Role of Sorbent Surface Functionalities, Partition and Microporosity in 2, 2′, 4, 4′-Tetrabromodiphenyl Ether Sorption onto Biochars in a Single-Solute System

摘要

A study was conducted to investigate the sorption behavior and mechanisms of 2, 2′, 4, 4′-tetrabromodiphenyl ether (BDE-47) onto a series of corn straw biochars pyrolysed at 300, 500 and 700°C (BC300, BC500 and BC700). The micropore volume of BC700 was 34 times higher than BC300 and BC500, which indicates that the biochar developed more high energy pore-filling adsorption sites and the carbonization was accelerated as pyrolytic temperatures increased,. The kinetics results showed that the fast sorption rate constants ranged from 4.01 h–1 to 6.62 h–1 while the slow sorption rate constants ranged from 0.18 h–1 to 0.40 h–1. The fast sorption was attributed to the partitioning. The adsorption isotherm parameters indicate that the sorption mechanisms were different among the different biochars. For BC300, partitioning was the main adsorption mechanism while for BC500, the pore-filling adsorption dominated the sorption progress at low concentration, while partitioning dominated at high concentration. The pore-filling adsorption dominated the entire sorption progress for BC700.