Mineral wool, i.e. rock and glass wool, represents considerable challenge after its functional-ti... more Mineral wool, i.e. rock and glass wool, represents considerable challenge after its functional-time runs out due to its small density leading to large volume consumption during transport and in landfills where it usually ends. Because rock wool is mineralogically and chemically a promising precursor material for alkali-activation, it was milled from few centimetres-decimeters long fibres to micron-sized fibres. Since fibres in alkali-activated materials generally show an increase in mechanical strength, especially the bending strength, 1 m% of additional fibres (basalt, cellulose (2 types), glass, polypropylene, polyvinyl alcohol and steel fibres) was used in the alkali mixture, that was curred at 40 °C for 3 days. Time dependence of the mechanical strengths of alkali-activated materials with and without additional fibres was followed. Maximal increase of compressive and bending strength after 28 days was reached with polypropylene fibres, i.e. it was 20% and 30% higher than compressive and bending strength of alkali-activated material without additional fibres respectively.
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
This work reports the development of ultralight interwoven ultrathin graphitic carbon nitride (g-... more This work reports the development of ultralight interwoven ultrathin graphitic carbon nitride (g-CN) nanosheets for use as a potential adsorbent in a passive sampler (PAS) designed to bind Hg 2+ ions. The g-CN nanosheets were prepared from bulk g-CN synthesised via a modified high-temperature short-time (HTST) polycondensation process. The crystal structure, surface functional groups, and morphology of the g-CN nanosheets were characterised using a battery of instruments. The results confirmed that the as-synthesized product is composed of few-layered nanosheets. The adsorption efficiency of g-CN for binding Hg 2+ (100 ng mL −1) in sea, river, rain, and Milli-Q quality water was 89%, 93%, 97%, and 100%, respectively, at natural pH. Interference studies found that the cations tested (Co 2+ , Ca 2+ , Zn 2+ , Fe 2+ , Mn 2+ , Ni 2+ , Bi 3+ , Na + , and K +) had no significant effect on the adsorption efficiency of Hg 2+. Different parameters were optimised to improve the performance of g-CN such as pH, contact time, and amount of adsorbent. Optimum conditions were pH 7, 120 min incubation time and 10 mg of nanosheets. The yield of nanosheets was 72.5%, which is higher compared to other polycondensation processes using different monomers. The g-CN sheets could also be regenerated up to eight times with only a 20% loss in binding efficiency. Overall, nano-knitted g-CN is a promising low-cost green adsorbent for use in passive samplers or as a transducing material in sensor applications.
Gypsum from the wet flue gas desulfurization system of the lignite fired thermal power plant Šošt... more Gypsum from the wet flue gas desulfurization system of the lignite fired thermal power plant Šoštanj, Slovenia, can efficiently retain mercury (Hg), of which most is contained in finer gypsum fractions, with concentrations above 10 kg −1. The aim of this work was to identify and study the temperature stability of Hg species in gypsum by a temperature fractionation (TF) method. A selfconstructed apparatus was used that consisted of an electrical furnace for controlled heating up to 700˚C, with a heating rate of 2.2˚C•min −1 , and an AAS detector with Zeeman background correction. The pattern of Hg release during temperature increase depends highly on the matrix/substrate in which it is contained. Based on spiking gypsum with known Hg compounds we concluded that the largest proportion of Hg in gypsum belongs to Hg-Cl and Hg-Br compounds appearing at 160˚C to 200˚C, followed by smaller amounts of HgO, HgS and Hg sulfates appearing at 300˚C and 450˚C. Further development of methodology for identifying Hg species would require identification of the decomposition fragments of Hg and other compounds, complemented by a better understanding of Hg reactivity at higher temperatures.
The inhibitory effect of the hydrophobic layer on the surface of copper in an acidic medium was s... more The inhibitory effect of the hydrophobic layer on the surface of copper in an acidic medium was studied by the classical potentiodynamic method and the impedance spectroscopy method. The hydrophobic character of the copper surface was achieved by immersing the sample in ethanolic octadecanoic acid with and without the addition of dog rose oil extract. The selected concentrations of the added dog rose oil extract were 0.5, 1.0, and 2.0 wt% in 0.05 molL-1 alcoholic solution of octadecanoic acid. Based on electrochemical measurements, an inhibition effect of ≈ 65% was obtained when the surface was modified by immersion in ethanolic octadecanoic acid only. With the addition of dog rose oil extract, this value increased to over 90%, depending on the concentration of dog rose oil extract added. 2 5 TH INTERNATIONAL CONFERENCE ON TECHNOLOGIES & BUSINESS MODELS FOR CIRCULAR ECONOMY: CONFERENCE PROCEEDINGS.
