title: Preliminary investigation of phosphorus adsorption onto two types of iron oxide-organic matter complexes.
abstract: Iron oxide (FeO) coated by natural organic matter (NOM) is ubiquitous. The associations of minerals with organic matter (OM) significantly changes their surface properties and reactivity, and thus affect the environmental fate of pollutants, including nutrients (e.g., phosphorus (P)). In this study, ferrihydrite/goethite-humic acid (FH/GE-HA) complexes were prepared and their adsorption characteristics on P at various pH and ionic strength were investigated. The results indicated that the FeO-OM complexes showed a decreased P adsorption capacity in comparison with bare FeO. The maximum adsorption capacity (Qmax) decreased in the order of FH (22.17 mg/g)>FH-HA (5.43 mg/g)>GE (4.67 mg/g)>GE-HA (3.27 mg/g). After coating with HA, the amorphous FH-HA complex still showed higher P adsorption than the crystalline GE-HA complex. The decreased P adsorption observed might be attributed to changes of the FeO surface charges caused by OM association. The dependence of P adsorption on the specific surface area of adsorbents suggests that the FeO component in the complexes is still the main contributor for the adsorption surfaces. The P adsorptions on FeO-HA complexes decreased with increasing initial pH or decreasing initial ionic strength. A strong dependence of P adsorption on ionic strength and pH may demonstrate that outer-sphere complexes between the OM component on the surface and P possibly coexist with inner-sphere surface complexes between the FeO component and P. Therefore, previous over-emphasis on the contributions of original minerals to P immobilization possibly over-estimates the P loading capacity of soils, especially in humic-rich areas.
authors.affiliation: Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, Chongqing Key Laboratory of Agricultural Resources and Environment, College of Resources and Environment, Department of Environmental Science and Engineering, Southwest University, Chongqing 400716, China. Electronic address: yanjinlong6439@126.com.
authors.forename: Jinlong
authors.initials: J
authors.lastname: Yan
authors.affiliation: Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, Chongqing Key Laboratory of Agricultural Resources and Environment, College of Resources and Environment, Department of Environmental Science and Engineering, Southwest University, Chongqing 400716, China; Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå SE-90183, Sweden. Electronic address: jiangtower666@163.com.
authors.forename: Tao
authors.initials: T
authors.lastname: Jiang
authors.affiliation: School of Material Science & Engineering, Beijing Institute of Technology, Beijing 100081, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Yao
authors.affiliation: Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, Chongqing Key Laboratory of Agricultural Resources and Environment, College of Resources and Environment, Department of Environmental Science and Engineering, Southwest University, Chongqing 400716, China.
authors.forename: Song
authors.initials: S
authors.lastname: Lu
authors.affiliation: Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, Chongqing Key Laboratory of Agricultural Resources and Environment, College of Resources and Environment, Department of Environmental Science and Engineering, Southwest University, Chongqing 400716, China.
authors.forename: Qilei
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, Chongqing Key Laboratory of Agricultural Resources and Environment, College of Resources and Environment, Department of Environmental Science and Engineering, Southwest University, Chongqing 400716, China. Electronic address: sqwei@swu.edu.cn.
authors.forename: Shiqiang
authors.initials: S
authors.lastname: Wei
mesh_terms: D000327:Adsorption; D005290:Ferric Compounds / Q000737:chemistry*; D006812:Humic Substances; D006863:Hydrogen-Ion Concentration; D058085:Iron Compounds; D008903:Minerals; D008956:Models, Chemical; D010758:Phosphorus / Q000737:chemistry*; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D005290:Ferric Compounds; D006812:Humic Substances; D058085:Iron Compounds; D008903:Minerals; D012987:Soil; D012989:Soil Pollutants; C094886:goethite; C000499:ferric oxide; D010758:Phosphorus
keywords: Adsorption; Ferrihydrite–humic acid complex; Goethite–humic acid complex; Phosphorus