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Wood-free paper is paper created exclusively from chemical pulp rather than mechanical pulp. [1] Chemical pulp is normally made from pulpwood, but is not considered wood as most of the lignin is removed and separated from the cellulose fibers during processing, whereas mechanical pulp retains most of its wood components and can therefore still be described as wood. [2] [3] [4] Wood-free paper is not as susceptible to yellowing as paper containing mechanical pulp. Wood-free paper offers several environmental and economic benefits, including reduced deforestation, decreased energy consumption, and improved waste management. [5] [6] The term Wood-free paper can be rather misleading or confusing for someone unfamiliar with the papermaking process because paper is normally made from wood pulp derived from trees and shrubs.
However, wood free paper does not mean that the paper in question is not made from wood pulp but it means that the lignin in the wood fiber has been removed by a chemical process. Paradoxically, lignin is the complex polymers containing aromatic groups that provide much of the tree strength. In its natural form, it gives rigidity and resilience to the tree, but its presence causes paper to weaken and turn yellow as it ages and eventually disintegrate. The reason for this is that as the paper ages, lignin releases acid which degrades the paper. [7] Wood is technically a lignocellulosic material and a xylem tissue that comes from shrubs and cambium, the inner bark of trees made up of extractives, lignin, hemicellulose and cellulose. [8] Pulp consists of wood and other lignocellulosic materials that have been broken down chemically and physically and filtered and mixed in water to reform into a web. [8] [9] Creating pulp by breaking down the materials chemically is called chemical pulping, while creating pulp by breaking them down mechanically is called mechanical pulping.
In chemical pulping, chemicals separate the wood fibers. The chemicals lower the lignin content because chemical action solubilizes and degrades components of wood fibers, especially hemicelluloses and lignin. Chemical pulping yields single unbroken fibers that produce strong quality papers because the lignin that interferes with hydrogen bonding of wood fibers has been removed. Chemical pulps are used to create wood free paper that is of high quality and lasts long, such as is used in arts and archiving. [8] Chemical pulping processes take place at high pressures and temperatures under aqueous alkaline, neutral or acidic conditions, with the goal of totally removing the lignin and preserving the carbohydrates. Normally, about 90% of the lignin is removed. [9]
Mechanical pulping, in contrast, converts raw wood into pulp without separating the lignin from the wood fiber. [9] No chemicals other than water or steam are used. The yield is about 90% to 98%. High yields result from the fact that lignin is retained. Mechanical pulps are characterized by low cost, high stiffness, high bulk, and high yield. Mechanical pulp has low strength because the lignin interferes with hydrogen bonding between wood fibers. The lignin also makes the pulp turn yellow when exposed to light and air. Mechanical pulps are used in the production of non-permanent papers such as newsprint and catalog papers. Mechanical pulps made up 20% to 25% of the world production and this is increasing because of the high yield of the process and increasing competition for fiber resources. Advances in technology have also made mechanical pulp increasingly desirable. [8]
Wood-free paper is made from a variety of raw materials, including
Wood-free paper has a number of advantages over paper that contains mechanical pulp:
Wood-free paper is used in a variety of applications:
Wood-free paper is made from non-wood materials, such as cotton, hemp, linen, and bamboo. [18] [27] [28] It is often used in applications where a high-quality, durable paper is needed, such as for printing, writing, and packaging.
There are two main types of wood-free paper:
Tissue pulp paper is smooth and opaque, making it ideal for printing and writing. [30] [31] [32] It is also relatively inexpensive, making it a popular choice for many applications. Non-wood pulp paper is more expensive than tissue pulp paper, but it is also more durable and has a higher quality. [33] [34] [35] It is often used for high-end printing and writing applications, as well as for packaging.
Here are some of the specific types of wood-free papers:
Wood-free paper is a good choice for applications where a high-quality, durable paper is needed. [10] It is also a sustainable choice, as it is made from renewable and recyclable materials.
