The increasing amount of untreated electronic waste, particularly in the telecommunications sector, is having a negative impact on the environment, not only by increasing the production of greenhouse gases, but also by reducing the availability of resources such as metals. At the same time, these metals are increasingly in demand to meet the manufacturing needs of new technologies. One solution is to recover metals by recycling end-of-life electronic boards. However, current processes are often implemented by large companies but are not suitable for small organizations or those with fewer resources, thus limiting their participation in local electronic waste management. Based on laboratory-scale analyses, this project compares the metal concentration results of three pre-treatments that could be suitable for smaller organizations: magnetic separation, chemical pre-treatment with sodium hydroxide, and centrifugation. The proposed preparation step, after the shredding of telecom electronic boards down to a particle diameter of less than 1 mm, is two-stage centrifugation. This pre-treatment enables metals to be concentrated efficiently and safely prior to hydrometallurgical processing.

As the demand for critical rare earth elements increases, their recovery from e-waste has become a sustainable alternative to traditional mining. Cerium, widely used in strategic technologies, remains challenging to recover efficiently. In this study, a three-layer bio-based composite adsorbent containing cellulose, phosphorylated cellulose, and electrospun chitosan nanofibers was developed to selectively adsorb and recover Ce3+ ions from aqueous solutions. The composite's constituents strongly influenced its adsorption performance: phosphorylated cellulose introduced phosphate groups that enhanced Ce3+ binding through electrostatic interactions, while chitosan nanofibers provided amino and hydroxyl sites that improved chelation, porosity, and mechanical integrity. The optimized combination of these components achieved a balance between functionality, permeability, and stability. Characterization (e.g., scanning electron microscopy, energy-dispersive X-ray spectroscopy, image analysis) confirmed the uniform distribution of active layers and the presence of functional groups responsible for adsorption. Batch adsorption tests revealed a high adsorption capacity of over 64 mg/g within 60 min, following a pseudo-first-order kinetic model and the Langmuir isotherm behavior. Thermodynamic analysis indicated an exothermic process, and the composite exhibited selectivity toward Ce3+ and Nd3+ over Cu2+. Cerium was effectively desorbed and recovered, and the material maintained over 83% of its performance after four cycles, demonstrating its strong potential for sustainable rare earth recovery in line with circular economy principles.

The mechanical characteristics of natural fibre composites (NFCs) are closely linked to fibre-matrix and fibre-fibre interactions. This work investigates the improvement of tensile properties of a flax/epoxy composite through the application of click chemistry reaction to a unidirectional-mat (UDM) reinforcement with modifications made on the short fibre mat and unidirectional flax fibre phases of the reinforcement. The surface of short flax fibres was fibrillated to increase the accessibility of hydroxyl groups for all preliminary reactions and the final click chemistry cross-linking, which creates stable covalent triazole bonds between azide and alkyne groups. A small percentage of treated nanocellulose was incorporated to further enhance the reinforcement properties. FTIR and EDX analysis confirmed the presence of the various functional groups on the surface of nanocellulose and flax fibres with very high degrees of substitution. The treatment significantly improved the mechanical properties of the dry reinforcement, including a 220% mean increase in the tensile strength. However, the treatments, particularly the addition of nanocellulose, resulted in a reduction in the permeability to liquid resin of the reinforcements, highlighting the need for compromises in their manufacture. Nonetheless, marked improvements in tensile strength and Young’s modulus were obtained for composites made of pre-compacted and cross-linked fibre preforms. Increases in elastic modulus, strength and strain at break of up to 50.1%, 53.8% and 10.1% were obtained, respectively.

The mechanical properties of composite materials are strongly related to the fiber–matrix interface properties. This study focuses on the click chemistry modification of short flax fibers using the Cu(I)-catalyzed Huisgen cycloaddition type, to strengthen the fiber–fiber interface for composite applications. The flax fibers are functionalized in three steps: a mechanical fibrillation pre-treatment of the fibers surface, followed by a chemical cleaning treatment to eliminate pectin, lignin, hemicelluloses and waxes, allowing exposure of the hydroxyl groups in flax fibers in view of the final treatment of click chemistry. The chosen strategy allows the adaptation of propargylation and tosylation reactions to flax fibers in aqueous media. FTIR and EDX analysis of fibers treated at intermediate stages confirmed the presence of various surface functions of modified fibers with a very high degree of substitution. The properties obtained are strongly improved for reinforcements containing covalent fiber–fiber contacts. Tensile, tearing and bursting tests performed on dry mat reinforcements showed increases in the tensile index, elongation at break, tensile stiffness, burst and tear indexes of 519

