4 Material und Umwelt
Filtern
Erscheinungsjahr
- 2021 (23) (entfernen)
Dokumenttyp
Sprache
- Englisch (23) (entfernen)
Schlagworte
- Bottom ash (5)
- Phosphorus (5)
- Sewage sludge (4)
- Combustion ion chromatography (3)
- PFAS (3)
- X-ray absorption near-edge structure (XANES) spectroscopy (3)
- Construction products (2)
- Design of experiments (2)
- Diffusive gradients in thin-films (DGT) (2)
- Fertilizer (2)
- Geosynthetics (2)
- Leaching of waste materials (2)
- Soil (2)
- Air pollution control (1)
- Ammonium (1)
- Artificial ageing (1)
- Bauxite Residue (1)
- Biocides (1)
- Biocides in the environment (1)
- Chromium (1)
- Circular Economy (1)
- Circular economy (1)
- Coastal protection (1)
- Contaminant transfer (1)
- Density separation (1)
- Dry treatment (1)
- Dynamic surface leaching test (1)
- EOF/AOF (1)
- Ecotoxicity testing (1)
- Ecotoxicity tests (1)
- Emission (1)
- European research area (1)
- Fungi (1)
- Geotextiles (1)
- Grouts (1)
- HR-CS-GFMAS (1)
- Inter-laboratory test (1)
- Leaching tests (1)
- Limit values (1)
- Lysimeter (1)
- Marine littering (1)
- Nano metal fluorides (1)
- Nitrate (1)
- Oil (1)
- PFAS analytics (1)
- Passive sampling (1)
- Per- and polyfluoroalkyl substances (PFAS) (1)
- Potential toxic elements (1)
- Raman spectroscopy (1)
- Recovery (1)
- Red Mud (1)
- Regulation (1)
- Salts (1)
- Sc recovery (1)
- Scandium (1)
- Secondary building materials (1)
- Sediment (1)
- Simulation of materials degradation (1)
- Solubility (1)
- Substance release (1)
- Sum parameter analyis (1)
- Termites (1)
- Thermal treatment (1)
- Transformation (1)
- Transport modeling (1)
- UV radiation (1)
- Waste incineration (1)
- Waste-to-energy (1)
- Water contact (1)
- Wood protection (1)
- X-ray diffraction (1)
- XANES (1)
- XANES spectroscopy (1)
- microspectroscopy (1)
- soil (1)
- x-ray diffraction (1)
Organisationseinheit der BAM
- 4.3 Schadstofftransfer und Umwelttechnologien (23) (entfernen)
Eingeladener Vortrag
- nein (8)
This work is aimed at exploring the recovery of heavy metals from the fine fraction of solid waste incineration bottom ash.
For this study, wet-discharged bottom ash fine-fraction samples from full-scale treatment plants in Germany and Sweden were analyzed. The potential for the recovery of heavy metal compounds was investigated through wet density-separation with a shaking table. The feed materials were processed without any pre-treatment and the optimum processing conditions were determined by means of design of experiments. Tilt angle and stroke frequency were identified as the most relevant parameters, and the optimum settings were − 7.5° and 266 rpm, respectively. The obtained balanced copper enrichments (and yields) were 4.4 (41%), 6.2 (28%) and 2.4 (23%). A maximum copper enrichment of 14.5 with 2% yield was achieved, providing a concentrate containing 35.9 wt.% relevant heavy metal elements. This included 26.3 wt.% iron, 4.3 wt.% zinc and 3.8 wt.% copper. In conclusion, density separation with shaking tables can recover heavy metals from bottom ash fine fractions. Medium levels of heavy metal enrichment (e.g., for Cu 2.7–4.4) and yield (Cu: 26–41%) can be reached simultaneously.
However, the separation performance also depends on the individual bottom ash sample.