A quadrupole mass spectrometer was used to study the thermal release of mercury from wet flue gas... more A quadrupole mass spectrometer was used to study the thermal release of mercury from wet flue gas desulphurization (WFGD) gypsum using temperatureprogrammed desorption/decomposition (TPD). The inability in direct detection of low concentrations of mercury halogenides in gypsum by mass spectrometry is discussed in detail. The hydrolysis of HgCl 2 vapours under specific experimental conditions in the mass spectrometer was considered theoretically and proved experimentally. The mercury concentration in different gypsum fractions varies from 0.22 mg kg-1 (3.27-148 µm, coarse particles) to 20.6 mg kg-1 (0.41-88.0 µm, fine particles). All samples had a similar, symmetrical, single-peak (peak maximum 253-266°C) in the TPD spectra. In the present study, the use of 'wet' methods for preparing mercury compounds is introduced in addition to the mercury standards prepared using the 'dry' method, as commonly found in TPD. The study showed that selected metals, such as Fe enriched in gypsum samples, significantly influence the shape and the maximum temperature of the Hg TPD curves and that during the mercury compound preparation and the TPD process, Hg species undergo transformations that prevent the identification of their original identity.
The major aim of the newly adopted Mercury Convention is to reduce global mercury (Hg) emissions ... more The major aim of the newly adopted Mercury Convention is to reduce global mercury (Hg) emissions to the environment. In high temperature industrial processes, including coal combustion, Hg compounds present as impurities in solid materials are decomposed and evaporated leading to the emission of Hg to the atmosphere. The behaviour of different Hg compounds and their mixtures during heating have been the subject of numerous studies, and is the topic of the present work. Controlled heating can be used to fractionate Hg compounds in solid substrates, offering the possibility of identification and quantification of Hg compounds. In the attempt to develop a method for temperature fractionation of Hg, experiments were conducted with pure Hg compounds, and the compounds mixed with different substrates (SiO 2 and CaSO 4 • 2H 2 O), for calibration purposes. Detection was performed by two methods, namely Cold Vapour Atomic Absorption Spectrometry (CV AAS) with Zeeman background correction, and Nier-type Mass Spectrometry with a Knudsen cell (MS). Further investigation is in process.
Alkali-activated materials are promising materials for the construction industry due to the acces... more Alkali-activated materials are promising materials for the construction industry due to the accessibility of the precursors, which are mainly secondary industrial by-products, and their cost-effective and energy-efficient production. Although these materials are not new, some of the parameters in the technological process are not yet fully understood and tested. Therefore, in this paper in the means of mechanical strength, the preparation of alkali-activated pastes by using a three-roll mill homogenization method is discussed. The influence of homogenization of alkali-activated slurry has been evaluated on different waste materials (fly ash, fly ash with metakaolin, slag mixture (electric arc furnace slag and ladle slag), glass wool, waste green ceramics), which are treated with different alkali activators (NaOH, commercial sodium silicate solution, laboratory-produced alkali activators based on waste cathode- ray tube glass) with different curing regimes (60 °C and 70 °C) and different drying methods (drying at room temperature, drying at 105 °C). The viscosity of the slurry before homogenization was higher than after homogenization, the distribution of elements was more uniform and the compressive strength higher in all homogenized alkali activated materials, regardless of other parameters.
