Engineering sulfuric acid-pretreated biochar supporting MnO2 for efficient toxic organic pollutants removal from aqueous solution in a wide pH range

• Published in: Journal of cleaner production Vol. 416; p. 137968
• Main Authors: Zhang, Lingjie, Zhang, Tingting, Cai, Yue, Zhao, Yunliang, Song, Shaoxian, Quintana, Mildred
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.09.2023
• Subjects: adsorption; aqueous solutions; biochar; density functional theory; deprotonation; Engineered biochar; hydrogen bonding; hydroxyl radicals; manganese; Manganese dioxide; oxidation; reaction kinetics; remediation; river water; singlet oxygen; sulfonic acids; sulfuric acid; Sulfuric acid pretreatment; surface area; tetracycline; Tetracycline removal; Toxic organic pollutants; toxicity; Manganese dioxide; Engineered biochar; Tetracycline removal; Toxic organic pollutants; Sulfuric acid pretreatment
• ISSN: 0959-6526; 1879-1786
• DOI: 10.1016/j.jclepro.2023.137968

Manganese dioxides (MnO2) and biochar materials are both desirable candidates for environmental remediation of toxic organic pollutants (TOPs) in water due to wide availability and environmental-friendly. In practical application, however, MnO2 suffers from low redox activity owing to deprotonation, while biochar is subject to limited removal capacity. Herein, a difunctional engineering sulfuric acid-pretreated biochar supporting MnO2 composite (MBC-A) was firstly synthesized and optimized to remove various TOPs from aqueous solution. Specifically, sulfuric acid not only served as an active agent to improve the specific surface area of biochar for improvement of adsorption capacity and more MnO2 loading, but also facilitated the introduction of sulfonic acid groups (-SO3H) as an internal proton reservoir to inhibit inactivation of MnO2 due to deprotonation in alkaline. Thanks to adsorption and oxidation, MBC-A showed excellent removal capacity (214.9 mg/g) and fast reaction kinetics (360 min) for tetracycline (TC), exceeding precursor and other materials reported in literature. Importantly, the effective operation pH range of MBC-A was broadened to 1–13 with the help of buffering capacity of –SO3H groups. The dominant driving force of adsorption were π-π interaction and hydrogen bond; while reactive oxidative species were mainly ascribed to singlet oxygen (1O2), hydroxyl radical (·OH) and reactive Mn3+. The possible reactive sites and pathway were investigated by combining experimental results with density functional theory (DFT) calculation. Further, the results of multiple cyclic runs, removal in real river water and toxicity assessment demonstrated well reusability, high environmental security, and excellent practical applicability of MBC-A. [Display omitted] •A novel –SO3H modified biochar-supported MnO2 composite (MBC-A) was prepared.•MBC-A exhibited observably enhanced removal of toxic organic pollutants (TOPs).•With the introduction of –SO3H, the working pH range of MBC-A was broadened to 1–13.•1O2, ·OH, and Mn3+ served as main reactive species for oxidation of TOPs by MBC-A.•MBC-A showed well reusability, nontoxicity, and excellent applicability in real water.