The concept of circular economy supports mitigation of climate change and other environmental pressures to the planet. Circulating materials in anthropogenic processes come with the risk of accumulating hazardous substances and compounds. In this concept, waste incineration or waste-to-energy (WtE) is a necessary technology to remove these compounds from the life cycle. In this mini-review, contaminants of major importance in the flue gas from waste incineration plants and their environmental impact are discussed. Air pollution of WtE is often seen as the most relevant environmental impact of this treatment option. The emission values parameter set for different countries is presented and compared. The most stringent legally set of emission values could be found in parts of Europe and South Korea. Japan also permits similar strict values when authorising individual incineration plants. In North America, the values are partially less strict as the best available technologies in Europe suggest being possible. Emerging economies, such as India and China, have shown efforts to improve their environmental protection standards but still have room to improve. This could be set in relation to other industrial emitting processes and therefore could be used to assess the relevance of this industry sector to the national emission inventories.
2021 marks the 10th anniversary of the first ERA.Net RUS joint call for European-Russian STI cooperation projects. Pooling the resources of more than 20 European and Russian funding agencies, more than 150 projects were funded with an estimated budget of about € 60 million.
Being even larger than many thematic ERA.NETs, the ERA.Net RUS Plus has been the biggest and most successful regional ERA.NET so far. Indicating a strong demand for scientific cooperation, the smaller-scale projects funded within the ERA.Net RUS (Plus) calls perfectly complement Russian participation in the EU Framework Programmes.
Not least of all, the ERA-Net RUS calls are examples of successful collaboration at a time when cooperation in other fields is complicated by the politically challenging situation. These calls contributed to keeping the communication channels open.
Against this background a dedicated event in late 2021 highlighted what has been achieved within the first decade of the initiative. The project EI-GEO coordinated by BAM was selected as best practice project. The presentation displays the main results of the project and discusses the key success factors.
Phosphorus (P) resource availability and quality is declining and recycling P-fertilizers from waste materials are becoming increasingly important. One important secondary P resource is sewage sludge (SSL) where P is often bound as aluminum phosphate (Al-P), iron phosphate (Fe-P) and polyphosphate (poly-P), respectively. Thermal treatment in different ways is a promising way in P recycling to produce highly plant-available P-fertilizers. To investigate mechanisms behind transformation of hardly available P-species toward plant-available P forms we treated a model SSL containing different kinds of defined P sources by low-temperature conversion (LTC) at 500 °C and subsequent thermochemical treatment of the LTC product with Na additives (TCT) at 950 °C, respectively. Pot experiments with ryegrass were carried out to determine the plant availability of P of the different treatments. The poly-P (here pyrophosphates) based fertilizers had a very high plant availability after both thermal treatments. During LTC treatment the plant availability of the Fe-P and Al-P variants increased because of the Formation of Fe(II) phosphates and/or pyro-/polyphosphates. Especially the formation of Al-polyphosphate shows a high plant availability. The subsequent TCT further increased strongly the plant availability of the Fe-P variants because of the formation of highly plant-available CaNaPO4. Thus, a direct TCT without prior LTC probably also produce CaNaPO4 and is recommended for Fe-P based SSL. However, a molar Ca/P ratio of 1 in the fertilizer is favorable for CaNaPO4 formation. Thus, the knowledge on the source of primary P in SSL is essential for choosing the accurate thermal treatment method to produce highly plant-available P-fertilizers from SSL.
For the first time, fluorine K-edge X-ray absorption near-edge structure (XANES) spectroscopy was applied to detect per- and polyfluoroalkyl substances (PFAS) in various soil and sewage sludge samples. The method can be used to determine the speciation of inorganic and organic fluorides, without pre-treatment of solid samples. Therefore, XANES spectra of several inorganic fluorides as well as selected fluorinated organic compounds were recorded. While inorganic fluorides partially exhibit a variety of sharp spectral features in the XANES spectrum, almost all inspected organofluorine compounds show two distinct broad features at 688.5 and 692.0 eV. Moreover, the peak intensity ratio 688.5 eV/692.0 eV in the PFAS XANES spectrum can be inversely correlated to the chain length of the perfluoro sulfonic acid group. The detection of targeted PFAS by bulk-XANES spectroscopy in combination with linear combination fitting in soils and sewage sludges was not applicable due to the low organic fluorine to total fluorine ratio of the samples (0.01–1.84%). Nonetheless, direct analysis of pure PFAS revealed that analysis of organofluorine species might be achieved in higher concentrated samples. Furthermore, quantitative measurements by combustion ion chromatography (CIC) evaluated as sum parameters extractable organically bound fluorine (EOF) and total fluorine (TF) emphasize that besides soils, sewage sludges are a significant source of organic fluorine in agriculture (154–7209 μg/kg).