The objective of the present study was to evaluate the relation between maternal blood levels of ... more The objective of the present study was to evaluate the relation between maternal blood levels of selected toxic and potentially toxic elements (manganese (Mn), copper (Cu), zinc (Zn), arsenic (As), selenium (Se), cadmium (Cd), lead (Pb) and mercury (Hg)) and birth weight of their new-borns in a Slovenian population, taking into account maternal socio-demographic characteristics and dietary habits. 535 women from 12 regions of Slovenia were recruited at delivery. Maternal blood was collected at 1.5 months after birth. Associations between birth weight and a) predictors obtained through the questionnaires and b) levels of selected elements were tested using bivariate tests and multiple linear regression. Multiple regression models revealed maternal age as an additional predictor for birth weight and confirmed pre-pregnancy body mass, estimated gestational age and gender of the baby as the main predictors for birth weight. Mn in maternal blood was significantly and positively associated with birth weight. The positive association observed between birth weight and Mn in maternal blood could be explained by the essentiality of Mn in foetal development as an important cofactor in enzyme reactions in bone formation and in metabolic regulation for amino acid, lipid, protein and carbohydrate levels.
5th International Conference on Technologies & Business Models for Circular Economy: Conference Proceedings, Jan 30, 2023
The inhibitory effect of the hydrophobic layer on the surface of copper in an acidic medium was s... more The inhibitory effect of the hydrophobic layer on the surface of copper in an acidic medium was studied by the classical potentiodynamic method and the impedance spectroscopy method. The hydrophobic character of the copper surface was achieved by immersing the sample in ethanolic octadecanoic acid with and without the addition of dog rose oil extract. The selected concentrations of the added dog rose oil extract were 0.5, 1.0, and 2.0 wt% in 0.05 molL-1 alcoholic solution of octadecanoic acid. Based on electrochemical measurements, an inhibition effect of ≈ 65% was obtained when the surface was modified by immersion in ethanolic octadecanoic acid only. With the addition of dog rose oil extract, this value increased to over 90%, depending on the concentration of dog rose oil extract added. 2 5 TH INTERNATIONAL CONFERENCE ON TECHNOLOGIES & BUSINESS MODELS FOR CIRCULAR ECONOMY: CONFERENCE PROCEEDINGS.
5th International Conference on Technologies & Business Models for Circular Economy: Conference Proceedings
The building and civil engineering industry generates more than 40% of man-caused carbon emission... more The building and civil engineering industry generates more than 40% of man-caused carbon emissions, consumes a lot of energy just to produce building materials, generates a large amount of waste through construction and demolition, and consumes a large amount of natural resources. One of the possible solutions is to use alkali-activated materials, which can use waste instead of raw materials and are produced at lower temperatures, with less energy consumption and in less time than traditional building products. All of this lowers the carbon footprint, which could be further reduced by the timely-short implementation of microwave irradiation in the early stages of alkali-activation synthesis. Therefore, metakaolin activated with Na-water glass in a theoretically optimal ratio was irradiated with microwaves of 2.45 GHz at powers of 100 W and 1000 W for 1 min, and compared to non-irradiated reference cured only at room conditions. Samples prepared at higher power, i.e., 1000 W, solidif...
In the present study, four different locally available waste glass materials (bottle glass-BG, gl... more In the present study, four different locally available waste glass materials (bottle glass-BG, glass wool-GW, stone wool-SW and cathode-ray tube glass-CRTG) were treated with hot concentrated potassium hydroxide (KOH) in order to obtain alternative alkali activators (AAAs). We evaluated the suitability of the solutions obtained for use as AAAs in the production of AAMs. AAMs were prepared using electric arc furnace slag and selected AAAs with a higher content of dissolved Si. We evaluated the performance of the AAMs in comparison to that of slags activated with KOH or potassium-silicate (K-silicate). The compressive strength of the AAMs prepared with KOH-based AAAs were high when Si and Al were simultaneously abundant in the AAA (9.47 MPa when using the activator sourced from the CRTG), and low with the addition of KOH alone (1.97 MPa). The AAM produced using commercial K-silicate yielded the highest compressive strength (27.7 MPa). The porosity of the KOH-based AAM was lowest when ...
3rd International Conference on Technologies & Business Models for Circular Economy: Conference Proceedings
Alkali-activated materials are promising materials for the construction industry due to the acces... more Alkali-activated materials are promising materials for the construction industry due to the accessibility of the precursors, which are mainly secondary industrial by-products, and their cost-effective and energy-efficient production. Although these materials are not new, some of the parameters in the technological process are not yet fully understood and tested. Therefore, in this paper in the means of mechanical strength, the preparation of alkali-activated pastes by using a three-roll mill homogenization method is discussed. The influence of homogenization of alkali-activated slurry has been evaluated on different waste materials (fly ash, fly ash with metakaolin, slag mixture (electric arc furnace slag and ladle slag), glass wool, waste green ceramics), which are treated with different alkali activators (NaOH, commercial sodium silicate solution, laboratory-produced alkali activators based on waste cathode- ray tube glass) with different curing regimes (60 °C and 70 °C) and diffe...
