STUDY ON Zn (II) ION ADSORPTION BY RICE HUSK DIGESTED WITH NITRIC ACID AND SODIUM HYDROXIDE

There are two procedures that commonly govern the studies on metal adsorption by
rice husk. They are the treatment process of the rice husk and the adsorption process
of the metal ion. Raw rice husk will be treated with acidic or basic solution and then
pyrolised before it can be used as adsorbent. The treatment process of the rice husk
can enhance the surface properties and thus, increase the capability of the rice husk to
be used as adsorbent.
In this piece of work, three factors were considered in order to compare the
performances of the acid and base treated rice husk. Effect of digestion times,
contact time and initial metal ion concentration on the Zn (II) ion adsorption were
conducted in this research. The performance of the rice husk as adsorbent was
compared by analyzing the percent metal uptake and the adsorption capacity of the
rice husk.
As the digestion time increased, the percent metal uptake also increased. For effect
of contact time, the percent metal uptake increased as the contact time increased until
an optimum time was reached, whereby further increase in the contact time did not
change the adsorption rate. The percent metal uptake increased as the initial metal
ion concentration increased until an optimum initial metal ion concentration was
reached. After the optimum initial metal concentration was reached, further increase
in the initial metal concentration resulted in the reduction of the percent metal uptake.
Based on these three effect studies, it was found out that the acid treated rice husk
was better adsorbent compared to base treated rice husk.