Preparation of Porous and Durable Metakaolin-Based Alkali-Activated Materials with Active Metal as Composites for Catalytic Wet Air Oxidation

AbstractNovel porous and durable metakaolin-based alkali-activated materials (MK-AAMs) with active metal as composites were produced to degrade bisphenol A (BPA) in catalytic wet air oxidation (CWAO). Two composite producing processes were employed. The first process consisted of mixing metakaolin (MK), a foaming agent and active metal oxide (CuO, MnO₂) in a strongly alkaline solution of K₂SiO₃ and KOH. Paste was cured under microwave radiation to produce porous CuO and MnO₂ composites. A porous blank MK-AAM was produced as described above but without active metal and was used as a reference as well. Cu(OH)₂ composite was produced by refluxing a blank MK-AAM in 0.5 M CuSO₄ solution for 24 h. The specific surface area (SSA) of the reference, CuO, MnO₂, and Cu(OH)₂ composites were 36, 53, 61, 89 m²/g, respectively. Mechanical durability was determined in terms of compressive strength and 2.8, 3.4, 3.2, 3.6 MPa were received, respectively. The activity of the reference and the composites were tested in CWAO at 1 MPa and 150 °C for 5 h by using an aqueous model solution of BPA. Under the optimal conditions for CWAO (pressure: 1 MPa; temperature: 150 °C; initial pH 5–6; c[catalyst]: 4.0 g/L) with Cu(OH)₂ composite, the BPA and total organic carbon (TOC) conversions of 100% and 53% were reached. During 5 h oxidation, the composites degraded due to the combined effect of erosion (1.5 wt%) and active metal (Cu, Mn) leaching (1.1 wt%, 3.6 wt%). It was proposed that BPA can be degraded energy-efficiently via CWAO into less harmful compounds under mild reaction conditions without losing the desired properties of the composites. Abstract Novel porous and durable metakaolin-based alkali-activated materials (MK-AAMs) with active metal as composites were produced to degrade bisphenol A (BPA) in catalytic wet air oxidation (CWAO). Two composite producing processes were employed. The first process consisted of mixing metakaolin (MK), a foaming agent and active metal oxide (CuO, MnO₂) in a strongly alkaline solution of K₂SiO₃ and KOH. Paste was cured under microwave radiation to produce porous CuO and MnO₂ composites. A porous blank MK-AAM was produced as described above but without active metal and was used as a reference as well. Cu(OH)₂ composite was produced by refluxing a blank MK-AAM in 0.5 M CuSO₄ solution for 24 h. The specific surface area (SSA) of the reference, CuO, MnO₂, and Cu(OH)₂ composites were 36, 53, 61, 89 m²/g, respectively. Mechanical durability was determined in terms of compressive strength and 2.8, 3.4, 3.2, 3.6 MPa were received, respectively. The activity of the reference and the composites were tested in CWAO at 1 MPa and 150 °C for 5 h by using an aqueous model solution of BPA. Under the optimal conditions for CWAO (pressure: 1 MPa; temperature: 150 °C; initial pH 5–6; c[catalyst]: 4.0 g/L) with Cu(OH)₂ composite, the BPA and total organic carbon (TOC) conversions of 100% and 53% were reached. During 5 h oxidation, the composites degraded due to the combined effect of erosion (1.5 wt%) and active metal (Cu, Mn) leaching (1.1 wt%, 3.6 wt%). It was proposed that BPA can be degraded energy-efficiently via CWAO into less harmful compounds under mild reaction conditions without losing the desired properties of the composites

Chemical aspects of peracetic acid based wastewater disinfection

Peracetic acid (PAA) has been studied for wastewater disinfection  applications for some 30 years and has been shown to be an effective disinfectant against many indicator microbes, including bacteria, viruses, and protozoa. One of the key advantages compared to, e.g., chlorine is the lack of harmful disinfection by-products. In this paper a pilot-scale study of PAA-based disinfection is presented. Indicator microbes (E. coli, total coliforms and coliphage viruses) as well as chemical parameters (pH, oxidation-reduction potential (ORP), chemical and biochemical oxygen  demand (COD and BOD), and residual PAA and hydrogen peroxide) were studied. The main aim of this investigation was to study how these  selected chemical parameters change during PAA treatment. Based on the results, disinfection was efficient at C·t values of 15 to 30 (mg·min)/l which equals to a PAA dose of 1.5 to 2 mg/l and a contact time of 10 to 15 min. In this concentration area changes in pH, COD and BOD were negligible. However, hydrogen peroxide residues may interfere with COD   measurements and apparent COD can be higher than the calculated   theoretical oxygen demand (ThOD). Additionally PAA or hydrogen peroxide residues interfere with the BOD test resulting in BOD values that are too  low. Residual PAA and ORP were found to correlate with remaining amounts of bacteria.Keywords: tertiary wastewater disinfection, peracetic acid, total coliform, E. coli, coliphage