A wide range of analytical methods are used to estimate the plant-availability of soil phosphorus (P). Previous investigations showed that analytical methods based on the Diffusive Gradients in Thin films (DGT) technique provide a very good correlations to the amount of bioavailable nutrients and pollutants in environmental samples (Davison 2016, Vogel et al. 2017). However, the DGT results do not identify which P compound of the soil has the high bioavailability. But there are various spectroscopic techniques (infrared, Raman, P K-edge and L-edge XANES and P NMR spectroscopy) available to characterize P species in soils. Therefore, spectroscopic investigation of DGT binding layers after deployment allow us to determine the specific compounds. Nutrients such as phosphorus and nitrogen are often, together with other elements, present as molecules in the environment. These ions are detectable and distinguishable by infrared, P K- and L-edge X-ray absorption near-edge structure (XANES) and NMR spectroscopy, respectively. Additionally, microspectroscopic techniques make it also possible to analyze P compounds on the DGT binding layer with a lateral resolution down to 1 μm2. Therefore, species of elements and compounds of e.g. a spatial soil segment (e.g. rhizosphere) can be mapped and analyzed, providing valuable insight to understand the dynamics of nutrients in the environment.
The aim of this study was to investigate the passive sampler method Diffusive Gradients in Thin-films (DGT) for ammonium and nitrate in amended soils. Therefore, we used soils from a pot experiment with maize where nitrogen (N) was supplied as ammonium sulfate nitrate (ASN), without and with a nitrification inhibitor (NI). The additional use of a NI can delay the nitrification in the soil and making the ammonium available for a longer period in the soil solution after its application. Homogenized soil samples were collected directly from each pot after one week of incubation before sowing and after harvesting the maize. Nitrate and ammonium in these soil samples were extracted using DGT devices equipped with a Putolite A520E (for nitrate) and Microlite PrCH (for ammonium) binding layer. Ammonium DGT which determined the mobile and labile ammonium forms based on diffusion and the resupplies from the solid soil phase, only showed a significantly higher amount of extractable ammonium with NI compared to that without NI for some samples. However, significantly lower values were found for nitrate of treatments with NI compared to without NI after harvest. Thus, the lower nitrate amounts for treatments with NI compared to the treatments without NI after harvest indicated the delay of the nitrification process by the NI. Furthermore, we compared also the ammonium and nitrate
DGT results to chemical extraction with KCl solutions. The results demonstrated that the trends of DGT results and chemical extraction were complimentary through all the treatments.
Phosphorus (P) fertilizers from secondary resources became increasingly important in the last years. However, these novel P-fertilizers can also contain toxic pollutants. Chromium in its hexavalent state (Cr(VI)) is regulated with low limit values for agricultural products due to its high toxicity, but the determination of Cr(VI) in these novel fertilizer matrices can be hampered by redox processes that lead to false results. Thus, we applied the passive sampler technique Diffusive Gradients in Thin-films (DGT) for the determination of Cr(VI) in fertilizers and compared the results with the standard wet chemical extraction method (German norm DIN EN 15192) and Cr K-edge X-ray absorption near-edge structure (XANES) spectroscopy. We determined an overall good correlation between the wet chemical extraction and the DGT method. DGT was very sensitive and in most cases selective for the analysis of Cr(VI) in P-fertilizers. However, hardly soluble Cr(VI) compounds cannot be detected with the DGT method since only mobile Cr(VI) is analyzed. Furthermore, Cr K-edge XANES spectroscopy showed that the DGT binding layer also adsorbs small amounts of mobile Cr(III) compounds which leads to overestimated Cr(VI) values. The results of certain types of P-fertilizers containing mobile Cr(III) or partly immobile Cr(VI), showed that optimization of the DGT method is required to avoid over- or underestimation of Cr(VI).
