Three-dimensional flower-like multifunctional adsorbents with excellent sorptive removal and colorimetric detection of arsenate

Abstract

It is highly desirable to construct advanced adsorbents with superb adsorption and visual detectivity of arsenate from complex environmental systems. In this work, a novel kind of iron alkoxide for simultaneous sorptive removal and colorimetric detection of arsenate from environmental water is reported. This adsorbent displays a three-dimensional (3D) flower-like structure with a specific surface area calculated as 93.13 m2 g−1. It is employed to remove arsenate from environmental water based on the specific interaction between arsenate and hydroxyl group on the iron alkoxide. The adsorption experiments show that iron alkoxide possesses strong removal efficiency to arsenate, and its theoretical maximum adsorption capacity is calculated as high as 97.14 mg g−1. Moreover, the anti-interference experiment reveals that iron alkoxide can resist the disturbance of most of co-existing ions. Additionally, the as-prepared iron alkoxide exhibits excellent oxidase-mimicking activity to catalyze the dissolved O2 to form superoxide anion free radical, turning the colorless 3,3′,5,5′-tetramethylbenzidine (TMB) to blue oxidized TMB (TMBox). In the case of the capture of arsenate by iron alkoxide, it results in the mask of active catalytic sites and inhabitation of oxidase-mimicking activity, and a visual quantitative colorimetric assay for detection of arsenate is established. Based on this strategy, visual detectivity of arsenate provides for a linear range from 3.33 to 333.33 µg L−1 and a LOD of 1.57 µg L−1 (S/N = 3). These results demonstrate that iron alkoxide has a very appealing application prospect in the field of sorptive removal and colorimetric detection of arsenate from environmental water.