Studies OnZn(II) and Cu(II) Ions Adsorption by Rice Husks Digested With Nitric Acid

This research studies the effects of different preparation conditions on the yield of activated
carbons and also to study the adsorption capacity of activated carbons produced towards
Zn(II) ions and Cu(II) ions, hi this research, the effects of carbonization time, the weight
ratio of nitric acid to rice husks, sample loading size and contact time will be studied while
observing the condition of the activated carbons produced from rice husks. This study is
significant as Zn(II) and Cu(II) ions removal from industrial and municipal wastewater is
vital in view of the many health and environmental hazards caused by heavy metal
contaminated water. Since the current methods of Zn(II) and Cu(II) removal with
commercial activated carbon are expensive, this study onricehusks based activated carbon is
timely as rice husks are readily available and costs less than commercial adsorbents. The
methodology employed in this study is to first treat therice husks with nitric acid at different
weight ratios of 1:1, 1.5:1, 2:1 and 2.5:1, before carbonizing attemperature of 500°C varying
periods of 1 hour, 2 hours, 3 hours and 4 hours. An FTIR scan was done on one of the
samples to determine the functional groups of the activated carbon produced. The activated
carbonwould then be used as adsorbents to adsorb Zn(II) ions in Zinc(II) Nitrate and Cu(II)
ions from Copper(II) Nitrate solutions. The adsorption capacity towards both metal ions will
finally be determined using the Atomic Absorption Spectrophotometer (AAS). It was found
that the activated carbons are more suitable for the removal of Zn (II) ions as the percentage
of removal is higher than that of Cu(II) ions. Carbonization time and weight ratio generally
increases the adsorption capacity. However, both parameters have their limits whereby any
increment of weight ratio or carbonization time would deteriorate the adsorption capacity.
The optimum experimental conditions for maximum removal of Zn(II) ions are 2 hours
carbonization time with nitric acid to rice husks weight ratio of 1:1, loading size of 0.4 g and
contacttime of lhour. As for Cu(II) ions removal, the optimum experimental conditions are 4
hours carbonization, 2.5:1 weight ratio ,0.4g loading sizeand 4 hours contact time.