Development of Amyloid-Fibrils-like Functional Materials from Both Anaerobically Digested Sludge and Waste Activated Sludge for Heavy Metal Adsorption
Min Yang, Jiaqi Wang, Ruiping Liu, Chengzhi Hu, Huijuan Liu, Jiuhui Qu
Abstract
Proper disposal of sludge from wastewater treatment plants became a great challenge because of the increasing massive production along with strict environmental specifications, and resource utilization was an attractive alternative solution. In this study, we prepared the dissolved organic substance-based amyloid-fibrils-like functional materials (DOS-AFs) with a long-chain fibrous structure and plentiful active surface groups from both anaerobically digested sludge (ADS) and waste activated sludge (WAS). The optimum pH for DOS fibrosis is observed to be pH 1 and 2. The tiny particle rather than fiber is observed at an elevated pH of 5. DOS-AFs exhibit a good performance toward different heavy metals of Cu, Ni, Zn, Pd, and Ag, and the adsorption capability of WAS-DOS-AFs-1 was 4.9, 3.8, 4.5, 11.5, and 23.2 μg/mg dry solid, respectively. The 3-D excitation–emission matrix (EEM) spectra results indicated that the proteins and humic substances in DOS-AFs were both strong ligands for heavy metals. The formation of surface complexes was the dominant mechanisms involved in the adsorption; and Fourier transform infrared (FTIR) spectroscopy analysis indicated the amide and ether groups are the main adsorption sites on ADS-DOS-AFs, whereas the amide and hydroxyl groups on WAS-DOS-AFs dominate in the adsorption. DOS-AFs with good adsorption performance are potentially valuable for the removal of heavy metals from wastewater and the recovery of precious metals.