Clean Technology Research Articles

Chelator-Assisted Precipitation-Based Separation of the Rare Earth Elements Neodymium and Dysprosium from Aqueous Solutions.

The rare earth elements (REEs) are critical resources for many clean energy technologies, but are difficult to obtain in their elementally pure forms because of their nearly identical chemical properties. Here, an analogue of macropa, G-macropa, was synthesized and employed for an aqueous precipitation-based separation of Nd3+ and Dy3+. G-macropa maintains the same thermodynamic preference for the large REEs as macropa, but shows smaller thermodynamic stability constants. Molecular dynamics studies demonstrate that the binding affinity differences of these chelators for Nd3+ and Dy3+ is a consequence of the presence or absence of an inner-sphere water molecule, which alters the donor strength of the macrocyclic ethers. Leveraging the small REE affinity of G-macropa, we demonstrate that within aqueous solutions of Nd3+, Dy3+, and G-macropa, the addition of HCO3 - selectively precipitates Dy2(CO3)3, leaving the Nd3+-G-macropa complex in solution. With this method, remarkably high separation factors of 841 and 741 are achieved for 50 : 50 and 75 : 25 mixtures. Further studies involving Nd3+:Dy3+ ratios of 95 : 5 in authentic magnet waste also afford an efficient separation as well. Lastly, G-macropa is recovered via crystallization with HCl and used for subsequent extractions, demonstrating its good recyclability.

Highly efficient bimetallic counter cations-based tungsten bronzes electrocatalysts developed for sustainable oxygen evolution in acidic solution

This study involves the designing of monophosphate tungsten bronzes (MPTBs) with a combination of earth-abundant Al and Ni counter cations synthesized via the solution combustion as robust, highly efficient electrocatalysts for oxygen evolution reaction (OER) in 1.0 M H2SO4 solution. A series of mixed Al and Ni counter cations-based MPTBs was prepared at different temperatures and characterized with various sophisticated techniques concerning their compositions, morphologies, microstates, and electronic states. The catalyst with Al/Ni ratio of 1:3 of tetragonal cube-shaped MPTB calcined at 700 °C ((Al1/3,Ni)-MPTB7) exhibited an extraordinary OER performance with a larger electrochemically active surface area, almost zero onset overpotential (η), and a lower solar cell-equivalent η (i.e., at 10 mA cm−2) of 199 mV that is lower than that obtained with the state-of-the-art RuO2 catalyst. A progressive enhancement of the performance of the catalysts was noticed for a 12 h OER run, ensuring the robustness of the materials developed for a long-term application. The mixed valency states of tungsten (W), i.e., W5+/W6+ states, along with higher oxygen vacancies of (Al1/3,Ni)-MPTB7 are evaluated to tender suitably oriented active sites for effective adsorption of H2O during the OER. A substantial increase in oxygen vacancies and W5+ state, particularly the W5+4f7/2 state in the catalysts, resulted from a spin-exchange phenomenon during a long-term OER is associated with OER catalytic enhancement. The thus-developed acid-stable, robust MPTBs with mixed Al and Ni counter cations would be an alternative to the pricy noble metal counterparts used in clean energy water splitting technology.

In Situ and Ex Situ Bioremediation of Different Persistent Soil Pollutants as Agroecology Tool

Contamination or pollution of our environment has become a real global concern, especially in parallel with the increasing evolution of urbanization and industrialization, which in turn have released a plethora of different pollutants that end up being deposited in soils. It is crucial to investigate solutions that can minimize the extent of damage, and that are cost-effective, feasible and environmentally friendly, to treat a wide variety of contaminants in soils, as well as to detoxify various compounds. Bioremediation is a safe technique that has demonstrated satisfactory results and is easy to apply and maintain. This technique explores the degradation pathways of various biological agents (microorganisms, plants, algae, etc.) to neutralize contaminants. It is based on biodegradation through a complete mineralization of organic pollutants into inorganic innocuous compounds, such as carbon dioxide and water. This review aims to determine the feasibility of bioremediation as a cleanup technology for soils contaminated with pesticides, agrochemicals, chlorinated compounds, heavy metals, organic halogens, greenhouse gases, petroleum hydrocarbons, and many others, either in situ or ex situ. Different bioremediation approaches are described and compared, showing their advantages and drawbacks from a critical point of view. Moreover, both the economic and technical barriers of bioremediation are addressed, along with the outlook for the role of microorganisms in the process, the aim to identify future directions, and the application feasibility of this process.

