Metal biosorption on plant-based materials and
agricultural wastes is a well practiced but a complex
process affected by several factors. The biosorption of
chromium(VI) from aqueous solution onto waste plant
biomass of
Portulaca Oleracea
was studied in the present
work. Batch studies were carried out to examine the
effects of process parameters. Influence of altering various
process parameters was studied. The biosorption process
was fast, and equilibrium was achieved in 45 min of
contact time. It was found that the biosorption capacity of
plant material depends on many factors mainly on solution
pH, with a maximum biosorption capacity for chromium
at pH 2. The biosorption kinetics was tested with pseudofirst-
order and pseudo-second-order reaction, and results
showed that biosorption followed pseudo-second-order
rate expression. Experimental equilibrium data were
applied to two different isotherm models. Isotherm tests
showed that equilibrium sorption data were better represented
by Langmuir model, and the sorption capacity of
plant biomass was found to be 54.945 mg/g. Thermodynamic
parameters like Δ
G°, Δ
H° and Δ
S° were also
evaluated, and it was found that the biosorption was
spontaneous and endothermic in nature. Plant biomass was
found to be an effective adsorbent for chromium(VI) from
aqueous solution. This study indicated that plant biomass
could be used as an efficient, cost-effective and environmentally
safe biosorbent for the treatment of chromium
containing aqueous solutions
