This research was performed to evaluate the recycling characteristics by physico-chemical analysis of wasted and regenerated activated carbons. Three types of waste carbons for gas treatment, drinking water purification, and wastewater treatment were sampled and analyzed. Heavy metals concentrations of As, Zn, Pb and Cd for all regenerated carbons satisfied the standard criteria of the granular activated carbon for drinking water purification. The sieve residues of the regenerated activated carbons for drinking water purification and wastewater treatment were in the range of 85.3 ~ 97.7% and 97.7 ~ 99.7%, respectively. Some samples of the regenerated activated carbons were not able to satisfy the standard criteria for methylene blue adsorption ( 150 mL/g) and iodine adsorption ( 950 mg/g). All activated carbons for gas treatment and drinking water purification satisfied the standard criteria for hardness and bulk density. One of three activated carbon samples for drinking water purification did not satisfied the standard criteria for phenol number and ABS (alkyl benzene sulfonate) number. The observed results concluded that there was no problem of heavy metals accumulation in the regenerated activated carbon, but partially against standard criteria such as sieve residue, moisture content, methylene blue adsorption, and iodine adsorption.

The activated carbon was prepared from waste citrus peels using NaOH. With the increase of NaOH ratio, iodine adsorptivity and specific surface area of the activated carbon prepared were increased, but activation yield was decreased. The optimal condition of activation was at 300% NaOH and 700℃ for 1.5 hr. For the activated carbon produced under optimal condition, iodine adsorptivity was 1,006 mg/g, specific surface area was 1,356 m2/g, and average pore diameter was 20～25Å. From the adsorption experiment for benzene vapor in fixed bed reactor, it was found that the adsorption capacity of activated carbon prepared from waste citrus peel was higher than that of activated carbon purchased from Calgon company. This result implied that the activated carbon prepared from waste citrus peel could be used for gas phase adsorption.

Activated carbon was prepared from waste citrus peels by chemical activation with ZnCl2. The optimal condition of carbonization was at 300℃ for 1.5 hr. Activation experiments with carbonized samples prepared at optimal carboniztion condition were carried out under various conditions such as activation temperature of 400 to 900℃, activation time of 0.5 to 2.0 hr, and ZnCl2 ratio of 100 to 300%. In order to investigate the physical properties of the activated carbons prepared, iodine adsorptivities and specific surface areas were measured and their morphologies were observed from scanning electron microscopy. As ZnCl2 ratio increased, activation yield decreased, while iodine adsorptivity and specific surface area increased. The optimal condition of activation was at 300% ZnCl2 ratio and 300℃ for 1.5 hr, and then iodine adsorptivity and specific surface area was measured as about 862 mg/g and 756 m2/g, respectively. SEM photography showed that the surface morphology was changed and many active pore were produced by chemical activation.