Study of Ni(II) removal by olive tree pruning and pine cone shell by experimental design methodology

Abstract

The overall objective of this study is to model and optimize the elimination of nickel ions from aqueous solutions by pine cone shell and olive tree pruning as biosorbents. A 33 full factorial design was employed for experimental design and analysis of the results. The flow rate (4–8 mL/min), the mass of biosorbent (5–15 g), and the initial Ni(II) concentration (10–100 ppm) were the critical variables of the removal optimized. The results have shown that initial concentration of Ni(II) is the most influential factor in biosorption capacity as much as in total nickel removal. The optimum flow rate, mass of biosorbent, and initial concentration of Ni(II) to obtain the maximum total nickel removal coincided with both biosorbents and were found to be 6 mL/min, 15 g, and 10 ppm. Meanwhile, to maximize the biosorption capacity, the optimum flow rate, mass of biosorbent, and initial concentration of Ni(II), were 8 mL/min, 5 g, and 100 ppm for olive tree pruning and 6 mL/min, 15 g, and 100 ppm for pine cone shell. The experimental breakthrough curves obtained under optimum conditions were modeled using Bohart–Adams, Thomas, Yoon–Nelson, and Dose-Response models. The last one is the model that best reproduced the total breakthrough curves.