06-10-2012, 04:25 PM
Biosorption of lead from aqueous solution by Ficus religiosa leaves:
Batch and column study
Biosorption of lead from aqueous solution by Ficus religiosa leaves.pdf (Size: 853.83 KB / Downloads: 51)
Introduction
The contamination ofwastewater by toxic metal ions is aworldwide
environmental problem. The tremendous increase in the use
of heavy metals over the past few decades has inevitably increased
the metallic contents in the aquatic environment. Heavy metal ions
are of great concern, due to their mobility in natural water ecosystems
and due to their toxicity [1]. These metal contaminants are
introduced into surface waters through various industrial operations.
The pollutants of concern include lead, chromium, zinc, and
copper.
Lead is among the most toxic heavy metal ions, affecting the
environment [2]. Lead pipes used as drains from the baths, are
still in service. Main sources of lead are the manufacture of storage
batteries, pigments, leaded glass, mining, metal electroplating,
painting, coating, smelting, petrochemical, plumbing fuels, photographic
materials, matches and explosives [3,4]. Apart from this
lead is also used in insecticides, plasticwater pipes, food, beverages,
ointments and medicinal concoctions for flavoring and sweetening.
Materials and methods
Chemicals
Chemicals used were of analytical reagent grade. Polysulfone
(Cat No. 18244-3) and n,n-dimethyl-formamide (DMF) were
obtained fromAldrich chemicals. Stock lead solution of 1000mgl−1
concentration was prepared by dissolving 1.6 g of lead nitrate
(Merck Germany) in 1 l of distilled water. The stock solution was
diluted to obtain solutions of various knownconcentrations of lead.
For pH adjustment, 0.1M nitric acid and 0.1M ammonia solutions
were used.
Preparation of biosorbent
FRLs were collected locally, from University of Engineering and
Technology Lahore, Pakistan. These leaves were washed, repeatedly
with tap water to remove dust and soluble impurities and
were allowed to dry at room temperature in shadow. The dried
leaveswere converted into fine powder by grinding in amechanical
grinder. The powderwas sieved and the size fraction 60–80mwas
used in the experiments. This powderwas soaked in 0.1MHNO3 for
24 h (50 g FRLs powder was soaked per litre). The biosorbent was
filtered and washed with distilled water to remove acid contents.
The washing was continued till the pH of the filtrate was close to 7.
Itwas first dried at room temperature and then in an oven at 105 ◦C
to completely remove moisture. Finally, it was stored in air tight
glass bottles to protect it from humidity. Similar treatment of FRLs
was performed with 0.1M CaCl2 solution.
Results and discussion
Characterization of the biosorbent
The FTIR spectra of Ca-treated and lead loaded FRLs is shown
in Fig. 1. The FTIR spectra of Ca-treated FRLs, showed the presence
of many functional groups, indicating the complex nature of FRLs
biomass. A broad band at 3450cm−1 indicates the presence of OH
and NH groups. The absorbance at 2860 and 2920cm−1 are due
to aliphatic stretching. The peak at1656cm−1 is the indication of
C Nbending, whichfurther confirms the presence of amino groups.