title: A green sorbent of esterified egg-shell membrane for highly selective uptake of arsenate and speciation of inorganic arsenic.
abstract: Egg-shell membrane (ESM) is a promising adsorbent for heavy metal uptake. However, carboxylic groups on ESM surface barrier arsenic adsorption. Herein, ESM is modified by esterification and the methyl esterified egg-shell membrane (MESM) possesses positive charge within pH 1-9. As a novel green sorbent material, MESM exhibits 200-fold improvement on sorption capacity of arsenate with respect to bare ESM. It presents an ultra-high selectivity of 256:1 toward arsenate against arsenite. At pH 6, 100% sorption efficiency is achieved for 2 μg L(-1) As(V) by 10 mg MESM, while virtually no adsorption of As(III) is observed. This provides great potential for selective sorption of arsenate in the presence of arsenite. By loading 4.0 mL sample within 0.05-5.00 μg L(-1) As(V) followed by elution with 300 μL HCl (1.5 mol L(-1)), a detection limit of 15 ng L(-1) is obtained along with a RSD of 3.5% at 0.5 μg L(-1). Total inorganic arsenic is achieved by converting As(III) to As(V) and following the same sorption process. This procedure is applied for arsenate determination and inorganic arsenic speciation in Hijiki and water samples. The results are confirmed by graphite furnace atomic absorption spectrometry and spiking recovery.
authors.affiliation: Research Center for Analytical Sciences, College of Sciences, Northeastern University, Box 332, Shenyang 110819, China.
authors.forename: Ming-Li
authors.initials: ML
authors.lastname: Chen
authors.forename: Cui-Bo
authors.initials: CB
authors.lastname: Gu
authors.forename: Ting
authors.initials: T
authors.lastname: Yang
authors.forename: Yan
authors.initials: Y
authors.lastname: Sun
authors.forename: Jian-Hua
authors.initials: JH
authors.lastname: Wang
mesh_terms: D000327:Adsorption; D000818:Animals; D001149:Arsenates / Q000302:isolation & purification*; D018053:Arsenites / Q000302:isolation & purification*; D004528:Egg Shell / Q000737:chemistry*; D004951:Esterification; D005618:Fresh Water / Q000737:chemistry*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D057230:Limit of Detection; D008566:Membranes / Q000737:chemistry*; D052616:Solid Phase Extraction / Q000379:methods; D013054:Spectrophotometry, Atomic; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*
chemical_list: D001149:Arsenates; D018053:Arsenites; D014874:Water Pollutants, Chemical; C015001:arsenite; C025657:arsenic acid
keywords: Arsenic speciation; Egg-shell membrane; Hydride generation atomic fluorescence spectrometry; Methyl esterification; Solid phase extraction