Optimization and Study of the Enzymatic Aqueous Extraction of Coffee Beans and Its Residual Cake

ABSTRACT Agroindustrial processes have increasingly focused on sustainability and pressing coffee beans generates a waste known as the residual cake. This study evaluated the effects of aqueous enzymatic extraction with carbohydrases applied in coffee bean and its residual cake. Optimized conditions for enzymatic extraction were 75 min, pH 4.5 and 49°C (CB); 51 min, pH 5.0 and 46 °C(RC). The extracts obtained from aqueous enzymatic extraction, when compared to their respective control groups, showed statistically significant increases in the extraction of caffeine (0.32 ± 0.02 and 0.73 ± 0.10 g/100 g for CB RC, respectively) phenolic compounds (3.06 ± 0.30 and 3.85 ± 0.51 g/100 g, for CB and RC, respectively), oil content and improved antioxidant activity by the DPPH and ABTS methods (184.1 ± 2.5 for CB and 153.6 ± 8.4 µmolTrolox/g for RC). These results also showed the potential of the residual cake as a raw material for the production of extracts rich in bioactive compounds and the use of clean technology.

Pharmaceutical Wastewater and Sludge Valorization: A Review on Innovative Strategies for Energy Recovery and Waste Treatment

Currently, a large amount of pharmaceutical waste (PW) and its derivatives are being produced and, in some cases, inadequate management or treatment practices are applied. In this regard, this research explores the adoption of several alternatives to deal with these problems, including biocarbon within the framework of the circular economy. Photocatalytic nanomaterials have been also extensively discussed as a feasible way to remove pharmaceutical compounds in wastewater. Although there are existing reports in this area, this document provides a detailed study of the synthesis process, experimental conditions, the integration of photocatalysts, and their impact on enhancing photocatalytic efficiency. Additionally, the low cost and ease of fabrication of lab-scale microbial fuel cells (MFCs) are thoroughly examined. This innovative technology not only facilitates the degradation of hazardous compounds in wastewater but also harnesses their energy to generate electricity simultaneously. The aforementioned approaches are covered and discussed in detail by documenting interesting recently published research and case studies worldwide. Furthermore, this research is of significant importance because it addresses the valorization of PW by generating valuable by-products, such as H2 and O2, which can occur simultaneously during the photodegradation process, contributing to more sustainable industrial practices and clean energy technologies.

The Impact of Industrial Robots on Green Total Factor Energy Efficiency: Empirical Evidence from Chinese Cities

Improving energy utilization efficiency is a crucial means to achieve energy conservation, emission reduction, and green development. At present, to establish a high-quality development framework and satisfy the growing need for a better life among all its people, China must steadfastly pursue the path of green development. Although China’s substantial economic scale and achievements in ecological civilization construction provide favorable conditions for green transformation, there remains a significant gap compared to developed countries in the application of green and clean technologies. Confronted with technological bottlenecks, leveraging emerging technologies such as industrial robots from the new round of scientific and technological revolutions to improve the green total factor energy efficiency (GTFEE) is of critical importance to China’s green development. This study explores the potential impact of industrial robots on enhancing China’s GTFEE. It begins by reviewing the current research landscape in this field, highlighting its shortcomings, and theorizing potential impact pathways of industrial robots. Subsequently, the paper analyzes data from 2010 to 2019 on the usage of industrial robots and GTFEE across 276 cities at the prefectural level or above in China. Through empirical regression models that incorporate control variables and interaction terms, the study investigates the specific impacts of industrial robots on energy efficiency and their mechanisms of action. The results indicate that industrial robots significantly enhance the GTFEE of Chinese cities, especially in the Northeastern region. Industrial robots notably improve the GTFEE in resource-based cities, old industrial bases, and low-carbon pilot cities. Additionally, robots indirectly boost GTFEE by increasing labor productivity. Enhanced levels of green innovation and environmental regulations also positively moderate the effectiveness of industrial robots in improving energy efficiency. The findings of this research can assist local government agencies in coordinating and implementing policies that are conducive to green development, making better use of industrial robots to serve the people, and are of significant importance for promoting the transformation of China’s economy and society towards high-quality development.

