β-FeOOH Decorated Graphene Oxide For Arsenic Removal From Water And Arsenic Proconcentration At Ultra-trace Level

Arsenic is a toxic element, and excessive intake or excessive exposure to it will cause serious adverse effect to human beings. The investigations have shown that inorganic arsenic species are quickly absorbed by the human body and more toxic than their organic counterparts. Thus it is crucial to develop an analytical method for the removal of inorganic arsenic and to conduct separation and preconcentration of arsenic at low level.Due to its large surface area and abundent functional groups, graphene oxide has been used as a new solid-phase extraction adsorbent for organic substances, biomolecules and heavy metals. But up to now, quite little attention has been paied to the specific function of graphene oxide in the removal and sepatation and preconcentration of trace and toxic elements. Here the J3-FeOOH@GO-COOH composite is prepared and characterized by FT-IR, SEM, XRD and Zeta potential (surface charge) analysis. The adsorption behavior of the inorganic arsenic, i.e., As(Ⅲ) and As(V), has been thoroughly investigated and the adsorption capacities of 77.5 mg g-1 and 45.7 mg g-1 are obtained for As(Ⅲ) and As(V) respectively. The β-FeOOH@GO-COOH composite has great potential for sorption of As(Ⅲ) and As(Ⅴ) in a wide pH range and an adsorption efficiency of 100% can be retained. The adsorbed As(Ⅴ) can be readily recovered by NaOH as eluent. Total inorganic arsenic concentration is achieved after converting As(Ⅲ) to As(V) and then following the same procedure as that for separation and preconcentration by hydride generation atomic fluorescence spectromentry. Then, a separation and preconcentration procedure for trace inorganic arsenic has been developed. With a sample volume of 4000 μL and an eluate volume of 400μL, accurate determination of As(Ⅴ) in the range of 0.10-3.00 μg L-1 and an enrichment factor of 8.1 can be achieved, along with a limit of detection of 29 ng L-1 (3σ, n=9) and a RSD of 5.2%(0.30μg L-1, n=7). This procedure is validated by analyzing inorganic arsenic in a certified reference material of human hair, achieving satisfactory agreements between the certified and the obtained values. Spiking recoveries are also performed by using a series of environmental water samples.