What is Organosolv process?
Organosolv pulping is a two-stage process involving hydrolysis (decomposition of wood by use of a catalyst) and removal of lignin with an organic solvent (usually a mixture of alcohol and water).
What is kraft lignin?
Kraft lignin is a kind of industrial lignin obtained from Kraft pulp, which accounts for about 85% of the total lignin production in the world. The Kraft pulp method is the main method for converting coniferous wood to pulp; the pulping yield is higher than other alkaline pulping methods.
What is alkaline lignin?
Lignin, alkali is a complex, three dimensional polymer that is also known as kraft lignin that has undergone hydrolytic degradation. It is one of the major components of lignocellulosic materials.
What is solvent pulping?
Solvents. Organosolv pulping involves contacting a lignocellulosic feedstock such as chipped wood with an aqueous organic solvent at temperatures ranging from 140 to 220 °C. This causes lignin to break down by hydrolytic cleavage of alpha aryl-ether links into fragments that are soluble in the solvent system.
What are the properties of lignin?
Lignin contains five hydroxyl and five methoxyl groups per building unit. Lignin has a glass transition temperature of about 90°C and melting temperature of about 170°C. It is soluble in hot alkali, easily oxidizable, and condensable with phenol but does not hydrolyze by acids.
What is steam explosion pretreatment?
Steam explosion is a physicochemical pretreatment technology in which the biomass is heated to 160–260°C in a closed vessel under high pressure (7–50 bar) for a short period of time (30 s–20 min), and then the pressure is quickly released, causing an explosive effect on the cells [51].
Why lignin is removed from pulp?
(Lignin, the natural “glue” that holds cellulose fibers together and stiffens plant stems, causes paper made of wood pulp to weaken and discolor rapidly if not removed in the pulp mill; but the removal processes are harsh, and shorten the fibers on which the paper’s strength depends.)
How does kraft pulp mill work?
The kraft pulping process (see Figure 10.2-1) involves the digesting of wood chips at elevated temperature and pressure in “white liquor”, which is a water solution of sodium sulfide and sodium hydroxide. The white liquor chemically dissolves the lignin that binds the cellulose fibers together.
What is the difference between pectin and lignin?
The key difference between pectin and lignin is that pectin is an acidic heteropolysaccharide found in the middle lamella, the primary and secondary cell wall of the plants, while lignin is a polyphenyl propane polymer found in the middle lamella and secondary cell wall of the plants.
What are the major chemicals used for bleaching of pulp?
For ECF pulp, chlorine dioxide and hydrogen peroxide are the main bleaching agents. For TCF, hydrogen peroxide is the main bleaching agent. In all chemical pulp mills, oxygen delignification is used prior to bleaching to reduce the amount of bleaching chemicals required.
What is lignin in pulp?
A complex, organic material in wood that binds fibers of cellulose together. One of the purposes of the pulping process is to separate the cellulose fibers from the lignin and other non-fibrous materials such as hemicelluloses.
What is Organosolv pulping?
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.
What is the Alcell process?
In 1987 the APR process was renamed the Alcell process. The process uses aqueous ethanol solutions (40–60% v/v) to delignifying wood at temperatures from 180–210 °C and 2–3.5 MPa. Solvent is recovered with flash evaporation, vapour condensation and vacuum stripping.
Is the Alcell process effective for lignin extraction?
Even though Alcell processes have not yet been operated at the commercial scale [70–72], their effective lignin extraction has attracted much attention. The Alcell process developed by Lignol Energy Corporation [73] has been put into pilot-scale use to produce high-purity organosolv lignin.
How to recover lignin from ethylene glycol organosolv pulping?
The recovery of lignin from ethylene glycol organosolv pulping can be effected by 3 times dilution with acidified water. The lignin precipitates and forms spherical aggregates ranging from 0.5–2.5 µm. Filtration, while time consuming, is then most effective while the mixture is hot (>100 °C).