This study presents the development of a biobased paint by integrating TEMPO-oxidized cellulose nanofibers (TOCN) with polypyrrole (PPy) and incorporating polyvinyl alcohol (PVA) as a binder and glycerol as a plasticizer. The TOCN-PPy composite was synthesized via in-situ polymerization, followed by a washing process to ensure compositional purity. High-shear mixing and controlled thermal treatment produced homogeneous and stable formulations. Scanning Electron Microscopy (SEM) revealed a well-dispersed nanofiber network, with increased glycerol content contributing to smoother surface morphology. This may correlate with improved flexibility observed during handling. Raman analysis further confirmed the presence of polypyrrole and revealed spectral shifts associated with enhanced polymer dispersion and hydrogen bonding influenced by PVA and glycerol. Contact angle measurements showed that higher glycerol content increased wettability, reducing hydrophobicity and enhancing adaptability for coating applications. Thermogravimetric Analysis (TGA) revealed multi-stage degradation, with polypyrrole improving thermal stability. The enhanced flexibility observed in glycerol-containing samples is attributed to its plasticizing effect, as evidenced by morphological and handling observations. DSC was also employed for glass transition, melting and thermal decomposition behavior, and thermal stability trends. These findings emphasize the tunability of TOCN-PPy coatings, balancing structural integrity, thermal performance, and wettability for various industrial applications. The results also highlight the potential of TOCN-PPy composites as high-performance, eco-friendly coatings, supporting innovations in green chemistry and the circular bioeconomy.

The growth in the consumption of electronic products in recent years has resulted in increasing electronic device waste. At the same time, there is a decrease in the availability of raw metals required to produce electronic boards. Recycling through the recovery of precious and critical metals contained in electronic board waste is a solution, but the processes need to be safer for the environment. This paper presents the steps that lead to investment in the development of an eco-friendly and cost-effective process for recovering precious metals from end-of-life electronic telecommunications cards. Social organizations can also become involved in the recycling of electronic cards, thus enabling the integration of marginalized people into society. We examine the case of a non-profit organization whose mission is to help people living with mental health problems through the recycling of end-of-life telecommunication devices. This recycling process must operate within constraints specific to this organization and to the employment of people with mental health issues. The literature review showed that considering ecological and economic factors, the hydrometallurgical process appeared to be a logical choice.

The Cu(i)-catalyzed Huisgen cycloaddition click chemistry reaction is of particular interest in the production of paper sheets or natural fiber composites since it leads to the formation of chemically stable bonds between two fibers.

Designing bio-composites for structural applications requires a thorough understanding of their mechanical behavior. In this study, we examined the differences in the tensile strength and drop-weight impact response between polypropylene reinforced with flax fibers and that reinforced with pinewood short fibers, as both fibers differ in composition (cellulose, hemicellulose, and lignin) and length-to-diameter ratio. We found that flax fibers, which have higher cellulose content and are twice as long as pine fibers, increased the stiffness and shock resistance of bio-composite materials. However, pine fibers, which contain more lignin, showed increased material ductility and energy absorption. Impulse excitation, acoustic emission and micro-CT techniques were used to evaluate the post-impact mechanical properties and the contribution of each damage mechanism to the final material failure (tearing). The experimental results were used to validate a model based on finite elements. Our results revealed that the experimental and finite-element analyses were in good agreement.

Proteinaceous amyloid fibrils are one of the stiffest biopolymers due to their extensive cross-β-sheet quaternary structure, whereas cellulose nanofibrils (CNFs) exhibit interesting properties associated with their nanoscale size, morphology, large surface area, and biodegradability. Herein, CNFs were supplemented with amyloid fibrils assembled from the Curli-specific gene A (CsgA) protein, the main component of bacterial biofilms. The resulting composites showed superior mechanical properties, up to a 7-fold increase compared to unmodified CNF films. Wettability and thermogravimetric analyses demonstrated high surface hydrophobicity and robust thermal tolerance. Bulk spectroscopic characterization of CNF-CsgA films revealed key insights into the molecular organization within the bionanocomposites. Atomic force microscopy and photoinduced force microscopy revealed the high-resolution location of curli assemblies into the CNF films. This novel sustainable and cost-effective CNF-based bionanocomposites supplemented with intertwined bacterial amyloid fibrils opens novel directions for environmentally friendly applications demanding high mechanical, water-repelling properties, and thermal resistance.

