Abstract:
Toxic heavy metal ions; cadmium, copper, chromium and lead removal is important from the
environment due to the health effect of plants and animals. Among the different approaches such
as precipitation, membrane process, ionic exchange, floatation and others, adsorption is one of
the promising approaches. For this purpose, Banana peel powders in the modified (MBP) and
unmodified (UNMBP) forms were prepared as adsorbents. The effects of different experimental
parameters, namely, solution pH, dosage, contact time, and initial metal ions concentrations, on
adsorption of metal ions, were investigated. The optimum value of each parameter was
determined, respectively, for both MBP and UNMBP. The metal ions adsorption was found to be
highly pH dependent. The experimental results showed that the adsorbed amounts of heavy metal
ions tend to decrease with increase in pH from 6 up to 8 except for chromium. Chromium
showed maximum adsorption at pH 2 but declined from pH 2 to 8. Both Freundlich and
Langmuir isotherm models were applied to the experimental data but Langmuir isotherm model
was fitted with the experimental data well. The adsorption capacities (qmax , mg/g) of UNMBP
were 6.25, 2.56, 4.78 and 1.13 mg/g for cadmium, chromium, copper and lead adsorption,respectively, and adsorption capacities (qmax , mg/g) of MBP were 20.09, 3.5, 19.23, and 4.65
mg/g for cadmium, chromium, copper and lead adsorption, respectively. With regard to
adsorption kinetics, the two common models (ie, Pseudo - first and pseudo-second order models)
were applied. The desorption efficiency decreased as number of cycles increased and based on
the obtained results the modified banana peel was found to be recyclable and environmentally
friendly adsorbent for the removal of heavy metal ions from wastewater.