Modification of Layered Oxide Cathode Materials

AbstractLayer-structured cathode materials for lithium-ion batteries are considered. These materials, such as LCO, NCM, NCA, lithium rich cathode oxides and blended cathodes are well-known for the intercalation mechanism. Future of lithium-ion batteries is also strongly based on these cathode chemistries, but to overcome some drawbacks and challenges, the improved materials are needed. In this chapter, modification of layer-structured cathode materials by doping and coating are discussed. Especially, coating materials and doping methods are considered.Abstract Layer-structured cathode materials for lithium-ion batteries are considered. These materials, such as LCO, NCM, NCA, lithium rich cathode oxides and blended cathodes are well-known for the intercalation mechanism. Future of lithium-ion batteries is also strongly based on these cathode chemistries, but to overcome some drawbacks and challenges, the improved materials are needed. In this chapter, modification of layer-structured cathode materials by doping and coating are discussed. Especially, coating materials and doping methods are considered

Effect of Some Process Parameters on the Main Properties of Activated Carbon Produced from Peat in a Lab-Scale Process

AbstractActivated carbons (ACs) are widely used in different industrial processes as adsorbents for pollutant removal or as catalytic material support. The parameters and methods of activation can vary, and they affect the final characteristics of ACs, e.g., specific surface area, pore size distribution, and surface functional groups. The results of this study show that microporosity and mesoporosity can be modified, variating these parameters. ACs from Northern Finland Region peat have been prepared through physical activation with steam. The process has been evaluated using the design of experiment approach. Different parameters have been considered as factors, including holding time, oven temperature, heating rate, steam flow, nitrogen flow, kiln rotation, and biomass initial mass. Based on these factors, several responses characterizing the porosity and the elemental analysis of ACs have been selected. All the data collected have been processed statistically using the Fractional Factorial Resolution IV design linear model in a screening configuration fitted with a partial least squares regression using MODDE 9.1 by Umetrics Software.Abstract Activated carbons (ACs) are widely used in different industrial processes as adsorbents for pollutant removal or as catalytic material support. The parameters and methods of activation can vary, and they affect the final characteristics of ACs, e.g., specific surface area, pore size distribution, and surface functional groups. The results of this study show that microporosity and mesoporosity can be modified, variating these parameters. ACs from Northern Finland Region peat have been prepared through physical activation with steam. The process has been evaluated using the design of experiment approach. Different parameters have been considered as factors, including holding time, oven temperature, heating rate, steam flow, nitrogen flow, kiln rotation, and biomass initial mass. Based on these factors, several responses characterizing the porosity and the elemental analysis of ACs have been selected. All the data collected have been processed statistically using the Fractional Factorial Resolution IV design linear model in a screening configuration fitted with a partial least squares regression using MODDE 9.1 by Umetrics Software

Multifunctional Behaviour of Graphite in Lithium-Sulfur Batteries

AbstractLithium-sulfur batteries (LSBs) have attracted significant attention as next-generation energy-storage systems beyond common lithium-ion batteries (LIBs), due to their high energy density potential and low-cost materials. Although graphite (Gr) is well-known as a state-of-the-art anode material in LIBs, it also has a great potential to be employed as a multifunctional material in LSBs. Gr and/or expanded Gr (EGr) particles along with S are promising cathode composites for LSBs. The EGr, with exceptional structure flexibility and high electronic conductivity, has been used as the most popular material in the LSB cathodes. Additionally, the Gr can be employed as an anode material of LSBs instead of Li metal, when Li₂S is a cathode. On the other side, many straightforward approaches have been planned to optimize the electrochemical performance of LSBs by modifying the separator via Gr coating or introducing an interlayer made by Gr particles between the cathode and separator to block polysulfides shuttle physically or chemically without reducing the active cathode material. Herein, the current status, critical findings, and challenges in improving Gr as a promising multifunctional material for the development of LSBs will be discussed.Abstract Lithium-sulfur batteries (LSBs) have attracted significant attention as next-generation energy-storage systems beyond common lithium-ion batteries (LIBs), due to their high energy density potential and low-cost materials. Although graphite (Gr) is well-known as a state-of-the-art anode material in LIBs, it also has a great potential to be employed as a multifunctional material in LSBs. Gr and/or expanded Gr (EGr) particles along with S are promising cathode composites for LSBs. The EGr, with exceptional structure flexibility and high electronic conductivity, has been used as the most popular material in the LSB cathodes. Additionally, the Gr can be employed as an anode material of LSBs instead of Li metal, when Li₂S is a cathode. On the other side, many straightforward approaches have been planned to optimize the electrochemical performance of LSBs by modifying the separator via Gr coating or introducing an interlayer made by Gr particles between the cathode and separator to block polysulfides shuttle physically or chemically without reducing the active cathode material. Herein, the current status, critical findings, and challenges in improving Gr as a promising multifunctional material for the development of LSBs will be discussed

