Waste Components Research Articles

Leftover love: Exploring the behavioural heterogeneity of household meal wasters

Meal leftovers are a major component of household food waste. However, there is a limited understanding of leftover food management behaviours, which can assist in reducing food waste in household settings. This study segments households with distinctive behaviours associated with meal leftover management. Principal component analysis and cluster analysis were used for consumer segmentation. Data on meal leftovers and food management behaviours were collected using a national-level survey of 1728 Australian households. We identified two heterogenous groups of households regarding leftover meal management, ‘Self-sufficient savers’ (59% of the sample) and ‘Naïve discarders’ (41% of the sample). The findings indicate that inefficient cooking and storing behaviours lead to cooked meals being discarded. ‘Naïve discarders’ dispose of leftover meals either immediately or after storing them because they do not have sufficient cooking skills to repurpose leftovers or judge the safety of the food after storing them. They also lack meal-planning skills. In contrast, the ‘Self-sufficient savers’ demonstrated efficient cooking skills and storing behaviours. They read and followed the storage and meal portioning instructions. Results highlight the need for customised interventions targeting consumers with low cooking and storing knowledge to contribute towards overall food waste minimisation.

Hybrid XGB model for predicting unconfined compressive strength of solid waste-cement-stabilized cohesive soil

The utilization of cement has been found to have negative environmental impacts. In order to reduce the quantity of cement used and improve the mechanical properties of solid waste-cement-stabilized cohesive soil, the incorporation of solid waste as additives has been investigated. Unconfined compressive strength is a crucial parameter in geotechnical engineering. However, existing empirical formulas have limited accuracy and applicability when it comes to the unconfined compressive strength of solid waste-cement-stabilized cohesive soil. The machine learning model can be used to provide accurate and comprehensive predictions by considering the nonlinear relationships between independent and dependent variables. This study aims to propose a machine learning model tuned by optimization algorithms with high generalization performance in accurately predicting the unconfined compressive strength. Firstly, a database containing 474 specimens was developed. Secondly, eight machine learning models were established, composed five single models and three hybrid models, to train and test the database. Six performance indicators were employed to evaluate the generalization ability of these models. Finally, the optimal model was selected for analysis of the importance of the feature variables using shapley additive explanations, which were compared with those of the existing empirical model. The research findings indicated that, the extreme gradient boosting model tuned with tree-structured parzen estimators exhibited the highest predictive accuracy and generalization ability. The curing age, cement content, plastic limit, and water content were identified as the most critical factors influencing the unconfined compressive strength. Among the chemical components in solid waste, the aluminum oxide content and silicon dioxide content were found to significantly influence the unconfined compressive strength, while the impact of calcium oxide content was relatively minor. Furthermore, the optimal solid waste content was found to be around 10 %. This study made a significant contribution to the effective utilization of waste resources in the context of sustainable construction practices.

Degradation of toxic components in kitchen waste during hydrothermal carbonization process

Hydrothermal carbonization (HTC) is a promising technique for kitchen waste (KW) disposal. However, KW may contain heavy metals (HMs), aflatoxin, nitrites and sulfites, posing risk for hydrochar utilization. In order to clarify the migration of these toxic components during hydrochar formation process, 7 kinds of kitchen wastes were adopted to carry out HTC experiments at 180–240 °C. Concentration detections results showed that Fe, Mn, Cr, Ni, Cu, and Zn contents were relatively high with a range of 30–2500 mg/kg in KW feedstocks. After HTC treatment, Fe, Cr, Cu were mainly (>80 %) enriched in hydrochar, the enrichment factors of Mn, Ni, Zn was almost above 50 %. From the perspective of species and valence distributions, Mn, Fe, Ni, and Zn in hydrochar were below moderate risk level. No aflatoxin was detected in hydrochar, because AFB1 and AFB2 can be completely degraded into organic acids in the HTC environment at 180 °C. Part benzene rings in aflatoxin were reduced and the C-C bonds were further broken, the C-O bonds were oxidized to produce carboxylic acids. Some benzene rings in aflatoxin remained to form organic acids with aromatic structures. NO2− and SO32- ions with strong ecotoxicity were mostly converted into NO3− and SO42- and flowed into the liquid phase. Some NO2− ions were also converted to and ammonia N and pyridine N; some SO32- ions were converted to sulfonic and sulfinic acid organics, which were successively transformed into sulfonyl/sulfinyl and sulfone/sulfoxide organics. The above findings are of great significance for the transformation mechanism of toxic substances in HTC environment and environment-friendly utilization of hydrochar.