The incorporation and trophic transfer of total and methyl mercury (THg, MeHg) were examined in t... more The incorporation and trophic transfer of total and methyl mercury (THg, MeHg) were examined in three size classes of plankton (10-53, 53-200, and[200 lm size range) and a small planktivorous fish, Galaxias maculatus, from the large multi-branched Lake Nahuel Huapi (North Patagonia, Argentina). Three sites representing a large range of lake benthic-pelagic structures (based on depth and shoreline characteristics) and precipitation regimes were sampled. Nitrogen and carbon stable isotopes (d 15 N, d 13 C) were analyzed to assess Hg trophodynamics. Selenium concentrations were determined together with THg in order to consider its potential effect on Hg trophodynamics. High THg concentrations (0.1-255 lg g-1 dry weight (DW)) were measured in plankton, largely in inorganic form (MeHg: 3-29 ng g-1 DW, 0.02-7 % of THg, in the two larger size classes). A trend of increasing THg concentrations, varying in two to three orders of magnitude, with decreasing plankton size was associated with precipitation measured prior to each sampling event. Passive adsorption of dissolved Hg 2? from wet deposition and runoff is considered to be the principal Hg uptake mechanism at the base of the pelagic food web. Despite the initially high THg uptake in the smaller plankton classes, the transfer to G. maculatus, and consequently to the entire food web, is likely limited due to low proportion of MeHg to THg in plankton. Furthermore, evidence of G. maculatus with benthic feeding habits having higher impact on MeHg trophic transfer compared to the same species with more pelagic (e.g., zooplankton) feeding habits, was observed. Although there is a high THg uptake in plankton, limited amounts are incorporated in the entire food web from the pelagic compartment.
Mineral wool, i.e. rock and glass wool, represents considerable challenge after its functional-ti... more Mineral wool, i.e. rock and glass wool, represents considerable challenge after its functional-time runs out due to its small density leading to large volume consumption during transport and in landfills where it usually ends. Because rock wool is mineralogically and chemically a promising precursor material for alkali-activation, it was milled from few centimetres-decimeters long fibres to micron-sized fibres. Since fibres in alkali-activated materials generally show an increase in mechanical strength, especially the bending strength, 1 m% of additional fibres (basalt, cellulose (2 types), glass, polypropylene, polyvinyl alcohol and steel fibres) was used in the alkali mixture, that was curred at 40 °C for 3 days. Time dependence of the mechanical strengths of alkali-activated materials with and without additional fibres was followed. Maximal increase of compressive and bending strength after 28 days was reached with polypropylene fibres, i.e. it was 20% and 30% higher than compressive and bending strength of alkali-activated material without additional fibres respectively.
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
This work reports the development of ultralight interwoven ultrathin graphitic carbon nitride (g-... more This work reports the development of ultralight interwoven ultrathin graphitic carbon nitride (g-CN) nanosheets for use as a potential adsorbent in a passive sampler (PAS) designed to bind Hg 2+ ions. The g-CN nanosheets were prepared from bulk g-CN synthesised via a modified high-temperature short-time (HTST) polycondensation process. The crystal structure, surface functional groups, and morphology of the g-CN nanosheets were characterised using a battery of instruments. The results confirmed that the as-synthesized product is composed of few-layered nanosheets. The adsorption efficiency of g-CN for binding Hg 2+ (100 ng mL −1) in sea, river, rain, and Milli-Q quality water was 89%, 93%, 97%, and 100%, respectively, at natural pH. Interference studies found that the cations tested (Co 2+ , Ca 2+ , Zn 2+ , Fe 2+ , Mn 2+ , Ni 2+ , Bi 3+ , Na + , and K +) had no significant effect on the adsorption efficiency of Hg 2+. Different parameters were optimised to improve the performance of g-CN such as pH, contact time, and amount of adsorbent. Optimum conditions were pH 7, 120 min incubation time and 10 mg of nanosheets. The yield of nanosheets was 72.5%, which is higher compared to other polycondensation processes using different monomers. The g-CN sheets could also be regenerated up to eight times with only a 20% loss in binding efficiency. Overall, nano-knitted g-CN is a promising low-cost green adsorbent for use in passive samplers or as a transducing material in sensor applications.
