Removal of toxic metals using iron sulfide particles: A brief overview of modifications and mechanisms.

Growing mechanization has released higher concentrations of toxic metals in water and sediment, which is a critical concern for the environment and human health. Recent studies show that naturally occurring and synthetic iron sulfide particles are efficient at removing these hazardous pollutants. This review seeks to provide a concise summary of the evolution in the production of iron sulfide particles, specifically nanoparticles, through the years. This review presents an outline of the synthesis process for the most dominant forms of iron sulfide: mackinawite (FeS), pyrite (FeS2), pyrrhotite (Fe1-x S), and greigite (Fe3S4). The review confirms that both natural forms of iron sulfide and modified forms of iron sulfide are highly effective at removing different heavy metals and metalloids from water. Concurrently, this review reveals the interaction mechanism between toxic metals and iron sulfide, along with the impact of conditions for remedy and rectification. None the less, modifications and future investigations into the synthesis of novel iron sulfides, their use to adsorb diverse environmental pollutants, and their fate after injection into polluted aquifers, remain crucial to maximizing pollution control.

A simple method for the synthesis of copper nanoparticles from metastable intermediates.

Copper nanoparticles have attracted a wide attention because of their low cost and high specific surface area. At present, the synthesis of copper nanoparticles has the problems of complicated process and environmentally unfriendly materials like hydrazine hydrate and sodium hypophosphite that would pollute water, harm human health and may even cause cancer. In this paper, a simple and low-cost two-step synthesis method was used to prepare highly stable and well-dispersed spherical copper nanoparticles in solution with a particle size of about 34 nm. The prepared spherical copper nanoparticles were kept in solution for one month without precipitation. Using non-toxic l-ascorbic acid as the reducing and secondary coating agent, polyvinylpyrrolidone (PVP) as the primary coating agent, and NaOH as the pH modulator, the metastable intermediate CuCl was prepared. Due to the characteristics of the metastable state, copper nanoparticles were rapidly prepared. Moreover, to improve the dispersibility and antioxidant, the PVP and l-ascorbic acid were used to coat the surface of copper nanoparticles. Finally, the mechanism of the two-step synthesis of copper nanoparticles was discussed. This mechanism mainly relies on the two-step dehydrogenation of l-ascorbic acid to obtain copper nanoparticles.

Sequential exposures of single walled carbon nanotubes and heavy metal ions to macrophages induce different cytotoxicity.

The probability of occupational exposure rises with the increasing production and biomedical application of carbon nanotubes (CNTs). Thus, the risk of co-exposure of nanomaterials with environmental pollutants is also increasing. Although many studies have focused on the combined toxicity of nanomaterials and pollutants, more attention has been paid to the toxicity of nanomaterials after adsorbing pollutants or the toxicity of nanomaterials and pollutants exposed simultaneously. Few studies have been conducted on the toxicity and toxicity mechanisms of nanomaterials and environmental pollutants following sequential exposure. In this study, we employed THP-1 cells to investigate how pristine single walled CNTs (p-SWCNTs) and oxidized single walled CNTs (SWCNT-COOHs) pretreatments at a non-lethal dose of 10 µg/mL affect cell responses to metal ions (i. e., Pb2+, Cu2+, and Cr(VI)). We found that p-SWCNTs caused more significant damage to cell membrane integrity than SWCNT-COOHs, which led to higher metallothionein (MT) levels and increased transport of metal ions into cells. Pretreatment of p-SWCNTs in cells significantly increased the cytotoxicity of Pb2+, Cu2+, and Cr(VI) by 2-4-fold, whereas SWCNT-COOHs pretreated cells showed no noteworthy changes in response to heavy metals, which were further confirmed by the cellular reactive oxygen species (ROS) assays. These findings indicate that understanding the effects of the exposure sequence of engineered nanomaterials and environmental pollutants on their toxicity provides an excellent complement to combined toxicity evaluation.

Li-Rich Antiperovskite/Nitrile Butadiene Rubber Composite Electrolyte for Sheet-Type Solid-State Lithium Metal Battery.

Lithium-rich antiperovskites (LiRAPs) hold great promise to be the choice of solid-state electrolytes (SSEs) owing to their high ionic conductivity, low activation energy, and low cost. However, processing sheet-type solid-state Li metal batteries (SSLiB) with LiRAPs remains challenging due to the lack of robust techniques for battery processing. Herein, we propose a scalable slurry-based procedure to prepare a flexible composite electrolyte (CPE), in which LiRAP (e.g., Li2OHCl0.5Br0.5, LOCB) and nitrile butadiene rubber (NBR) serve as an active filler and as a polymer scaffold, respectively. The low-polar solvent helps to stabilize the LiRAP phase during slurry processing. It is found that the addition of LOCB into the NBR polymer enhances the Li ion conductivity for 2.3 times at 60°C and reduces the activation energy (max. 0.07 eV). The as-prepared LOCB/NBR CPE film exhibits an improved critical current of 0.4 mA cm-2 and can stably cycle for over 1000 h at 0.04 mA cm-2 under 60°C. In the SSLiB with the sheet-type configuration of LiFePO4(LFP)||LOCB/NBR CPE||Li, LFP exhibits a capacity of 137 mAh/g under 60 at 0.1°C. This work delivers an effective strategy for fabrication of LiRAP-based CPE film, advancing the LiRAP-family SSEs toward practical applications.