The design of biocomposite structures for outdoor applications should consider the influence of ultraviolet (UV) irradiation on the mechanical performances to more accurately determine their durability characteristics and prevent significant damage. Ultraviolet radiation causes the discoloration, surface roughness, mass loss, and degradation of the mechanical properties of biocomposites. In this study, the flexural strength and low-velocity impact response of polypropylene reinforced with short flax or pine fibers, which differed with respect to their physical and chemical properties, were investigated. Flax fibers are twice the length of pine fibers, and exhibit higher cellulose contents. Moreover, flax fibers have been demonstrated to increase the flexural strength and impact resistance of biocomposites. However, under UV irradiation, pine fibers containing more lignin dampened the degradation. Under photo-oxidative conditions, lignin is degraded to protect crystalline cellulose by acting as a light-absorbing compound. Non-destructive techniques such as Fourier transform infrared spectroscopy (FTIR), colorimetry, confocal imaging, acoustic emission, and CT scanning were therefore used to evaluate the effect of UV radiation on the chemical properties, color change, surface roughness, bending behavior, and drop-impact damage.

Bacterial contamination of drinking water is becoming a major issue for increasing populations around the world. Current water treatment technologies based on chlorination are effective but generate toxic disinfection by-products. In this study, antibacterial electrospun chitosan-PEO/TEMPO-oxidized cellulose composite was tested for the first time for the deactivation of Gram-positive Bacillus subtilis and Gram-negative Escherichia coli bacteria and their removal by filtration from aqueous solution. Results of the disk diffusion method, confocal microscopy and scanning electron microscopy show that both bactericidal and bacteriostatic behavior against both bacteria depend on the content and mobility of protonated amino groups. It was also found that these properties are enhanced when the biocomposite is doped with copper ions. Filtration tests in a dead-end stainless-steel cell show that both bacteria are completely removed from aqueous solutions (> 95% during the first filtration and 100% after subsequent filtrations). Finally, the composites tested can be used up to three times without significant loss of permeability. However, it was CS-PEO/TOC Cu2+ bio-based composite which displayed the slightest reduction in permeability (2.20%) after three filtrations.

Safety glazing is a type of laminated glazing that holds together when shattered, due to the presence of an interlayer usually made of polyvinyl butyral (PVB). It is widely used in industrial application where the glazing could fall, or become a projectile to avoid serious injuries to humans after an impact with a foreign object. To replace the PVB, we have developed a modified cellulose nanofibers (NFC) by grafting poly(glycidyl methacrylate) with glycerol addition. This modification has improved the NFC pure performance as well as their compatibility with polar polymers. Therefore, this study reports the preparation and characterization of laminated glazing with composites of PVB reinforced with 40, 50 and 70% by weight of modified NFC. Composites interlayers are very transparent (up to 93% light transmission) with an interesting light character (up to 18.72% weight loss) in comparison to a PVB interlayer only. The chosen laminated glazing have been characterized by quasi-static (three-point bending) and dynamic impact loading (drop weight test). The quasi-static show the force–displacement curves of glazing while the dynamic testing give the energy absorption capability and maximum impact force. In our testing, the glazing with modified NFC have shown increased mechanical properties. Moreover, the laminated glazing made with an interlayer reinforced with 40% NFC exhibits the highest impact properties with a maximum force at break of 36,270 N and 24.81 J of absorbed energy. This study has shown that the modified NFC is indeed a lighter and environment-friendlier alternative for laminated glazing.

