title: [Mechanism of groundwater As(V) removal with ferric flocculation and direct filtration].
abstract: The As removal process and mechanism from groundwater using ferric flocculation-direct filtration system was investigated using batch, field pilot tests, extended X-ray absorption fine structure ( EXAFS) spectroscopy, and charge-distribution multisite complexation (CD-MUSIC) model. The results showed that arsenate [As(V)] was the dominant As species in the groundwater with a concentration of 40 μg x L(-1). The treatment system could supply 64 984 L As-safe drinking water (< 10 μg L(-1)) using Fe 1.5 mg x L(-1). Toxicity characteristic leaching procedure (TCLP) demonstrated that the leachate As was 3.4 μg x L(-1), much lower than the EPA regulatory concentration (5 mg x L(-1)). EXAFS and CD-MUSIC model indicated that As(V) was adsorbed onto ferric hydroxide via bidentate binuclear complexes in the pH range of 3 to 9.5, while formation of precipitate with Ca or Mg dominated the As removal at pH > 9.5.
authors.forename: Ying
authors.initials: Y
authors.lastname: Kang
authors.forename: Jin-Ming
authors.initials: JM
authors.lastname: Duan
authors.forename: Chuan-Yong
authors.initials: CY
authors.lastname: Jing
mesh_terms: D000327:Adsorption; D001149:Arsenates / Q000302:isolation & purification*; D052918:Environmental Restoration and Remediation / Q000379:methods*; D005290:Ferric Compounds / Q000737:chemistry*; D005374:Filtration; D005427:Flocculation; D060587:Groundwater / Q000737:chemistry*; D056928:X-Ray Absorption Spectroscopy
chemical_list: D001149:Arsenates; D005290:Ferric Compounds; C021024:ferric hydroxide; C025657:arsenic acid