Alkali-activated materials containing mine tailings and zeolite for seepage water treatment in a closed nickel mine

Abstract In the present study, alkali-activated materials were assessed as adsorbents for mine water treatment. The composition of alkali-activated materials, involving mixtures of metakaolin, blast-furnace slag, mine tailings, and zeolite, was optimized based on their leaching behavior and adsorption performance. The most effective adsorbent contained solely blast furnace slag as an aluminosilicate precursor and was selected for a pilot-scale study at a closed nickel mine in Finland. In the pilot, seepage water from a gangue area with an influent flow rate of 0.5 m3/d was treated using a permeable reactive barrier set-up containing 10 kg of slag-based adsorbent prepared by a granulation-alkali activation process. During a one-week experiment, the adsorbent granules were capable of effectively uptaking Ni, Fe, and Mn from the seepage water; the removal percentages of Ni, Fe, and Mn were 82.4%, 81.6%, and 82.5%, respectively. The results indicated the feasibility of blast furnace slag-based adsorbents for toxic element removal in a potentially sustainable approach.Abstract In the present study, alkali-activated materials were assessed as adsorbents for mine water treatment. The composition of alkali-activated materials, involving mixtures of metakaolin, blast-furnace slag, mine tailings, and zeolite, was optimized based on their leaching behavior and adsorption performance. The most effective adsorbent contained solely blast furnace slag as an aluminosilicate precursor and was selected for a pilot-scale study at a closed nickel mine in Finland. In the pilot, seepage water from a gangue area with an influent flow rate of 0.5 m3/d was treated using a permeable reactive barrier set-up containing 10 kg of slag-based adsorbent prepared by a granulation-alkali activation process. During a one-week experiment, the adsorbent granules were capable of effectively uptaking Ni, Fe, and Mn from the seepage water; the removal percentages of Ni, Fe, and Mn were 82.4%, 81.6%, and 82.5%, respectively. The results indicated the feasibility of blast furnace slag-based adsorbents for toxic element removal in a potentially sustainable approach

The catalytic wet air oxidation of pharmaceutical wastewater with alkali-activated Mn and Cu composites: preparation of precursors by calcination of kaolin with Mn and Cu

Abstract In recent decades, the concentration of pharmaceutical residues and narcotics has increased in municipal wastewater. Decomposing these toxic organic chemicals is challenging and requires new techniques and advanced catalytic materials. Precursors of metal composites were prepared by calcining an aqueous suspension of natural clay–based kaolin with Mn and Cu, binding chemically the active metals to the aluminosilicate frame structure of the precursor. The specific surface area of Mn and Cu composite was 67 m2/g and 81 m2/g, respectively. The mechanical durability was determined in terms of compressive strength, and 3.3 MPa and 3.6 MPa were obtained, respectively. In the CWAO of pharmaceutical wastewater, Mn composite gave the highest conversions of 54% and 46% of the chemical oxygen demand (COD) and total organic carbon (TOC), respectively. Metal composites were mechanically and chemically highly durable, inducing only 1.2 wt.% and 1.4 wt.% mass loss. In CWAO, Mn and Cu composite increased the biodegradation of organic species in the wastewater by 65% and 75%, respectively.Abstract In recent decades, the concentration of pharmaceutical residues and narcotics has increased in municipal wastewater. Decomposing these toxic organic chemicals is challenging and requires new techniques and advanced catalytic materials. Precursors of metal composites were prepared by calcining an aqueous suspension of natural clay–based kaolin with Mn and Cu, binding chemically the active metals to the aluminosilicate frame structure of the precursor. The specific surface area of Mn and Cu composite was 67 m2/g and 81 m2/g, respectively. The mechanical durability was determined in terms of compressive strength, and 3.3 MPa and 3.6 MPa were obtained, respectively. In the CWAO of pharmaceutical wastewater, Mn composite gave the highest conversions of 54% and 46% of the chemical oxygen demand (COD) and total organic carbon (TOC), respectively. Metal composites were mechanically and chemically highly durable, inducing only 1.2 wt.% and 1.4 wt.% mass loss. In CWAO, Mn and Cu composite increased the biodegradation of organic species in the wastewater by 65% and 75%, respectively

