High-value Materials Research Articles

From pollutant to purifier: Leveraging plastic waste-derived activated carbon for sustainable water remediation solutions.

The ubiquitous presence of plastic waste presents a significant environmental challenge, characterized by its persistence and detrimental impacts on ecosystems. The valorization of plastic waste through conversion into high-value carbon materials offers a promising circular economy approach. This review critically examines the potential of plastic waste-derived activated carbon (PAC) as a sustainable and effective adsorbent for water remediation. The manuscript commences with a concise overview of the multifaceted nature of plastic pollution, highlighting its classification, environmental implications, and the limitations of existing waste management frameworks. Subsequently, it delves into the intricacies of PAC production, critically analyzing various preparation methods and their associated challenges. A comprehensive exploration of modification strategies, including chemical activation and surface functionalization, is undertaken to elucidate their role in enhancing PAC's adsorption selectivity and capacity for diverse pollutants. The effectiveness of PAC in removing a diverse array of pollutants, including emerging contaminants and recalcitrant organic compounds, is thoroughly examined. While acknowledging the influence of key factors such as pollutant characteristics and solution chemistry on adsorption efficiency, the review also identifies critical challenges, including the high production costs associated with PAC synthesis, variability of plastic waste composition, the potential for leaching of residual monomers, and the complexities of multi-pollutant adsorption. Future research directions are outlined, emphasizing the need for advanced characterization techniques, computational modeling to optimize adsorbent design, and rigorous life cycle assessments to evaluate the environmental sustainability of PAC production. By addressing these challenges, PAC offers a promising pathway towards a circular economy, mitigating plastic pollution while providing a sustainable and effective solution for water remediation.

Valorization of Cyanophyta by hydrothermal carbonization: Co-production of CO2 adsorbents and fluorescent carbon dots

Cyanophyta blooms can lead to eutrophication and generate algal toxins. To reduce their environmental risks, hydrothermal carbonization was innovatively applied to simultaneously produce activated carbon (AC) and carbon dots (CDs). AC was further used for CO2 adsorption while CDs were for preparing fluorescent materials. Yields of AC and CDs were investigated under mild conditions of 160-240 °C and 15-240 min. Characterization results show that AC exhibited a large specific surface area of 990 m2·g-1 and pore volume of 1.14 cm3·g-1, contributing to high CO2 adsorption capacities of 3.26 mmol·g-1 (0 °C) and 2.06 mmol·g-1 (25 °C). Additionally, nitrogen and oxygen self-doping heteroatoms CDs, with a photoluminescence quantum yield of 2.58 %, emitted stable blue fluorescence under the ultraviolet light and were successfully applied to produce invisible ink. This work provides a paradigm for CO2 reduction and high-value material synthesis via the thermochemical conversion of hazardous biomass.

Treatment and Valorization of Waste Wind Turbines: Component Identification and Analysis.

Recycling end-of-life wind turbines poses a significant challenge due to the increasing number of turbines going out of use. After many years of operation, turbines lose their functional properties, generating a substantial amount of composite waste that requires efficient and environmentally friendly processing methods. Wind turbine blades, in particular, are a problematic component in the recycling process due to their complex material composition. They are primarily made of composites containing glass and carbon fibers embedded in polymer matrices such as epoxies and polyester resins. This study presents an innovative approach to analyzing and valorizing these composite wastes. The research methodology incorporates integrated processing and analysis techniques, including mechanical waste treatment using a novel compression milling process, instead of traditional knife mills, which reduces wear on the milling tools. Based on the differences in the structure and colors of the materials, 15 different kinds of samples named WT1-WT15 were distinguished from crushed wind turbines, enabling a detailed analysis of their physicochemical properties and the identification of the constituent components. Fourier transform infrared spectroscopy (FTIR) identified key functional groups, confirming the presence of thermoplastic polymers (PET, PE, and PP), epoxy and polyester resins, wood, and fillers such as glass fibers. Thermogravimetric analysis (TGA) provided insights into thermal stability, degradation behavior, and the heterogeneity of the samples, indicating a mix of organic and inorganic constituents. Differential scanning calorimetry (DSC) further characterized phase transitions in polymers, revealing variations in thermal properties among samples. The fractionation process was carried out using both wet and dry methods, allowing for a more effective separation of components. Based on the wet separation process, three fractions-GF1, GF2, and GF3-along with other components were obtained. For instance, in the case of the GF1 < 40 µm fraction, thermogravimetric analysis (TGA) revealed that the residual mass is as high as 89.7%, indicating a predominance of glass fibers. This result highlights the effectiveness of the proposed methods in facilitating the efficient recovery of high-value materials.

