Two-Dimensional Titanium Carbides (Ti3C2Tx) Functionalized by Poly(m-phenylenediamine) for Efficient Adsorption and Reduction of Hexavalent Chromium.

Linfeng Jin,Weichun Yang,Liyuan Zhang,Liyuan Chai,Haiying Wang

doi:10.3390/ijerph17010167

Abstract

Titanium carbides (MXenes) are promising multifunctional materials. However, the negative surface charge and layer-by-layer restacking of MXenes severely restrict their application in the field of anionic pollutants, including in hexavalent chromium (Cr(VI)). Herein, Ti3C2Tx MXenes was functionalized through in situ polymerization and intercalation of poly(m-phenylenediamine) (PmPD), then Ti3C2Tx/PmPD composites were obtained. Delightedly, Ti3C2Tx/PmPD composites exhibited positive surface charge, expanded interlayer spacing, and enhanced hydrophobicity. Furthermore, the specific surface area of Ti3C2Tx/PmPD composite was five and 23 times that of Ti3C2Tx and PmPD, respectively. These advantages endowed Ti3C2Tx/PmPD composite with an excellent adsorption capacity of Cr(VI) (540.47 mg g−1), which was superior to PmPD (384.73 mg g−1), Ti3C2Tx MXene (137.45 mg g−1), and the reported MXene-based adsorbents. The Cr(VI) removal mechanism mainly involved electrostatic adsorption, reduction, and chelation interaction. This study developed a simple functionalization strategy, which would greatly explore the potential of MXenes in the field of anionic pollutants.

Highlights

Hexavalent chromium (Cr(VI)) pollution poses a serious crisis to human beings and the ecosystem, due to its high mobility, toxicity, and potential carcinogenicity [1,2]
Adsorption remains an effective method for Cr(VI) remediation [6], which involves the conversion from toxic Cr(VI) to mild
To synthesis Ti3 C2 Tx /PmPD, 1 g mPD monomer was firstly dissolved in 30 mL DI water, and added to a certain concentration of 100 mL Ti3 C2 Tx dispersion

Summary

Introduction

Hexavalent chromium (Cr(VI)) pollution poses a serious crisis to human beings and the ecosystem, due to its high mobility, toxicity, and potential carcinogenicity [1,2]. Trivalent chromium (Cr(III)) usually has low levels of toxicity, is immobile, and even is an essential micronutrient for organisms [3,4,5]. Adsorption remains an effective method for Cr(VI) remediation [6], which involves the conversion from toxic Cr(VI) to mild. Cr(III) in the adsorption process [7,8]. Various adsorbents have been developed, such as biochar [9,10], the metal–organic framework [11,12], nanoscale zero-valent iron [13,14], graphene oxide [15,16], and organic polymer [17,18]. Current adsorbents generally suffer from unsatisfactory removal capacity, a low adsorption rate, and weak reduction capacity. The development of novel adsorbents with an outstanding performance is still a paramount challenge

Methods

Results

Conclusion