Using CO2 in pyrolysis to neutralise toxic aromatic compounds derived from blended textile waste

Blended textiles are favoured for their enhanced properties, combining the strengths of constituent fibres (typically synthetic fibres integrated with natural cellulosic fibres). However, the presence of aromatic components in blended textile waste (BTW) complicates its disposal and raises environmental concerns due to the release of toxic chemicals. To resolve this issue, this study suggests a pyrolysis system as a strategy to neutralise toxic aromatic compounds derived from BTW. Carbon dioxide (CO2) was used as the partial oxidative reagent. The characterisation of BTW revealed its composition, containing rayon and polyester. The complex composition of BTW, particularly the recalcitrant nature of polyester, leads to the massive generation of toxic aromatic chemicals, such as terephthalic acid and its analogues, during thermolysis. However, introducing CO2 to pyrolysis facilitates interacting with these toxic compounds, converting them into carbon monoxide (CO). The effectiveness of CO2 for the suppression of toxic aromatic formations was further enhanced when adopting a nickel-based catalyst. CO2-assisted catalytic pyrolysis achieved a 64.87 % reduction in toxic aromatic chemicals and an 11.36-fold increase in CO production compared with conventional pyrolysis. This study presents a promising approach for the sustainable disposal of BTW, emphasising the oxidative functionality of CO2 in neutralising toxic aromatic chemicals into detoxified products, especially CO.

Steel mill solid waste transformation: Optimizing converter sludge recycling through RHF technology

Current methods for treating converter sludge include reintroducing it into the sintering or pelletizing process. However, this method leads to the enrichment of zinc in the blast furnace, which affects the stability of the production operation. To solve this problem, a direct reduction process utilizing multi-solid waste collaborative rotary hearth furnace (RHF) has been implemented in steel plants to recover and safely dispose of valuable components in waste. The laboratory results show that the dezincization rate of the metallized pellets is 99.12 % and the metallization rate is 80.51 % under the premise of reducing 50 °C by calcination at 1200 °C for 15 min in the nitrogen atmosphere. In the industrial test conducted in RHF production line of Shagang from March 2022 to August 2023, the temperature in the high temperature zone was reduced by 50 °C, and the time in the high temperature zone was controlled to 15 min. The industrial test results showed that the residual zinc content in the metallized pellets was 0.63 %, and the metallization rate was about 75.12 %. These particles can be used as feedstock or coolant in the steelmaking process. The average grade of by-product zinc oxide coarse powder can reach 65.88 %, which can be further processed into zinc products with remarkable economic benefit. Through RHF integrated management of converter sludge and other solid waste in steel mills, metallized pellets and high-value products can be produced, which can effectively reduce solid waste in steel enterprises and improve resource utilization.

Assessment of household solid waste characteristics, quantity, and management practices in Dangila Town, Ethiopia.