Comparative Analysis of Phenolic Profiles and Antioxidant Activity in the Leaves of Invasive Amelanchier × spicata (Lam.) K. Koch in Lithuania.

The environmental impact of invasive species necessitates creating a strategy for managing their spread by utilising them as a source of potentially high-value raw materials. Amelanchier × spicata (Lam.) K. Koch (dwarf serviceberry) is a shrub species in the Rosaceae Juss. family. The evaluation of different populations of plants that accumulate great amounts of biologically active compounds is requisite for the quality determination of plant materials and medicinal and nutritional products. The assessment of natural resources from a phytogeographic point of view is relevant. Phytochemical analysis of A. spicata leaf samples was carried out using spectrophotometric methods, HPLC-PDA, and HPLC-MS techniques, while antioxidant activity was determined using ABTS, FRAP, and CUPRAC assays. A significant diversification of phenolic compounds and antioxidant activity was determined in the A. spicata leaf samples collected in different habitats. Due to their characteristic chemical heterogeneity, natural habitats lead to the diversity of indicators characterising the quality of plant raw materials. Chlorogenic acid and neochlorogenic acid, as well as quercitrin, rutin, and hyperoside, were found to be predominant among the phenolic compounds. Thus, these compounds can be considered phytochemical markers, characteristic of the A. spicata leaf material from northern Europe.

Rapid electrothermal upcycling hexachlorobutadiene (HCBD) polluted distillation residue into turbostratic graphene for enhanced electromagnetic wave absorption.

The trichloroethylene production industry generates high-boiling-point solid residues during rectification, which contain high concentrations of chlorinated contaminants, particularly hexachlorobutadiene (HCBD). Traditionally, these distillation residues are managed through co-incineration or landfilling, leading to environmental and economic challenges. In this study, we present a rapid and environmentally friendly electrothermal approach for both detoxifying and upcycling distillation residue into graphene-based electromagnetic wave (EMW) absorbing materials. By employing a DC power pulse discharge with a 10 s duration, we achieved over 99 % HCBD degradation efficiency. Characterization results indicate that the thermal shock transforms the distillation residue into high-value turbostratic pulse graphene (tPG). This tPG, featuring a unique structure, demonstrates substantial potential as an EMW absorber, with an effective absorption bandwidth of 3.9 GHz and a reflection loss of -42.0 dB at a minimal matching thickness of 1.6 mm. The method offers a sustainable, cost-effective solution for hazardous waste management, combining rapid processing with high-value material production.

From flat to twisted - multifunctional phosphacyclic nanocarbons based on Vat Orange 3.

The field of π-conjugated organic materials has seen significant advances in recent years. However, enhancing the functionality of well-established, mass-produced compounds remains a considerable challenge, despite being an intriguing strategy for designing high-value organic materials with low production costs. In this context, vat dyes, known for their wide range of colors and extensive use in the textile industry are particularly attractive. Here, we present an innovative approach that conjoins phosphorus heterocycles with the dye Vat Orange 3 (VO3) to yield novel nanocarbons with enhanced functional properties. X-ray crystallography reveals distinct twisting of the scaffold in the solid state, while the modification of the phosphorus centers leads to intriguing and versatile photophysics. Thin-film analyses show unusual, pronounced emission features that switch from green to orange upon aggregation. Furthermore, Lewis-adduct formation induces a fluorescence redshift upon coordination to the phosphorus moiety and cyclic voltammetry confirms the acceptor character of the system. This work demonstrates the versatility of phosphorus-modified vat dyes as value-added organic compounds and paves the way for the development of new functional 2D nanocarbons with broad technological relevance.