Urine is better for rare earth elements bimonitoring in long-term exposed population: An exposure-response relationship study

With the soaring use of rare earth elements (REEs) worldwidely in high-technology and clean energy industries, there were growing concerns for adverse health effect from the REEs exposure. However, there is a lack of biomonitoring research concerning both urine and blood in population with definite exposure. We performed a biomonitoring study that involved 103 REEs exposed males and 110 males as non-REEs exposed controls. We measured the levels of REEs in environment and urine and blood samples from participants, and explored the exposure-response relationship between REEs in environment and body fluids. The effects of exposure duration and smoking status on the internal exposure level of REEs were also investigated. The results showed environmental REEs level of exposure group was significantly higher than that of control group (range of geometric mean of exposure vs. control: 1.08-4.07 × 104 ng/m3 vs. <LOD-2.16 × 102 ng/m3). Six elements with detection rates higher than 60% in blood or urine samples were lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), gadolinium (Gd). We found the REEs concentrations both in urine and blood of exposure population were significantly higher than controls, median range of the above 6 elements of urine and blood was 0.02–1.06 μmol/mol vs. <LOD-0.01 μmol/mol creatinine and 0.01–0.79 μg/L vs. <LOD-0.38 μg/L. The correlations between both blood and urine level of REEs and environment level showed significant. The correlation coefficients with urine levels are higher than with blood. Biomonitoring results showed good exposure-response relationship in urine REEs, while no positive response in blood samples. Smoking status, drinking status and years of exposure showed little effect on the level of REEs. Our results suggested that both blood and urine can be used to monitor REEs exposure, while urinary REEs is promising for risk assessment in population.

Gamma irradiation-induced degradation of hexachlorobenzene in methanol: Kinetics, mechanism and dehalogenation pathway

Hexachlorobenzene (HCB), a persistent organic pollutant (POP) and organochlorine compound (OCC), poses significant environmental and health risks due to its high stability and solubility in fats, oils, and organic solvents. This study investigates the degradation of HCB in methanol using gamma irradiation with a60Co source. A 2 × 10−4 M solution of HCB in methanol was prepared and irradiated at a dose rate of 1.74 Gy/s. The degradation process was monitored using Gas Chromatography-Mass Spectrometry (GC-MS), with optimized parameters for effective separation and analysis of byproducts.The results demonstrated a 100% degradation of HCB at an absorbed dose of approximately 51 kGy. The degradation pathway involved successive dechlorination, forming various chlorinated benzene (CB) byproducts such as pentachlorobenzene (PCB), tetrachlorobenzenes (TeCB), trichlorobenzenes (TCB), dichlorobenzenes (DCB), and ultimately benzene.Ion chromatography (IC) analysis revealed a dose-dependent increase in Cl⁻ concentrations, confirming the efficiency of dechlorination. A chlorine mass balance was performed to evaluate the distribution of chlorine during the degradation process, tracking Cl⁻ ions, CBs, and residual HCB. As the dose increases, the chlorine content in residual HCB decreases significantly, with none remaining at 50.2 kGy and beyond. At 169.5 kGy, nearly all chlorine (99.96%) is unaccounted for, suggesting that it has likely been released as gaseous byproducts, such as Cl₂ or other volatile chlorinated compounds.The formation of solvated electrons and hydrogen radicals initiated the dechlorination process, as evidenced by the identified reaction mechanisms. Kinetic analysis indicated that the degradation followed pseudo-first-order kinetics, with a rate constant of 5 × 10−4 s−1. The study also outlines a dose-dependent trend in radiation chemical yields (G values), initially increasing to a peak of 7.3 × 10−2 molecules per 100 eV at 12.6 kGy and subsequently decreasing to as low as 5.4 × 10−4 at 50.2 kGy.This study highlights the effectiveness of gamma irradiation for the complete degradation of HCB in methanol, offering a promising method for the remediation of POPs-contaminated environments. The proposed mechanism and kinetic properties provide a comprehensive understanding of the radiolytic degradation process, paving the way for further applications in environmental cleanup technologies.

