Tall oil

Last updated

Tall oil, also called liquid rosin or tallol, is a viscous yellow-black odorous liquid obtained as a by-product of the kraft process of wood pulp manufacture when pulping mainly coniferous trees. [1] [2] The name originated as an anglicization of the Swedish tallolja ('pine oil'). [3] Tall oil is the third largest chemical by-product in a kraft mill after lignin and hemicellulose; the yield of crude tall oil from the process is in the range of 30–50 kg / ton pulp. [4] It may contribute to 1.0–1.5% of the mill's revenue if not used internally.

Contents

Manufacturing

Forchem tall oil refinery in Rauma, Finland Forchem Rauma 2.jpg
Forchem tall oil refinery in Rauma, Finland

In the kraft process, high alkalinity and temperature convert the esters and carboxylic acids in rosin into soluble sodium soaps of lignin, rosin, and fatty acids. The spent cooking liquor is called weak black liquor and is about 15% dry content. The black liquor is concentrated in a multiple effect evaporator and after the first stage the black liquor is about 20–30%. At this stage it is called intermediate liquor. Normally the soaps start to float in the storage tank for the weak or intermediate liquors and are skimmed off and collected. A good soap skimming operation reduces the soap content of the black liquor down to 0.2–0.4% w/w of the dry residue. The collected soap is called raw rosin soap or rosinate. The raw rosin soap is then allowed to settle or is centrifuged to release as much as possible of the entrained black liquor. The soap goes then to the acidulator where it is heated and acidified with sulfuric acid to produce crude tall oil (CTO).[ citation needed ]

The soap skimming and acidulator operation can be improved by addition of flocculants. A flocculant will shorten the separation time and give a cleaner soap with lower viscosity. This makes the acidulator run smoother as well.[ citation needed ]

Most pines give a soap yield of 5–25 kg/ton pulp, while Scots pine gives 20–50 kg/ton. Scots pine grown in northern Scandinavia give a yield of even more than 50 kg/ton. Globally about 2 mill ton/year of CTO are refined. [2]

Composition

The composition of crude tall oil varies a great deal, depending on the type of wood used. A common quality measure for tall oil is acid number. With pure pines it is possible to have acid numbers in the range 160–165, while mills using a mix of softwoods and hardwoods might give acid numbers in the range of 125–135. [2]

Normally crude tall oil contains rosins, which contains resin acids (mainly abietic acid and its isomers), fatty acids (mainly palmitic acid, oleic acid and linoleic acid) and fatty alcohols, unsaponifiable sterols (5–10%), some sterols, and other alkyl hydrocarbon derivates. [3]

By fractional distillation tall oil rosin is obtained, with rosin content reduced to 10–35%. By further reduction of the rosin content to 1–10%, tall oil fatty acid (TOFA) can be obtained, which is cheap, consists mostly of oleic acid, and is a source of volatile fatty acids.[ citation needed ]

Applications

The tall oil rosin finds use as a component of adhesives, rubbers, and inks, and as an emulsifier. The pitch is used as a binder in cement, an adhesive, and an emulsifier for asphalt.[ citation needed ] [5]

TOFA is a low-cost and vegetarian lifestyle-friendly alternative to tallow fatty acids for production of soaps and lubricants. When esterified with pentaerythritol, it is used as a compound of adhesives and oil-based varnishes. When reacted with amines, polyamidoamines are produced which may be used as epoxy resin curing agents. [6]

Related Research Articles

<span class="mw-page-title-main">Turpentine</span> Liquid distilled from pine resin

Turpentine is a fluid obtained by the distillation of resin harvested from living trees, mainly pines. Mainly used as a specialized solvent, it is also a source of material for organic syntheses.

<span class="mw-page-title-main">Pulp (paper)</span> Fibrous material used notably in papermaking

Pulp is a lignocellulosic fibrous material prepared by chemically or mechanically separating cellulose fibers from wood, fiber crops, waste paper, or rags. Mixed with water and other chemical or plant-based additives, pulp is the major raw material used in papermaking and the industrial production of other paper products.

<span class="mw-page-title-main">Rosin</span> Solid form of resin

Rosin, also called colophony or Greek pitch, is a solid form of resin obtained from pines and some other plants, mostly conifers, produced by heating fresh liquid resin to vaporize the volatile liquid terpene components. It is semi-transparent and varies in color from yellow to black. At room temperature rosin is brittle, but it melts at stove-top temperature. It chiefly consists of various resin acids, especially abietic acid. The term colophony comes from colophonia resina, Latin for "resin from Colophon", an ancient Ionic city.

<span class="mw-page-title-main">Kenaf</span> Species of flowering plant

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.

<span class="mw-page-title-main">Saponification value</span> Milligrams of a base required to saponify 1g of fat

Saponification value or saponification number represents the number of milligrams of potassium hydroxide (KOH) or sodium hydroxide (NaOH) required to saponify one gram of fat under the conditions specified. It is a measure of the average molecular weight of all the fatty acids present in the sample in form of triglycerides. The higher the saponification value, the lower the fatty acids average length, the lighter the mean molecular weight of triglycerides and vice versa. Practically, fats or oils with high saponification value are more suitable for soap making.

<span class="mw-page-title-main">Kraft process</span> Process of converting wood into wood pulp

The kraft process (also known as kraft pulping or sulfate process) is a process for conversion of wood into wood pulp, which consists of almost pure cellulose fibres, the main component of paper. The kraft process involves treatment of wood chips with a hot mixture of water, sodium hydroxide (NaOH), and sodium sulfide (Na2S), known as white liquor, that breaks the bonds that link lignin, hemicellulose, and cellulose. The technology entails several steps, both mechanical and chemical. It is the dominant method for producing paper. In some situations, the process has been controversial because kraft plants can release odorous products and in some situations produce substantial liquid wastes.

