مقاله انگلیسی رایگان در مورد چهارچوب فلز-آلی آب-پایدار برای حذف مایع فلزات سنگین – الزویر 2018

Heavy metals and radionuclides in water are a global environmental issue, which has been receiving considerable attention worldwide. Water-stable MOFs are green and recyclable materials to eliminate the environmental impacts caused by the hazardous heavy metal ions and radionuclides in water. This paper presents a systematical review on the current status of waterstable MOFs that capture and convert a wide range of heavy metal ions (e.g., As(III)/As(V), Pb(II), Hg(II), Cd(II), and Cr(III)/Cr(VI)) and radionuclides (e.g., U(VI), Se(IV)/Se(VI) and Cs(I)) in aqueous solution. Water-stable MOFs and MOF-based composites exhibit the superior adsorption capability for these metal species in water. Significantly, MOFs show high selectivity in capturing target metal ions even in the presence of multiple water constituents. Mechanisms involved in capturing metal ions are described. MOFs also have excellent catalytic performance (photocatalysis and catalytic reduction by formic acid) for Cr(VI) conversion to Cr(III). Future research is suggested to provide insightful guidance to enhance the performance of the MOFs in capturing target pollutants in aquatic environment.

Introduction

In the past decades, contamination with heavy metals and organic pollutants has attracted increasing attention at a global scale due to their adverse health effects to human and aquatic organisms (Elzwayie et al., 2017; Fu et al., 2017; Schwarzenbach et al., 2010; Zou et al., 2016a; Ren et al., 2018a, 2018b, 2018c). Examples of the heavy metals include arsenic (As), lead (Pb), mercury (Hg), cadmium (Cd) and chromium (Cr), which have been found in concentrations ranging from ng/L to mg/L in surface water and industrial wastewater (Fu et al., 2017; Kim et al., 2013; Liu et al., 2017a; Singh et al., 2015; Smith and Steinmaus, 2009). Heavy metals have potential to induce acute and chronic toxicity (e.g., oxidative stress), developmental and reproductive toxicity, genotoxicity, and carcinogenicity on aquatic biota (Fu et al., 2017; Villaescusa and Bollinger, 2008; Wu et al., 2016a; Zhitkovich, 2011). Pb(II) released from pipe corrosion worldwide have recently apprehended serious concern (Abokifa and Biswas, 2017; Delile et al., 2016; Deshommes et al., 2016; Laidlaw et al., 2016; Masters et al., 2016; Pieper et al., 2017). Another great environmental concern emerges with the development of nuclear power, which produces and releases the radionuclides in natural waters (e.g., 235U, 79Se, 99Tc, 137Cs, and 90Sr) (Ding et al., 2016; Little et al., 2016; Sheng et al., 2017; Steinhauser, 2014). Hence, a variety of removal techniques have been investigated. These techniques include physical adsorption by different kinds of adsorbents (e.g., carbon-based materials and metal oxides) and membrane-based filtration as well as photocatalytic redox processes to efficiently recover these heavy metals and radionuclides from the water (Carboni et al., 2013; Ding et al., 2016; Fu and Wang, 2011; Howarth et al., 2015; Hua et al., 2012; Huang et al., 2014; Kim et al., 2013; Liu et al., 2017a; Ma et al., 2016; Singh et al., 2015; Vellingiri et al., 2018; Vilela et al., 2016; Yu et al., 2015; Zou et al., 2016a).