Nano ferric oxide adsorbents with self-acidification effect for efficient adsorption of Sb(V).

It is urgent and essential to remove antimony from wastewater due to its potential carcinogenicity. In this paper, a nano ferric oxide (NFO) adsorbent was synthesized in a one-step low temperature calcination (150 °C) process. It presents a surprising self-acidification behavior, could automatically adjust the pH to around 4 from different intimal pH values (4-9), which enable it to efficiently remove more than 99% of Sb(V) from wastewater in a wide pH range. X-ray photoelectron spectroscopy analysis proved that the self-acidification function was originated from the hydrolyzation of surface Fe atoms on ferric oxide nanoparticles. The maximum adsorption capacity of this adsorbent is 78.1 mg/g which is 2-3 times higher than that of the samples obtained at higher temperatures (250 °C and 350 °C), and also its adsorption kinetic constant is ten times higher, which can be attributed to the larger surface areas and smaller sizes of ferric oxides synthesized at 150 °C. In the actual wastewater treatment, the effluent's concentration after treatment can be maintained below the instrument detection limit even under low initial antimony concentration. We believe that this new adsorbent has great potential in the practical application in the treatment of Sb polluted wastewaters due to its simple synthesis, high efficiency, and low cost.

Contribution of attendant anions on cadmium toxicity to soil enzymes.

Sorption and desorption are critical processes to control the mobility and biotoxicity of cadmium (Cd) in soils. It is known that attendant anion species of heavy metals could affect metal adsorption on soils and might further alter their biotoxicity. However, for Cd, the influence of attendant anions on its sorption in soils and subsequent toxicity on soil enzymes are still unknown. In this work, four Cd compounds with different salt anions (SO42-, NO3-, Cl-, and Ac-) were selected to investigate their impact of on the sorption, soil dehydrogenase activity (DHA) and alkaline phosphatase activity (ALP). Thus, a series of simulated Cd pollution batch experiments including measuring adsorption-desorption behavior of Cd on soils and soil enzyme activities were carried out. Results showed that CdSO4 exhibited highest sorption capacity among the tested soils except in Hunan soil. The Cd sorption with NO3- displayed a similar behavior with Cl- on all tested soils. Compared with soil properties, all four kinds of anions on Cd sorption played a more significant role affecting Cd ecological toxicity to soil DHA and ALP. Cd in acetate or nitrate form appears more sensitive towards DHA than sulphate and chloride, while the later pair is more toxic towards ALP than the former. These results have important implications for evaluation of Cd contamination using soil enzyme as bioindicator.

General Method for the Synthesis of Ultrastable Core/Shell Quantum Dots by Aluminum Doping.

Semiconductor quantum dots (QDs) have attracted extensive attention in various applications because of their unique optical and electronic properties. However, long-term photostability remains a challenge for their practical application. Here, we present a simple method to enhance the photostability of QDs against oxidation by doping aluminum into the shell of core/shell QDs. We demonstrate that Al in the coating shell can be oxidized to Al2O3, which can serve as a self-passivation layer on the surface of the core/shell QDs and effectively stop further photodegradation during long-term light irradiation. The prepared CdSe/CdS:Al QDs survived 24 h without significant degradation when they were subjected to intense illumination under LED light (450 nm, 0.35 W/cm(2)), whereas conventional CdSe/CdS QDs were bleached within 3 h.

Effects of Extract from Mangifera indica Leaf on Monosodium Urate Crystal-Induced Gouty Arthritis in Rats.

The leaves of Mangifera indica L. (Anacardiaceae) is used as a medicinal material in traditional herb medicine for a long time in India, China, and other Eastern Asian countries. Our present study investigated the therapeutic effects of the ethanol extract from Mangifera indica (EMI) in rat with monosodium urate (MSU) crystals-induced gouty arthritis. Effects of EMI (50, 100, and 200 mg/kg, p.o.) administrated for 9 days on the ankle swelling, synovial tumor necrosis factor-alpha (TNF-α), and interleukin-1beta (IL-1ß) levels were assessed in MSU crystal rat. Data from our study showed that rat with gouty arthritis induced by MSU crystal demonstrated an elevation in ankle swelling, synovial TNF-α, IL-1ß mRNA, and protein levels. Oral administration of 100 and 200 mg/kg EMI for 9 days reversed the abnormalities in ankle swelling, synovial TNF-α, IL-1ß mRNA, and protein levels. The results indicated that the beneficial antigouty arthritis effect of EMI may be mediated, at least in part, by inhibiting TNF-α and IL-1ß expression in the synovial tissues. Our study suggests that Mangifera indica and its extract may have a considerable potential for development as an anti-gouty arthritis agent for clinical application.