Wood-free papers come in two varieties: uncoated and coated. Uncoated is typically used for printing and writing but also used in some packaging applications, whereas coated is used for things such as packaging and labels. [40]
Agricultural residues refer to the organic materials that are left over after crops are harvested. [50] [51] These residues include the stems, leaves, husks, and other parts of plants that are not used for food or other primary products. [52] [53] They are a significant component of agricultural ecosystems and have various potential uses, both beneficial and detrimental. [54] [55] [56] Here's a detailed overview of agricultural residues:
Cotton is a natural fiber that has been used for thousands of years to make textiles. It is derived from the fibers surrounding the seeds of the cotton plant (Gossypium). [96] [97] Here's a detailed overview of cotton:
Hemp, scientifically known as Cannabis sativa, is a versatile plant that has been cultivated for thousands of years for various purposes, including fiber, food, medicine, and industrial applications. Here's a detailed overview of hemp:
Cellulose is an organic compound with the formula (C
6H
10O
5)
n, a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wall of green plants, many forms of algae and the oomycetes. Some species of bacteria secrete it to form biofilms. Cellulose is the most abundant organic polymer on Earth. The cellulose content of cotton fibre is 90%, that of wood is 40–50%, and that of dried hemp is approximately 57%.
Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity and do not rot easily. Chemically, lignins are polymers made by cross-linking phenolic precursors.
Pulp is a fibrous lignocellulosic material prepared by chemically, semi-chemically or mechanically producing cellulosic fibers from wood, fiber crops, waste paper, or rags. Mixed with water and other chemicals or plant-based additives, pulp is the major raw material used in papermaking and the industrial production of other paper products.
Pyrolysis is the process of thermal decomposition of materials at elevated temperatures, often in an inert atmosphere without access to oxygen.
In agriculture, cover crops are plants that are planted to cover the soil rather than for the purpose of being harvested. Cover crops manage soil erosion, soil fertility, soil quality, water, weeds, pests, diseases, biodiversity and wildlife in an agroecosystem—an ecological system managed and shaped by humans. Cover crops can increase microbial activity in the soil, which has a positive effect on nitrogen availability, nitrogen uptake in target crops, and crop yields. Cover crops reduce water pollution risks and remove CO2 from the atmosphere. Cover crops may be an off-season crop planted after harvesting the cash crop. Cover crops are nurse crops in that they increase the survival of the main crop being harvested, and are often grown over the winter. In the United States, cover cropping may cost as much as $35 per acre.
Kenaf [etymology: Persian], Hibiscus cannabinus, is a plant in the family Malvaceae also called Deccan hemp and Java jute. Hibiscus cannabinus is in the genus Hibiscus and is native to Africa, though its exact origin is unknown. The name also applies to the fibre obtained from this plant. Kenaf is one of the allied fibres of jute and shows similar characteristics.
Fiber crops are field crops grown for their fibers, which are traditionally used to make paper, cloth, or rope.
Bagasse is the dry pulpy fibrous material that remains after crushing sugarcane or sorghum stalks to extract their juice. It is used as a biofuel for the production of heat, energy, and electricity, and in the manufacture of pulp and building materials. Agave bagasse is similar, but is the material remnants after extracting blue agave sap.
Hemp, or industrial hemp, is a plant in the botanical class of Cannabis sativa cultivars grown specifically for industrial and consumable use. It can be used to make a wide range of products. Along with bamboo, hemp is among the fastest growing plants on Earth. It was also one of the first plants to be spun into usable fiber 50,000 years ago. It can be refined into a variety of commercial items, including paper, rope, textiles, clothing, biodegradable plastics, paint, insulation, biofuel, food, and animal feed.
