption is usually obtained by highly developed countries. Paper Export (2022) predicted that there will be an increase in paper packaging in terms of corrugated and containerboard to alternate with plastic packaging. These papers have skyrocketed since 2020 reported for 18% of all global retail sales and will keep on growing via e-commerce business. For example, e-commerce sales in the United States booming with an increase of $80 billion reaching $438 billion in the first half of 2021 (Paper Export, 2022).

1.2.4 Fast growth of nonwood plant fibers

Based on the studies of Hurter (1997), nonwood plants can be categorized into common and specialty nonwoods. It is also called hardwood or softwood substitutes. The common nonwood plant comprises sugarcane bagasse, bamboo, reeds, grasses, and esparto, while specialty nonwood involves cotton linters, flax, hemp, sisal, abaca, kenaf bast, and more. Liu et al. (2018) divided nonwood plants according to plant’s components listed as gramineous, bast, seed hull, and leaf fiber materials.

1.3 Nonwood plant fibers

Nonwood plant fibers are lignocellulosic plants that contain mainly cellulose, hemicellulose, aromatic polymer like lignin and other small portion of chemical substances (Tarique et al., 2021; Ilyas et al., 2019, 2021). These substances are considered chemical composition in a plant. Chemical composition differs among lignocellulosic plants based on its ages, climate, soil, and geographical location (Ilyas et al., 2017). In addition, the variation is also found in different parts of the same plant. Lignocellulosic plants can be generally divided into wood and nonwood plants (Hammett et al., 2001). The nonwood plant usually has higher hemicellulose and lower lignin content compared to wood plant that has greater cellulose content yielding higher pulp content after cooking process (Abd El-Sayed et al., 2020). Lignin is responsible for binding the cellulose fiber together. In papermaking, lignin is undesirable as it might lower the performance of the paper (Małachowska et al., 2020). The low content of lignin in nonwood plant is favorable since it eases the delignification process with less chemicals and ultimately reducing hazard contamination to the environment (Daud et al., 2013). Nonwood plants can be classified into three main types according to their origin, which are agricultural by-products, industrial crops, and naturally growing plants (Table 1.3). Agricultural by-products are defined as the secondary products of the principal crops such as rice straw and wheat straw, which possess moderate quality and low cost (Ilyas et al., 2022a,b,c; Azman et al., 2021). Industrial crops such as kenaf, hemp, and jute are cultivated particularly to yield fibers, hence, exploiting these crops for pulp production is weighted by the high expense of raw materials. Naturally growing plants, including bamboo, reed, and sabia grass, have also been utilized to produce high-quality pulps (Table 1.4).

Table 1.3

Table 1.4

Nonwood has some differences compared to wood materials (Table. 1.5).

Table 1.5

The problems that rise in managing these resources include collection, transportation, storage, handling, washing, bleaching, papermaking, and chemical recovery.

1.4 Challenges and future of nonwood plants

More countries showing their initiatives to use nonwood fibers for pulp and papermaking besides countries that are having limited wood supply. The future of nonwood plant in pulp and paper industries getting brighter due to the four factors discussed earlier. However, the utilization of nonwood fiber sources in the pulp and paper industry has several disadvantages (Abd El-Sayed et al., 2020). The most common issues are technological (Jahan et al., 2021), and they necessitate research in this field to compete with wood fibers. The following section discusses some of the challenges faced by mills utilizing nonwood plant fibers as source of raw material, as well as some of the solutions proposed to make nonwoods more appealing as papermaking raw material. Currently, a high-tech breakthrough in all areas of papermaking (including raw materials processing, paper machine, and nanotechnology) has made nonwood more economical when compared to wood as a raw material for papermaking. Challenges for nonwood plants are shown in Fig. 1.2 and Table 1.6.

Figure 1.2 Challenges for nonwood plants.

Table 1.6

The pulp and paper industry has supplied over 6 billion people worldwide. Paper is used for a variety of applications, such as writing media, printing materials, documentation tools, beauty tools, packaging tools, transaction tools, cleaning tools, and decorations. Pulp and paper mills around the world produce more than 400 million tons of paper annually. These paper-producing activities generated a variety of jobs but led to extreme deforestation (Furszyfer Del Rio et al., 2022). Forest impacts associated with unsustainable pulpwood production can negatively impact climate, such as in Sumatra where carbon is released from deep peatlands that are converted to pulp plantations. In addition, pulp and paper manufacturing is among the world’s most energy-intensive industries. Although paper mills do utilize some of their own waste products as fuel, emissions and pollution from paper mills can be significant. The largest share of greenhouse gases released in pulp and paper manufacturing comes from the energy production to power the mills. Some companies in the pulp and paper industry leave an unacceptably large ecological footprint on the planet. Irresponsible harvesting from natural forests and an establishment of pulp plantations on converted natural forests can threaten fragile ecosystems and species and cause soil erosion. Some proposed new pulpwood plantations and mills threaten natural habitats in regions with high conservation values and high rates of illegal logging. For example, the remaining natural forests and associated wildlife species in Borneo and Sumatra, Papua New Guinea, the Russian Far East, Southern Chile, and the Atlantic forest region in Brazil are all at risk because of growing demand for pulpwood.

By 2020, global paper consumption is estimated to have reached 500 million tonnes. The challenge of how to meet the growing worldwide demand for paper and paperboard arises. The increasing demand for paper will almost certainly be met by one or more of several potential sources of supply, including:

1. Innovation of environmentally friendly pulp process alternative as bio pulp

2. Increased use of nonwood fiber

3. Increased use of forest waste

4. Increased recycling of waste paper

5. Increased world timber supply

6. Increased yield with better control of pests

1.5 Conclusion

Pulp technology from nonwood sources will continue to develop rapidly due to the significant increase in demand for paper products due to the high cost of pulp imports as well as the lack of timber resources in developing countries. Due to the increasing current rate of investment in pulp and paper mills, the pulp and paper industry in developing countries began to look for alternative raw materials to wood. Furthermore, due to economic and environmental considerations, agricultural waste pulp is becoming increasingly popular. Pulp research from nonwood sources has produced a wide range of products over the years. The use of nonwood fibers in the pulp and paper manufacturing industry is no longer a concern as it once was. However, the nonwood paper industry continues to face some challenges. Through research done over 20 years, bagasse fibers are seen to have good papermaking properties. By-products from the sugar mills such as sugarcane bagasse have provided a source of ancillary income to the industry. In addition, it provides additional benefits to the sugarcane industry. This is due to the reduction in the cost of collecting sugarcane residue, which indirectly the sugarcane mill becomes the center for the collection of sugarcane residue. As a result, in countries where the cost of replacement fuel for sugarcane bagasse in sugar mills is cheap, using sugarcane residue as a raw material for papermaking is an attractive proposition. Besides that, the use of empty fruit bunch as a source of pulp and paper is also seen as a great potential, especially in countries that plant oil palm trees such as in Malaysia and Indonesia. In addition, the utilization of straw as a raw material for papermaking shows several issues, but research has offered solutions to the majority of them. Rice straw is a cheap nonwood fiber material for papermaking. Despite the current concern about the expansion of wood-based pulp mills, the expansion of nonwood pulp mills has not stopped. In fact, for the foreseeable future, it is predicted to grow faster than wood-based paper mills. Taking this factor into account, it is predicted that the use of nonplant wood fibers in the pulp and paper industry will continue to increase at a rapid rate and contribute to a partial percentage of the total raw materials of papermaking.

References

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