CORRELATION OF CARBONIZED AVOCADO SEEDS (Persea americana) AND CARBONIZED ORANGE PEELS (Citrus sinensis) ADSORPTIVE POTENCY IN REMOVING Cd2+ IONS IN AQUEOUS SOLUTION

Abstract

Man cannot survive without water and water contamination has reduced the availability of
healthy water to man. The dried Avocado Pear seed and orange peels were ground into
powdery form and sieved using standard test sieve with size BSS-53μm mesh sieve. The
pulverized avocado pear seed and orange peel were separately carbonized in a muffle
furnace at a temperature of 300 °C for 40 minutes. The physicochemical characterization of
the carbonized avocado pear seed (CAPS) and carbonized orange peels (COP) was done
using scanning electron microscope (SEM) and Fourier-transform infrared (FTIR)
spectrophotometer. The adsorption process of Cd2+ ions onto CAPS and COP was studied
using the batch adsorption isotherm experiments. Langmuir, Freundlich, Tempkin and
Flory-Huggins isotherm models were used to evaluate the data obtained. Cadmium ions had
a stronger affinity for CAPS than for COP due to the functional groups present, while the
COP had higher intensity, adsorption capacity and spontaneously adsorbed Cd2+ ions due to
the large number of pores of varied sizes it possesses compared to CAPS. The adsorption
mechanism is dominated by physiosorption process. Tempkin adsorption isotherm revealed
that the COP a higher heat of adsoption (B) and maximum binding energy than CAPS an
indication that the COP held the cadmium ions firmer on its surface compared to that of
CAPS. The COP is a better adsorbent compared with CAPS for effective removal of
Cadmium ions based on its maximum adsorption capacity of 8.84 and 5.67 for COP and
CAPS respectively from Langmuir isotherm model.