Mo₃S₁₃²⁻ Intercalated Layered Double Hydroxide: Highly Selective Removal of Heavy Metals and Simultaneous Reduction of Ag⁺ Ions to Metallic Ag⁰ Ribbons

Abstract

We demonstrate an ew material by intercalating Mo 3 S 13 2À into Mg/Al layered double hydroxide (abbr.Mo 3 S 13 -LDH), exhibiting excellent capture capability for toxicH g 2+ and noble metal silver (Ag). The as-prepared Mo 3 S 13 -LDH displays ultra-high selectivity of Ag + ,H g 2+ and Cu 2+ in the presence of various competitive ions,w ith the order of Ag + > Hg 2+ > Cu 2+ > Pb 2+ ! Co 2+ ,N i 2+ ,Z n 2+ ,C d 2+ .F or Ag + and Hg 2+ ,e xtremely fast adsorption rates ( % 90 %w ithin 10 min, > 99 %i n1h) are observed. Much high selectivity is present for Ag + and Cu 2+ ,e specially for trace amounts of Ag + ( % 1ppm), achieving al arge separation factor (SF Ag/Cu )o f % 8000 at the large Cu/Ag ratio of 520. The overwhelming adsorption capacities for Ag + (q m Ag = 1073 mg g À1 )a nd Hg 2+ (q m Hg = 594 mg g À1 )p lace the Mo 3 S 13 -LDH at the top of performing sorbent materials.M ost importantly,M o 3 S 13 -LDH captures Ag + via two paths:a )f ormation of Ag 2 Sd ue to Ag-S complexation and precipitation, and b) reduction of Ag + to metallic silver (Ag 0 ). The Mo 3 S 13 -LDH is ap romising material to extract low-grade silver from copper-rich minerals and trap highly toxic Hg 2+ from polluted water.

Recovery of Ag(I) from Wastewater by Adsorption: Status and Challenges

“…Therefore, the development of novel adsorbent materials serves as the foundation and key to achieving efficient adsorption recovery technologies. With the advancement of materials chemistry globally, various new adsorbents have been applied to recover Ag(I) from wastewater, such as metal-organic frameworks [20], covalent-organic frameworks [4], and layered double hydroxides [21]. Their high specific surface area, porosity, and abundant functional groups play crucial roles in achieving selective separation and directed recovery of Ag(I).…”

Compositional engineering of HKUST‐1/sulfidized NiMn‐LDH on functionalized MWCNTs as remarkable bifunctional electrocatalysts for water splitting

“…LDHs are layered hydrotalcite‐like compounds with positively charged layers that are neutralized by anions and water molecules in between the layers 58 . Due to their tunable composition, LDHs are capable of ion exchange, which can accelerate the redox reactions, 59,60 and have been applied for catalysis, photofunctional materials, drug delivery, sensing, electrochemistry, supercapacitors, water splitting, and so on 61–64 . Recently, LDHs containing first‐raw transition metals were used as electrocatalysts for OER, 65–68 despite modest conductivities in some cases 69–72 .…”

“…58 Due to their tunable composition, LDHs are capable of ion exchange, which can accelerate the redox reactions, 59,60 and have been applied for catalysis, photofunctional materials, drug delivery, sensing, electrochemistry, supercapacitors, water splitting, and so on. [61][62][63][64] Recently, LDHs containing first-raw transition metals were used as electrocatalysts for OER, [65][66][67][68] despite modest conductivities in some cases. [69][70][71][72] To improve the performance of LDHs, these can be deposited on a carbon substrate 73 or modified via sulfidation.…”

Unveiling the Potential of [Sn2S6]4– Functionalized Layered Double Hydroxides for the Sorption of ReO4– as a Surrogate for 99TcO4–

“…In recent years, metal–organic frameworks (MOFs), specifically cationic MOFs, have appealed to attention because of their efficient uptake of TcO 4 – from defense legacy nuclear waste, but their complex synthetic procedures, scalability, reusability, and high cost hinder their practical application. − On the other hand, layered double hydroxides (LDHs), a hydrotalcite type clay, are attractive because of their low cost, scalability, and efficient sorption properties for TcO 4 – . LDH can be defined by the general formula [M II (1– x ) M III x (OH) 2 ] x + [(A n – ) x / n · m H 2 O] x − , where M II and M III correspond to divalent and trivalent cations and A n – is an anion. − In LDH, the positively charged metal hydroxide layers are counterbalanced with exchangeable anions that inhabit the interlayer spacings. , Because of such distinct structural features, LDHs adopt diverse sorption mechanisms for TcO 4 – and its oxoanionic surrogates, such as adsorption on the outer surface via M 2+ /M 3+ –O–H···O 4 –Tc interactions, ion-exchange-driven trapping in between the positively charged host LDH layers, and reconstruction of the LDH structures . Furthermore, metal sulfides/polysulfides are known to remove TcO 4 – from the solution by reductive precipitation (Tc 7+ (sol) → Tc 4+ (s) ) and surface sorption through S···TcO 4 covalent interactions. − These features, along with the LDH’s intrinsic sorption properties toward TcO 4 – , appealed to us to design and fabricate an LDH with metal sulfide anions to produce LDH-Mo 3 S 13 .…”