Influence of boundary effect on supersonic flows and non-equilibrium condensation in a Laval nozzle for natural gas dehydration

The natural gas extraction process is often accompanied by large amounts of water vapor, so natural gas dehydration is the first step in achieving natural gas utilization. Current work focuses on a clean technology that captures water vapor in natural gas through expansion refrigeration. Using water vapor as a medium, a mathematical model for predicting spontaneous condensation caused by non-equilibrium state is established and validated. The influence of boundary effect including surface roughness and wall temperature on supersonic flows and non-equilibrium condensation are studied. The surface roughness affects the energy and momentum exchange between the fluid in the main stream area and near the wall, and thus affects the Wilson point, boundary layer, and non-equilibrium condensation. When the roughness rises by 0.1 mm, the boundary layer thickness increases by 56.7%, and the radial nucleation range decreases by 11.4% from y=±5.27 mm to y=±4.67 mm. The influence of wall temperature on the central area in the nozzle is not significant, but it affects the presence of liquid phase. The radial scope of liquid-phase drops by 3.58% when the wall temperature increases by 100 K.

Evaluate the safety of a novel photohydrolysis technology used to clean and disinfect indoor air: A murine study.

There is a pressing need to develop new technologies that continuously eliminates harmful pollutants and pathogens in occupied indoor spaces without compromising safety. This study was undertaken to test the safety of a novel air cleaning and disinfection technology called Advanced Photohydrolysis. Advanced Photohydrolysis generates a complex mixture of ions and molecules that are released into the air and has been shown to reduce airborne and surface pathogens. Mice (6-8-week-old) were exposed to therapeutic levels of Advanced Photohydrolysis for 90-days. During the study, the Advanced-Photohydrolysis-exposed and control mice were monitored for food consumption, body weight gain, and any overt adverse effects. In addition, at the conclusion of the study, the blood chemistry and hematology values of both groups were determined. Finally, the tissues of the conduction and respiratory portions of the airways of mice from both groups were examined for any pathological changes. The mice of both groups were found to be normal and healthy throughout the 90-day study; there were no differences in the behavior, food consumption and weight gain. Analysis of clinical chemistry values found no differences in hepatocellular function or other markers of cellular and organ function, and clinical hematology values were also unremarkable. Finally, and importantly, histopathology of the upper and lower airway tissues showed no deleterious effects. These results are the first to demonstrate directly the safety of Advanced Photohydrolysis on live mammals and encourage additional studies.

Revolutionizing Food Quality and Safety: Recent Advances in Clean-Label Technology

The rising incidence of foodborne illnesses and scandals, coupled with heightened consumer awareness of the negative impacts of artificial ingredients, has driven a significant shift toward clean label products—foods defined by simple, recognizable ingredients and minimal processing. This review provides a comprehensive analysis of clean label technology, exploring its historical evolution, key definitions, applications, and current market trends. It also examines consumer behavior toward clean label products and the marketing strategies employed by brands to foster transparency. Drawing on 61 peer-reviewed references published between 2020 and 2024, this narrative review integrates findings from academic research and industry reports to offer a holistic perspective on clean label practices. Key challenges hindering the implementation of clean label technologies, such as the effectiveness of natural preservatives, the impact of ingredient removal on sensory qualities, and the financial implications of transitioning to clean label practices, are discussed. The findings underscore the necessity for the food industry to address these challenges to ensure the sustained growth of the clean label movement, aligning with consumer preferences for healthier and more transparent food options.