Gypsum from the wet flue gas desulfurization system of the lignite fired thermal power plant Šošt... more Gypsum from the wet flue gas desulfurization system of the lignite fired thermal power plant Šoštanj, Slovenia, can efficiently retain mercury (Hg), of which most is contained in finer gypsum fractions, with concentrations above 10 kg −1. The aim of this work was to identify and study the temperature stability of Hg species in gypsum by a temperature fractionation (TF) method. A selfconstructed apparatus was used that consisted of an electrical furnace for controlled heating up to 700˚C, with a heating rate of 2.2˚C•min −1 , and an AAS detector with Zeeman background correction. The pattern of Hg release during temperature increase depends highly on the matrix/substrate in which it is contained. Based on spiking gypsum with known Hg compounds we concluded that the largest proportion of Hg in gypsum belongs to Hg-Cl and Hg-Br compounds appearing at 160˚C to 200˚C, followed by smaller amounts of HgO, HgS and Hg sulfates appearing at 300˚C and 450˚C. Further development of methodology for identifying Hg species would require identification of the decomposition fragments of Hg and other compounds, complemented by a better understanding of Hg reactivity at higher temperatures.
The inhibitory effect of the hydrophobic layer on the surface of copper in an acidic medium was s... more The inhibitory effect of the hydrophobic layer on the surface of copper in an acidic medium was studied by the classical potentiodynamic method and the impedance spectroscopy method. The hydrophobic character of the copper surface was achieved by immersing the sample in ethanolic octadecanoic acid with and without the addition of dog rose oil extract. The selected concentrations of the added dog rose oil extract were 0.5, 1.0, and 2.0 wt% in 0.05 molL-1 alcoholic solution of octadecanoic acid. Based on electrochemical measurements, an inhibition effect of ≈ 65% was obtained when the surface was modified by immersion in ethanolic octadecanoic acid only. With the addition of dog rose oil extract, this value increased to over 90%, depending on the concentration of dog rose oil extract added. 2 5 TH INTERNATIONAL CONFERENCE ON TECHNOLOGIES & BUSINESS MODELS FOR CIRCULAR ECONOMY: CONFERENCE PROCEEDINGS.
A quadrupole mass spectrometer was used to study the thermal release of mercury from wet flue gas... more A quadrupole mass spectrometer was used to study the thermal release of mercury from wet flue gas desulphurization (WFGD) gypsum using temperatureprogrammed desorption/decomposition (TPD). The inability in direct detection of low concentrations of mercury halogenides in gypsum by mass spectrometry is discussed in detail. The hydrolysis of HgCl 2 vapours under specific experimental conditions in the mass spectrometer was considered theoretically and proved experimentally. The mercury concentration in different gypsum fractions varies from 0.22 mg kg-1 (3.27-148 µm, coarse particles) to 20.6 mg kg-1 (0.41-88.0 µm, fine particles). All samples had a similar, symmetrical, single-peak (peak maximum 253-266°C) in the TPD spectra. In the present study, the use of 'wet' methods for preparing mercury compounds is introduced in addition to the mercury standards prepared using the 'dry' method, as commonly found in TPD. The study showed that selected metals, such as Fe enriched in gypsum samples, significantly influence the shape and the maximum temperature of the Hg TPD curves and that during the mercury compound preparation and the TPD process, Hg species undergo transformations that prevent the identification of their original identity.
