Mercury as an indicator of geological and environmental risks in the development of various mineral raw materials

Mercury is a highly toxic pollutant of the environment, and a quantitative assessment of its emission and migration in the technogenic transformation of mining regions is vital. The presented study focuses on the features of mercury concentration in the natural mineral raw materials, commercial products and processing waste by the example of mercury-containing copper pyrite deposits in the Urals. Mercury (its quantitative indicators) is used as a reliable element-tracer of the evolution of the technogenic system: mineral raw materials – subsurface use wastes – environmental components – food products – the human body. Such integrated approach is recommended for optimizing the forecasting, assessment and management of geological and environmental risks, as well as for the geological and environmental monitoring of the modern mining engineering system.

Thiol-Functionalization Carbonaceous Adsorbents for the Removal of Methyl-Mercury from Water in the ppb Levels

Mercury is a highly toxic pollutant of major public health concern, and human exposure is mainly related to the aqueous phase, where its dominant form is methyl-mercury (MeHg). In the current work, two carbon-based adsorbents, i.e., a commercial activated carbon and a sunflower seeds’ biochar, were modified by the introduction of thiol-active groups onto their surfaces for the MeHg removal from natural-like water in ppb concentration levels. The examined thiol-functionalization was a two-step process, since the raw materials were initially treated with nitric acid (6 N), which is a reagent that favors the formation of surface carboxyl groups, and subsequently by the thiol surface bonding groups through an esterification reaction in methanol matrix. The adsorbents’ capacity was evaluated toward the Hgtotal legislative regulation limit (1 μg/L) in drinking water (denoted as Q1). The respective isothermal adsorption results revealed an increased affinity between MeHg and thiol-functionalized materials, where the commercial carbon showed slightly higher capacity (0.116 μg Hg/mg) compared with the biochar (0.108 μg Hg/mg). This variation can be attributed to the respective higher surface area, resulting, also, to higher thiol groups loading. Regarding the proposed mechanism, it was proved that the S-Hg bond was formed, based on the characterization of the best performed saturated adsorbent.

Development of Differential Pulse Anodic Stripping Voltammetry Technique for Cadmium(II) Detection and Its Application in Water Spinach

Cadmium is a toxic pollutant that is harmful to the environment and humans. The purpose of this research was to develop a method for cadmium(II) detection using differential pulse anodic stripping voltammetry (DPASV) using a glassy carbon electrode. The developed method was then applied for cadmium detection in the vegetable samples which is water spinach. The developed method was optimized in several parameters such as potential window, deposition potential, deposition time, and scan rate. The developed method for cadmium(II) detection was also investigated in its analytical performance includes linearity, precision, detection limit, and quantitation limit. The optimum conditions for cadmium(II) detection in 0.1 M KCl using DPASV technique obtained such as potential window from -1200 to -100 mV, deposition potential of -1100 mV (vs Ag/AgCl), and deposition time of 360 s. It was obtained good linearity for cadmium(II) detection using the DPASV technique with an R2 of 0.996. The precision was expressed as %SBR with 0.66%. The detection and quantitation limits for cadmium(II) detection were 0.4206 µM~0.0771 ppm and 0.5525 µM~0.1013 ppm, respectively. The developed method was then applied for cadmium(II) measurement in the water spinach sample and the obtained cadmium(II) concentration in water spinach was 0.2399 mg/Kg.

Synthesis and Application of Silver and Cobalt Nanoparticles Immobilized on Ionic Liquid-Functionalized Halloysite Nanotubes in the Reduction of 4-Nitrophenol in Aqueous Solution

4-nitrophenol (4-NP) is a highly toxic pollutant for aquatic ecosystem and human life. Therefore, the catalytic reduction of 4-NP into useful 4-aminophenol (4-AP) is of interest. In this regard, two heterogeneous nanocatalysts, including Ag@HNTs-ILs and Co@HNTs-ILs were prepared by grafting imidazolium-based ionic liquids (ILs) onto the halloysite nanotubes (HNTs), followed by immobilization of Ag and Co nanoparticles (NPs), and characterized by means of FT-IR, SEM, EDX, TEM and XRD. The catalytic activity of the prepared nanocatalysts was evaluated for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) under environmentally friendly condition. A set of time, temperature, nanocatalyst amount and NaBH4/4-NP molar ratios was screened. The reusability experiments demonstrated that Ag@HNTs-ILs and Co@HNTs-ILs were highly reusable, up to five reduction cycles without considerable changes in the reaction time. As the synthesized hybrid nanocatalysts could be re-collected and reused for various catalytic runs without any significant loss in their catalytic activity, they could be considered very promising nanomaterials from sustainability point of view.

