Layered Double Hydroxides as Effective Adsorbents for U(VI) and Toxic Heavy Metals Removal from Aqueous Media

Abstract

Capacities of different synthesized Zn,Al-hydrotalcite-like adsorbents, including the initial carbonate [Zn4Al2(OH)12]·CO3·8H2O and its forms intercalated with chelating agents (ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), and hexamethylenediaminetetraacetic acid (HMDTA)) and heat-treated form Zn4Al2O7, to adsorb uranium(VI) and ions of toxic heavy metals have been compared. Metal sorption capacities of hydrotalcite-like adsorbents have been shown to correlate with the stability of their complexes with the mentioned chelating agents in a solution. The synthesized layered double hydroxides (LDHs) containing chelating agents in the interlayer space are rather efficient for sorption purification of aqueous media free from U(VI) irrespective of its forms of natural abundance (including water-soluble bi- and tricarbonate forms) and from heavy metal ions. [Zn4Al2(OH)12]·EDTA·nH2O is recommended for practical application as one of the most efficient and inexpensive synthetic adsorbents designed for recovery of both cationic and particularly important anionic forms of U(VI) and other heavy metals from aqueous media. Carbonate forms of LDHs turned out to be most efficient for recovery of Cu(II) from aqueous media withpH0≥7owing to precipitation of Cu(II) basic carbonates and Cu(II) hydroxides. Chromate ions are efficiently adsorbed from water only by calcinated forms of LDHs.

Layered Double Hydroxide Catalysts Preparation, Characterization and Applications for Process Development: An Environmentally Green Approach

“…LDHs have been well known as adsorbents and photocatalysts [182,183]. Due to the dual properties as surface adsorption and interlayer adsorption of anions, LDHs can effectively adsorb anionic contaminants in dyeing, printing, and wastewater [184][185][186][187][188].…”

Inorganic nanolayers: structure, preparation, and biomedical applications

“…58 Moreover, LDHs have been successfully applied in the removal of toxic metals in the form of their oxides, such as selenium, arsenic, chromium in wastewater, and radioactive uranium (VI), and have also been utilized for the removal of other heavy metals. [58][59][60][61] Also, halogen anions and perchlorate anions have been removed by LDH application. [62][63][64][65] Organic 32,[67][68][69][70] In water-treatment plants, disinfection is an important procedure, and currently halogens and ozone are employed as disinfectants.…”

Effect of Interlamelar Composition on ZnAl Hydrotalcites: Synthesis and Characterization

“…They exhibit a remarkable broad spectrum of properties and allow modification of chemical, structural composition, and/or structural modification of the interlamellar composition. Layered double hydroxides or hydrotalcites have existed for a long time but only recently have they attracted recognition because they possess potential applications (You et al, 2001;Pshinko, 2013). This is as a result of their very simplified structure, flexible composition, and ease of synthesis.…”