Modification of biochar by phosphoric acid via wet pyrolysis and using it for adsorption of methylene blue

Jia Xu; Meiyuan Fu; Qianhui Ma; Xiaopeng Zhang; Chenghang You; Zaifeng Shi; Qiang Lin; Xianghui Wang; Wen Feng

doi:10.1039/d3ra00680h

Modification of biochar by phosphoric acid via wet pyrolysis and using it for adsorption of methylene blue

RSC Adv. 2023 May 22;13(22):15327-15333. doi: 10.1039/d3ra00680h. eCollection 2023 May 15.

Authors

Jia Xu¹, Meiyuan Fu¹, Qianhui Ma¹, Xiaopeng Zhang¹, Chenghang You², Zaifeng Shi¹, Qiang Lin¹, Xianghui Wang¹, Wen Feng¹

Affiliations

¹ Key Laboratory of Water Pollution Treatment and Resource Rouse of Hainan Province, Key Laboratory of Soil Pollution Remediation and Resource Utilization of Haikou, College of Chemistry and Chemical Engineering, Hainan Normal University Haikou 571158 China.
² State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan Provincial Key Lab of Fine Chemistry, School of Chemical Engineering and Technology, Hainan University Haikou 570228 China.

Abstract

Algae biochar (ABC), coconut shell biochar (CSBC), and coconut coat biochar (CCBC) were prepared by wet pyrolysis in a phosphoric acid solvent under normal pressure. Materials were characterized for their micromorphology, specific surface area, and surface functional groups by scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) nitrogen adsorption-desorption spectrum technique and Fourier transform infrared diffraction (FT-IR). The evaluation of the liquid-phase adsorption performance using methylene blue (MB) as a pigment model, and the effects of temperature, pH, adsorbent dosage, and pollutant concentration of the MB adsorption onto modified biochars were fully investigated. The adsorption mechanism was proposed based on the adsorption kinetics curve and adsorption isotherm. The synthetic biochar showed great adsorption properties toward cationic dyes rather than anionic dyes. Specifically, the adsorption abilities for algal biochar, coconut shell biochar, and coconut coat biochar were determined to be 97.5%, 95.4% and 21.2%, respectively. The isothermal adsorption of MB by the three kinds of biochar conformed to the Langmuir equation, and the adsorption process fitted to the quasi-second-order kinetic equation, which suggested that ABC and CSBC effectively adsorbed MB dye molecules through hydrogen bonding, π-π stacking, and electrostatic interactions.