Silica-Biomacromolecule Interactions: Toward a Mechanistic Understanding of Silicification.

Silica-organic composites are receiving renewed attention for their versatility and environmentally benign compositions. Of particular interest is how macromolecules interact with aqueous silica to produce functional materials that confer remarkable physical properties to living organisms. This Review first examines silicification in organisms and the biomacromolecule properties proposed to modulate these reactions. We then highlight findings from silicification studies organized by major classes of biomacromolecules. Most investigations are qualitative, using disparate experimental and analytical methods and minimally characterized materials. Many findings are contradictory and, altogether, demonstrate that a consistent picture of biomacromolecule-Si interactions has not emerged. However, the collective evidence shows that functional groups, rather than molecular classes, are key to understanding macromolecule controls on mineralization. With recent advances in biopolymer chemistry, there are new opportunities for hypothesis-based studies that use quantitative experimental methods to decipher how macromolecule functional group chemistry and configuration influence thermodynamic and kinetic barriers to silicification. Harnessing the principles of silica-macromolecule interactions holds promise for biocomposites with specialized applications from biomedical and clean energy industries to other material-dependent industries.

Governance and policy implications of the Inflation Reduction Act: A European perspective

AbstractThis paper examines the US 2022 Inflation Reduction Act (IRA) alongside the EU's Net‐Zero Industry Act (NZIA) and Critical Raw Materials Act (CRMA) of 2023. We analyze their differential approaches to accelerating investment in clean technology, enhancing energy security and fortifying supply chains. Both regions share the objective of diminishing reliance on Chinese dominance in clean industries. The US seeks to stimulate private investment primarily via uncapped tax credits from 2022 to 2031, some of them subject to stringent domestic content requirements. The EU has reacted to the potential violation of World Trade Organization's rules and a possible green investment shift to the US In doing so, the EU is relying heavily on a regulatory strategy, with emphasis on the simplification of procedures. However, the EU's public funding model is vague and leaves details to the discretion of member states, risking fragmentation within the single market. Through the application of a dynamic computable general equilibrium model, we show that a 50% increase in demand for the IRA's uncapped tax credits could nearly triple US GDP outcomes by 2027. We highlight the contrast between the IRA's immediate fiscal incentives and the NZIA's regulatory approach, emphasising that the former are more attractive for firms.

Financial Barriers to Reducing Nitrogen Pollution in Dutch Dairy Farms

SummaryNitrogen fertiliser boosts agricultural yields, but its excessive use destabilises ecosystems. That is why Dutch policy makers want to reduce nitrogen pollution on dairy farms. Cleaner technologies and structural changes could reduce farm emissions. We benchmarked farms, organised an expert consultation, and reviewed the literature to determine the degree to which the lack of available internal and external finance is a barrier to reducing nitrogen pollution. Although the average dairy farm in our sample can finance these investments, a significant share of farmers cannot. We find that investments vastly drain the currently accessible finances available to dairy farmers. Subsidies to reduce the price of investments and measures to increase farm net cash flows could mitigate this problem, while equity funds or preferential interest rate systems would be ineffective. Farm management is not bound by access to finance. Our findings suggest that improved management could vastly reduce the accumulation of nitrogen surplus on farms. Interestingly, we estimate that this can be achieved while increasing profits. The wide‐scale adoption of best practices can be facilitated by establishing and financing advisory services and peer learning programmes to spread knowledge and awareness.

