Unlocking the potential of biochar: an iron-phosphorus-based composite modified adsorbent for adsorption of Pb(II) and Cd(II) in aqueous environments and response surface optimization of adsorption conditions

Xu Li; Yuan Chi; Feng Ma; Xiaoxin Wang; Rui Du; Zhipeng Wang; Xiaoyan Dang; Chaoyue Zhao; Yanping Zhang; Shumin He; Youzhao Wang; Tong Zhu

doi:10.1007/s11356-024-33238-5

Unlocking the potential of biochar: an iron-phosphorus-based composite modified adsorbent for adsorption of Pb(II) and Cd(II) in aqueous environments and response surface optimization of adsorption conditions

Environ Sci Pollut Res Int. 2024 May 13. doi: 10.1007/s11356-024-33238-5. Online ahead of print.

Authors

Xu Li^#¹, Yuan Chi^#¹, Feng Ma¹, Xiaoxin Wang², Rui Du², Zhipeng Wang¹, Xiaoyan Dang¹, Chaoyue Zhao¹, Yanping Zhang¹, Shumin He¹, Youzhao Wang¹, Tong Zhu³

Affiliations

¹ Institute of Process Equipment and Environmental Engineering, School of Mechanical Engineering and Automation, Northeastern University, Shenyang, 110819, China.
² Baotou Renewable Water Resources and Sewage Treatment Co., LTD, Baotou, 014000, China.
³ Institute of Process Equipment and Environmental Engineering, School of Mechanical Engineering and Automation, Northeastern University, Shenyang, 110819, China. tongzhu@mail.neu.edu.cn.

^# Contributed equally.

PMID: 38740681
DOI: 10.1007/s11356-024-33238-5

Abstract

In this work, iron-phosphorus based composite biochar (FPBC) was prepared by modification with potassium phosphate and iron oxides for the removal of heavy metal ions from single and mixed heavy metal (Pb and Cd) solutions. FTIR and XPS characterization experiments showed that the novel modified biochar had a greater number of surface functional groups compared to the pristine biochar. The maximum adsorption capacities of FPBC for Pb(II) and Cd(II) were 211.66 mg·g^-1 and 94.08 mg·g^-1 at 293 K. The adsorption of Pb(II) and Cd(II) by FPBC followed the proposed two-step adsorption kinetic model and the Freundlich isothermal adsorption model, suggesting that the mechanism of adsorption of Pb(II) and Cd(II) by FPBC involved chemical adsorption of multiple layers. Mechanistic studies showed that the introduction of -PO₄ and -PO₃ chemisorbed with Pb(II) and Cd(II), and the introduction of -Fe-O increased the ion exchange with Pb(II) and Cd(II) during the adsorption process and produced precipitates such as Pb₃Fe(PO₄)₃ and Cd₅Fe₂(P₂O₇)₄. Additionally, the abundant -OH and -COOH groups also participated in the removal of Pb(II) and Cd(II). In addition, FPBC demonstrated strong selective adsorption of Pb(II) in mixed heavy metal solutions. The Response Surface Methodology(RSM) analysis determined the optimal adsorption conditions for FPBC as pH 5.31, temperature 26.01 °C, and Pb(II) concentration 306.30 mg·L^-1 for Pb(II). Similarly, the optimal adsorption conditions for Cd(II) were found to be pH 5.66, temperature 39.34 °C, and Cd(II) concentration 267.68 mg·L^-1. Therefore, FPBC has the potential for application as a composite-modified adsorbent for the adsorption of multiple heavy metal ions.

Keywords: Adsorption mechanism; Cadmium; Competitive adsorption; Iron-phosphorus-based biochar; Lead; Response Surface Methodology.

Abstract

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