Extraction of high-purity lignin from the kraft pulping black liquor by enzyme purification process with alkaline-resistant xylanase and cellulase.

In this study, the response surface methodology was first utilized to optimize the enzyme treatment conditions as reaction pH, temperature, time and enzyme dosage of 9.5, 45 °C, 94.5 min and 100 U/L. Under these parameters, the kraft pulping black liquor was treated with alkaline-resistant xylanase and cellulase, followed by acid precipitation to obtain enzyme-purified lignin (EPL). The yield, purity and physicochemical characteristics of EPL were contrasted with acid-purified lignin (APL) prepared at the same pH values. Results showed that the enzyme purification method generated lignin with lower molecular weight of 3532 g/mol, greater purity of 96.79 % and higher yield of 2.89 %. Compared with APL, EPL exhibited stronger UV absorption capacity. SEM images revealed that EPL had a rough and porous surface, whereas the surface of APL was relatively smooth. TGA analysis indicated the thermal stability of EPL (Tmax = 333.5 °C) was superior to APL (Tmax = 309.2 °C). Moreover, no significant differences were observed in the chemical functional groups and molecular structures of APL and EPL, suggesting that the addition of alkaline-resistant xylanase and cellulase didn't change the chemical structure of lignin. The favorable properties of EPL make it a promising application in the development of high-value composite materials and biodegradable plastics.

From industrial by-products to high-value materials: synthesizing sulfur-rich polymers for lithium–sulfur battery cathodes from the C5 fraction and sulfur

Sulfur-rich polymers synthesized from the C5 fraction via inverse vulcanization exhibit strong thermal stability and electrochemical performance, making them promising candidates for cost-effective lithium–sulfur battery cathodes.

A sustainable route for producing reduced graphene oxide nanosheets from recycled plastic waste for high-performance supercapacitor applications

Among the environmental issues, plastic waste is one of the most significant problems, and thus, searching for ways to solve it is critical. In the present work, a green process is proposed for synthesizing RGO nanosheets from recycled plastic waste for efficient supercapacitor applications. The suggested approach consists of the transformation of plastic waste into GO using a direct and reproducible strategy and then the transformation of GO to RGO via an eco-friendly reducing agent. The synthesized RGO nanosheets possessed desirable electrochemical characteristics such as a specific capacitance of 104[Formula: see text]F/g at 0.5[Formula: see text]A/g, 90% capacitance retention after 5000 cycles, and good rate capability. The RGO nanosheets were further employed as electrode materials for the supercapacitor devices which has been evidenced with high energy density and power density. Physical properties have been characterized by XRD, Raman spectroscopy and transmission electron microscope have clearly observed the structure and the morphology of Graphene nanosheets has been established. The electrochemical properties of RGO have been examined and demonstrated to be regular. The proposed structure exhibits a nearly rectangular shape within the range of the potential window, conforming to the standard characteristics of an ideal capacitor. The findings of this study represent a viable and techno-economically feasible strategy to address the global issue of plastic waste and generate high-value graphene materials for energy storage technologies.

Industrial Carbonate Production with Ornamental Stone Quarry Waste: From the Waste Pile to Final Product

Objective: The objective of this study is to analyze the utilization of ornamental stone quarry waste and its transformation into industrial carbonate production, aiming to promote circular economy practices in mining. Theoretical Framework: This research is grounded in concepts of sustainable waste management and circular economy in the mining sector, emphasizing theories related to waste transformation into valuable industrial products. Method: The methodology included technical visits to a quarry and a processing plant, where extraction, storage, and processing practices of waste were observed and documented. Data collection involved interviews with production teams and 3D modeling of mining areas. Results and Discussion: The results revealed that quarry waste from ornamental rock production can be used to produce carbonates of various particle sizes, suitable for applications in the construction, thermoplastics, and other industries. The analysis highlighted the feasibility of converting mining waste into high-value materials, contributing to the sustainability of the sector. Research Implications: This research provides practical insights into how mining waste can be efficiently managed and repurposed, promoting a more sustainable approach to waste management. Originality/Value: The study contributes by demonstrating and documenting the utilization of waste materials, showcasing their applications across diverse sectors, and reinforcing the economic and environmental benefits of circular economy practices in mining.

