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Heavy metal cations such as Ag+, Pb2+, and Hg2+ can accumulate in living organisms, posing severe risks to biological systems, including humans. Therefore, removing heavy metal cations from wastewater is crucial before discharging them to the environment. However, trace levels and high-capacity removal of the heavy metals remain a critical challenge. This work demonstrates the synthesis and characterization of [Mo2S12]2− intercalated cobalt aluminum-layered double hydroxide, CoAl―Mo2S12―LDH (CoAl―Mo2S12), and its remarkable sorption properties for heavy metals. This material shows high efficiency for removing over 99.9% of Ag+, Cu2+, Hg2+, and Pb2+ from 10 ppm aqueous solutions with a distribution constant, Kd, as high as 107 mL/g. The selectivity order for removing these ions, determined from the mixed ion state experiment, was Pb2+ < Cu2+ ≪ Hg2+ < Ag+. This study also suggests that CoAl―Mo2S12 is not selective for Ni2+, Cd2+, and Zn2+ cations. CoAl―Mo2S12 is an efficient sorbent for Ag+, Cu2+, Hg2+, and Pb2+ ions at pH~12, with the removal performance of both Ag+ and Hg2+ cations retaining > 99.7% across the pH range of ~2 to 12. Our study also shows that the CoAl―Mo2S12 is a highly competent silver cation adsorbent exhibiting removal capacity (qm) as high as ~918 mg/g compared with the reported data. A detailed mechanistic analysis of the post-treated solid samples with Ag+, Hg2+, and Pb2+ reveals the formation of Ag2S, HgS, and PbMoO4, respectively, suggesting the precipitation reaction mechanism. [ABSTRACT FROM AUTHOR]

Chalcogenide-based aerogels, known as chalcogels, represent a novel class of nanoparticle-based porous amorphous materials characterized by high surface polarizability and Lewis base properties, exhibiting promising applications in clean energy and separation science. This work presents a K--Co--Mo--Sx (KCMS) chalcogel as a highly efficient sorbent for heavy metal ions and details its sorption mechanisms. Its incoherent structure comprises Mo2V(S2)6 and Mo3IVS(S6)2 anion-like clusters with four- and sixcoordinated Co--S polyhedra, forming a Co--Mo--S covalent network that hosts K+ ions through electrostatic attraction. The interactions of KCMS with heavy metal ions, particularly Pb2+ and Ag+, reveal that KCMS is exceptionally effective in removing these ions from ppm concentrations down to trace levels (#5 ppb). KCMS rapidly removes Ag+ (z81.7%) and Pb2+ (z99.5%) within five minutes, achieving >99.9% removal within an hour, with a distribution constant Kd $108 mL g-1. KCMS exhibits an impressive removal capacity of 1378 mg g-1 for Ag+ and 1146 mg g-1 for Pb2+, establishing it as one of the most effective materials known to date for heavy metal removal. This material is also effective for the removal of Ag+ and Pb2+ along with Hg2+, Ni2+, Cu2+, and Cd2+ from various water sources even in the presence of highly concentrated and chemically diverse cations, anions, and organic species. Analysis of the post-interacted KCMS by synchrotron X-ray pair distribution function (PDF), X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDS) revealed that the sorption of Pb2+, Ag+, and Hg2+ mainly occurs by the exchange of K+ and Co2+. Despite being amorphous, this material exhibits unprecedented ion-exchange mechanisms both for the ionically and covalently bound K+ and Co2+, respectively. This discovery advances our knowledge of amorphous gels and guides material synthesis principles for the highly selective and efficient removal of heavy metal ions from water. [ABSTRACT FROM AUTHOR]

