Contamination of groundwater and surface water with arsenic (Asic) has become emerging health and environmental problem around the world. This problem has received significant attention amongst scientists for the development of new adsorbents to remediate Asic -contaminated water. The ability of the immobilized powdered eggshell (Poes), as adsorbent, to remove Asic was studied under batch conditions. Equilibrium data were analysed using non-linear and linearized two-parameter adsorption isotherms models (Langmuir, Freundlich, Elovich, Flory–Huggins, Temkin, Frenkel- Hasley- Hill; Langmuir- Vageler, Hill-de Boer, Kiselev, Fowler- Guggenheim, Dubinin –Radushkevich, Jovanovic, Harkins–Jura and Halsey). The performance of adsorption equilibrium isotherm models was evaluated statistically using the following analysis of variance (ANOVA), model of' selection criterion (MSC), Coefficient of Determination (CD), Correlation coefficient (R) and Akaike Information Criterion (AIC). The study revealed that for non-linear equilibrium isotherm models, Freundlich (0.986 and 3.906) > Fowler—Guggenheim (0.996 and 5.176) and Hasley (0.986 and 3.906) performed well in predicting experimental data-based on the magnitudes of R and MSC. The linearized adsorption equilibrium isotherm models, Dubinin – Radushkevich (0.993 and 4.621)
Key words: Arsenic, adsorbent, non-linear and linearized isotherm models, removal efficiencies, two-parameter adsorption isotherms
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