RSC Adv., 2015,5,14129

Acid-vacuo heat treated low cost banana stems
fiber for efficient biosorption of Hg(II)†

The potential of banana stem fiber (BSF) as a low cost biosorbent for Hg(II) removal was studied. HCl
treatment increased the cellulose accessibility which led to an enhanced interaction of Hg(II) and BSF.
Activation of BSF-HCl in vacuo at 373 K increased the maximum biosorption capacity from 28 to 372 mg
g1 and altered the activation energy from 3.5 to 76.9 kJ mol1 showing an increase in Hg(II)
chemisorption. FTIR and ESR results confirmed the large amount of structural defects on the activated
BSF-HCl which led to the increase in Hg(II) uptake. Batch biosorption models showed that the kinetics
follow pseudo-second-order and the equilibrium uptake fitted to all three-parameter models showing
the Hg(II) biosorption behaves as a Langmuir isotherm. The non-linear regression method exhibited
higher coefficient of determination values for isotherm and kinetic analyses compared to the linear
method. The thermodynamic functions indicated that the nature of Hg(II) biosorption is an exothermic
and non-spontaneous process.