Microplastics in the environment occur in different sizes and shapes and are made of various polymers. Therefore, they also considerably differ in their properties and ecotoxicity. However, the ...majority of microplastics research uses pre-made spherical microplastics, which practically do not exist in the environment. Our work focused on a comprehensive study of six different types of microplastic that were prepared to simulate common microplastics found in the environment. All types of microplastics where chemically and physically characterized using Fourier-transform infrared spectroscopy, thermal analysis, field-emission scanning electron microscopy, optical microscopy and laser diffraction analysis. The specific surface area was determined using the BET method. Furthermore, effects of microplastics and microplastic leachates on a common duckweed (Lemna minor) were evaluated. All tested microplastics did not affect specific growth rate and chlorophyll a content in duckweed, while microplastics with a rough surface and sharp edges caused a significant reduction of duckweed root length. Microplastics made of Bakelite also showed an intensive leaching, which increased their ecotoxicity potential. Natural particles used as a control did not have any negative effect on duckweed. Overall, microplastic particles have significantly different ecotoxicity profiles depending on their physico-chemical properties. Therefore, the testing of environmentally relevant particles and their proper characterization, as well as the testing of microplastic leaching properties, is crucial for understanding of microplastics ecotoxicological potential.
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•MPs with rough surface and sharp edges had negative impact on duckweed's root length.•MPs made of Bakelite had negative impact on root length due to leaching of chemicals.•Natural particles, used as control, showed no negative impact on duckweed.
Microplastics are very common contaminants in the environment. Despite increasing efforts to assess the effects of microplastics on soil organisms, there remains a lack of knowledge on how organisms ...respond to diverse types of microplastics after different exposure durations. In the present study, we investigated the immune response of the terrestrial crustacean Porcellio scaber exposed to the two most common microplastic particles in the environment: polyester fibres and tyre particles. We also tested two natural particles: wood dust and silica powder, with all treatments performed at 1.5% w/w. The response of P. scaber was evaluated at the level of the immune system, and also the biochemical, organism and population level, after different exposure durations (1, 2, 4, 7, 14, 21 days). These data reveal dynamic changes in the levels of some immune parameters shortly after exposure, with a gradual return to control values. The total number of haemocytes was significantly decreased after 4 days of exposure to tyre particles, while the proportion of different haemocyte types in the haemolymph was altered shortly after exposure to both polyester fibres and tyre particles. Moreover, 7 days of exposure to tyre particles resulted in increased superoxide dismutase activity in the haemolymph, while metabolic activity in whole woodlice (measured as electron transport system activity) was increased after exposure for 7, 14 and 21 days. In contrast, the natural particles did not elicit any significant changes in the measured parameters. Survival and feeding of P. scaber were not altered by exposure to the microplastics and natural particles in soil. Overall, this study defines a time-dependent transient immune response of P. scaber, which indicates that immune parameters represent sensitive biomarkers of exposure to microplastics. We discuss the importance of using natural particles in studies of microplastics exposure and their effects.
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•We studied natural particles and microplastics for immune effects in Porcellio scaber•Haemocyte proportions in haemolymph rapidly and transiently changed for microplastics•Exposure to tyre particles significantly increased whole woodlouse metabolic activity•There were no changes in measured parameters for exposure to natural particles
Bookkeeper, the most widely used deacidification process based on MgO particles, was systematically evaluated on two sets of nonvaluable historical paper samples. Established analytical methods, such ...as pH and alkaline reserve determination, were used, as well as SEM EDS analyses to evaluate the distribution of Mg-rich particles on the paper surface and in the cross-section of the paper. The degradation rate constants of untreated and deacidified paper samples after accelerated thermal degradation were calculated based on weight average molecular mass determination to evaluate the lifetime extension of paper. The efficiency factors determined after accelerated thermal degradation of untreated and treated paper showed that paper lifetime prolongation after Bookkeeper deacidification treatment is highly limited for most of the investigated paper samples. No correlation was found between the alkaline reserve content or the pH and the degradation rate constants of the deacidified paper samples, but the paper degradation rate correlated with the paper samples pH before deacidification treatment. SEM EDS analysis showed that Mg-rich particles remained on the paper surface, which explains the limited effectiveness of the treatment.