Water constitutes an indispensable resource for global life but remains susceptible to pollution from diverse human activities. To mitigate this issue, researchers are committed to purifying water using a variety of materials to remove harmful chemicals, such as heavy metals. Layered double hydroxides (LDHs), with their intriguing, layered structure and chemical behavior, have attained substantial attention for their effectiveness in removing heavy metal cations and various inorganic oxoanions from water. To enhance the efficiency, considerable endeavors have focused on functionalizing LDHs with different chemical species. Intercalation with metal sulfides has proven to be particularly effective, facilitating heavy metal absorption through multiple mechanisms, including ion-exchange, reductive precipitation, and surface sorption. This review concentrates on the synthesis and performance of polysulfide (Sx, x = 2–5), Mo–S, and Sn–S anion intercalated LDHs for heavy metal cations and inorganic oxoanion sorption, along with their mechanisms. Furthermore, the discussion includes prospects for expanding the chemistry of metal sulfide intercalated LDHs, with existing challenges and future outlooks. [ABSTRACT FROM AUTHOR]

In this article, an electrochemical sensor was prepared for the simultaneous detection of hydroquinone (HQ) and catechol (CT) by incorporating porous tal palm carbon nanosheets (PTPCNS) as the modifier substance on the surface of glassy carbon electrode (GCE). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were utilized to characterize the electrochemical properties of the designed (PTCNS/GCE) sensor. PTPCNS/GCE demonstrated excellent electro‐catalytic property toward resolving the individual voltametric signal of HQ and CT from their mixture. Differential pulse voltammetry (DPV) was applied to quantify the lower limit of HQ and CT. The calculated limit of detection (LOD) was 0.15 µM for HQ with the linear range of 1–300 µM and 0.49 µM for CT with the corresponding linear range 5–225 µM obtained for the proposed sensor. The limit of quantification (LOQ) was found 0.51 µM and 1.63 µM for HQ and CT, respectively. Modified PTPCNS/GCE exhibited excellent selectivity towards HQ and CT even in presence of 10 folds potential interference. The practical applicability of the proposed sensor was analyzed in tap water sample with an excellent recovery of 98–104% for HQ and 99–102% for CT. [ABSTRACT FROM AUTHOR]

Water pollution by hexavalent chromium, Cr(VI), poses serious concerns due to its detrimental public health effects. In this work, we report the synthesis, characterization, and sorption properties for Cr(VI) by MoS42- intercalated layered double hydroxide, CoAl-MoS4-LDH (CoAl-MoS4). Our results show that CoAl-MoS4 can effectively remove Cr(VI) ions from acidic, neutral, and basic media. At neutral medium, it exhibits a very strong affinity, Kd ∼ 1.91 × 105 mL/g, toward Cr(VI) ions. Under such conditions, this material can remove over 99% of Cr(VI) from a ∼104 ppb of Cr(VI) contaminated solutions, leaving behind residual concentration below the World Health Organization (WHO) defined limit for drinking water. Moreover, our study shows that CoAl-MoS4 is a highly-competent Cr(VI) adsorbent exhibiting a removal capacity (qm) as high as ∼231 mg/g. The CoAl-MoS4 follows pseudo-second order rate kinetics for the sorption of chromate, and the concentration dependent sorption data can be fitted well with the Langmuir sorption isotherm. Furthermore, CoAl-MoS4 is highly selective to Cr(VI) ions in the presence of various competitive ions in contaminated water systems. All these results suggest that CoAl-MoS4 is a very efficient sorbent for decontamination of hexavalent chromate from wastewater systems. [ABSTRACT FROM AUTHOR]

In this paper, refractory bricks were developed by using locally obtainable materials like red clay and glass sand in Bangladesh. The Preliminary investigation was conducted by measuring the compressive strength of bricks produced by adding a range of materials with red clay in different proportions. It was found that the brick containing 30% white Portland cement and 10% glass sand with red clay (60%) demonstrated the highest compressive strength (36.20 mpa). The suitability of refractory bricks was evaluated by examining their physical and thermal properties. The evaluation of these parameters revealed that the properties are suited with refractory requirements such as low water absorption (4.58%), moderate apparent porosity (13.32%), preferable bulk density (2.64 gm/cm3 ), less linear shrinkage (3.10%), better refractoriness (1408 °C), thermal conductivity (1.3 W/m.K) and thermal shock resistance (15 cycles). The mineralogical analysis carried out by XRD exhibits the presence of Quartz and Bavenite phase. The performance evaluation shows that this brick is able to fit most of the criteria of refractory brick needed for practical purposes. Since local materials were utilized, the proposed method can be used for the manufacture of low-cost refractory brick in Bangladesh. [ABSTRACT FROM AUTHOR]

