ABSTRACT
Raw
Banana Stalk (RBS), Acid Activated Banana Stalk (AABS) and Base Activated
Banana Stalk (BABS) prepared from banana stalk were used as biosorbents to remove
Lead(II) from aqueous solution. The biosorbents were characterised using
proximate analysis and Fourier Transform Infrared (FTIR) spectroscopy. Pb(II) of
1000 mg/L concentration was prepared from Pb(NO3)2 salt
and other concentrations were obtained from this stock through serial dilution.
Effects of adsorbent dose, temperature, initial metal concentration, contact
time and pH on the percentage Pb(II) removal were evaluated. The Pb(II) concentrations
in the solutions were analysed using Atomic Absorption Spectrophotometer.
Kinetic, isotherm and thermodynamic parameters were determined. FTIR
spectroscopy showed that RBS, AABS and BABS are rich in carboxyl, hydroxyl and
phenolic functional groups. At an equilibrium time of 180 minutes, the
percentage Pb(II) removal was 63.97%, 96.13% and 66.90% for RBS, AABS and BABS,
respectively. Pseudo-second order kinetics best described the process with R2 (0.95, 0.98, 0.97) for RBS,
AABS and BABS, respectively. Langmuir isotherm (AABS) has the maximum
adsorption capacity (qmax)
of 13.53 mg/g and R2 (0.99). Thermodynamic parameters obtained were △G0 (?18.75
kJ/mol), △H0 (12.63 kJ/mol), △S0 (0.05 kJ/mol·K) and Ea (4.37 kJ/mol). Banana stalk has viable
characteristics for preparing biosorbents. Acid activated banana biosorbent is
more efficient for removal of lead ions from its aqueous solution.