Preparation of Biochars from Different Sources and Study on Their Phosphorus Adsorption Properties

Yinlong Shao; Anqi Hu; Yongcan Jiang; Xianbiao Wang; Jingchen Li; Guanglong Liu

doi:10.3390/molecules30122633

Preparation of Biochars from Different Sources and Study on Their Phosphorus Adsorption Properties

Molecules. 2025 Jun 18;30(12):2633. doi: 10.3390/molecules30122633.

Authors

Yinlong Shao¹, Anqi Hu², Yongcan Jiang^{1

3}, Xianbiao Wang¹, Jingchen Li⁴, Guanglong Liu²

Affiliations

¹ PowerChina Huadong Engineering Corporation Ltd., Hangzhou 311122, China.
² Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture and Rural Affairs, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.
³ Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China.
⁴ College of Landscape and Horticulture, Hubei Vocational College of Bio-Technology, Wuhan 430070, China.

Abstract

Biochar is a solid product generated through the pyrolysis of biomass materials under anaerobic or hypoxic conditions, and it is characterized by its strong adsorption capacity. To investigate the phosphorus adsorption performance of biochar derived from wheat straw, bamboo, and water hyacinth in wastewater, iron modification treatments were applied to these biochars, and the most effective modified biochar was identified. The physicochemical properties of the modified biochars were characterized using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and scanning electron microscopy (SEM). The results showed that optimal modification was achieved with an iron-carbon mass ratio of 0.70 for wheat straw biochar (Fe-WBC) and 0.45 for both bamboo biochar (Fe-BBC) and water hyacinth biochar (Fe-HBC). The maximum phosphorus adsorption capacities of the three modified biochars were as follows: 31.76 mg g^-1 (Fe-WBC) > 27.14 mg g^-1 (Fe-HBC) > 25.31 mg g^-1 (Fe-BBC). It was demonstrated that the adsorption behavior of Fe-BBC was predominantly multi-molecular layer adsorption, whereas the adsorption behavior of Fe-WBC and Fe-HBC was primarily monolayer adsorption. All three types of modified biochars reached adsorption equilibrium within 30 min, with Fe-WBC exhibiting the best adsorption performance. Analysis revealed that the modified biochars contained a large number of unsaturated C bonds and aromatic rings, indicating relatively stable structures. The surfaces of the modified biochars were rich in hydroxyl and carbonyl groups, which contributed to their strong adsorption properties. Post-modification analysis indicated that iron in the biochars predominantly existed in forms such as goethite (FeOOH) and hematite (Fe₂O₃). The iron content in each type of modified biochar constituted approximately 3.08% for Fe-WBC, 5.94% for Fe-BBC, and 5.68% for Fe-HBC relative to their total elemental composition. Overall, the iron-modified biochars employed in this study significantly enhanced the adsorption capacity and efficiency for phosphorus removal in wastewater.

Keywords: adsorption; biochar; iron oxide; modification; phosphorus.

MeSH terms

Adsorption
Charcoal* / chemistry
Iron / chemistry
Phosphorus* / chemistry
Phosphorus* / isolation & purification
Spectroscopy, Fourier Transform Infrared
Triticum / chemistry
Wastewater / chemistry
Water Purification / methods
X-Ray Diffraction

Substances

Charcoal
Phosphorus
biochar
Iron
Wastewater

Grants and funding

ZKY2022-FJ-02-02/Science and Technology Project of the Huadong Engineering (Fujian) Corporation