Phosphate Removal Mechanisms in Aqueous Solutions by Three Different Fe-Modified Biochars

Yiyin Qin, Xinyi Wu, Qiqi Huang, Jingzi Beiyuan (), Jin Wang, Juan Liu, Wenbing Yuan, Chengrong Nie and Hailong Wang
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Yiyin Qin: School of Environmental and Chemical Engineering, Foshan University, Foshan 528000, China
Xinyi Wu: School of Environmental and Chemical Engineering, Foshan University, Foshan 528000, China
Qiqi Huang: School of Environmental and Chemical Engineering, Foshan University, Foshan 528000, China
Jingzi Beiyuan: School of Environmental and Chemical Engineering, Foshan University, Foshan 528000, China
Jin Wang: School of Environmental Science and Engineering, Key Laboratory of Water Quality and Conservation in the Pearl River Delta, Ministry of Education, Guangzhou University, Guangzhou 510006, China
Juan Liu: School of Environmental Science and Engineering, Key Laboratory of Water Quality and Conservation in the Pearl River Delta, Ministry of Education, Guangzhou University, Guangzhou 510006, China
Wenbing Yuan: School of Environmental and Chemical Engineering, Foshan University, Foshan 528000, China
Chengrong Nie: School of Food Science and Technology, Foshan University, Foshan 528000, China
Hailong Wang: School of Environmental and Chemical Engineering, Foshan University, Foshan 528000, China

IJERPH, 2022, vol. 20, issue 1, 1-18

Abstract: Iron-modified biochar can be used as an environmentally friendly adsorbent to remove the phosphate in wastewater because of its low cost. In this study, Fe-containing materials, such as zero-valent iron (ZVI), goethite, and magnetite, were successfully loaded on biochar. The phosphate adsorption mechanisms of the three Fe-modified biochars were studied and compared. Different characterization methods, including scanning electron microscopy/energy-dispersive spectrometry (SEM-EDS), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS), were used to study the physicochemical properties of the biochars. The dosage, adsorption time, pH, ionic strength, solution concentration of phosphate, and regeneration evaluations were carried out. Among the three Fe-modified biochars, biochar modified by goethite (GBC) is more suitable for phosphate removal in acidic conditions, especially when the pH = 2, while biochar modified by ZVI (ZBC) exhibits the fastest adsorption rate. The maximum phosphate adsorption capacities, calculated by the Langmuir–Freundlich isothermal model, are 19.66 mg g −1 , 12.33 mg g −1 , and 2.88 mg g −1 for ZBC, GBC, and CSBC (biochar modified by magnetite), respectively. However, ZBC has a poor capacity for reuse. The dominant mechanism for ZBC is surface precipitation, while for GBC and CSBC, the major mechanisms are ligand exchange and electrostatic attraction. The results of our study can enhance the understanding of phosphate removal mechanisms by Fe-modified biochar and can contribute to the application of Fe-modified biochar for phosphate removal in water.

Keywords: adsorption; phosphorus; eutrophication; modified-biochar (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2022
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