Evolution characteristics of microwave absorbing carbon material on surface of CoFe2O4@biochar during hydrogen production from methane decomposition process

This study proposes a strategy to convert carbon deposits, generated during the catalytic decomposition of methane for hydrogen production, into high-performance microwave-absorbing materials. This approach not only reduces carbon emissions but also achieves carbon fixation and reuse, promoting environmental sustainability. The research demonstrates that cobalt ferrite (CoFe2O4)-loaded biochar catalysts, at different proportions, exhibit highly efficient and selective hydrogen production capabilities in the process of methane decomposition and hydrogen production, with a peak methane conversion rate as high as 83.6 %, which is higher than that of pure biochar catalysts. The improvement was significant, with an increase of 2.2 times. This catalyst not only strengthens the stability of methane decomposition, but also effectively shortens the reaction induction period, showing excellent catalytic performance and stability. Following methane cracking, an ordered, highly crystalline graphitic carbon structure forms within the catalyst, significantly improving its microwave absorption capacity. At a thickness of 1.3 mm, the catalyst’s microwave absorption reaches a peak value of −41.39 dB, with an effective absorption bandwidth of 4.56 GHz. The catalyst’s outstanding microwave absorption performance arises from synergistic mechanisms, such as multi-layer reflection and interface polarization, which effectively convert electromagnetic energy into thermal energy, facilitating efficient electromagnetic wave dissipation. This research presents an efficient catalyst for the clean utilization of methane resources and explores new pathways to convert industrial by-products into high-value materials, particularly with potential applications in microwave-absorbing technologies.

Conversion of Lignocellulosic Amazonian Biomass into Biochar: Applications in Supercapacitors and Catalysts: Review.

This article explores the valorization of Amazonian biomass through its conversion into biochar, addressing the main technologies involved and their applications in supercapacitors and catalysts. The conversion of biomass into biochar is highlighted as a sustainable strategy for utilizing agroindustrial waste and generating high-value materials. The article reviews relevant technologies for this conversion, including hydrothermal carbonization, chemical activation, and pyrolysis, emphasizing their impacts on creating biochar with adjustable properties such as high surface area and controlled porosity. It also reviews recent studies investigating the valorization of Amazonian biomass for these specific applications, highlighting the advances made. Finally, future perspectives are discussed, including the exploration of new Amazonian biomass sources and the optimization of conversion techniques to expand biochar applications and promote technological innovation and sustainability in the Amazon region.

Green preparation and isolation of carrageenan oligosaccharides and assessment of their ability to inhibit melanogenesis

An efficient method was developed for generating carrageenan oligosaccharides, a high-value material with health benefits for humans. The study used microwave-assisted mild acid hydrolysis of κ-carrageenan to achieve complete liquefaction. Under optimal reaction conditions, the yield of κ-carrageenan disaccharide (KCO2) was 22.90% ± 0.80%, with a total sugar product recovery rate of approximately 90%, while retaining the sulfate groups. Different degrees of polymerization (DP) carrageenan oligosaccharides with 4-sulfate-D-galactose (D-G4S) as the non-reducing end were obtained, with purities of over 90% for both KCO2 and κ-carrageenan tetrasaccharide (KCO4). KCO2 was identified as the oligosaccharide with the highest tyrosinase inhibitory activity. Enzyme kinetics studies revealed that KCO2 exhibited typical reversible competitive inhibition, with an IC50 of 1.09 ± 0.04 mg/mL and a Ki value of 0.16 ± 0.01 mg/mL. Molecular docking showed that KCO2 primarily interacted with key His residues at the tyrosinase active site through its sulfate groups. Molecular dynamics (MD) simulations indicated that the KCO2-tyrosinase complex structure was stable. These findings show that the carrageenan oligosaccharides generated by this strategy could be used as tyrosinase inhibitors in the food, cosmetic, and nutraceutical fields.

A comprehensive review of lignin-reinforced lignocellulosic composites: Enhancing fire resistance and reducing formaldehyde emission.

