title: Interactions of aluminum with biochars and oxidized biochars: implications for the biochar aging process.
abstract: Interactions of aluminum with primary and oxidized biochars were compared to understand the changes in the adsorption properties of aged biochars. The structural characteristics of rice straw-derived biochars, before and after oxidation by HNO3/H2SO4, were analyzed by element composition, FTIR, and XPS. The adsorption of Al to primary biochars was dominated by binding to inorganic components (such as silicon particles) and surface complexation of oxygen-containing functional groups via esterification reactions. Oxidization (aging) introduced carboxylic functional groups on biochar surfaces, which served as additional binding sites for Al(3+). At pH 2.5-3.5, the Al(3+) binding was significantly greater on oxidized biochars than primary biochars. After loading with Al, the -COOH groups anchored to biochar surfaces were transformed into COO(-) groups, and the negative surface charge diminished, which indicated that Al(3+) coordinated with COO(-). Biochar is suggested as a potential adsorbent for removing Al from acidic soils.
authors.affiliation: Department of Environmental Science and Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Zhejiang University , Hangzhou, Zhejiang 310058, China.
authors.forename: Linbo
authors.initials: L
authors.lastname: Qian
authors.forename: Baoliang
authors.initials: B
authors.lastname: Chen
mesh_terms: D000327:Adsorption; D000535:Aluminum / Q000737:chemistry*; D002606:Charcoal / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D017942:Nitric Acid / Q000737:chemistry; D012275:Oryza; D010084:Oxidation-Reduction; D012987:Soil; D012989:Soil Pollutants / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013464:Sulfuric Acids / Q000737:chemistry; D013997:Time Factors
chemical_list: D012987:Soil; D012989:Soil Pollutants; D013464:Sulfuric Acids; C540010:biochar; D002606:Charcoal; D017942:Nitric Acid; D000535:Aluminum; C033158:sulfuric acid
keywords: aging process; aluminum; carboxyl functional groups; oxidized biochar; soil remediation