Arsenic(V) Removal Using Activated Alumina: Kinetics and Modeling by Response Surface

Abstract

Arsenic(V) removal using activated alumina (AA) was carried out in batch mode and was modeled using response surface method. The Doehlert design of experiment (DOE) was used to model the experimental data, and the Doehlert design matrix was used to have uniformly distributed experimental points. The effect of contact time, adsorbent dose, pH level, and initial arsenic(V) concentration was studied. The statistical model developed for arsenic(V) removal suggested that maximum removal took place at a pH value of 6.26. There was strong interaction between pH and arsenic(V) removal. Within the range of the factors studied (pH level 2–12; dose of AA 1–5 g; contact time 1–6 h; and arsenate conc. .1–.5 mg/L), the optimum condition for arsenic(V) removal obtained using the model was at pH=6.26, dose of AA=3.29 g, shaking time=3.16 h, and arsenic(V) conc.=.213 mg/L. The maximum removal obtained at optimum condition was found to be 93.6%. The model predicts arsenic(V) removal condition with reasonably low error and high coefficient of determination (R2=.9835). The model validation result suggested very low error (2.2%) in predicting targeted removal. The model developed can effectively predict adsorption and can be used for designing contact system for arsenic(V) removal from contaminated water.