(63b) Preparation and Characterization of (FURCRAEA spp) as Green Support of Iron Nanostructured Catalyst

PREPARATION AND CHARACTERIZATION OF (FURCRAEA spp)
AS “GREEN” SUPPORT OF IRON NANOSTRUCTURED CATALYST

Karen
G. Bastidas G¹, Anamaria Barrera B¹, Cesar A. Sierra A²,
Hugo R. Zea R³

¹  Department of
Chemical and Environmental Engineering. National University of Colombia (Bogota).

² Associate
professor. Director of the Research Group of Macromolecules. National
University of Colombia  (Bogota).

³ Associate professor.
Director of the Research Group of Materials, Catalysis and Environment. National
University of Colombia (Bogotá).

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Abstract.

The availability of natural water resources has declined over time, becoming one of the biggest problems today. Environmental risk in Colombia's rivers has
increase due to the widespread use of harmful chemicals in a variety of processes, ranging from illegal mineral extraction to industry wastewater, e.g. Medellin's river, due to its strategic location along a
textile industrial corridor might be subject to dye contamination; the gold and platinum mining zones in Choco
and Antioquia regions are being heavily affected by the use of mercury in the extraction processes. In 2009, 520 tons of mercury were imported
by miners
working in this area, amount that exceeds several times the
mercury used by regulated industry in previous years (Ministry of Mines and Energy of Colombia, 2007). Not only the environmental risk is a concern but also the
economic conditions of many low-income families whose livelihood in many cases depends
exclusively of the of the mining.

Due to the issues raised above, the main goal of this
study is to research,
develop and implement innovative technologies
in the synthesis of highly
efficient, low cost
and environmentally friendly iron based catalysts capable of degradate pollutants, ensuring operational
stability. A native fiber (Fique, FURCRAEA spp) has been selected as a solid support for these catalysts due to its abundance, low cost and special physical and chemical characteristics.

The combination of cellulosic fibers with iron oxide nanoparticles could provide exceptional biodegradable composite materials
for the treatment of organic
dyes and heavy metals present in wastewater. Likewise, the use of iron
particles immobilized on fique fibers allows an easy separation catalyst-treated
water, turning the
biocatalyst
in highly recyclable and reusable material.

Fique fiber was initially characterized
by determining the percentage of ashes, total lignin, soluble and insoluble
lignin, cellulose, hemicellulose, total solids and humidity, obtaining 0.94,
22.58, 0.5, 22.8, 36.3, 27.5  0.701 and
2.1%, respectively. Additionally, the isoelectric point (pzc),
acidic and basic sites were measured.

Then,
the fiber was subjected to a pretreatment in order to expose more active sites which
on time serve as nucleation points for the deposition of nanoparticles. This
was done by means of an ultrasound-assisted procedure, varying the sonication time
(30, 60 and 90 minutes). The effect of the sonication was followed by measuring
the contents of lignin, cellulose and hemicellulose within the fiber after each
time. 60 minutes of sonication was found to be most beneficial time since the
amount of lignin and hemicellulose present in the fiber was reduced, while
conversely the amount of crystalline cellulose exposed increases.

In
order to improve the chemical ability of the nucleation sites to interact with
iron and then to form stable and size controllable nanoparticles, a
cationization procedure was performed on the fiber; this was achieved by the
exposure of the fiber to acidic and basic conditions promoting cationization. Three cationization
times (1, 2 and 3 hours) were studied and their effect on the fiber chemical surface
was evaluated using FTIR-ATR and XRD analysis. The results showed 3 hours as the
optimal cationizing time.

Subsequent
to the cationization of the fiber surface, a procedure of ionic/cationic exchange
was implemented by exposing the fiber to a solution of iron salts in order to
replace the cations in the fiber surface and anchoring the iron nanoparticles.
Different conditions were studied in order to synthetize zero valent iron nanoparticles (nZVI)
and others with different oxidation states. Finally, to track the impregnation
process on the fiber, samples from the precursor solution were taken at different
times and its iron concentration was determined by atomic absorption
spectrophotometry (AAS). Complementary characterization performed by X-ray
diffraction, BET surface area and electronic microscopy, among others.

Key words: Natural
support (fique), iron nanoparticles, bionanocatalyst.