A biorefinery is a refinery that converts biomass to energy and other beneficial byproducts. The International Energy Agency Bioenergy Task 42 defined biorefining as "the sustainable processing of biomass into a spectrum of bio-based products and bioenergy ". As refineries, biorefineries can provide multiple chemicals by fractioning an initial raw material (biomass) into multiple intermediates that can be further converted into value-added products. Each refining phase is also referred to as a "cascading phase". The use of biomass as feedstock can provide a benefit by reducing the impacts on the environment, as lower pollutants emissions and reduction in the emissions of hazard products. In addition, biorefineries are intended to achieve the following goals:
Crop residues are waste materials generated by agriculture. The two types are:
A pulp mill is a manufacturing facility that converts wood chips or other plant fiber sources into a thick fiber board which can be shipped to a paper mill for further processing. Pulp can be manufactured using mechanical, semi-chemical, or fully chemical methods. The finished product may be either bleached or non-bleached, depending on the customer requirements.
Lignosulfonates (LS) are water-soluble anionic polyelectrolyte polymers: they are byproducts from the production of wood pulp using sulfite pulping. Most delignification in sulfite pulping involves acidic cleavage of ether bonds, which connect many of the constituents of lignin. Sulfonated lignin (SL) refers to other forms of lignin by-product, such as those derived from the much more popular Kraft process, that have been processed to add sulfonic acid groups. The two have similar uses and are commonly confused with each other, with SL being much cheaper. LS and SL both appear as free-flowing powders; the former is light brown while the latter is dark brown.
Lignocellulose refers to plant dry matter (biomass), so called lignocellulosic biomass. It is the most abundantly available raw material on the Earth for the production of biofuels. It is composed of two kinds of carbohydrate polymers, cellulose and hemicellulose, and an aromatic-rich polymer called lignin. Any biomass rich in cellulose, hemicelluloses, and lignin are commonly referred to as lignocellulosic biomass. Each component has a distinct chemical behavior. Being a composite of three very different components makes the processing of lignocellulose challenging. The evolved resistance to degradation or even separation is referred to as recalcitrance. Overcoming this recalcitrance to produce useful, high value products requires a combination of heat, chemicals, enzymes, and microorganisms. These carbohydrate-containing polymers contain different sugar monomers and they are covalently bound to lignin.
Tree-free paper, also known as no tree paper, offers an alternative to traditional wood-pulp paper due to its unique raw material composition. This type of paper is considered more eco-friendly especially when evaluating its entire life cycle.
Cellulose fibers are fibers made with ethers or esters of cellulose, which can be obtained from the bark, wood or leaves of plants, or from other plant-based material. In addition to cellulose, the fibers may also contain hemicellulose and lignin, with different percentages of these components altering the mechanical properties of the fibers.
Used coffee grounds is the result of brewing coffee, and are the final product after preparation of coffee. Despite having several highly-desirable chemical components, used coffee grounds are generally regarded as waste, and they are usually thrown away or composted. As of 2019, it was estimated that over 15 million tonnes of spent coffee grounds are generated annually. Due to this quantity of waste and the chemical properties of used coffee grounds, they have several potential uses.
A genetically modified tree is a tree whose DNA has been modified using genetic engineering techniques. In most cases the aim is to introduce a novel trait to the plant which does not occur naturally within the species. Examples include resistance to certain pests, diseases, environmental conditions, and herbicide tolerance, or the alteration of lignin levels in order to reduce pulping costs.
Hemp paper is a paper variety consisting exclusively or to a large extent from pulp obtained from fibers of industrial hemp. The products are mainly specialty papers such as cigarette paper, banknotes and technical filter papers. Compared to wood pulp, hemp pulp offers a four to five times longer fibre, a significantly lower lignin fraction as well as a higher tear resistance and tensile strength. Because the paper industry's processes have been optimized for wood as the feedstock, production costs currently are much higher than for paper from wood.
Brewer's spent grain (BSG) or draff is a food waste that is a byproduct of the brewing industry that makes up 85 percent of brewing waste. BSG is obtained as a mostly solid residue after wort production in the brewing process. The product is initially wet, with a short shelf-life, but can be dried and processed in various ways to preserve it.
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(help)There are two main types of woodfree paper: uncoated and coated. Uncoated woodfree paper is typically used for printing and writing. It is also used in some packaging applications. Coated woodfree paper is used for packaging, labels, and other applications where a more durable paper is needed.
[Woodfree paper] is also less likely to warp or curl.