Eupatorium adenophorum derived adsorbent by hydrothermal-assisted HNO3 modification and application to Pb2+ adsorption. Issue 5 (October 2021) - Liu, Dongdong
Abstract: Eupatorium adenophorum (EA), a kind of invasive plant, was utilized as feedstock to prepare the adsorbent using HNO3 impregnation (2.0 mol·L -1 ) before or after hydrothermal carbonization (HTC) for Pb 2+ adsorption in wastewater. A series of batch adsorption experiments including the solution pH, adsorbent dose and contact time showed prominent Pb 2+ adsorption performance of HNO3 -HTC-EA prepared by HNO3 modification first and then HTC treatment (e.g., equilibrium adsorption amount, 164.68 mg·g -1 ). The kinetic and isotherm analysis demonstrated that a physico-chemical complex adsorption was the main controlled step for two kinds of HNO3 -modified hydrochars adsorption, and Pb 2+ adsorption process of HNO3 -HTC-EA was multi-molecular layer adsorption. According to the physicochemical structure of HNO3 -modified hydrochars comparison before and after Pb 2+ adsorption, the surface complexation, electrostatic attraction, cation-π bond interactions and physical adsorption were main adsorption mechanisms. In addition, the developed mesopores of adsorbent could ensure the full binding of functional groups in the pores/channel with Pb 2+, improving the Pb 2+ adsorption capacity. Hydrothermal-assisted HNO3 modification provided a method to make use of Eupatorium adenophorum and other global exotic plants. Graphical Abstract: ga1 Highlights: This study provided a method to make use of Eupatorium adenophorum. Pb 2+ adsorption mechanism of Eupatorium adenophorum-based adsorbent was elucidated. The developed mesopores played an important role for Pb 2+ adsorption.