Competitive adsorption and selectivity sequence of heavy metals by chicken bone-derived biochar: Batch and column experiment

Abstract

The objective of this research was to evaluate adsorption of heavy metals in single- and ternary-metal forms onto chicken bone biochar (CBB). Competitive sorption of heavy metals by CBB has never been reported previously. The maximum adsorption capacities of metals by CBB were in the order of Cu (130 mg g⁻¹) > Cd (109 mg g⁻¹) > Zn (93 mg g⁻¹) in the single-metal adsorption isotherm and Cu (108 mg g⁻¹) >> Cd (54 mg g⁻¹) ≥ Zn (44 mg g⁻¹) in the ternary-metal adsorption isotherm. Cu was the most retained cation, whereas Zn could be easily exchanged and substituted by Cu. Batch experimental data best fit the Langmuir model rather than the Freundlich isotherms. In the column experiments, the total adsorbed amounts of the metals were in the following order of Cu (210 mg g⁻¹) > Cd (192 mg g⁻¹) > Zn (178) in single-metal conditions, and Cu (156) > Cd (123) > Zn (92) in ternary-metal conditions. Results from both the batch and column experiments indicate that competitive adsorption among metals increases the mobility of these metals. Especially, Zn in single-metal conditions lost it adsorption capacity most significantly. Based on the 3D simulation graphs of heavy metals, adsorption patterns under single adsorption condition were different than under competitive adsorption condition. Results from both the batch and column experiments show that competitive adsorption among metals increases the mobility of these metals. The maximum metal adsorption capacity of the metals in the column experiments was higher than that in the batch experiment indicating other metal retention mechanisms rather than adsorption may be involved. Therefore, both column and batch experiments are needed for estimating retention capacities and removal efficiencies of metals in CBB.

Keywords:

• Biochar
• chicken bone
• competitive adsorption
• Freundlich isotherm
• Langmuir isotherm
• single-metal
• ternary-metal
• three-dimensional simulation

Acknowledgments

Authors Jong-Hwan Park and Ju-Sik Cho contributed equally to this work and are considered as co-first authors.

Funding

This work was supported by the National Research Foundation of Korea grant funded by the Korea Government (Ministry of Education, Science and Technology), [2012R1A2A2A01015706, NRF-2014R1A1A2007515]. This work was also carried out with the support of “Cooperative Research Program for Agriculture Science & Technology Development (Project No. PJ011227042015)” by by Rural Development Administration, Republic of Korea.