In Europe, nearly 19 Mt/y of bottom ash (BA) are produced. Of this quota, only 46 %wt. was treated, often in poorly performing plants, leaving behind 10 Mt of untreated and unrecovered BA, destined to landfill. The resulting 2.14 Mt loss of valuable materials included 1 Mt mineral fraction and 0.97 Mt ferrous metals, mostly from untreated BA, and 0.18 Mt non-ferrous metals, mostly from unrecovered BA. For the coarser fractions, the main obstacle to BA being used as recycling aggregate is the content of salts and potential toxic elements (PTEs), concentrated in a layer that coats BA particles. For the fine BA fractions, usually underexploited and landfilled, it is estimated that up to 0.95 Mt/y of ferrous and non-ferrous metals are not recovered in Europe.
During the workshop, the key results of BASH Treat project will be presented: the results of 2 industrial tests performed in BA treatment plants in Germany and Sweden; a novel dry treatment for the removal of salts and PTEs from BA coarse particles; a wet process for the recovery of heavy metal compounds from the fine fraction; a technical-economic assessment of the EU potential for the optimization of BA management.
In 2018 municipal solid waste (MSW) incineration in Europe produced nearly 19 Mt of bottom ash (BA); only 46 %-wt. was treated, often in poorly performing plants, leaving behind 10 Mt of untreated and unrecovered BA, destined to landfill. This work was based on the inventory of BA across Europe, and on the hypothesis to achieve complete BA valorisation through two assumptions: treating 100% BA and minimizing the loss of valuable fractions due to technical limitations of state-of-the-art processes in comparison to advanced innovative processes. The research involved three phases: characterization of potential secondary raw materials (metals and mineral fraction) currently lost from untreated (the surplus compared to treatment capacity) and unrecovered BA (the fine fraction) through material flow analysis; environmental assessment (energy balance and net GHG emissions) of complete BA valorisation; investigation of the economic feasibility of complete BA Valorisation through state-of-the-art technologies. The resulting 2.14 Mt loss of valuable materials included 1 Mt Mineral fraction and 0.97 Mt ferrous metals, mostly from untreated BA, and 0.18 Mt non-ferrous metals, mostly from unrecovered BA. The energy balance and GHGs emissions required by the treatment of the currently untreated and unrecovered fractions of BA resulted in energy and GHGs emissions savings. Economic profitability was driven by iron and copper recycling and avoided landfill fees. Profitability was achieved by two thirds of considered countries (average values: NPV 83 M€, ROI 20%, payback time 11 years) with BA mass flow exceeding 0.02 Mt.
Due to its large mineral fraction, incineration bottom ash (IBA) from municipal solid waste incineration is an interesting raw material that can be used for road construction or to produce secondary building materials. However, leaching chloride, sulfate, and potentially harmful heavy metals may cause problems in using IBA in civil engineering. Investigating leaching behavior is crucial for the assessment of the environmental compatibility of IBA applications. Various test procedures are available for that purpose. In the present study, a long-term leaching test of a wet-mechanically treated IBA was performed in a lysimeter for almost six years.
While concentrations of chloride, sulfate and the majority of the heavy metals started to decrease rapidly with progressive liquid-to-solid ratio (L/S), antimony (Sb) and vanadium (V) behaved differently. At the beginning of the lysimeter test, the Sb and V concentrations were low, but after approximately one year of operation at an L/S ratio of around 0.8 L/kg, a steady increase was observed. It was shown that this increase is the result of low Ca concentrations due to the formation of CaCO3.
With the data, the solubility products from Ca-antimonate and Ca-vanadate were calculated. The unusual leaching behavior of Sb and V should be kept in mind when considering field scenarios and evaluating the impact on the environment.
Background
A European inter-laboratory test with 29 participating laboratories investigated whether a battery of four ecotoxicological tests is suitable for assessing the environmental compatibility of construction products. For this purpose, a construction product was investigated with the dynamic surface leaching test (DIN CEN/TS 16637-2) and the percolation test (DIN CEN/TS 16637-3). The eluates were produced centrally by one laboratory and were tested by the participants using the following biotests: algae test (ISO 8692), acute daphnia test (ISO 6341), luminescent bacteria test (DIN EN ISO 11348), and fish egg test (DIN EN ISO 15088). As toxicity measures, EC50 and LID values were calculated.