The rising environmental concerns and the growing demand for renewable materials have surged across various industries. In this context, lignin, being a plentiful natural aromatic compound that possesses advantageous functional groups suitable for utilization in biocomposite systems, has gained notable attention as a promising and sustainable alternative to fossil-derived materials. It can be obtained from lignocellulosic biomass through extraction via various techniques, which may cause variability in its thermal, mechanical, and physical properties. Due to its excellent biocompatibility, eco-friendliness, and low toxicity, lignin has been extensively researched for the development of high-value materials including lignin-based biocomposites. Its aromatic properties also allow it to successfully substitute phenol in the production of phenolic resin adhesives, resulting in decreased formaldehyde emission. This review investigated and evaluated the role of lignin as a green filler in lignin-based lignocellulosic composites, aimed at enhancing their fire retardancy and decreasing formaldehyde emission. In addition, relevant composite properties, such as thermal properties, were investigated in this study. Markedly, technical challenges, including compatibility with other matrix polymers that are influenced by limited reactivity, remain. Some impurities in lignin and various sources of lignin also affect the performance of composites. While lignin utilization can address certain environmental issues, its large-scale use is limited by both process costs and market factors. Therefore, the exact mechanism by which lignin enhances flame retardancy, reduces formaldehyde emissions, and improves the long-term durability of lignocellulosic composites under various environmental conditions remains unclear and requires thorough investigation. Life cycle analysis and techno-economic analysis of lignin-based composites may contribute to understanding the overall influence of systems not only at the laboratory scale but also at a larger industrial scale.

Preparation and properties of calcium oxide and calcium peroxide from eggshell waste for enhanced antimicrobial activity

Calcium peroxide (CaO2), which releases hydrogen peroxide (H2O2) upon contact with water, has garnered attention as a potential alternative to liquid H2O2. Researchers have explored various methods to enhance the production of CaO2 with reduced environmental impact. This study focuses on the preparation of two potent antimicrobial agents, calcined calcium oxide (C-CaO) and synthesized calcium peroxide (S-CaO2) from eggshell waste. These agents were then incorporated into ethylene vinyl alcohol (EVOH) composite films for antimicrobial packaging. The synthesized CaO and CaO2 were analyzed using Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Thermogravimetric analysis (TGA) and Scanning electron microscopy (SEM). The results confirmed the successful synthesis of high-purity CaO and CaO2 from eggshell waste. Compared to CaO (a well-known antimicrobial agent), CaO2 exhibited approximately 1.6 to 2 times higher antimicrobial activity, which is attributed to its release of H2O2. EVOH films containing 3% of CaO2 demonstrated significant microbial growth deactivation, reaching 99.99% and 97.24% for gram-negative and gram-positive bacteria, while EVOH films containing 3% of CaO exhibited relatively low deactivation ability of 79.01% and 48.82, respectively. This study underscores the potential of eggshell waste as a valuable resource for producing high-value materials. Moreover, CaO2 emerges as an effective antimicrobial agent, particularly in antimicrobial packaging applications, showcasing its versatility across various sectors.

Design Process, Evaluation, and Sensitivity Analysis of an Activated Carbon Production Plant from Single-use Plastic Waste at the National University of Engineering

Objective: The objective of this study is to investigate the design process, economic evaluation, and sensitivity analysis for the construction of an activated carbon production plant from single-use plastic waste at the National University of Engineering. This project aims to transform plastic waste into a high-value-added product, thereby contributing to sustainability and aligning with circular economy principles. Theoretical Framework: The theoretical framework covers concepts related to the circular economy and sustainable waste management, emphasizing the need to reduce environmental impact through innovative alternatives such as recycling PET into activated carbon. Previous studies on pyrolysis and thermal or chemical activation of plastics for conversion into high-value materials are cited, establishing a solid foundation to contextualize the activated carbon production process. Method: The methodology adopted for this research includes a technical and economic study design based on the assessment of processes and equipment required for activated carbon production. An experimental approach is proposed, wherein plastic waste is collected, shredded, washed, dried, carbonized, activated, and finally packaged. Data collection involved detailed calculations of investment, energy consumption, and mass and energy balances for each stage of the production process. Results and Discussion: The results revealed that the project is economically viable, with a Net Present Value (NPV) of 59,733 USD and an Internal Rate of Return (IRR) of 13%. In the discussion, the project’s profitability is contextualized through a sensitivity analysis evaluating different scenarios of exchange rate and sale price. This analysis confirms that, in optimistic scenarios, the IRR can reach up to 341%, reducing the payback period to less than a year. Research Implications: The practical implications of this research include the potential to implement a circular economy model in educational institutions, promoting sustainability and efficient waste management. Theoretically, the study contributes to the field of plastic waste valorization through its transformation into activated carbon, which could positively impact sectors such as environmental management and industrial recycling. Originality/Value: This study contributes to the literature by presenting an innovative approach for plastic waste valorization into activated carbon within an educational institution, using pyrolysis and activation processes in a circular economy context. The relevance of this research lies in its practical applicability in academic settings and its potential impact on reducing plastic waste.