Synergistic effects of feni bimetal-doped biochar on oxygen evolution reaction kinetics: A one-step, low-temperature pyrolysis approach

As the hydrogen energy sector progresses, water electrolysis technology played a crucial role in producing green hydrogen. A major challenge in this endeavor lied in the oxygen evolution reaction (OER), where the overpotential has consistently been high leading to an increase in the energy demand. This study developed a one-step pyrolysis technique to transform metal-supported biomass into FeNi/NC catalysts having enhanced crystallinity and defect sites. This process without activation step using strong acids or bases reduced the operational procedures and the treatment of intermediate products, which reduced the technical difficulty. As the pyrolysis temperature increases, the metal ions in the biochar gradually formed stable metal oxides, which catalyze the alkaline OER and markedly boosted catalytic efficiency. Crucially, the abundance of lattice oxygen and oxygen vacancies in the catalyst played a key role in enhancing the OER kinetics. Notably, the catalyst pyrolyzed at 750 °C demonstrated good performance, with an overpotential of 270 mV at a concentration of 10 mA cm−2 of the density of current, which was superior to RuO2(η10=315 mV) and IrO2(η10=300 mV). Overall, this study reported an approach for the fabrication of high-performance OER catalysts and the strategic utilization of biomass resources for application in clean energy technologies.

Unveiling active sites in FeOOH nanorods@NiOOH nanosheets heterojunction for superior OER and HER electrocatalysis in water splitting

The development of cost-effective, highly active, and stable electrocatalysts for water splitting to produce green hydrogen is crucial for advancing clean and sustainable energy technologies. Herein, we present an innovative in-situ synthesis of FeOOH nanorods@NiOOH nanosheets on nickel foam (FeOOH@NiOOH/NF) at an unprecedentedly low temperature, resulting in a highly efficient electrocatalyst for overall water splitting. The optimized FeOOH@NiOOH/NF sample, evaluated through time-dependent studies, exhibits exceptional oxygen evolution reaction (OER) performance with a low overpotential of 261 mV at a current density of 20 mA cm−2, alongside outstanding hydrogen evolution reaction (HER) activity with an overpotential of 150 mV at a current density of 10 mA cm−2, demonstrating excellent stability in alkaline solution. The water-splitting device featuring FeOOH@NiOOH/NF-2 electrodes achieves a voltage of 1.59 V at a current density of 10 mA cm−2, rivalling the state-of-the-art RuO2/NF||PtC/NF electrode system. Density functional theory (DFT) calculations unveil the efficient functionality of the Fe sites within the FeOOH@NiOOH heterojunction as the active OER catalyst, while the Ni centres are identified as the active HER sites. The enhanced performance of OER and HER is attributed to the tailored electronic structure at the heterojunction, modified magnetic moments of active sites, and increased electron density in the dx2-y2 orbital of Fe. This work provides critical insights into the rational design of advanced electrocatalysts for efficient water splitting.

Asymmetric dependency among US national financial conditions and clean energy markets

This paper examines the relationship between the US National Financial Conditions Index (NFCI) and the clean energy industry using quantile and frequency connectedness, cross-quantile, and wavelet quantile correlation (WQC) techniques. Results reveal (a) a stronger dependence between the NFCI and clean energy under bullish market states. Moreover, the total connectedness between the NFCI and clean energy mostly exhibits time-varying characteristics. In particular, clean energy has a greater spillover effect than the NFCI. (b) Dynamic frequency total connectedness at extreme quantiles provided a more comprehensive view of structural shocks in financial markets, and major crises, such as COVID-19, significantly amplified this connectedness. Overall, the WilderHill Clean Energy Index and the NASDAQ OMX Renewable Energy Index demonstrate substantial potential for hedging financial conditions. (c) The cross-quantile correlation results revealed an asymmetric dependency, demonstrating a sustained significant positive relationship between the NFCI and clean energy index (CEI) across the relative higher quantiles and middle quantiles. The WQC showed that the NFCI and specific CEIs tended to exhibit the strongest positive correlations in nonextreme quantiles and lower frequencies. These results can be of considerable interest to various financial market participants.