Role of Autophagy in Cadmium-Induced Hepatotoxicity and Liver Diseases

Cadmium (Cd) is a toxic pollutant that is associated with several severe human diseases. Cd can be easily absorbed in significant quantities from air contamination/industrial pollution, cigarette smoke, food, and water and primarily affects the liver, kidney, and lungs. Toxic effects of Cd include hepatotoxicity, nephrotoxicity, pulmonary toxicity, and the development of various human cancers. Cd is also involved in the development and progression of fatty liver diseases and hepatocellular carcinoma. Cd affects liver function via modulation of cell survival/proliferation, differentiation, and apoptosis. Moreover, Cd dysregulates hepatic autophagy, an endogenous catabolic process that detoxifies damaged cell organelles or dysfunctional cytosolic proteins through vacuole-mediated sequestration and lysosomal degradation. In this article, we review recent developments and findings regarding the role of Cd in the modulation of hepatotoxicity, autophagic function, and liver diseases at the molecular level.

Microbial Fuel Cell for Energy Production, Nutrient Removal and Recovery from Wastewater: A Review

The world is facing serious threats from the depletion of non-renewable energy resources, freshwater shortages and food scarcity. As the world population grows, the demand for fresh water, energy, and food will increase, and the need for treating and recycling wastewater will rise. In the past decade, wastewater has been recognized as a resource as it primarily consists of water, energy-latent organics and nutrients. Microbial fuel cells (MFC) have attracted considerable attention due to their versatility in their applications in wastewater treatment, power generation, toxic pollutant removal, environmental monitoring sensors, and more. This article provides a review of MFC technologies applied to the removal and/or recovery of nutrients (such as P and N), organics (COD), and bioenergy (as electricity) from various wastewaters. This review aims to provide the current perspective on MFCs, focusing on the recent advancements in the areas of nutrient removal and/or recovery with simultaneous power generation.

All-Dielectric Metasurface for Sensing Microcystin-LR

Sensing Microcystin-LR (MC-LR) is an important issue for environmental monitoring, as the MC-LR is a common toxic pollutant found in freshwater bodies. The demand for sensitive detection method of MC-LR at low concentrations can be addressed by metasurface-based sensors, which are feasible and highly efficient. Here, we demonstrate an all-dielectric metasurface for sensing MC-LR. Its working principle is based on quasi-bound states in the continuum mode (QBIC), and it manifests a high-quality factor and high sensitivity. The dielectric metasurface can detect a small change in the refractive index of the surrounding environment with a quality factor of ~170 and a sensitivity of ~788 nm/RIU. MC-LR can be specifically identified in mixed water with a concentration limit of as low as 0.002 μg/L by a specific recognition technique for combined antigen and antibody. Furthermore, the demonstrated detection of MC-LR can be extended to the identification and monitoring of other analytes, such as viruses, and the designed dielectric metasurface can serve as a monitor platform with high sensitivity and high specific recognition capability.

Atmospheric mercury pollution: the current methodological framework outlined by environmental legislation

Mercury is a toxic pollutant that exists in the atmosphere in several forms, operationally identified according to their chemical and physical characteristics. The problem of atmospheric mercury pollution has recently received increasing attention, as evidenced by the numerous European regulations issued in the last years. The normative question is closely related to the methodological one, as the quantification of the mercury species is strictly linked to the sampling and analysis methods. Due to their different bioavailability, airborne mercury forms detection is fundamental both in outdoor and indoor (i.e., workplace) environments. This paper presents an overview of European legislation on atmospheric mercury pollution, with particular attention to the Italian legislation. Starting from the regulatory protocols, the methodological framework for mercury quantification was reviewed, underlining the limits and the problems of the different methodologies and providing new guidance for the analysis. Regulatory and methodological updates have led to great specificity in mercury quantification, which is distinguished for the outdoor and indoor environments. For workplace environments, all mercury species (i.e., gaseous and particulate mercury) are required to be quantified by the Italian legislation; on the contrary, only gaseous compounds are monitored in outdoor conditions. It hence appears of primary importance that the monitoring operator chooses the sampling and analytical method for mercury sampling and analysis that correctly adheres to the normative regulations. Detailed norms describe how to carry on the monitoring in both outdoor and indoor conditions, preventing the operator’s arbitrariness, which otherwise can lead to airborne mercury underestimation/overestimation.