The major aim of the newly adopted Mercury Convention is to reduce global mercury (Hg) emissions ... more The major aim of the newly adopted Mercury Convention is to reduce global mercury (Hg) emissions to the environment. In high temperature industrial processes, including coal combustion, Hg compounds present as impurities in solid materials are decomposed and evaporated leading to the emission of Hg to the atmosphere. The behaviour of different Hg compounds and their mixtures during heating have been the subject of numerous studies, and is the topic of the present work. Controlled heating can be used to fractionate Hg compounds in solid substrates, offering the possibility of identification and quantification of Hg compounds. In the attempt to develop a method for temperature fractionation of Hg, experiments were conducted with pure Hg compounds, and the compounds mixed with different substrates (SiO 2 and CaSO 4 • 2H 2 O), for calibration purposes. Detection was performed by two methods, namely Cold Vapour Atomic Absorption Spectrometry (CV AAS) with Zeeman background correction, and Nier-type Mass Spectrometry with a Knudsen cell (MS). Further investigation is in process.
Alkali-activated materials are promising materials for the construction industry due to the acces... more Alkali-activated materials are promising materials for the construction industry due to the accessibility of the precursors, which are mainly secondary industrial by-products, and their cost-effective and energy-efficient production. Although these materials are not new, some of the parameters in the technological process are not yet fully understood and tested. Therefore, in this paper in the means of mechanical strength, the preparation of alkali-activated pastes by using a three-roll mill homogenization method is discussed. The influence of homogenization of alkali-activated slurry has been evaluated on different waste materials (fly ash, fly ash with metakaolin, slag mixture (electric arc furnace slag and ladle slag), glass wool, waste green ceramics), which are treated with different alkali activators (NaOH, commercial sodium silicate solution, laboratory-produced alkali activators based on waste cathode- ray tube glass) with different curing regimes (60 °C and 70 °C) and different drying methods (drying at room temperature, drying at 105 °C). The viscosity of the slurry before homogenization was higher than after homogenization, the distribution of elements was more uniform and the compressive strength higher in all homogenized alkali activated materials, regardless of other parameters.
The objective of the present study was to evaluate the relation between maternal blood levels of ... more The objective of the present study was to evaluate the relation between maternal blood levels of selected toxic and potentially toxic elements (manganese (Mn), copper (Cu), zinc (Zn), arsenic (As), selenium (Se), cadmium (Cd), lead (Pb) and mercury (Hg)) and birth weight of their new-borns in a Slovenian population, taking into account maternal socio-demographic characteristics and dietary habits. 535 women from 12 regions of Slovenia were recruited at delivery. Maternal blood was collected at 1.5 months after birth. Associations between birth weight and a) predictors obtained through the questionnaires and b) levels of selected elements were tested using bivariate tests and multiple linear regression. Multiple regression models revealed maternal age as an additional predictor for birth weight and confirmed pre-pregnancy body mass, estimated gestational age and gender of the baby as the main predictors for birth weight. Mn in maternal blood was significantly and positively associated with birth weight. The positive association observed between birth weight and Mn in maternal blood could be explained by the essentiality of Mn in foetal development as an important cofactor in enzyme reactions in bone formation and in metabolic regulation for amino acid, lipid, protein and carbohydrate levels.
5th International Conference on Technologies & Business Models for Circular Economy: Conference Proceedings, Jan 30, 2023
The inhibitory effect of the hydrophobic layer on the surface of copper in an acidic medium was s... more The inhibitory effect of the hydrophobic layer on the surface of copper in an acidic medium was studied by the classical potentiodynamic method and the impedance spectroscopy method. The hydrophobic character of the copper surface was achieved by immersing the sample in ethanolic octadecanoic acid with and without the addition of dog rose oil extract. The selected concentrations of the added dog rose oil extract were 0.5, 1.0, and 2.0 wt% in 0.05 molL-1 alcoholic solution of octadecanoic acid. Based on electrochemical measurements, an inhibition effect of ≈ 65% was obtained when the surface was modified by immersion in ethanolic octadecanoic acid only. With the addition of dog rose oil extract, this value increased to over 90%, depending on the concentration of dog rose oil extract added. 2 5 TH INTERNATIONAL CONFERENCE ON TECHNOLOGIES & BUSINESS MODELS FOR CIRCULAR ECONOMY: CONFERENCE PROCEEDINGS.
