Russian Journal of Applied Chemistry, 2010, Vol. 83, No. 2, pp. 316−319.
Pleiades Publishing, Ltd., 2010.
Original Russian Text
G.L. Bykov, B.G. Ershov, 2010, published in Zhurnal Prikladnoi Khimii, 2010, Vol. 83, No. 2, pp. 317−320.
AND POLYMERIC MATERIALS
A Sorbent Based on Phosphorylated Lignin
G. L. Bykov and B. G. Ershov
Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, Russia
Received March 30, 2009
A procedure was developed for preparing an effective sorbent based on lignin phosphorylated in
the presence of urea. The phosphorus content was 16.6 wt %. The total exchange capacity was 0.86 mmol g
ions and 0.23 mmol g
ions. The effect of urea on the lignin phosphorylation was
examined by IR spectroscopy.
Crude lignin is a waste from pulp-and-paper industry.
Its content reaches almost 30% relative to the wood, and
it is accumulated in large amounts. Lignin impregnated
with acids and other reagents pollutes atmosphere and
soil and presents ﬁ re hazard. Attempts are made to
utilize crude lignin in building, medical industry, and
production of fuels and fertilizers. It is suggested to use
hydrolyzed lignin as a sorption material for treatment of
wastewaters from atomic industry and of natural waters
in contaminated territories to remove toxic metals. The
sorbent preparation procedure involves phosphorylation
of lignin with phosphoric acid in the presence of urea.
The resulting sorbent has maximum possible phosphorus
content and exhibits high sorption activity.
Studies in this direction were performed previously.
For example, lignin was phosphorylated with phosphoric
anhydride , hypophosphorous acid , or tributyl
phosphate . The processes yielded cation exchangers
containing from 3.6  to 6–13% phosphorus , which
were capable of recovering toxic metal ions from
Experiments were performed with spruce lignin.
Lignin was preliminarily impregnated with a solution
containing phosphoric acid and urea at a solid-to-liquid
ratio S : L = 1 : 10 for 1 h at 80°C. This temperature
was limiting, because at higher temperatures urea
decomposes in aqueous solutions to form ammonium
carbamate. After that, the lignin was dried and
phosphorylated. To this end, the samples were heated at
a higher temperature. After heating, the products were
washed with hot water and 0.1 N HCl.
The amount of acid groups in phosphorylated lignin
was determined by potentiometric titration . A sample
(0.2 g) was kept for 7 days in 20 ml of a solution
containing 0.5 M NaCl and various amounts of NaOH.
The measurements were performed on an Akvilon I-500
ionometric converter. The phosphorus content in the
sorbent was determined by the molybdate method .
Samples for measuring the IR spectra were prepared
in KBr pellets. The spectra were recorded on a Specord
M-80 device (Carl Zeiss, Jena) with the spectrum
resolution of 4 cm
The derivatograms were recorded with an MOM
derivatograph (Hungary). Samples were heated in
a platinum crucible to 500°С.
Experiments on uranium sorption were performed
with uranyl nitrate. The concentration of uranyl ions was
measured photometrically with Arsenazo III. Sorption
of copper ions was studied with copper sulfate. The
copper concentration was measured photometrically by
the ammonia method .
Below are data on the dependence of the phosphorus
content on the time of heat treatment (T
= 145°C) of
lignin impregnated with the phosphorylating mixture: