The aim of this review is to bring together the main natural polymer applications for environmental remediation, as a class of nexus materials with advanced properties that offer the opportunity of integration in single or simultaneous decontamination processes. By identifying the main natural polymers derived from agro-industrial sources or monomers converted by biotechnology into sustainable polymers, the paper offers the main performances identified in the literature for: (i) the treatment of water contaminated with heavy metals and emerging pollutants such as dyes and organics, (ii) the decontamination and remediation of soils, and (iii) the reduction in the number of suspended solids of a particulate matter (PM) type in the atmosphere. Because nanotechnology offers new horizons in materials science, nanocomposite tunable polymers are also studied and presented as promising materials in the context of developing sustainable and integrated products in society to ensure quality of life. As a class of future smart materials, the natural polymers and their nanocomposites are obtained from renewable resources, which are inexpensive materials with high surface area, porosity, and high adsorption properties due to their various functional groups. The information gathered in this review paper is based on the publications in the field from the last two decades. The future perspectives of these fascinating materials should take into account the scale-up, the toxicity of nanoparticles, and the competition with food production, as well as the environmental regulations.

This paper focuses on identifying the human health risks as a result of the presence of polycyclic aromatic hydrocarbons (PAHs) in groundwater due to the Bucharest landfill leakages. The main subjects were neighboring areas as the main receptors. The functional landfill located near the capital of Romania was selected as a case study. Fluorene (Pf), phenanthrene (Phe), anthracene (Ant), fluoranthene (Flu) and pyrene (Pyr) were detected using gas chromatography-tandem mass spectrometry (GC-MS/MS) analysis. The health risks for receptors via ingestion and dermal exposure scenarios were developed considering dermal contact once per day during showering for 20 min and regular ingestion of the groundwater most contaminated with PAHs at a rate of 2 L per day. The concentration ranges of PAHs in groundwater wer <0.0010–0.0037 μg L⁻¹ for Pf, 0.0014–0.0065 μg L⁻¹ for Phe, <0.0010–0.0013 μg L⁻¹ for Ant, <0.0010–0.0011 μg L⁻¹ for Flu, and 0.0030–0.0032 μg L⁻¹ for Pyr. The rest of the PAHs were under the limit of detection. Both the cumulative hazard and risk quotient are well below the value of 1, which indicates a significant low risk for the ingestion of PAH-contaminated groundwater. However, the risk due to daily groundwater consumption and skin contact is minimal.

This study aims to investigate the Co content on a Co_xCrFeNiMo (x = 0; 0.5) high entropy alloy (HEA) but also the effects of replacing the Co element with Al in terms of single-phase structure forming, processing behavior, and microstructural characteristics when being processed by mechanical alloying with a planetary ball mill. Recent HEA-related research aimed toward identifying the effect that certain alloying elements in different concentrations influence the microstructure and properties but also regulate their composition. HEAs present promising properties (e.g., corrosion and wear resistance) being applicable in domains that require protection against harsh environmental conditions, benefiting from the specific core effects of this type of material. To obtain a high alloying and homogenization degree, for this research, mechanical alloying was selected for processing the mixtures, with the aid of N-Heptane as a process control agent (PCA). The mixtures were monitored in terms of alloying degree evolution, elemental distribution, particle morphology, crystalline structure, and also technological characterization (packing ratio, free flow, and slope angle). The results indicated that a high degree of alloying was obtained after 30 h of solid-state processing, with notable crystallization of two major phases FCC and BCC identified confirming the HEA phase stability calculations.

A novel processing route of producing CrFeNiMo, Co_0.5CrFeNiMo, and Al_0.5CrFeNiMo high-entropy alloy coatings was proposed in this work. Pre-alloyed HEAs were consolidated by spark plasma sintering (SPS) in order to fabricate electrodes for electrospark deposition (ESD) coatings on carbon steel substrates. Investigations were performed to observe aspects such as phase composition and stability, contamination level, homogeneity, elemental distribution, and microstructural integrity. The results indicated phase stability and lower porosity when increasing the SPS temperature by 50 °C for all cases, with tetragonal distortion related to the HEAs’ severe lattice distortion core effect. The coating surface analysis indicated that a continuous and compact coating was obtained, correlated with the ESD layering count, but microfissures were present after 6 layers were applied due to the reduced ductility combined with rapid cooling under Ar atmosphere. The chemical integrity of both the sintered samples and the coatings was preserved during the processing, revealing a uniform elemental distribution with no contaminations or impurities present. The results indicated successful HEA sintering and deposition, highlighting the potential of the combined SPS-ESD process for high-performance material fabrication with possible applications in aggressive environments.