A novel nitrified aerobic granular sludge biosorbent for Pb(II) removal: behaviors and mechanisms

In this study, nitrified aerobic granular sludge (NAGS) was used as a raw material to prepare a biosorbent and investigated for the lead removal from waste water. The adsorption effects under different conditions (pH, ionic strength, contact time, temperature and biosorbent dose) were investigated. NAGS characterized with Scanning electron microscopies (SEM), Fourier transformed infrared spectroscopy (FT-IR) and surface area analyzer (BET). The Batch adsorption experimental results show that the nitrified aerobic granular sludge has excellent Pb2+ removal performance. The Langmuir isotherm model and pseudo-second-order kinetic model were well described the adsorption of Pb2+ onto NAGS and the maximum adsorption capacity could reach 89.29 mg/g within an hour. Furthermore, Webber–Morris models investigated that intraparticle diffusion is the main factor controlling the adsorption rate of Pb2+. The mechanism of Pb2+ adsorbed into NAGS was further studied, and the results show that the adsorption of Pb2+ by NAGS was mainly the monolayer chemisorption, and the hydroxyl and amino groups on surface and intragranular were active sites. Particularly, the obtained results could provide a novel nitrified aerobic granule based biosorbent for efficient and cost effective treatment of heavy metal ions from wastewater.