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This paper presents a report on adsorption kinetics and mechanism of arsenic ions onto powdered eggshell (PES).
Raw eggshells (chickens) were collected from Obafemi Awolowo University, Ile-Ife, Nigeria. The eggshells were
cleaned using distilled water, air-dried, pulverised into powder, separated according to sieve sizes using British
Standard sieves and stored in desiccators. The elemental contents and micrograph structure of the PES were
determined using standard methods. Adsorption kinetics and mechanisms of arsenic onto PES were monitored using
standard models. Effects of pH, particle size and initial lead concentrations on the kinetics and mechanism of arsenic
adsorption onto PES were studied. The study revealed that moisture content of the PES was 0.899 %, volatile solid
were 2.002 %, and 20.760 % at 550oC and 1200oC respectively. Acid and water solubilities of the PES were 6.048 %
and 0.450 % respectively. The elemental contents of the PES were 22.465 mg/g of iron as Fe2+, 12.545 mg /g of
aluminium as Al3+ and 418 mg /g of Calcium as Ca2+. Adsorption kinetics and mechanism of arsenic ion onto PES
revealed that the Boyd et al. plots were neither linear nor passed through the origin, which indicates that film diffusion
is the rate-limiting sorption process for arsenic ions unto PES. The rates of ion-exchange of PES – arsenic kinetics
were between 0.0009 and 0.0118 /h, and 0.0088 and 0.0122/h for wastewater and natural water respectively. It was
concluded that PES can adsorbed arsenic ion and the presence of metallic ions such as Fe, Ca and Al aided arsenic removal.