Chemistry

CLC number: X523

Mg(NO₃)₂·6H₂O-Assisted in situ-Fabrication of Tea Residual Biochar for Ultra-Fast and High Adsorption of Rhodamine B

¹ School of Chemistry & Chemical Engineering, Shaanxi Xueqian Normal University, Xi'an 710100, Shaanxi, China
² Safe College, Xi'an University of Science and Technology, Xi'an 710054, Shaanxi, China

^† Corresponding author. E-mail: yjwu76@163.com

Received: 9 October 2023

Abstract

In this work, porous biochar (MN-TRB₇₅₀) was fabricated via direct pyrolysis of tea residue (TR) and Mg(NO₃)₂·6H₂O (MN). The as-synthesized MN-TRB₇₅₀ reached a specific surface area of 839.54 m²·g^-1 and an average pore size of 3.75 nm with multi-level pore architecture. MN decreased TR's carbonization temperature and promoted the aromatics extent, pore structure for the frizzly flake-like biochar. Rhodamine B (RhB) was chosen as the adsorbate to explore the removal performance of organic dyes in this study. The results indicated that the maximum adsorption capacity of RhB on MN-TRB₇₅₀ at 20 ℃ is up to 809.0 mg·g^-1 with isotherms fitted well to Freundlich and Dubinin-Radushkevic models. The adsorption kinetics followed pseudo-second-order and Elovich models with an equilibrium adsorption capacity of 757.6 mg·g^-1 as the initial concentration of RhB is 260 mg·L^-1. High pore filling, hydrogen bond, π-π interaction determined the adsorption of RhB onto MN-TRB₈₅₀ through a multi-active center and exothermic chemical sorption process.