LEAD AND CADMIUM REMOVAL FROM AQUEOUS SOLUTION USING WASTE MATERIAL (MICROWAVE INCINERATED RICE HUSK ASH)

Presence of heavy metals in aquatic systems has become a serious problem. Heavy
metals such Cadmium (Cd) and Lead (Pb) are mostly resulted from industrial activities
and adverse effects on environment as well as human health. As a result, there has been
a great deal of attention given to new technologies for removal of heavy metal ions from
contaminated waters. Commonly used treatment technologies were mostly effective,
except for their high operational cost. Thus, this study proposed Microwave Incinerated
Rice Husk Ash (MIRRA), locally available agricultural waste for the removal of Pb (II)
and Cd (II) from synthetic wastewater by batch adsorption process. Adsorption involves
separation of a substance from one phase accompanied by its accumulation or
concentration at the surface of another. Influences of pH, initial metal concentration,
contact time and absorbent dosage on the removal efficiency of those metals from
aqueous solution were studied. pH 3.0 and 4.0 were found to be optimum condition for
maximum adsorption of Pb (II) and Cd (II) ions from aqueous solution. The removal
efficiency of both metals correlated with the contact time between adsorbent and
adsorbate, initial metal concentration as well as adsorbent dosage. Adsorption of Pb (II)
and Cd (IT) were reached equilibrium after 60 and 120 minutes respectively; with both
found to be better fitted with pseudo second order kinetic model. The maximum
removal percentage of Pb (II) and Cd (II) were achieved at an adsorbent loading weight
of 400 mg and 200 mg correspondingly. The equilibrium adsorption capacity of
adsorbent used for Pb (II) and Cd (II) was calculated to be Langmuir and Freundlich
respectively. The experimental data were found to fit the Langmuir isotherm for Pb (II)
(R2 = 0.9991) and Freundlich isothetm for Cd (II) (R2 = 0.7951 ).