5th International Conference on Technologies & Business Models for Circular Economy: Conference Proceedings
The building and civil engineering industry generates more than 40% of man-caused carbon emission... more The building and civil engineering industry generates more than 40% of man-caused carbon emissions, consumes a lot of energy just to produce building materials, generates a large amount of waste through construction and demolition, and consumes a large amount of natural resources. One of the possible solutions is to use alkali-activated materials, which can use waste instead of raw materials and are produced at lower temperatures, with less energy consumption and in less time than traditional building products. All of this lowers the carbon footprint, which could be further reduced by the timely-short implementation of microwave irradiation in the early stages of alkali-activation synthesis. Therefore, metakaolin activated with Na-water glass in a theoretically optimal ratio was irradiated with microwaves of 2.45 GHz at powers of 100 W and 1000 W for 1 min, and compared to non-irradiated reference cured only at room conditions. Samples prepared at higher power, i.e., 1000 W, solidif...
In the present study, four different locally available waste glass materials (bottle glass-BG, gl... more In the present study, four different locally available waste glass materials (bottle glass-BG, glass wool-GW, stone wool-SW and cathode-ray tube glass-CRTG) were treated with hot concentrated potassium hydroxide (KOH) in order to obtain alternative alkali activators (AAAs). We evaluated the suitability of the solutions obtained for use as AAAs in the production of AAMs. AAMs were prepared using electric arc furnace slag and selected AAAs with a higher content of dissolved Si. We evaluated the performance of the AAMs in comparison to that of slags activated with KOH or potassium-silicate (K-silicate). The compressive strength of the AAMs prepared with KOH-based AAAs were high when Si and Al were simultaneously abundant in the AAA (9.47 MPa when using the activator sourced from the CRTG), and low with the addition of KOH alone (1.97 MPa). The AAM produced using commercial K-silicate yielded the highest compressive strength (27.7 MPa). The porosity of the KOH-based AAM was lowest when ...
3rd International Conference on Technologies & Business Models for Circular Economy: Conference Proceedings
Alkali-activated materials are promising materials for the construction industry due to the acces... more Alkali-activated materials are promising materials for the construction industry due to the accessibility of the precursors, which are mainly secondary industrial by-products, and their cost-effective and energy-efficient production. Although these materials are not new, some of the parameters in the technological process are not yet fully understood and tested. Therefore, in this paper in the means of mechanical strength, the preparation of alkali-activated pastes by using a three-roll mill homogenization method is discussed. The influence of homogenization of alkali-activated slurry has been evaluated on different waste materials (fly ash, fly ash with metakaolin, slag mixture (electric arc furnace slag and ladle slag), glass wool, waste green ceramics), which are treated with different alkali activators (NaOH, commercial sodium silicate solution, laboratory-produced alkali activators based on waste cathode- ray tube glass) with different curing regimes (60 °C and 70 °C) and diffe...
The incorporation and trophic transfer of total and methyl mercury (THg, MeHg) were examined in t... more The incorporation and trophic transfer of total and methyl mercury (THg, MeHg) were examined in three size classes of plankton (10-53, 53-200, and[200 lm size range) and a small planktivorous fish, Galaxias maculatus, from the large multi-branched Lake Nahuel Huapi (North Patagonia, Argentina). Three sites representing a large range of lake benthic-pelagic structures (based on depth and shoreline characteristics) and precipitation regimes were sampled. Nitrogen and carbon stable isotopes (d 15 N, d 13 C) were analyzed to assess Hg trophodynamics. Selenium concentrations were determined together with THg in order to consider its potential effect on Hg trophodynamics. High THg concentrations (0.1-255 lg g-1 dry weight (DW)) were measured in plankton, largely in inorganic form (MeHg: 3-29 ng g-1 DW, 0.02-7 % of THg, in the two larger size classes). A trend of increasing THg concentrations, varying in two to three orders of magnitude, with decreasing plankton size was associated with precipitation measured prior to each sampling event. Passive adsorption of dissolved Hg 2? from wet deposition and runoff is considered to be the principal Hg uptake mechanism at the base of the pelagic food web. Despite the initially high THg uptake in the smaller plankton classes, the transfer to G. maculatus, and consequently to the entire food web, is likely limited due to low proportion of MeHg to THg in plankton. Furthermore, evidence of G. maculatus with benthic feeding habits having higher impact on MeHg trophic transfer compared to the same species with more pelagic (e.g., zooplankton) feeding habits, was observed. Although there is a high THg uptake in plankton, limited amounts are incorporated in the entire food web from the pelagic compartment.
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