Results
Toxic effects of the eluates were detected by all four biotests. The bacteria test was by far the most sensitive, followed by the algae test and the daphnia test; the fish egg test was the least sensitive for eluates of both leaching tests. The toxicity level of the eluates was very high in the bacteria, daphnia, and algae test, with lowest ineffective dilution values of LID = 70 to LID = 13,000 and corresponding EC50 values around or even below 1 volume percent. The reproducibility (approximated by interlaboratory variability) of the biotests was good (< 53%) to very good (< 20%), regardless of the toxicity level of the eluates. The reproducibility of the algae test was up to 80%, and thus still acceptable.
Conclusion
It can be confirmed that the combination of leaching and ecotoxicity tests is suitable to characterize with sufficient reproducibility the environmental impact posed by the release of hazardous substances from construction products.
Per- and polyfluoralkyl surfactants (PFAS) are industrially produced surface chemicals used in daily applications that have gained public and political attention due their unnaturally high appearance in drinking water, nourishments and soils.[1] Their chemical structures exhibit both lipophilic and hydrophilic properties, leading to a highly inert and persistent character.[2] Various PFAS have shown to be bioaccumulative in plants and animals, and some have been characterized as highly toxic when ingested.[3] When exposed to the environment, PFAS slowly get mobilized by natural water resources, leading to contamination of large areas of soil and natural water sources.[4] While PFAS contamination of drinking water has been investigated intensively, perfluoralkyl contamination of soils has been rarely examined as of yet. At the same time, an increasing amount of PFAS contamination sites are being discovered worldwide, calling for a sophisticated strategy towards analytical characterization.[5] Since the number of known PFAS already exceeds 4700, the established sum parameters like extractable organic fluorine (EOF) and adsorbable organic fluorine (AOF) are key elements to fully survey the impact of exposure.[6] Simultaneously, innovative soil remediation strategies are required to contain environmental destruction and to minimize further spreading of contaminants.[7] Addressing these challenges requires suitable analytical devices that are capable of mobilizing PFAS in the solid as well as in the liquid phase. The use of combustion ion chromatography (CIC) enables analysis of both immobile and volatile PFAS and allows the detection of both total fluorine (TF) and EOF or AOF of a given soil or aqueous sample. Based on preliminary results, the clean-up of a PFAS contaminated matrix is monitored via EOF detection over time. Additionally, we tested the effectiveness of urea (CH₄N₂O) as fluoride scavenger with the aim to improve the separation of inorganic and organic fluorine and therefore, to improve AOF accuracy. The presented findings can be contributive with regard to future AOF/EOF sum parameter development and application.
Several thousand PFAS are in circulation and the current challenge lies in detection of these compounds. Wheter environmental contamination occurs via industrial emission or direct PFAS exposure, as through the use of AFFF fire fighting foams. Wheter PFAS need to be detected in consumer products or agricultral soil, or wheter human and wildlife exposure to PFSA needs to be evaluated, suitable analytical methods are required to identifiy the target class within a hugh variety of matrices. At the same time it is critical to detect trace amounts of compounds within various matrices, we want to make sure that we consider very volatile and mobile species, simultaneously want to assure that we do not overlook less and insoluble compounds. We require methods that allow both single and multi target analysis and want to have an ideal overview with the help of sum parameters.
The main obstacle to bottom ash (BA) being used as a recycling aggregate is the content of salts and potential toxic elements (PTEs), concentrated in a layer that coats BA particles. This work presents a dry treatment for the removal of salts and PTEs from BA particles. Two pilotscale abrasion units (with/without the removal of the fine particles) were fed with different BA samples. The performance of the abrasion tests was assessed through the analyses of particle size and moisture, and that of the column leaching tests at solid-to-liquid ratios between 0.3 and 4.
