MgFe-LDH@biochars for removing ammonia nitrogen and phosphorus from biogas slurry: Synthesis routes, composite performance, and adsorption mechanisms. (May 2023)

• Record Type: Journal Article
• Authors: Bian, Haohao; Wang, Minyan; Han, Jialin; Hu, Xiaopiao; Xia, Honglei; Wang, Lei; Fang, Chaochu; Shen, Cheng; Man, Yu Bon; Wong, Ming Hung; Shan, Shengdao; Zhang, Jin
• Is Part Of: Chemosphere. Volume 324(2023)
• Publication Date: 2023-05
• Subjects: Metal-biochar composites -- LDH fabrication methods -- Wastewater treatment -- Resource recovery -- Controlled release fertilizer; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2023.138333
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Layered double hydroxide-biochar composites (LDH@BCs) have been developed for ammonia nitrogen (AN) and phosphorus (P) removal from wastewater. Improvement of LDH@BCs was limited due to the lack of comparative evaluation based on LDH@BCs characteristics and synthetic methods and information on the adsorption properties of LDH@BCs for N and P from natural wastewater. In this study, MgFe-LDH@BCs were synthesized by three different co-precipitation procedures. The differences in physicochemical and morphological properties were compared. They were then employed to remove AN and P from biogas slurry. The adsorption performance of the three MgFe-LDH@BCs was compared and evaluated. Different synthesis procedures can significantly affect the physicochemical and morphological characteristics of MgFe-LDH@BCs. The LDH@BC composite fabricated through a novel method (labeled 'MgFe-LDH@BC1') has the largest specific surface area, Mg and Fe content, and excellent magnetic response performance. Moreover, the composite has the best adsorption property of AN and P from biogas slurry (30.0% and 81.8%, respectively). The main reaction mechanisms include memory effect, ion exchange, and co-precipitation. Applying 2% MgFe-LDH@BC1 saturated with AN and P adsorption from biogas slurry as a fertilizer substitute can substantially improve soil fertility and increase plant production by 139.3%. These results indicate that the facile LDH@BC synthesis method is an effective method to overcome the shortcomings of LDH@BC in practical application, and provide a basis for further exploration of the potential application of biochar based fertilizers in agriculture. Graphical abstract: Image 1 Highlights: A post-pyrolysis synthesis procedure of MgFe-LDH@BC was optimized. The performance of MgFe-LDH@BC synthesized by three routes are compared. LDH@BC fabricated through the optimized procedure shows the best performance. Memory effect, ion exchange, and co-precipitation are the main adsorption mechanisms. Adsorption-saturated MgFe-LDH@BC could be reused as a fertilizer substitute.