Progress in antimony capturing by superior materials: Mechanisms, properties and perspectives

Highlights

• Possible removal mechanism on account of chemical properties of Sb were assessed.

• Properties, performance and mechanism for Sb by various types of advanced materials were reviewed.

• Merits and challenge for different types of synthetic materials were proposed.

Abstract

Antimony (Sb) is naturally present and abundant in the Earth’s crust, and meanwhile, it is widely used in manufacturing industries. Recently the capturing/removal of excess Sb from water has attracted large attention due to its un-expected high toxicity. This review summarizes the recent advances in Sb removal by promising materials, including bimetal (hydro)oxides, layered double hydroxides, metal–organic frameworks (MOFs), magnetic nanostructured materials and polymer-based composite materials. The relationship between individual chemical properties of Sb species and their removal mechanisms is firstly demonstrated, and the removal mechanisms are also analyzed at micro- and macroscopic levels. The typical features, preparation procedures, performance, relative merits as well as the challenges and perspectives of these promising materials are reviewed and discussed. The removal of Sb species by the new-born poly(ionic liquid)s and imprinted polymer is also briefly presented. This review will provide inspiring information on designing novel and superior materials for the removal of antimony species from aqueous media.

Introduction

Environmental degradation caused by pollutants have motivated interests in developing functional materials for capture of them such as heavy metals and organic contaminants. This is especially true when the pollutants are largely released into environment due to the anthropogenic activities. Antimony (Sb) is listed as one of poisonous heavy metals due to its certified adverse effects on humans and biological systems [86]. Natural processes such as rock weathering and volcanic activities, especially the anthropogenic activities such as exploitation and overuse of materials containing Sb in manufacturing industries, resulting in serious Sb decontamination in aquatic systems. Nowadays, many countries and areas have increasing aggravations of Sb pollution, such as China [36], [63], [137], Canada [91], Italy [94], Iran [108] and India [18]. Unfortunately, the capturing/removal of Sb species was not paid attention until the detectable toxicity and harm to humans at 1990 s.

Sb has a typical of s²p³ outer electric orbits with four oxidation states (-3, 0, +3 and + 5). They are subjected to hydrolyze in aquatic systems and mainly existed in negatively-charged pentavalent (Sb(V)) and uncharged trivalent (Sb(III)) species, in which Sb(III) is ten times more toxic than Sb(V). Among various technologies, adsorption is one of the most important methods for the removal of toxic metals involving the merits of simplicity, economics and high efficiency. Considerable researches have been devoted to concentrate and adsorb Sb species by the natural minerals with abundant hydroxyl groups via surface complexation, including goethite (α-FeOOH), hydrous ferric oxide (HFO), hematite (α-Fe₂O₃), maghemite (γ-Fe₂O₃), ferrihydrite and magnetite (Fe₃O₄) [32], [52], [96], [97], [124], [125]. However, the natural minerals generally have a low purity, instability, low adsorption rate and powered nature [29]. Thus, various types of advanced synthetic materials have been intentionally designed and developed for effective removal of Sb species from aqueous media. Fig. 1 illustrates important developmental progresses of synthetic materials for the removal of Sb such as bimetallic (hydro)oxides, mixed matrix membranes (MMMs) and metal–organic frameworks (MOFs). To date, there are numerous reviews summarizing the speciation, toxicity, distribution, mobility and fate of Sb, as well as the removal technologies using iron-based materials for Sb [20], [27], [35], [39], [62], [112], [121], [123]. However, to the best of the author’s knowledge, recent advances of various advanced synthetic materials for the capturing of Sb has not yet been reported. Similar literature reviews regarding other heavy metals such as arsenic have been reported [69]. Considering the worsening contamination and rigorous Sb regulation in water, it is of great importance and urgency to give a comprehensive summary about the recent advances on the development of artificial materials for Sb pollution control.

In this review, we provide a critical summary of the state of the art in the fields of design, properties and removal mechanism for capturing of Sb species by superior materials. Firstly, we discuss the possible removal mechanism combing the chemical properties of Sb species. Secondly, we critically review the recent progress on the application of bimetal-based (hydro)oxides, nanostructured materials, and polymer-host materials. Moreover, the material fabrication path, removal performance and mechanism are systematically summarized. Finally, future challenges and perspectives for capturing of Sb are addressed in this review.