Solid waste refers to the material that is discarded because of human activity. In developing countries like Ethiopia, rapid urbanization leads to the production of large amounts of solid waste in towns. As a consequence, it causes severe problems to human health, aesthetics, and the environment, particularly in Dangila Town. Therefore, this study aimed to assess household solid waste characteristics, quantity, and management practices. Data was collected for seven days in January 2020 from 73 households, which were divided into three income groups. Observations, interviews, field measurements, sorting, and open-ended questionnaires were used as data collection tools. The research showed that food waste and ash and dust were the most dominant fractions, comprising 41.04% and 26.18%, respectively. It was also revealed that 77.88%, 12.74%, and 9.38% of household solid waste was decomposable, recyclable, and disposable waste, respectively. Furthermore, the waste components showed a significant statistical difference among income groups, except for the metal and miscellaneous groups. The quantification result indicated that the per capita household generation rate was 0.26kg/day. The management practice assessment found that most households did not practice integrated solid waste management options. They disposed of waste indiscriminately, leading to environmental pollution. The results of this study suggest that the municipality needs to create awareness among households regarding proper solid waste management practices. It is crucial to apply appropriate solid waste management mechanisms and establish a well-organized institution that will collect solid waste in the town and achieve a circular economy.

Novel Bacterial Consortium for Mitigation of Odor and Enhance Compost Maturation Rate of Municipal Solid Waste: A Step Toward a Greener Economy

Composting is an integral component of sustainable Municipal Solid Waste (MSW) management within the circular bio-economy platform. However, it faces challenges due to malodorous emissions that impact environmental and societal equilibrium. The present study aims to minimize odorous emissions and expedite compost maturation using a novel, efficient microbial consortium. Bacteria sourced from open dump sites in Sri Lanka were carefully screened based on concurrent enzyme production. Five developed consortia were tested for their performance in reducing malodors during the composting process of MSW. Consortium No. 5 (C5), comprised of Bacillus haynesii, Bacillus amyloliquefaciens, and Bacillus safensis, demonstrated outstanding performance with a significant (p < 0.05) reduction in odorous emissions. Additionally, consortium C5 exhibited impressive control over gas emissions, maintaining VOC, CH4, NH3, and H2S concentrations within ranges of 0.5-6 ppm, 0.5-0.8 ppm, 0.3-0.5 ppm, and 0.5-0.6 ppm, respectively, compared to control concentrations of 4.5-10.2 ppm, 0.5-5.5 ppm, 0.3-5.5 ppm, and 0.5-6.4 ppm, respectively. Additionally, comprehensive Electronic nose (E-nose) analysis substantiated C5’s efficiency in attenuating Methane-Aliphatic compounds, Sulfur and Aromatic compounds, along with low-polarity aromatic and alkane compounds, all with statistical significance (p < 0.05). Further, the developed consortium could reduce the composting time from 110 ± 10 days to 17 ± 3 days, offering a sustainable solution for global MSW management.

Green directional conversion of food waste into glycerol in a two-step differentiation enzymolysis and facultative fermentation using Saccharomyces cerevisiae: Performance assessment and mechanism

Valorization of food waste into high value-added glycerol was designed and prepared via directional green transformation using multi-enzymolysis saccharification coupled facultative fermentation by Saccharomyces cerevisiae. The optimal conditions for the first step of multienzyme hydrolysis and the second step of facultative fermentation were 55 °C and pH 5.0 for 6 h, 30 °C and pH 7.0 for 70 h, respectively. The glycerol yield efficiency and kinetic rate constant were 73.6 % (w/w) and 0.681 h−1 for dry component of food waste, while the other 27.4 % was utilized as the growth energy substrate. The key points of transformation were the synergistic directed enzymolysis to produce 3 % glycerol and 95 % reducing sugars. Furthermore, the reducing sugars were converted into glycerol by switch the metabolic pathway from ethanol into glycerol through the quantitative expression of functional gpd1 and gpp2 genes activated GPD and GPP enzymatic activity and synchronous inhibition of adh gene for glycerol production with Na2SO3 regulation. The economic income was 135.52 USD/ton for converting 80 % water content of kitchen waste into glycerol. This finding provided an economic value-added approach to produce high-value glycerol for cost-effective recycling of food waste using commercial yeast.

