Parametric Statistical Significance of Iron (II) Ions Adsorption by Coconut Shell in Aqueous Solutions

Abstract

The parametric statistical adsorption of chemically unmodified coconut shell powder (CSP) to adsorb iron (II) ions from aqueous solutions was examined in this work. It was observed that the adsorption capacity increased with increasing adsorbent dose, reducing adsorbate dose, increasing contact time, decreasing temperature and reducing particle size. As observed about one gram of the adsorbent was sufficient enough to remove 98 % iron (II) ions. A total contact time of about 40 minutes was sufficient for almost complete adsorption of the ions, while a pH of about 6.0 exhibited the maximum adsorption capacity. The sorption data were fitted into Langmuir, Freundlich, Temkin and the Dubinin-Radushkevich isotherms, fitted most with the Freundlich Isotherm model. The energy values obtained from the Temkin and Dubinin-Radushkevich isotherm model indicated high chemisorption phenomenon with the adsorbents. Investigation of some kinetic models confirmed that the adsorption of iron (II) ions using CSP was a pseudo-second order kinetic process, which further corroborates that chemisorption dominates the adsorption. Fourier Transform Analysis (FTIR) further established and justified the outcome of the study. The adsorption was parametrically justified statistically with Analysis of Variance (ANOVA) and Bonferroni-Holm Posthoc significance test. Conclusively, coconut shell proved strongly to be an effective and suitable adsorbent for removing iron (II) ions from aqueous solutions.