Polymer Inclusion Membranes Based on Ionic Liquids for Cobalt, Nickel, and Lithium Ions Separation

The proper handling of end-of-life (EOL) lithium-ion batteries (LIBs) has become an urgent and challenging issue with the surging use of LIBs, in which recovering high-value cathode materials from EOL LIBs not only relieves the pressure on the raw material supply chain, but also minimizes environmental pollution of EOL LIBs. These spent LIBs pose significant environmental challenges due to the potential release of toxic but useful materials, including cobalt, nickel, and lithium. The efficient recovery of these valuable metals is crucial for both environmental sustainability and resource conservation. Existing separation technologies have disadvantages, including the use of large quantity solvents, prompting the need for the development of economical, efficient, and ecofriendly processes for recovering these valuable materials. A membrane system using ion-exchange polymer inclusion membranes (IEPIM) based on ionic liquids (ILs) has been developed for the separation of these metal ions. Our approach relies on proton pumping in ILs, which is driven by the pH gradient between the feed and stripping solutions and facilitates the metal ion transport through the membrane, making the separation process effective while avoiding the use of large quantity solvents. Through systematic experimentation and optimization, cobalt and nickel ions were selectively transported from lithium ions in an aqueous feed solution into a hydrochloric acid receiving solution, effectively separating these metal ions. The IEPIM demonstrated good selectivity and efficiency in metal ion separation, achieving high recovery rates (~90%) of these metals and maintaining the recovery rate over several cycles, indicating high stability over successive use, thus providing a promising and sustainable process for the separation of cathode materials from spent EOL LIBs. These results indicate that the IEPIM can be used as a viable alternative to the conventional method of metal ion separation. Recent results of different ILs concentration effects and other experimental conditions will be discussed in this presentation.

PV Silicon Recovery for Lithium Ion Battery Anodes

As solar photovoltaic (PV) devices across the globe reach the end of their approximately 30-year lifetimes, an emerging challenge is how to handle the waste from large volumes of end-of-life (EOL) PV modules. It is projected that the cumulative mass of EOL PV modules could be up to 8 million tonnes (Mt) by 2030 so recovery of high value materials from these EOL modules through a cost efficient recycling process would minimize environmental impacts compared to disposing them in landfills[1]. A typical recycling process for EOL PV modules involves mechanical disassembly, separation of the tempered cover glass and silicon wafer followed by purification and recovery of other constituents such as Pb or Ag with the goal of reinstating the recovered materials as a PV module. However, since new module prices continue to decline and the recovered PV modules typically have a shorter lifetime and lower efficiency, the economic value of using the recovered PV materials to manufacture a new PV module is uncertain[2]. Since silicon, particularly boron-doped, is a promising candidate for next-generation anodes for lithium-ion batteries (LIB), recovering the silicon from PV modules for use in LIB anodes could be an attractive alternative. A ball milling process was developed at Oak Ridge National Laboratory to prepare ball milled silicon from washed silicon boules as well as EOL PV modules sourced from a commercial PV module recycler. In this talk we will be discussing the purification process, contaminant removal requirements and key anode performance metrics of recycled PV silicon materials. Organic acid washing with and without microwave-treatment as the heat source was conducted on ball milled boron-doped silicon and reference undoped silicon. The organic acid washing was conducted several times and followed by centrifugation and drying to attempt to remove unwanted contaminant species and compared to a single step microwave-assisted process. The initial carbon species present after ball milling the silicon remained on the ball milled silicon based on FTIR data and the structure of the ball milled silicon was unchanged based on XRD analysis. Elemental analysis and half cells tests were conducted to observe the effect of boron-doping and contaminants inherent to the EoL PV Si material with pristine boron-doped silicon showing noticeably better performance than non-doped ball milled silicon or contaminated silicon PV silicon. Determining the maximum amount of each potential contaminant from PV panels will help facilitate these materials being introduced into local supply chains as a silicon precursor material for more highly engineered silicon anode materials. IRENA, I.-P., End-of-Life Management: Solar Photovoltaic Panels 2016: International Renewable Energy Agency and International Energy Agency Photovoltaic Power Systems.A. Wade, P.S., K. Drozdiak, E. Brutsch. Beyond Waste – The Fate of End-of-Life Photovoltaic Panels from Large Scale PV Installations in the EU. The Socio-Economic Benefits of High Value Recycling Compared to Re-Use. in 33rd European Photovoltaic Solar Energy Conference and Exhibition. 2017.