Reactive molecular dynamics simulations of poly(vinyl alcohol) gasification in supercritical carbon dioxide

Supercritical fluid gasification technology, as an environmentally friendly technology, can convert organic components of plastic waste into fuels and chemical materials. Moreover, the utilization of CO2 as the gasification environment holds significant importance for reducing carbon emissions. To better comprehend the microscopic mechanism of plastic gasification in supercritical environment, this sthdy used the Reactive Force Field (ReaxFF) molecular dynamics method to study the gasification process of long-chain poly(vinyl alcohol) molecule in supercritical H2O/CO2 under different reaction conditions. The result illustrated that during the gasification process, poly(vinyl alcohol) initially depolymerized into multiple long carbon chain (C5+) molecular fragments. Subsequently, these fragments underwent cleavage into short carbon chains and various gaseous small molecules. In this reaction, O radicals generated by CO2 decomposition play a crucial role in promoting the cleavage of plastic C–C bonds. In addition, through the analysis of the products and chemical bonds, we found that increasing temperature and prolonging reaction time significantly enhance the gasification efficiency and hydrogen production of plastics. Conversely, exceedingly high pressure inhibits the gasification reaction.

Exploring black kite (Milvus migrans) dynamics: Seasonal abundance and habitat preferences in an urban gradient

Urban expansion globally has altered biodiversity by transforming urban habitats, leading to habitat loss and changes in ecological systems. Black kites (Milvus migrans) are adaptable raptors across diverse landscapes, from natural to highly urbanized areas. This study focuses on Gujranwala City, Pakistan, a unique habitat offering insights into black kite ecology along an urban gradient. The research assesses seasonal abundance, temperature and humidity impacts, behavioral activities, and habitat preferences of black kites. Results show higher abundance in urban areas, influenced by environmental factors and food availability from anthropogenic sources. Black kites exhibit time-dependent associations with temperature and humidity, especially before sunset. Additionally, a significant correlation is observed between black kite abundance and solid waste components, particularly food and plastic waste, in the urban area. These findings contribute to understanding urban ecology, highlighting the adaptability of black kites to human-modified environments and the potential implications for conservation and management strategies.

Hydrothermal solidification of siliceous and calcareous wastes into building materials: A generic mix design framework

The presence of inactive components in siliceous and calcareous wastes tends to cause a misunderstanding in their mix design for hydrothermal solidification. The contents of typical reactive elements (i.e. Caact, Siact and Alact) in raw materials are quickly determined by simulating hydrothermal conditions. A generic mix design framework is proposed, which utilizes the molar ratio of Caact/Siact as the controlling parameter. The framework was demonstrated through a series of studies, which involved the production of granular materials using a mixture of clayey soil with slaked lime, as well as the production of compacted cylinders using a mixture of clayey soil with either slaked lime or calcium carbide slag. Experimental results showed that the hydrothermal samples achieved their maximum strength when the molar ratio of Caact/Siact in raw materials approached the theoretical Ca/Si molar ratio (i.e. 0.83) in tobermorite, provided that the molar ratio of Alact/(Alact + Siact) remained below 21%.

Design, development and characterization of a chimeric protein with disulfide reductase and protease domain showing keratinase activity

Keratin is one of the major components of solid waste, and the degradation products have extensive applications in various commercial industries. Due to the complexity of the structure of keratin, especially the disulfide bonds between keratin polypeptides, keratinolytic activity is efficient with a mixture of proteins with proteases, peptidases, and oxidoreductase activity. The present work aimed to create an engineered chimeric protein with a disulfide reductase domain and a protease domain connected with a flexible linker. The structure, stability, and substrate interaction were analyzed using the protein modeling tools and codon-optimized synthetic gene cloned, expressed, and purified using Ni2+-NTA chromatography. The keratinolytic activity of the protein was at its maximum at 70 °C. The suitable pH for the enzyme activity was pH 8. While Ni2+, Mg2+, and Na+ inhibited the keratinolytic activity, Cu2+, Ca2+, and Mn2+ enhanced it significantly. Biochemical characterization of the protease domain indicated significant keratinolytic activity at 70 °C at pH 10.0 but was less efficient than the chimeric protein. Experiments using feathers as the substrate showed a clear degradation pattern in the SEM analysis. The samples collected from the degradation experiments indicated the release of proteins (2-fold) and amino acids (8.4-fold) in a time-dependent manner. Thus, the protease with an added disulfide reductase domain showed excellent keratin degradation activity and has the potential to be utilized in the commercial industries.