Graphical abstract
Industrial Cu/ZnO/Al
2
O
3
or novel rate catalysts, prepared with a photochemical deposition method, were studied under functional CH
3
OH synthesis conditions at the set temperature (
T
) range of ...240–350 °C, 20 bar pressure, and stoichiometric carbon dioxide/hydrogen composition. Analytical scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray adsorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) methods were systematically utilized to investigate the interfaces, measured local geometry, and chemical state electronics around the structured active sites of commercially available Cu/ZnO/Al
2
O
3
material or synthesized Cu/ZnO. Processed Cu K-edge EXAFS analysis suggested that various Cu atom species, clusters, metallic
fcc
Cu, Cu oxides (Cu
2
O or CuO) and the Cu
0.7
Zn
2
alloy with hexagonal crystalline particles are contained after testing. It was proposed that in addition to the model’s Cu surface area, the amount, ratio and dispersion of the mentioned bonded Cu compounds significantly influenced activity. Additionally, XPS revealed that carbon may be deposited on the commercial Cu/ZnO/Al
2
O
3
, forming the inactive carbide coating with Cu or/and Zn, which may be the cause of basicity’s severe deactivation during reactions. The selectivity to methanol decreased with increasing
T
, whereas more Cu
0.7
Zn
2
inhibited the CO formation through reverse water–gas shift (RWGS) CO
2
reduction.
Graphic Abstract
Most currently available research into Tibetan paper focuses on the earliest books from an archaeological perspective. On the other hand, scientific studies of the 19th−20th century Tibetan paper are ...largely missing, specifically with respect to material properties and paper permanence. To explore these, both conventional and modified methods were applied using reference historic material collection. Material properties such as fibre morphology, paper pH, degree of polymerisation (DP), water and ash contents were investigated. The measurement methods for starch and protein content were explored—and we report on a quantification method for the determination of starch content in paper. The degradation behaviour of Tibetan paper was studied using accelerated degradation experiments at two sets of conditions (80 ˚C, 65% RH and 60 ˚C, 80% RH) for up to 84 days in order to explore the applicability of existing dose-response functions. The results demonstrate that examined 19th−20th century papers used in Tibetan books, were prepared using diverse fibres, similar to traditional Chinese paper. Most of paper sheets presented laminated structures, where starch was used as the predominant glue. The layers within one paper sheet are identical, as evidenced by similar pH and DP values among layers in one sheet. The studied collection of papers tends to have similar properties to modern Chinese paper since most of both types of papers present pH 6.5–8 and DP 1000–2000. The accelerated degradation experiment shows that papers used as writing support in Tibetan books follows the same principle of degradation as western paper has demonstrated, i.e., the rate constants of degradation depend on paper pH, temperature, and relative humidity of the environment. This research expands our understanding of this collection and inform preventive conservation of modern Tibetan manuscripts.
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•Superactivated carbons were obtained by KOH activation of apple tree branches char.•β-Blocker medicine atenolol was used as target compound for liquid phase assays.•Monolayer ...adsorption capacities of lab-made carbons between 345 and 556 mg g−1.•Thermal decomposition of atenolol racemic mixture is a two-step process.•Adsorption of each atenolol specie is conditioned by the carbons’ surface chemistry.
This work approaches the preparation of KOH and K2CO3 activated carbons from apple tree small branches char with activation yields around 40%, and apparent surface areas up to 2472 m2 g−1. The treatment duration had a marked impact on the micropore structure, causing the widening of the narrow micropores to supermicropores.
The adsorption characteristics of lab-made carbons for atenolol removal from aqueous phase was assessed by kinetic and equilibrium experiments. Monolayer adsorption capacities between 346 and 556 mg g−1 were achieved.
