A Dual-Functional Electroactive Filter Towards Simultaneously Sb(III) Oxidation and Sequestration

Summary

A protocol for the rational design of a dual-functional electroactive filter consisting of carbon nanotubes and titanate nanowires is reported and their environmental applications towards Sb(III) oxidation and sequestration is presented.

Abstract

We have designed a facile method to synthesize a dual-functional electrochemical filter consisting of two 1-D materials: titanate nanowires and carbon nanotubes. The hybrid titanate-CNT filter was prepared by a sonication coupled with a post-filtration route. Due to the synergistic effects of the increased number of exposed sorption sites, electrochemical reactivity, small pore size of the titanate-CNT network coupled with a flow-through design, simultaneous Sb(III) oxidation and sequestration can be readily achieved. Atomic fluorescence spectrometer technology demonstrated that the applied electrical field accelerates the Sb(III) conversion rate and the as-obtained Sb(V) were adsorbed effectively by the titanate nanowires due to their Sb specificity. This protocol provides a practical solution for the removal of highly toxic Sb(III) and other similar heavy metal ions.

Introduction

Recently, the environmental pollution caused by emerging antimony (Sb) has attracted much attention^1,2. Extensive studies demonstrate that Sb compounds pose high toxicity to human and microorganisms, although present in low concentrations in the environment^3,4. Even worse, conventional physicochemical or biological methods are usually ineffective to remove these emerging contaminants due to their low concentrations and high toxicity⁵. The most abundant species of Sb are Sb(V) and Sb(III), of which the latter form is more toxic.<....

Protocol

CAUTION: Please carefully read relevant safety data sheets (SDS) of all chemicals and wear proper personal protection equipment (PPE) before use. Some of the chemicals are toxic and irritant. Be careful when handling carbon nanotubes, which may have additional hazards if inhaled or contacted by skin.

1. Preparation of the electroactive titanate-CNT filter

1. Preparation of titanate nanowires¹⁶
   1. Dissolve 56 g of potassium hydroxide (KOH) in 100 mL of deionized water under vigorous stirring.
   2. Add 3 g of titanium dioxide (TiO₂) powder into the as-dissolved KOH so....

Results

The electroactive filtration apparatus employed is an electrochemically modified polycarbonate filtration casing (Figure 1). Field emission scanning electron microscope (FESEM) and transmission electron microscopy (TEM) techniques are employed to characterize the morphology of the titanate-CNT filter (Figure 2). To demonstrate the efficacy of the electrochemical filtration system, the change of Sb_total and Sb valence state as a function of time is det.......

Discussion

The key to this technology is to fabricate an electroactive conductive and porous hybrid filter with high Sb-specificity. To do this, special care should be paid to the fabrication process. The amount of titanate nanowires need to be precisely controlled due to the "trade-off" effect between the filter's electrical conductivity and surface area.

In addition, it should be also noted that a proper applied voltage is necessary. Once the applied voltage is too high (e.g., >3 V), other competit.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Atomic fluorescence spectrometer	Ruili Co., Ltd
Carbon nanotubes (CNT)	TimesNano Co., Ltd
DC power supply	Dahua Co., Ltd
Ethanol, 96%	Sinopharm
Hydrochloric acid, 36%	Sinopharm		Corrosive
L-antimony potassium tartrate	Sigma-Aldrich		Highly toxic
N-methyl-2-pyrrolidinone (NMP), 99.5%	Sinopharm		Highly toxic
Potassium hydroxide, 85%	Sinopharm		Corrosive
Peristaltic pump	Ismatec Co., Ltd
Titanium dioxide powders	Sinopharm