Dynamic characteristics of compacted landfill waste material from cyclic triaxial tests

This study conducted a series of cyclic and monotonic triaxial tests on reconstituted landfill waste material from a closed landfill site in Sydney, Australia, to assess its dynamic behaviour under various testing conditions. Specifically, the effects of cyclic deviatoric stress, loading frequency, and effective confining stress on the cumulative plastic axial strain, resilient modulus, and damping ratio under undrained cyclic loading conditions were investigated. Results indicated that the plastic deformation, resilient modulus, and material damping are significantly influenced by dynamic stress and confining stress, with a lesser impact from loading frequency. Notably, as the number of loading cycles increased, the cumulative plastic axial strain and resilient modulus exhibited an increase, whereas the damping ratio decreased. Furthermore, increasing cyclic deviatoric stress led to an increase in both cumulative plastic axial strain and damping ratio, while an increase in confining stress resulted in a decrease in these parameters. Conversely, the resilient modulus showed an increase with rising cyclic deviatoric stress and confining stress. The influence of loading frequency on cumulative plastic axial strain and resilient modulus was minor, and its effect on the damping ratio was rather negligible. The study observed that initial loading cycles caused rearrangement and reorientation of waste components and the mobilisation of fibres with tensile forces as loading progressed, suggesting that these landfill waste samples behaved comparably to fibrous soil with randomly distributed fibres. Through nonlinear regression analysis, an empirical relationship for cumulative plastic axial strain incorporating cyclic deviatoric stress, confining stress, number of cycles, and frequency was derived. This research contributes valuable insights into the behaviour of compacted landfills as railway subgrades, providing a foundation for informed decision-making in the design of transport infrastructure over closed landfill sites.

Effects of neat and silver coated fly ash cenospheres on the properties of styrene-butadiene-styrene block copolymer composites obtained by a solution mixing method

Utilization of industrial by-products to develop novel value-added materials while mitigating their environmental impact is a crucial issue. Fly ash (FA) microparticles are a common component of power plant waste. This work aims to investigate the impact of varying concentrations of neat/silver-coated FA on the morphology and thermal properties of styrene-butadiene-styrene/FA composites. Composite materials based on styrene-butadiene styrene triblock copolymer (SBS) with various volume fractions of as-received and silver-coated FA were prepared using a solution mixing method. Silver-coated cenosphere particles were prepared using an electroless plating method. Scanning electron microscopy and optical microscopy showed that the solution mixing method obtains composite materials characterized by uniform dispersion of filler without large particle aggregates and predominantly unbroken cenospheres. The tensile strength of the composite with 10% of both as-received and silver-coated fly ash remains at the level of the unfilled SBS sample. However, at higher filler concentrations (20% and 30%), a decrease in strength by 27% and 42% respectively is observed, possibly due to the agglomeration of FA, which leads to a poorer interface and dispersion at higher filler weights. Additionally, thermal analysis in an oxygen atmosphere showed that the introduction of both as-received and metallized cenospheres in the same quantity increased the thermal stability of the tested composition. The temperatures at 5% mass loss of SBS/FA composites were on average 70°C higher than those of the original SBS.