Towards greener batteries: sustainable components and materials for next-generation batteries

Batteries are the main component of many electrical systems, and due to the elevated consumption of electric vehicles and portable electronic devices, they are the dominant and most rapidly growing energy storage technology. Consequently, they are set to play a crucial role in meeting the goal of cutting greenhouse gas emissions to achieve more sustainable societies. In this critical report, a rational basic-to-advanced compilation study of the effectiveness, techno-feasibility, and sustainability aspects of innovative greener manufacturing technologies and processes that deliver each battery component (anodes, cathodes, electrolytes, and separators) is accomplished, aiming to improve battery safety and the circularity of end-products. Special attention is given to biomass-derived anode materials and bio-based separators utilization that indicates excellent prospects considering green chemistry, greener binders, and energy storage applications. To fully reach this potential, one of the most promising ways to achieve sustainable batteries involves biomass-based electrodes and non-flammable and non-toxic electrolytes used in lithium-ion batteries and other chemistries, where the potential of a greener approach is highly beneficial, and challenges are addressed. The crucial obstacles related to the successful fabrication of greener batteries and potential future research directions are highlighted. Bridging the gap between fundamental and experimental research will provide critical insights and explore the potential of greener batteries as one of the frontrunners in the uptake of sustainability and value-added products in the battery markets of the future

Preparation and characterization of porous and stable sodium- and potassium-based alkali activated material (AAM)

AbstractThe aim of this work is to produce highly porous and stable alkali-activated material (AAM) prepared from two combinations of sodium (Na)- and potassium (K)-based alkali solutions (NaOH/Na₂SiO₃ and KOH/K₂SiO₃). The reactive metakaolin as precursor and AAM were characterized using X-ray diffraction spectroscopy (XRD), X-ray fluorescence spectroscopy (XRF), aluminum nuclear magnetic resonance spectroscopy (27Al MS-NMR), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), field emission scanning electron microscopy (FESEM), compressive strength measurement and Brunauer–Emmett–Teller (BET) surface analysis. The porosity of the AAMs were increased by using hydrogen peroxide and sodium percarbonate as foaming agents. Characterization results showed the viscosity of the K-AAM paste was 70% lower than that of the Na-AAM paste. However, the volume of the Na-AAM paste in an air-tight plastic tube was three times higher than that of K-AAM, but the specific surface area (SSA) of K-AAM were 30% higher than those of Na-AAM. In terms of compressive strength, the blank AAM (foaming agent-free) demonstrated the highest strength values: 6.1 MPa for K-AAM and 9.0 MPa for Na-AAM. When the concentration of the foaming agent was increased, the compressive strength of both the materials decreased but were still around 1.0 MPa. The FESEM images of the Na-AAM and K-AAM produced with H₂O₂ indicated the high porosity of materials which were also observed in SSA values of AAM. Furthermore, the XRD data showed that the Na-AAM contained water in hydrate form (halloysite) compared with the K-AAM, suggesting the different polymerization reaction route and speed between these AAM.Abstract The aim of this work is to produce highly porous and stable alkali-activated material (AAM) prepared from two combinations of sodium (Na)- and potassium (K)-based alkali solutions (NaOH/Na₂SiO₃ and KOH/K₂SiO₃). The reactive metakaolin as precursor and AAM were characterized using X-ray diffraction spectroscopy (XRD), X-ray fluorescence spectroscopy (XRF), aluminum nuclear magnetic resonance spectroscopy (27Al MS-NMR), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), field emission scanning electron microscopy (FESEM), compressive strength measurement and Brunauer–Emmett–Teller (BET) surface analysis. The porosity of the AAMs were increased by using hydrogen peroxide and sodium percarbonate as foaming agents. Characterization results showed the viscosity of the K-AAM paste was 70% lower than that of the Na-AAM paste. However, the volume of the Na-AAM paste in an air-tight plastic tube was three times higher than that of K-AAM, but the specific surface area (SSA) of K-AAM were 30% higher than those of Na-AAM. In terms of compressive strength, the blank AAM (foaming agent-free) demonstrated the highest strength values: 6.1 MPa for K-AAM and 9.0 MPa for Na-AAM. When the concentration of the foaming agent was increased, the compressive strength of both the materials decreased but were still around 1.0 MPa. The FESEM images of the Na-AAM and K-AAM produced with H₂O₂ indicated the high porosity of materials which were also observed in SSA values of AAM. Furthermore, the XRD data showed that the Na-AAM contained water in hydrate form (halloysite) compared with the K-AAM, suggesting the different polymerization reaction route and speed between these AAM