Ethylenesulfide as a useful agent for incorporation
on the biopolymer chitosan in a solvent-free reaction
for use in lead and cadmium removal
Edson C. da Silva Filho
•
Pedro D. R. Monteiro
•
Kaline S. Sousa
•
Claudio Airoldi
CBRATEC7 Conference Special Issue
Ó Akade
´
miai Kiado
´
, Budapest, Hungary 2010
Abstract In this work Chitosan (Ch) was chemically
modified with ethylenesulfide (Es) under solvent-free con-
ditions to give (ChEs), displaying a high content of thiol
groups due to opening of the three member cyclic reagent.
ChEs was used in studies of lead and cadmium adsorption
from aqueous solution, using the batchwise method and
calorimetric studies were accomplished to those interactions,
through the calorimetric titration technique. The obtained
results show that the modified Ch, ChEs is a material, that
besides presenting the advantages of being a biopolymer, it
showed a good adsorption capacity of the lead and cadmium
cation metallic, that are extremely poisonous and harmful to
the environment. The results of the calorimetric titration
showed that the related thermodynamic parameters to those
adsorptions shown favorable thermodynamic data.
Keywords Chitosan Á Modification Á Ethylenesulfide Á
Adsorption Á Calorimetry
Introduction
Chitosan (Ch) is a linear copolymer constituted by
b(1 ? 4) linking 2-acetamido-2-deoxy-b-
D
-glucopyranose
and 2-amino-2-deoxy-b-
D
-glucopyranose units obtained
through N-deacetylation of chitin under strongly basic
conditions. From the structural viewpoint, available amino
(NH
2
) and hydroxyl (OH) groups present single-pairs of
electrons, even though the N-deacetylation is almost never
complete [1, 2]. It is usually obtained trough alkaline
deacetylation from chitin that is a natural occurrence
polymer made up of acetylglucosamine units, which are
widely found in the exoskeleton of shellfish and crusta-
ceans, such as crab, lobsters, and shrimps [3], being the
second more abundant polysaccharide of the planet [4] and
defeated only by cellulose. Cellulose, chitin, and Ch have
related structures and occur in nature, being among the
most abundant materials in the world [5, 6]. Chitosan is
extensively exploited due to its innumerous advantages,
since besides its chemical behavior Ch exhibits also
physical and biological properties as non toxicity, bio-
compatibility, and biodegradability. When the biopoly-
meric Ch is submitted to chemical modification, this is a
promising route to yield new biomaterials. Through the
inclusion of desirable pendant molecules covalently bon-
ded to the main chain, some characteristic properties are
changed and, consequently, many other interesting areas
such as agriculture, medicine, food, industry, pharmaceu-
tical technology and so on become possible technological
applications [7]. A point toward these modifications is the
Ch sorption capacities studies, detaching its behavior with
divalent cations [8].
This investigation deals with the incorporation of eth-
ylenesulfide (Es) molecule in the polysaccharide chain
through the reaction of the available amino group. An
environmentally friendly solvent-free reaction was
explored and the activity in sorbing divalent lead and
cadmium from aqueous solution was studied through the
proposed model. The cation/basic center interactions at the
solid/liquid interface were also followed calorimetrically,
and the set of thermodynamic data involved in these
interactive processes was determined.
E. C. da Silva Filho (&) Á P. D. R. Monteiro
LIMAV, Chemistry, Federal University of Piauı
´
,
Teresina, PI 64049-550, Brazil
e-mail: edsonfilho@ufpi.edu.br
K. S. Sousa Á C. Airoldi
Institute of Chemistry, University of Campinas,
P.O. Box 6154, Campinas, SP 13084-971, Brazil
123
J Therm Anal Calorim (2011) 106:369–373
DOI 10.1007/s10973-010-1205-y