Solid waste circulation in tourism: a close study of accommodation service establishments in Hoi An City, Vietnam

ABSTRACT Tourism in Vietnam has become an important sector of the economy. Its environmental impacts include the quantity of waste generated. This study aims to assess the compositions of solid waste generated within diverse accommodation service establishments (ASEs) in Hoi An City to understand the differences across accommodation types and generating areas. The analysis indicated that most of the ASEs provided multiple services and waste components differed among generating areas. Initiatives for optimising the recovered material flows from waste at the ASEs were proposed. A decentralised-centralised hybrid model was suggested as a suitable approach for waste circulation in the accommodation service sector. The training of staff in the ASEs and tourists, as well, is crucial. So is the participation of social entities in the city’s waste management.

Recirculating frass from food waste bioconversion using black soldier fly larvae: Impacts on process efficiency and product quality

Biowaste generation is increasing worldwide and inadequate disposal has strong negative impacts on food systems and ecosystems. Biodigestion of biowaste using black soldier fly (Hermetia illucens) larvae (BSFL) generates valuable by-products such as animal feed (larval biomass) and organic fertiliser (frass). However, the latter is typically unstable immediately after waste conversion and is thus unsafe for use as a fertilizer in terms of maturity. This study evaluated recirculation of frass within bioconversion of post-consumer food waste (FW) as a dietary component for BSFL to improve the quality of the subsequent frass obtained. Frass was introduced at increasing inclusion levels replacing food waste (2.5–100% on wet-weight basis) as part of the larvae's feeding substrate. Bioconversion efficiency and material reduction were significantly reduced by frass inclusion, while larval yield per experimental unit remained unchanged. When considering only the waste component in the larval diet, larval yield (dry-weight basis) ranged between 207 (0% frass inclusion) and 403 (40% frass inclusion) kg tonne FW−1, thus increasing by up to 94% at higher frass inclusion. With increasing dietary inclusion rate of frass from 0% to 100%, crude protein content of larval biomass increased by 41%, while fat content was reduced by 32%. The recirculated frass (obtained after including frass in the larval diet) had elevated concentrations of P, K, S, Na and B and around 6% lower organic matter content, demonstrating a higher degree of decomposition. Frass inclusion in the larval diet generated recirculated frass that were more stable and mature, as indicated by self-heating capacity, CO2 and NH3 volatilisation, seed germination bioassays and other parameters. It was concluded that frass recirculation improves waste bioconversion efficiency in relation to food waste unit, as well as larval biomass and frass quality, ensuring safer use as a fertilizer.

Waste management systems in the context of sustainability

The present paper deals with waste management systems in the context of sustainability in selected municipalities. The author's team aimed to find the key waste groups according to the classification groups that have a major impact on the volume of waste and the cost of the system, thus facilitating management decision-making. In order to optimise the management of the entire waste management system from the perspective of the statutory municipality, it was first necessary to reduce the original list of 53 waste items to a significantly smaller number. With the help of waste management experts, criteria for reducing the number of waste input items were defined, resulting in a reduced statistical sample of 27 items. Each item is quantified by the amount of waste per year and the cost of the system per year. The mathematical apparatus consisted primarily of calculating average values as well as marginal slopes of waste quantity and cost. The interrelationships between waste groups were graphically recorded in perceptual maps. The individual analyses were carried out primarily for a statutory city, with secondary comparisons of the results with smaller towns and small villages. The analytical procedures verified that the catalogue of basic components of mixed municipal waste can be significantly reduced for decision-making in secondary resource management. The amount of waste selected in each group significantly impacts the cost of the whole waste management system. Of the original 15 waste groups, only three groups appear to be the main ones. The municipal waste group even has a decisive influence on both the quantity of waste and the cost of the whole system. Thanks to these findings, from the point of view of both the manager and the management of the statutory city, it is possible to focus on this core group, which contains the 13 original catalogue items.

Evaluating research waste and traits among randomized controlled trials of scars over the past 20years: a cross-sectional study.