The commercial atenolol, consisting in a racemic mixture, gave rise to a two-step thermal decomposition process. Thermogravimetric analysis of the exhausted samples revealed that the predominant atenolol specie adsorbed is conditioned by the carbons’ surface chemistry: neutral/acidic lab-made carbons generally favoured the decomposition of the more stable specie; basic commercial samples retained predominantly the less stable one.
ZnO nanoparticles were synthesized solvothermally in various diols (ethylene glycol, di(ethylene glycol), tetra(ethylene glycol), 1,2-propanediol, 1,4-butanediol), using basic zinc carbonate ...(2ZnCO3·3Zn(OH)2) as a precursor for the first time. Since ZnCO3 was sparingly soluble in diols the transformation reaction proceeded at a low reaction rate. Ethylene glycol was found as the most suitable medium among five diols studied yielding the smallest ZnO particles (~55nm) and short reaction time, tr (2h). Diols with shorter chain length produced smaller ZnO particles. p-Toluene sulfonic acid (p-TSA) acted as a catalyst and reduced tr from 8h to 2h in concentration of 0.02M. Optimum reaction conditions for the synthesis in ethylene glycol were 185°C and 2h. At higher p-TSA concentrations (0.04–0.08M) the size of ZnO particles was reduced from 500–800nm to 50–100nm and crystallite size to 25–30nm. Benzene sulfonic acid (BSA) and inorganic bases (LiOH, NaOH, and KOH) also showed catalytic activities. Raman and photoluminescence spectroscopies revealed high concentration of defects on ZnO surface causing the emission of visible light and giving this type of ZnO higher potential in various (opto)-electronic application in comparison to Zn(II) acetate based ZnO.
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•Basic zinc carbonate was used as a new precursor in solvothermal synthesis of ZnO.•The smallest ZnO particle size was obtained in ethylene glycol.•The correlation between diol chain length and ZnO particle size was established.•Sulfonic acids (p-TSA, BSA) showed catalytic and end capping activities.•High deffect concentrations on ZnO surface caused photoluminescence.
This paper investigates the origin of increased strength and water resistance of air lime mortar prepared by Triassic dolomite aggregate when exposed to humid or wet environments. The mortar ...specimens were exposed to various ageing conditions and analysed using petrographic and scanning electron microscopy equipped with X-ray microanalysis. Parallel to these analyses, X-ray powder diffraction and strength tests were performed on the specimens. It was revealed that reactions associated with the dedolomitisation process of the dolomite grains in the lime binder (hereafter alkali-carbonate reactions or ACRs) are the source of the improved strength and water resistance. An increasingly alkaline environment accelerated the ACRs substantially. Two parallel processes during the ACRs (dedolomitisation and CaCO3 dissolution/reprecipitation) were described in detail. Ageing temperature decisively influenced the kinetics of the dedolomitisation and dictated the path of the CaCO3 dissolution/reprecipitation process. After two years of ageing in a water-saturated environment at 60 °C, air lime mortar retained a great deal of its initial mechanical strength, and at 20 °C its strength was considerably increased. This somewhat unexpected observation was explained as being a result of microstructural changes and/or phase transitions.
•Combined lime-cement structural injection grouts were designed.•Time evolution of the grout setting process was monitored by proton NMR spectroscopy.•The grout setting process is significantly ...slowed down relative to the cement pastes.•Compressive strengths of the grouts are appropriate for historical buildings repair.•Swelling agent lowers the compressive strength of the grouts to an unacceptable level.
We present design and properties of combined air lime-white cement structural injection grouts containing 17.5% of air lime, 7.5% of cement and 75% of limestone filler, using white Portland cement. Time evolution of the grout setting process during hydration from early to late stages was monitored by NMR spectroscopy and compared to pure cement-paste control samples. The grout setting is significantly slowed down (by more than 10 days). The compressive strengths of the grouts were found in the range 1.5–2.5 MPa, making them efficient materials for the strengthening of historical masonry buildings in Slovenia.
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