<span class="mw-page-title-main">Biorefinery</span>

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:

  1. Supply the current fuels and chemical building blocks
  2. Supply new building blocks for the production of novel materials with disruptive characteristics
  3. Creation of new jobs, including rural areas
  4. Valorization of waste
  5. Achieve the ultimate goal of reducing GHG emissions
<span class="mw-page-title-main">Pulp mill</span>

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.

Resin acid refers to mixtures of several related carboxylic acids, primarily abietic acid, found in tree resins. Nearly all resin acids have the same basic skeleton: three fused rings having the empirical formula C19H29COOH. Resin acids are tacky, yellowish gums that are water-insoluble. They are used to produce soaps for diverse applications, but their use is being displaced increasingly by synthetic acids such as 2-ethylhexanoic acid or petroleum-derived naphthenic acids.

<span class="mw-page-title-main">Black liquor</span> Industrial by-product

In industrial chemistry, black liquor is the by-product from the kraft process when digesting pulpwood into paper pulp removing lignin, hemicelluloses and other extractives from the wood to free the cellulose fibers.

<span class="mw-page-title-main">Kraft paper</span> Paper or paperboard produced from chemical pulp produced in the kraft process

Kraft paper or kraft is paper or paperboard (cardboard) produced from chemical pulp produced in the kraft process.

Bleaching of wood pulp is the chemical processing of wood pulp to lighten its color and whiten the pulp. The primary product of wood pulp is paper, for which whiteness is an important characteristic. These processes and chemistry are also applicable to the bleaching of non-wood pulps, such as those made from bamboo or kenaf.

The sulfite process produces wood pulp that is almost pure cellulose fibers by treating wood chips with solutions of sulfite and bisulfite ions. These chemicals cleave the bonds between the cellulose and lignin components of the lignocellulose. A variety of sulfite/bisulfite salts are used, including sodium (Na+), calcium (Ca2+), potassium (K+), magnesium (Mg2+), and ammonium (NH4+). The lignin is converted to lignosulfonates, which are soluble and can be separated from the cellulose fibers. For the production of cellulose, the sulfite process competes with the Kraft process which produces stronger fibers and is less environmentally costly.

<span class="mw-page-title-main">Paper</span> Thin material for writing, printing, etc.

Paper is a thin sheet material produced by mechanically or chemically processing cellulose fibres derived from wood, rags, grasses or other vegetable sources in water, draining the water through fine mesh leaving the fibre evenly distributed on the surface, followed by pressing and drying. Although paper was originally made in single sheets by hand, almost all is now made on large machines—some making reels 10 metres wide, running at 2,000 metres per minute and up to 600,000 tonnes a year. It is a versatile material with many uses, including printing, painting, graphics, signage, design, packaging, decorating, writing, and cleaning. It may also be used as filter paper, wallpaper, book endpaper, conservation paper, laminated worktops, toilet tissue, or currency and security paper, or in a number of industrial and construction processes.

Deinking is the industrial process of removing printing ink from paperfibers of recycled paper to make deinked pulp.

White liquor is a strongly alkaline solution mainly of sodium hydroxide and sodium sulfide. It is used in the first stage of the Kraft process in which lignin and hemicellulose are separated from cellulose fiber for the production of pulp. The white liquor breaks the bonds between lignin and cellulose. It is called white liquor due to its white opaque colour.

In industrial paper-making processes, organosolv is a pulping technique that uses an organic solvent to solubilise lignin and hemicellulose. It has been considered in the context of both pulp and paper manufacture and biorefining for subsequent conversion of cellulose to fuel ethanol. The process was invented by Theodor Kleinert in 1968 as an environmentally benign alternative to kraft pulping.

The term "Lignin characterization" refers to a group of activities within lignin research aiming at describing the characteristics of a lignin by determination of its most important properties. Most often, this term is used to describe the characterization of technical lignins by means of chemical or thermo-chemical analysis. Technical lignins are lignins isolated from various biomasses during various kinds of technical processes such as wood pulping. The most common technical lignins include lignosulphonates, kraft lignins, organosolv lignins, soda lignins and lignin residue after enzymatic treatment of biomass.

Mechanical pulping is the process in which wood is separated or defibrated mechanically into pulp for the paper industry.

References

  1. Lars-Hugo Norlin (2002). "Tall Oil". Ullmann's Encyclopedia of Industrial Chemistry . Weinheim: Wiley-VCH. doi:10.1002/14356007.a26_057.
  2. 1 2 3 Gullichsen, Johan; Paulapuro, Hannu (2000). "18". Chemical Pulping. Papermaking Science and Technology. Vol. 6B. Finland. pp. B378–B388. ISBN   952-5216-06-3.
  3. 1 2 Biermann, Christopher J. (1993). Essentials of Pulping and Papermaking. San Diego: Academic Press, Inc. p.  107. ISBN   0-12-097360-X.
  4. Stenius, Per, ed. (2000). "2". Forest Products Chemistry. Papermaing Science and Technology. Vol. 3. Finland. pp. 73–76. ISBN   952-5216-03-9.
  5. "TALL OIL PITCH AS BITUMEN EXTENDER" (PDF).{{cite journal}}: Cite journal requires |journal= (help)
  6. "Hexion Amidoamine epoxy curing agents".