The results were: the particle-size distribution of the treated materials was homogeneous (25 wt % had dimensions <6.3 mm) and their moisture halved, as well as the electrical conductivity of the leachates. A significant decrease was observed in the leachates of the treated BA for sulphates (44%), chlorides (26%), and PTEs (53% Cr, 60% Cu and 8% Mo). The statistical analysis revealed good correlations between chloride and sulphate concentrations in the leachates with Ba, Cu, Mo, and Sr, illustrating the consistent behavior of the major and minor components of the layer surrounding BA particles. In conclusion, the tested process could be considered as promising for the improvement of BA valorization.
Here, we describe a fast and simple extraction method for the determination of per- and polyfluorinated alkyl substances (PFASs) utilizing extractable organic fluorine (EOF) sum parameter analysis and high resolution-continuum source-graphite furnace molecular absorption spectrometry (HR-CS-GFMAS) in soil samples. After extraction and separation of inorganic and organic fluorinated compounds, organically bound fluorinated compounds were indirectly determined via the molecular absorption of gallium mono-fluoride at 211.248 nm. The implementation of the decisions of the “Stockholm Convention on persistent organic pollutants” as well as the “Protocol on Persistent Organic Pollutants of the Convention on Long-Range Transboundary Air Pollution” of the UNECE include the reduction respectively the elimination of PFASs in the environment. Currently, regulations aim to target single compounds (mostly C8-PFAS). But the PFAS group includes over 4700 substances, which are potentially persistent and toxic, thus target analytical approaches are not suitable for a holistic approach investigating the PFAS pollutant situation. Furthermore, forbidden PFASs are substituted by short-chain PFASs, thus the number of unknow substances is steadily increasing. For this reason, sum parameter approaches are more suitable to investigate and assess the pollution situation as well as derive exposure limits. Our developed analytical method was successfully applied to determine PFASs in soil samples from a polluted site. In view of steadily increasing numbers of PFAS substances, our method will make an important contribution in assessing the pollution situation as well as support policy makers in deriving exposure limits for PFAS in the future.
Per- and polyfluoroalkyl substances (PFAS) have been used extensively in the past because of their inert chemical character and resistance to degradation by environmental influences. Since the beginning of their commercial use, PFAS have been widely exposed to the environment by application of PFAS in consumer products or as foaming agent in firefighting foams, thus several cases of contaminated soils sites have been reported. Since the number of known PFAS already exceeds 4700, their characterization and direct analysis is challenging given the current available techniques. Here, we introduce the novel fluorine (F) K-edge X-ray absorption near-edge structure (XANES) spectroscopy as a tool to analyze PFAS and inorganic fluorine compounds in contaminated soils and sewage sludges. While F K-edge bulk-XANES spectroscopy provide us information on the overall fluorine bonding in a sample micro X-ray fluorescence (XRF) in combination with F K-edge micro-XANES spectroscopy can also detect minor fluorine compounds and PFAS hotspots in investigated soils and sludges. Additionally, we used the combustion ion chromatography (CIC) to analyze the total amount of all PFAS as a sum parameter (extractable organic fluoride: EOF) in soils and sewage sludges. During combustion in the CIC, the PFAS in the sample get destroyed at temperatures of approx. 1000 °C and converted in inorganic fluorides that subsequently gets quantified by ion chromatography. Thus, for the first time we successfully combined F K-edge XANES spectroscopy and CIC as analytical tools to detect and quantify PFAS contaminants in soils and sewage sludges.
Stormwater from urban areas can transport biocidally active substances and related transformation products from buildings into the environment. The occurrence of these substances in urban runoff depends on the availability of water, and on ultraviolet radiation exposure that causes photolytic reactions. In a systematic laboratory study, painted test specimens were exposed to either ultraviolet radiation, water contact, or a combination of both. Leaching of the biocidally active substances carbendazim, diuron, octylisothiazolinone, terbutryn, and selected transformation products of terbutryn and diuron were observed under various exposure conditions. Remaining concentrations of these substances in the paint were quantified. It was demonstrated that the distribution of active substances and transformation products in eluates and in the coatings themselves differs with exposure conditions. Strategies for environmental monitoring of biocide emissions need to consider the most relevant transformation products. However, environmental concentrations of biocidally active substances and transformation products depend on earlier exposure conditions. As a consequence, monitoring data cannot describe emission processes and predict expected leaching of biocidally active substances from buildings if the data are collected only occasionally.