Tungsten and Niobium substituted αII-VOPO4 structure type solid solution (V1–x-yWxNby) OPO4 where x = 0.07 and y ≤ 0.05 was synthesized by solution combustion technique followed by heating in air at 700˚C for 3 days. Further incorporation of niobium (y > 0.05) leads to a mixture of αII-VOPO4 structure type solid solution and two very weak reflections of another unknown phase. The synthesized product was characterized by X-ray powder diffraction, SEM/EDX, FTIR, and magnetic property analysis. [ABSTRACT FROM AUTHOR]

Tungsten and Niobium substituted αII-VOPO4 structure type solid solution (V1–x-yWxNby) OPO4 where x = 0.07 and y ≤ 0.05 was synthesized by solution combustion technique followed by heating in air at 700˚C for 3 days. Further incorporation of niobium (y > 0.05) leads to a mixture of αII-VOPO4 structure type solid solution and two very weak reflections of another unknown phase. The synthesized product was characterized by X-ray powder diffraction, SEM/EDX, FTIR, and magnetic property analysis. [ABSTRACT FROM AUTHOR]

A series of hitherto unknown mixed-metal phosphates of the monophosphate tungsten bronze structure family [MPTB; (WO3)2 m(PO2)4] have been obtained by solution combustion synthesis followed by annealing ( ϑ = 850°C) at appropriate oxygen pressures. These new phosphates show substitution of W5+ by either M3+1/3W6+2/3 ( M: V, Cr, Fe, Mo) or Ti4+1/2W6+1/2. Members of the MPTB structural series with m = 2 [e.g. CrIII4/3WVI8/3O12(PO2)4; TiIV6/3WVI6/3O12(PO2)4] and m = 4 [e.g. Cr4/3W20/3O24(PO2)4] have been obtained. In the course of our investigation the crystal structure of WOPO4 (MPTB with m = 2: W4O12(PO2)4) has been re-determined from X-ray single-crystal data, showing monoclinic instead of the orthorhombic symmetry reported in literature ( P21 /m, Z = 1, 80 parameters, 1832 independent reflections R1 = 0.027, wR2 = 0.063). The crystal structures of MoIII4/3WVI8/3O12(PO2)4 and CrIII4/3WVI8/3O12(PO2)4 (MPTBs with m = 2) were also refined from single-crystal data {(Mo/W (Cr/W): P21 /m, Z = 1, 80(86) parameters, 1782(1769) independent reflections, R1 = 0.035(0.059), wR2 = 0.081(0.146)}. These refinements indicate statistical distribution of MIII and WVI over the metal sites. By selected area electron diffraction the unit cell dimensions of CrIII4/3WVI8/3O12(PO2)4 and CrIII4/3WVI20/3O24(PO2)4 derived from XRPD and SXRD are confirmed. HRTEM images of Cr4/3W20/3O24(PO2)4 are in agreement with its assumed close structural relation to W8O24(PO2)4 and show an highly ordered atomic arrangement. [ABSTRACT FROM AUTHOR]

