Pretreatment of wastepaper with an aqueous solution of amino acid-derived ionic liquid for biochar production as adsorbent

• Published in: Journal of environmental management Vol. 360; p. 121195
• Main Authors: Jia, Yi, Nian, Shuai, Zhao, Wenxia, Fu, Lin, Zhang, Xiaokai, Beadham, Ian, Zhao, Shuchang, Zhang, Changbo, Deng, Yun
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.06.2024
• Subjects: Adsorption mechanism; Amino acid ionic liquid; Wastepaper derived biochar; Wastepaper derived biochar; Amino acid ionic liquid; Adsorption mechanism
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2024.121195

The carbonization of lignocellulosic biomass with ionic liquids (ILs) are considered as an advantageous approach for the preparation of carbonaceous materials. The commonly used imidazolium and pyridinium based ILs have drawbacks such as toxicity, resistance to biodegradation, high cost and viscosity. These issues can be mitigated by diluting ILs with water, although excessive water content above 1 wt% can reduce the solubility of biomass. This research aims to investigate the potential of pretreating wastepaper with a “fully green” ILs, amino acid-based IL with high water content, followed by pyrolysis without IL, in enhancing the properties of biochar. For this purpose, the paper was treated with an aqueous solution of IL cysteine nitrate ([Cys][NO3]), and the IL was not involved in the pyrolysis process to prevent the formation of secondary gaseous pollutants. The findings revealed that the hemicellulose and mineral filler in the paper were eliminated during pretreatment, leading to higher carbon content but lower oxygen content. As a result, the biochar exhibited micropores of 0.42 cm3g-1 and a specific surface area of 1011.21 m2 g−1. The biochar demonstrated high adsorption capacities for Cd2+, enrofloxacin, bisphenol A, ciprofloxacin, and tetracycline, with values of 45.20 mg g−1, 49.82 mg g−1, 49.90 mg g−1, 49.88 mg g−1, and 49.65 mg g−1, respectively. The proposed mechanism for the adsorption of enrofloxacin by the biochar primarily involves physical adsorption such as pore filling and electrostatic interactions, along with chemical adsorption facilitated by graphitic nitrogen. [Display omitted] •Amino acid-based IL with high water content removed the hemicellulose and minerals.•The specific surface area was four times of that of biochar without pretreatment.•More nitrogen was retained in the biochar and provided adsorption sites.