Mechanisms for synergistically enhancing cadmium remediation performance of biochar: Silicon activation and functional group effects

• Published in: Bioresource technology 2024-07, Vol.404, p.130913, Article 130913
• Main Authors: Li, Anyu, Lu, Tao, Zhang, Yutong, Deng, Shengjun, Duan, Xianjie, Qiu, Guohong
• Format: Article
• Language: English
• Subjects: Active group introduction; Adsorption contributions; Heavy metal removal; Silicon forms; Silicon-rich biochar
• ISSN: 0960-8524; 1873-2976; 1873-2976
• DOI: 10.1016/j.biortech.2024.130913

[Display omitted] •Endogenous MgSiO3-based biochar presented ultra-stability after adsorption.•Soluble silicate and active OH endowed biochar with stable and rapid Cd adsorption.•β-CD@SiBC can meet the upper limit of Cd (0.05 mg L−1) under high Cd conditions.•Mineral (36 %) and ion exchange (29 %) in β-CD@SiBC dominated Cd removal from water. This work proposes an advanced biochar material (β-CD@SiBC) for controllable transformation of specific silicon (Si) forms through endogenous Si activation and functional group introduction for efficient cadmium (Cd) immobilization and removal. The maximum adsorption capacity of β-CD@SiBC for Cd(II) reached 137.6 mg g−1 with a remarkable removal efficiency of 99 % for 200 mg L−1Cd(II). Moreover, the developed β-CD@SiBC flow column exhibited excellent performance at the environmental Cd concentration, with the final concentration meeting the environmental standard for surface water quality (0.05 mg L−1). The remediation mechanism of β-CD@SiBC could be mainly attributed to mineral precipitation and ion exchange, which accounted for 42 % and 29 % of the remediation effect, respectively, while functional group introduction enhanced its binding stability with Cd. Overall, this work proposes the role and principle of transformation of Si forms within biochar, providing new strategies for better utilizing endogenous components in biomass.