Microspectroscopy reveals dust-derived apatite grains in acidic, highly-weathered Hawaiian soils
(2021)
Dust deposition is an important source of phosphorus (P) to many ecosystems. However, there is little evidence of dust-derived P-containing minerals in soils. Here we studied P forms along a well-described climatic Gradient on Hawaii, which is also a dust deposition gradient. Soil mineralogy and soil P forms from six sites along the climatic gradient were analyzed with bulk (X-ray diffraction and P K-edge X-ray absorption near edge structure) and microscale (X-ray fluorescence, P K-edge X-ray absorption near edge structure, and Raman) analysis methods. In the wettest soils, apatite grains ranging from 5 to 30 μm in size were co-located at the micro-scale with quartz, a known continental dust indicator suggesting recent atmospheric deposition. In addition to co-location with quartz, further evidence of dust-derived P included backward trajectory modeling indicating that dust particles could be brought to Hawaii from the major global dust-loading areas in central Asia and northern Africa. Although it is not certain whether the individual observed apatite grains were derived from long-distance transport of dust, or from local dust sources such as volcanic ash or windblown fertilizer, these observations offer direct evidence that P-containing minerals have reached surface layers of highly-weathered grassland soils through atmospheric deposition.
Geosynthetic materials are applied in measures for coastal protection. Weathering or any damage of constructions, as shown by a field study in Kaliningrad Oblast (Russia), could lead to the littering of the beach or the sea (marine littering) and the discharge of possibly harmful additives into the marine environment. The ageing behavior of a widely used geotextile made of polypropylene was studied by artificial accelerated ageing in water-filled autoclaves at temperatures of 30 to 80 °C and pressures of 10 to 50 bar. Tensile strength tests were used to evaluate the progress of ageing, concluding that temperature rather than pressure was the main factor influencing the ageing of geotextiles. Using a modified Arrhenius equation, it was possible to calculate the half-life for the loss of 50% of the strain, which corresponds to approximately 330 years. Dynamic surface leaching and ecotoxicological tests were performed to determine the possible release of contaminants. No harmful effects on the test organisms were observed.
This paper focuses on the scandium speciation in bauxite residues of different origin. Insights into mineralchemical similarities and differences of these materials will be presented and links to their natural geological background discussed. The presented research should provide fundamental knowledge for the future development of efficient and viable technologies for Sc-recovery from bauxite residues derived from different bauxites and accumulating at different localities. In total, five bauxite residues were investigated which originated from Greece, Germany, Hungary and Russia (North Ural & North Timan) using a combination of different analytical tools. Those included: laser ablation inductively coupled plasma mass spectrometry, X-ray absorption near Edge structure (XANES) spectroscopy, μ-Raman spectroscopy as well as scanning electron microscopy and electron microprobe analyses. X-ray fluorescence and inductively coupled plasma mass spectrometry were used to determine the overall chemical composition. The investigated samples were found to exhibit a relatively homogenous distribution of Sc between the larger mineral particles and the fine-grained matrix except for Al-phases like diaspore, boehmite and gibbsite. These phases were found to be particularly low in Sc. The only sample where Sc mass fractions in Al-phases exceeded 50 mg/kg was the Russian sample from North Ural. Fe-phases such as goethite, hematite and chamosite (for Russian samples) were more enriched in Sc than the Al-phases.
