Lignosulfonate
introduction
Copy from Wikipedia
Lignosulfonate: Any of several substances manufactured from waste
liquor of the sulfate pulping process of soft wood; used in the petroleum
industry to reduce the viscosity of oil well muds and slurries, and as
extenders in glues, synthetic resins, and cements.
Lignosulfonates, or sulfonated lignin, (CAS
number 8062-15-5) are water-soluble anionic polyelectrolyte polymers: they are
byproducts from the production of wood pulp using sulfite pulping.[1]
Most delignification in sulfite pulping involves
acidic cleavage of ether
bonds, which connect many of the constituents of lignin.[2]
The electrophilic carbocations produced
during ether cleavage react with bisulfite ions (HSO3-)
to give sulfonates.
R-O-R' + H+ → R+ + R'OH
R+ + HSO3- → R-SO3H
The primary site for ether cleavage is the α-carbon
(carbon atom attached to the aromatic ring) of the propyl (linear three carbon)
side chain. The following structures do not specify the structure since lignin
and its derivatives are complex mixtures: the purpose is to give a general idea
of the structure of lignosulfonates. The groups labeled "Q" can be a
wide variety of groups found in the structure of lignin. Sulfonation occurs on
the side chains, not on the aromatic rings, like in p-toluenesulfonic acid.

Lignosulfonate have very broad ranges of molecular
mass (they are very polydisperse). A range of from 1000–140,000 da has been
reported for softwood lignosulfonates with lower values reported for hardwoods.
Preparation
Lignosulfonates are recovered from the
spent pulping liquids (red or brown liquor) from sulfite pulping. The most
widely used industrial process is the Howard process, in which 90–95% yields of
calcium lignosulfonates (CAS number 904-76-3), are precipitated by adding of
excess calcium hydroxide. Ultrafiltration and ion-exchange can
also be used to separate lignosulfonates from the spent pulping liquid. A list
of CAS numbers for the various metal
salts of lignosulfonate is available.
Uses
Lignosulfonates have a wide variety of applications.[
The single largest use for lignosulfonates is as
plasticizers in making concrete, where they allow concrete to be made with less
water (giving stronger concrete) while maintaining the ability of the concrete
to flow. Lignosulfonates are also used during the production of cement, where
they act as grinding aids in the cement mill and as a rawmix slurry
deflocculant (that reduces the viscosity of the slurry).
Lignosulfonates are also used for the production of
plasterboard to reduce the amount of water required to make the stucco flow and
form the layer between two sheets of paper. The reduction in water content
allows lower kiln temperatures to dry the plasterboard, saving energy.
The ability of lignosulfonates to reduce the viscosity
of mineral slurries is used to advantage in oil drilling mud, where it replaced
tannic acids from quebracho (a tropical tree).
Lignosulfonates are used to disperse pesticides, dyes
carbon black and other insoluble solids and liquids into water. They are used
in tanning leather. They are also used to suppress dust on unpaved roads.[
Oxidation of lignosulfonates from softwood trees
produced vanillin (artificial vanilla flavor)
Dimethyl sulfide and dimethyl sulfoxide (an important
organic solvent) are produced from lignosulfonates. The first step involves
heating lignosulfonates with sulfides or elemental sulfur to produce dimethyl
sulfide. The methyl groups come from methyl ethers present in the lignin.
Oxidation of dimethyl sulfide with nitrogen dioxide produces
dimethyl sulfoxide (DMSO).
Also one of the very wide uses of
lignosulfonates is deflocculation of clays used in drilling fluids in the oil
and gas industry.
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specialize in producing all kinds of lignosulfonate, especially ferrochrome
lignosulfonate, for more information, welcome to visit our website: www.wfychina.com
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