While Li-ion batteries (LIBs) are a leading energy storage technology, their energy densities are limited by the low capacity of conventional intercalation cathodes, driving interest in high energy-density Li-S batteries that make use of conversion chemistry. Achieving high capacity, reversibility, and cycle stability, and controlling volume changes in conversion batteries during the charge-discharge process, however, remains challenging. Here, we present a porous, amorphous, sulfide-based Mn x Mo 3 S 13 chalcogel, which concurrently offers high capacity and cycle stability. The solution-processable room temperature synthesized Mn x Mo 3 S 13 ( x = 0.25) chalcogel exhibits a local structure that resembles the Mo 3 S 13 cluster with Mn 2+ distributed across the Mo 3 S 13 matrix, as determined by synchrotron X-ray pair distribution function (PDF) and extended X-ray absorption fine structure (EXAFS). Ab initio molecular dynamics (AIMD) simulations reveal that Mn 2+ incorporation shortens the polysulfide chain in the gel matrix compared to the Mo 3 S 13 chalcogel, while forming a coordination environment with disulfide groups, analogous to the experimental findings. A Li/Mn 0.25 Mo 3 S 13 half-cell delivers 897 mAh g -1 capacity during the first discharge and retains 571 mAh g -1 capacity after 100 cycles at a C/3 rate. Distribution of relaxation time (DRT) unveils a stable solid-electrolyte interphase (SEI) formation upon cycling that enables charge-discharge reversibility. Here, the enhanced capacity retention and cycle stability compared to those of the Li/Mo 3 S 13 cell are attributed to the reduced dissolution of active mass into the electrolyte, facilitated by the formation of shorter polysulfide chains within the Mn 0.25 Mo 3 S 13 structure and the strong affinity of Lewis-acidic Mn 2+ for polysulfide anions generated during the charge-discharge process of the Li/Mn 0.25 Mo 3 S 13 cell. Thus, this work illustrates a design principle of material for high-capacity and cycle-stable Li-metal sulfide batteries.

Chalcogel represents a unique class of meso- to macroporous nanomaterials that offer applications in energy and environmental pursuits. Here, the synthesis of an ion-exchangeable amorphous chalcogel using a nominal composition of K 2 CoMo 2 S 10 (KCMS) at room temperature is reported. Synchrotron X-ray pair distribution function (PDF), X-ray absorption near-edge structure (XANES), and extended X-ray absorption fine structure (EXAFS) reveal a plausible local structure of KCMS gel consisting of Mo 5+ 2 and Mo 4+ 3 clusters in the vicinity of di/polysulfides which are covalently linked by Co 2+ ions. The ionically bound K + ions remain in the percolating pores of the Co-Mo-S covalent network. XANES of Co K-edge shows multiple electronic transitions, including quadrupole (1s→3d), shakedown (1s→4p + MLCT), and dipole allowed 1s→4p transitions. Remarkably, despite a lack of regular channels as in some crystalline solids, the amorphous KCMS gel shows ion-exchange properties with UO 2 2+ ions. Additionally, it also presents surface sorption via [S∙∙∙∙UO 2 2+ ] covalent interactions. Overall, this study underscores the synthesis of quaternary chalcogels incorporating alkali metals and their potential to advance separation science for cations and oxo-cationic species by integrating a synergy of surface sorption and ion-exchange., (© 2024 Wiley‐VCH GmbH.)

Removal of chromate (CrO 4 2- ) and pertechnetate (TcO 4 - ) from the Hanford Low Activity Waste (LAW) is beneficial as it impacts the cost, life cycle, operational complexity of the Waste Treatment and Immobilization Plant (WTP), and integrity of vitrified glass for nuclear waste disposal. Here, we report the application of [Mo IV 3 S 13 ] 2- intercalated layer double hydroxides (LDH-Mo 3 S 13 ) for the removal of CrO 4 2- as a surrogate for TcO 4 - , from ppm to ppb levels from water and a simulated LAW off-gas condensate of Hanford's WTP. LDH-Mo 3 S 13 removes CrO 4 2- from the LAW condensate stream, having a pH of 7.5, from ppm (∼9.086 × 10 4 ppb of Cr 6+ ) to below 1 ppb levels with distribution constant ( K d ) values of up to ∼10 7 mL/g. Analysis of postadsorbed solids indicates that CrO 4 2- removal mainly proceeds by reduction of Cr 6+ to Cr 3+ . This study sets the first example of a metal sulfide intercalated LDH for the removal of CrO 4 2- , as relevant to TcO 4 - , from the simulated off-gas condensate streams of Hanford's LAW melter which contains highly concentrated competitive anions, namely F - , Cl - , CO 3 2- , NO 3 - , BO 3 3- , NO 2 - , SO 4 2- , and B 4 O 7 2- . LDH-Mo 3 S 13 's remarkable removal efficiency makes it a promising sorbent to remediate CrO 4 2- /TcO 4 - from surface water and an off-gas condensate of nuclear waste.