Paper wastes such as printed paper, paperboard, magazines,
and newspaper have contributed the largest portion of disposed
solid waste steam and imparted great impacts on the environment
and our lives [1]. Improper handling of paper wastes would result
in periodic fires, water pollution, greenhouse gases emission and
potential spread of diseases. Effective utilization of paper wastes
could therefore not only reduce the amount of municipal solid
waste, but also contribute towards environmental protection and
conservation. Papers consist mainly of cellulose fibers which have
been compressed into sheet during the papermaking process and
these cellulose fibers can be isolated using various mechanical and
chemical processes [1,2]. Cellulose, a linear homopolymer consisting
of D-anhydroglucopyranose units linked by β-(1-4)-glycosidic
bonds, can be modified into different morphological shapes
such as film, fiber, nanoparticles, as well as spherical beads [3].
Cellulose beads have attracted great attention of scientists due
to their abundance, biodegradability, renewability, and low cost.
Cellulose beads can be chemically modified to serve as potential
biomedical engineering materials [4,5], and are being widely used
as the stationary phase in chromatography systems for separation
due to their spherical shape which allow easy packing in column
and withstand very high flow rates [6]. Besides, cellulose beads
have been chemically modified with different types of anionic
groups for use as the absorbent material in water treatment, such
as the removal of heavy metals in water resources [7]. The drug
loading capacity and release kinetics of cellulose beads have also
been studied for pharmaceutical and biomedical applications [8].
Many methods have been reported in literatures on the preparation
of cellulose beads with different size range from micrometer
to millimeter scale using the viscose process. Nevertheless,
these reported procedures require the use of derivatizing cellulose
solvent and toxic chemicals such as carbon disulfide which cause
negative impacts to environment [9]. Besides, non-derivatizing
organic solvents and ionic liquids have been used for producing
cellulose beads. 1-allyl-3-methylimidozoium chloride (AMIMCl) is
a room temperature ionic liquid which has been shown to possess
excellent cellulose solubility of up to 14.5 wt% at 80 °C. Dissolved
cellulose can be easily regenerated in the gel form by using a nonsolvent
[10]. Regenerated cellulose with high specific surface area
could potentially be used in biomedical applications.
Herein, we have reported the preparation of cellulose beads
from regenerated cellulose isolated from printed paper wastes via
a facile dissolution and precipitation approach using AMIMCl as
the solvent, and ultrapure water as the non-solvent. The mean
diameter of cellulose beads formed could be precisely controlled
by varying the diameter of extruding syringe needle nozzle. These
cellulose beads exhibited high porosity and specific surface area
which varied significantly with their mean diameter. Due to their
abundance, biodegradability, biocompatibility, and low cost, cellulose
beads of high porosity and specific surface area are potentially
useful as drug delivery carriers.