Microstructure, mechanical properties and cross-sectional behaviour of additively manufactured stainless steel cylindrical shells

Powder bed fusion is a rapidly developing method of metal additive manufacturing that offers an unprecedented ability to manufacture complex and flexible components with high accuracy. Stainless steel is a high value material that particularly lends itself to the emerging opportunities offered by metal additive manufacturing. There is, however, limited information related to the microstructure, mechanical properties and structural performance of thin-walled stainless steel elements additively manufactured by powder bed fusion; this is addressed in the present study in the context of thin-walled circular shells, which are investigated through a series of physical experiments and numerical simulations. The experimental programme consisted of material coupon tests, microstructural characterisation, geometric measurements and axial compression tests on stainless steel thin-walled cylindrical shells with large diameter-to-thickness (D/t) ratios produced by powder bed fusion. Advanced measurement techniques—3D-laser scanning and digital image correlation, were utilised to capture the geometric properties prior to testing and the distribution and development of the deformations and strains during testing, respectively. The measured geometric imperfections in the shells were such that most specimens met the Class A fabrication quality requirements set out in EC3-1-6; all tested shells buckled below their yield loads in an asymmetric chequerboard pattern, showing significant sensitivity to local imperfections. In parallel with the experimental investigation, a numerical modelling programme was carried out, aimed at first replicating the compression tests and then extending the current test data pool over a wider range of slenderness values. The experimental and numerical data were analysed and employed to assess the applicability of existing design methods for conventionally formed tubular sections to those manufactured by powder bed fusion. EC3-1-6 was found to give consistent and safe-sided buckling resistance predictions for the studied stainless steel cylindrical shells under axial compression.

Solvent-free ball milling activation of cellulose for efficient surface modification and pyrolysis

Due to the innate recalcitrancy caused by robust hydrogen bonding interaction, cellulose cannot be easily processed into high-valued materials or chemicals. Herein, a solvent-free ball milling treatment was conducted to activate microcrystalline cellulose (MCC). The research results demonstrated that ball milling treatment rapidly reduced the average particle size (Ð) and crystalline index (CrI) of MCC. Ball milling treatment for 1 h resulted in the Ð and CrI of MCC decreasing from 48 μm and 84.5 % to 23.3 μm and 25.4 %, respectively. Further prolonging the ball milling time from 1 h to 4 h slightly reduced the Ð and CrI of cellulose but led to the degradation of cellulose. Furthermore, the ball milling-activated cellulose (BMC) was chemically modified for preparing polylactic acid (PLA)/modified cellulose (m-BMC) composite films. Benefitting from the decreased Ð and valid surface modification of BMC, the tensile strength and elongation at break of the achieved PLA/m-BMC improved by 77.2 % and 189.3 % compared with the PLA/MCC, respectively. Besides, ball milling for 1 h improved the relative contents of saccharides in the pyrolysis products of cellulose from 33.2 % to 60.4 %. This work provided some basic understanding of ball milling activation of cellulose for further efficient surface modification and pyrolysis.