Numerical simulation of co-firing LRC and ammonia in Pangkalan Susu 3 & 4 coal-fired steam power plant (CFSPP) capacity 210 megawatts

The effort to reduce CO2 and NOx emissions plays a crucial role in mitigating climate change, improving air quality, complying with environmental regulations, and promoting clean technology innovation. Ammonia, as an emission-free fuel, shows significant potential as a co-firing agent with Coal in coal-fired steam power plants (CFSPP). Previous studies have demonstrated promising results in emission reduction through ammonia co-firing. This research presents a numerical analysis based on Computational Fluid Dynamics (CFD) to investigate the co-firing of ammonia with low-calorific Coal (LRC) in the CFSPP Pangkalan Susu Units 3 and 4, with a capacity of 210 MW. The study employs fluid flow modelling and chemical reaction analysis using the Discrete Phase Model (DPM) to provide accurate predictions of temperature distribution and pollutant concentrations in pulverized coal boilers. Cofiring simulations were conducted with ammonia additions of 5 % and 15 % on a calorific basis. Injection experiments from each burner (A-D) were performed to identify the optimal injection location. The simulation results indicate changes in combustion characteristics, particularly in temperature distribution. The main finding reveals a temperature decrease when ammonia is added as a co-firing material, attributed to the higher H2O content, which leads to increased moisture losses. In terms of efficiency, co-firing showed a decline compared to the baseline combustion of 100 % LRC coal due to the more significant moisture losses. The highest reduction in CO2 emissions was observed when 15 % ammonia was injected from burner B in case #6, with a mass fraction value of 0.171 at the boiler outlet. Similarly, the most significant reduction in NOx emissions occurred with a 15 % ammonia co-firing from burner B, yielding a mass fraction value of 8.81E-04 at the boiler outlet. This co-firing technology is expected to enhance decarbonization efforts and optimize the use of renewable energy in the future.

Toxic-Free Environment: Forever Chemicals Removal from Water and Wastewater

Per- and polyfluoroalkyl substances (PFAS), commonly known as "forever chemicals," are persistent synthetic compounds that have been widely utilized since the mid-20th century across various industries. Due to their environmental persistence and potential health risks, PFAS has become a significant concern, particularly in relation to water and wastewater contamination. This paper investigates the complex challenges associated with PFAS, focusing on existing regulatory frameworks, treatment strategies, and innovative clean technologies that aim to reduce or eliminate these harmful substances. The study emphasizes the importance of advanced treatment methods such as electrochemical degradation, nanofiltration, adsorption, and biodegradation, each offering varying degrees of success. Despite advancements in treatment technologies, prevention remains the most effective strategy to minimize PFAS pollution. The paper calls for collaborative efforts from regulatory bodies, industries, and communities to implement more sustainable practices, ensuring a toxic-free environment and aligning with circular economy principles. Continuous research and international cooperation are crucial for developing effective long-term solutions to address PFAS contamination and safeguard both public health and the environment.

An innovative green method for efficient extraction of selenium by melt filtration-vacuum distillation

High-purity selenium is important for technological innovation in fields such as aerospace, military, new energy, and semiconductors, and has become a hot topic in developed countries. Unfortunately, traditional preparation of high-purity selenium faces challenges such as high cost, environmental pollution, and low efficiency. In this study, we introduce an innovative green method that efficiently extracts selenium from crude selenium by combining melt filtration and vacuum distillation. Our approach effectively addresses these challenges. We calculated the potential reactions of the impurities in the selenium melt and analyzed the saturated vapor pressures of various substances. The experimental results showed that volatile impurities such as PbSe and PbTe were largely removed in the form of filter residues during the melt filtration of crude selenium residue at 653 K. The filtered selenium melt was distilled for 120 min at 533 K to obtain refined Se with a total purity of 99.9 %. Through the melt filtration-vacuum distillation process, the removal rates of impurity elements Cu, Pb, As, and Te were 99.35 %, 99.97 %, 99.83 %, and 81.11 %, respectively. Impurity elements were enriched and recovered from the filter and distillation residues. The refined Se was efficiently recovered from crude selenium, and the economic benefits were superior to other processes. This process meets the demands of a clean and efficient selenium metallurgy industry.