In fact, in Greek samples goethite showed a higher capacity to incorporate or adsorb Sc than hematite. Accessory minerals like zircon, rutile/anatase and ilmenite were found to incorporate higher mass fractions of Sc (>150 mg/kg), however, those minerals are only present in small amounts and do not represent major host phases for Sc. In Russian samples from North Ural an additional Ca–Mg rich phase was found to contain significant mass fractions of Sc (>500 mg/kg). μ-XANES spectroscopy was able to show that Sc in bauxite residue occurs adsorbed onto mineral surfaces as well as incorporated into the crystal lattice of certain Fe-phases. According to our observations the bauxite type, i.e. karstic or lateritic, the atmospheric conditions during bauxitization, i.e. oxidizing or reducing, and consequently the dominant Sc-bearing species in the primary Bauxite influence the occurrence of Sc in bauxite residues. In karstic bauxites, underlying carbonate rocks can work as a pH-barrier and stabilize Sc. This prevents the Sc from being mobilized and removed during bauxitization. Hence, karstic bauxites are more prone to show a Sc enrichment than lateritic bauxites. Reducing conditions during bauxitization support the incorporation of Sc into clay minerals such as chamosite, which can dissolve and reprecipitate during Bayer processing causing Sc to be redistributed and primarily adsorb onto mineral surfaces in the bauxite residue. Oxidizing conditions support the incorporation of Sc into the crystal lattice of Fe-oxides and hydroxides, which are not affected in the Bayer process. The genetic history of the bauxite is therefore the major influential factor for the Sc occurrence in bauxite residues.
Throughout their life cycle—from production, via usage, through to disposal—materials and products interact with the environment (water, soil, air). At the same time, they are exposed to environmental influences and, through their emissions, have an impact on the environment, people, and health. Accelerated experimental testing processes can be used to predict the long-term environmental consequences of innovative products before these actually enter the environment.
The aim of this Special Issue of the journal Materials is to publish original research and review articles as well as short communications tackling the problem of reliable environmental measurement methods and reporting exemplary case studies.
In this study, nanoscopic particles of magnesium Fluoride (MgF2) and calcium fluoride (CaF2) also known as nano metal fluorides (NMFs), were evaluated for their potential to improve wood durability. Even though these fluorides are sparingly soluble, their synthesis in the form of nano-sized particles turns them into promising candidates for wood preservation. Their distinct property of low-water solubility is proposed to maintain long-lasting protection of treated wood by reducing the leaching of fluoride. Analytical methods were used to characterize the synthesized NMFs and their distribution in treated wood specimens. Transmission electron microscopy images showed that these fluoride particles are smaller than 10 nm. In nano metal fluoride (NMF) treated specimens, aggregates of these particles are uniformly distributed in the wood matrix as confirmed with scanning electron microscopy images and their corresponding energy-dispersive X-ray spectroscopy maps. The fluoride aggregates form a protective layer around the tracheid walls and block the bordered pits, thus reducing the possible flow path for water absorption into wood. This is reflected in the reduced swelling and increased hydrophobicity of wood treated with NMFs. The biocidal efficacy of NMFs was tested against brown-rot fungi (Coniophora puteanaand Rhodonia placenta), white-rot fungus (Trametes versicolor), and termites (Coptotermes formosanus). The fungal and termite tests were performed in accordance with the EN 113 (1996) and EN 117 (2012) standards, respectively. Prior to fungal tests, the NMF treated wood specimens were leached according to the EN 84 (1997)standard. Compared to untreated specimens, the NMF treated wood specimens have a higher resistance to decay caused by brown-rot fungi, white-rot fungus, and termites. Although all NMF treatments in wood reduce the mass loss caused by fungal decay, only the combined treatment of MgF2 and CaF2 has efficacy against both brown-rot fungi and white-rot fungus. Similarly, wood treated with the combined NMF formulation is the least susceptible to attack by C. formosanus.It is proposed that combining MgF2 and CaF2changes their overall solubility to promote the release of fluoride ions at the optimal concentration needed for biocidal efficacy against fungi and termites. In this thesis, it was proven that even after leaching, sufficient fluoride was present to protect NMF treated wood from fungal decay. This shows that NMFs are robust enough for above ground contact outdoor applications of wood, where permanent wetness cannot be avoided according to Use Class 3.2, as per the EN 335 (2013) standard. Also, they pose a low risk to human health and the environment because they are sparingly soluble. Since NMFs significantly reduce the decay of wood, the CO2 fixed in it will be retained for longer than in unpreserved wood. Overall, the novel results of this study show the potential of NMFs to increase the service life of building materials made from non-durable wood.