To analyze the changes in the characteristics of randomized controlled trials (RCTs) in the field of scarring over the last two decades, unveil the components of research waste (RW) within these RCTs, and identify targets for improvement. A search was conducted on ClinicalTrials.gov for RCTs registered from January 2000 to December 2023, using "scar" as the keyword. The search was carried out in January 2024. 391 RCTs were included in this analysis. The global registration of RCTs in scarring has exhibited a consistent increase annually, with the proportion in Asia gradually rising, while the shares in North America and Europe have demonstrated a declining trend. In the analysis of RW, 232 RCTs were included, of which 96 (41.4%) have been published. Among the published RCTs, 56 (58.3%) were evaluated to have sufficient reporting, while 47 RCTs (48.9%) were identified as having avoidable design flaws. Ultimately, 183 RCTs (78.9%) exhibited at least one form of RW. Multicenter design (OR: 3.324, 95%CI: 1.385-7.975, P = 0.018), non-pharmacological interventions (OR: 2.61, 95%CI: 1.253-5.435, P = 0.010), the absence of external funding (OR: 0.325, 95%CI: 0.144-0.732, P = 0.031), and participant numbers exceeding 50 (OR: 3.269, 95%CI: 1.573-6.794, P = 0.002) were identified as independent protective factors against waste. This study delineates the changes in the characteristics of scar RCTs globally over the past two decades, uncovering a substantial burden of RW in scarring research. It provides an evidential reference for more rational planning of future scar-related RCTs and for minimizing RW.

Immobilization of 137Cs in NaY type zeolite matrices using various heat treatment methods

The accumulation of liquid radioactive waste presents a significant global challenge, necessitating effective strategies for safe management. This study investigates the immobilization of 137Cs radionuclides, a prominent component of liquid radioactive waste, in ceramic matrices based on 137Cs-saturated NaY Faujasite zeolite. Various thermal methods were employed, including cold pressing and sintering, cold pressing and sintering with microwave assistance, hot pressing, and spark plasma sintering, to enhance immobilization capabilities. Zeolite powder was saturated with 137Cs radionuclides using an adsorption technique with low-activity model liquid radioactive waste. In-situ XRD and dilatometry methods were used to study the thermal behavior during NaY Faujasite annealing. The influence of calcination temperature on lattice parameters and crystallite size was assessed. Immobilization effectiveness was evaluated through relative density, Vickers microhardness, compressive strength, and metal ion leaching kinetics. Mechanistic evaluation was performed using XRD and SEM-EDX studies. Results showed that spark plasma sintering exhibited the highest efficiency for immobilizing 137Cs radionuclides in NaY Faujasite matrices. This research contributes to liquid radioactive waste management by providing insights into the thermal behavior and enhanced immobilization capabilities of ceramic matrices.

Molecular Hosts for the Sensing and Separation of 99TcO4.

In recent years, European Union member states have hastened energy policy deliberations to address supply and sustainability concerns, placing a significant emphasis on nuclear energy as a means to achieve decarbonization goals. However, despite its significant role in power generation, nuclear energy faces significant challenges linked to fuel reprocessing and waste disposal, that hinder its broader expansion. In this context, the separation of technetium represents a concerning issue. Indeed, technetium's catalytic activity can impede the extraction of uranium, neptunium, and plutonium, affecting waste reprocessing efficiency. Additionally, the stable form of technetium in aerobic conditions, pertechnetate (TcO4 -), poses risks of groundwater contamination due to its mobility and solubility. Hence, sensing and separation of TcO4 - is imperative for both nuclear fuel processing and minimising radioactive contamination in the environment. However, the binding of TcO4 - and its separation from contaminated solutions present challenges due to the acidic (or basic) waste components and the high ionic strength in real matrices. Supramolecular chemists have addressed these issues by designing receptors inspired by molecular recognition principles. This article explores recent advancements and future directions in TcO4 - sensing and separation (using extraction and sorption) with a focus on molecular hosts. Metal-organic receptors will also be discussed.