Slow pyrolysis is widely used to convert biomass into useable form of energy. Ultrasound pre-treatment assisted pyrolysis is a recently emerging methodology to improve the physicochemical properties of products derived. Biochar, the solid residues obtained from pyrolysis, is getting considerable attention because of its good physicochemical properties. Various modification techniques have been implemented on biochars to enhance their properties. Ultrasonic pre-treated wood biochar has showcased efficient surface and adsorption properties. Iron impregnated biochar is interesting as it has potentially proved the efficiency as an efficient low-cost catalyst. In this study, by combining the advantages of ultrasonic pre-treatment and iron impregnation, we have synthesized a series of Fe-impregnated biochar from softwood chips. Pre- and post-pyrolysis methods using a lab-scale pyrolyser had been implemented to compare the pyrolysis product yields and degree of impregnation. Biochars derived from ultrasound pre-treated woodchips by post pyrolysis demonstrated better impregnation of Fe ions on surface with better distribution of pyrolysis products such as biochar and biogas. The surface functionality of all ultrasound pre-treated biochars remained the same. However, post-pyrolysed samples at high frequency ultrasound pre-treatment showed better thermal stability. The chemical characteristics of these modified biochars are interesting and can indeed be used as a cost-effective replacement for various catalytic applications.

Physical and chemical modification on biochar is an interesting approach to enhance the properties and make them potential candidates in adsorption of heavy metals from water. Studies have shown that ultrasound treatments as well as alkali activations on biochar has positive impact on adsorption behaviour of the material. Base activation on biochar derived from ultrasound pre-treated woodchips were studied to understand the influence of ultrasound pre-treatment on chemical modification of biochar and the adsorption properties emerged from it. 40 and 170 kHz ultrasound pre-treated softwood woodchips were subjected to laboratory scale pyrolysis and the resulted biochars were treated with NaOH. The physicochemical properties were examined, and the adsorption experiments revealed that ultrasound pre-treatment assisted biochars have better adsorption capacity as compared to untreated biochar samples after activation. 170 kHz pre-treated sample exhibited an equilibrium adsorption capacity of 19.99 mg/g which is almost 22 times higher than that of corresponding non-activated sample. The ultrasound pre-treated samples showed improved competitive adsorption behaviour towards copper ions in comparison with nickel or lead. The overall study suggests that ultrasound pre-treated biochars combined with alkali activation enhances the heavy metal removal efficiency and these engineered biochars can be used as an effective adsorbent in the field of wastewater treatment.

Cellulose nanofibers (CNFs) and their applications have recently gained significant attention due to the attractive and unique combination of their properties including excellent mechanical properties, surface chemistry, biocompatibility, and most importantly, their abundance from sustainable and renewable resources. Although there are some commercial production plants, mostly in developed countries, the optimum CNF production is still restricted due to the expensive initial investment, high mechanical energy demand, and high relevant production cost. This paper discusses the development of the current trend and most applied methods to introduce energy-efficient approaches for the preparation of CNFs. The production of cost-effective CNFs represents a critical step for introducing bio-based materials to industrial markets and provides a platform for the development of novel high value applications. The key factor remains within the process and feedstock optimization of the production conditions to achieve high yields and quality with consistent production aimed at cost effective CNFs from different feedstock.

Electrospun chitosan–polyethylene oxide nanofiber mats were fabricated using a new collector design. Besides being reusable, it allows to assess the desired morphology of the mat in a quicker way. To test its efficiency, nonwoven mats designed for water treatment applications were prepared using conditions never been reported before. Under these conditions, continuous and flawless nanofibers of 151 ± 36 nm in diameter were achieved. Adsorption capacity of the mats for copper ions in aqueous solutions were investigated. Results showed that sorption equilibrium was achieved within 150 min with a homogenous distribution of copper ions within the nanofibrous mats. The pseudo-second order kinetic model best fitted the experimental data. The Langmuir isotherm best described the sorption process with a maximum adsorption capacity of 124 mg/g for trial temperatures ranging from 25 to 60 °C. Thermodynamic parameters (ΔG°, ΔH° and ΔS°) demonstrate that the adsorption was feasible, endothermic and spontaneous. The desorption potential and mat's reusability were also studied. Results reveal that the electrospun chitosan mats can be desorbed and reused up to 5 cycles without significant loss in adsorption performance.

The drainage- and dewatering-controlling mechanisms in a screw press were detailed in this work. Three pulps (kraft pulp, bleached chemi-thermomechanical pulp, and thermomechanical pulp) were studied to compare a wide range of wood fibre types. The dewatering was controlled by the screw press parameters and the pulps’ properties. Filtration was found to be the controlling mechanism in the first part of the screw press for the three pulps, and it was less important when the fines content was greater. In the compression zone, the degree of compression was affected by the pulp flexibility and the fibres’ tendency to entangle. Filtrate flow rate monitoring along the screw press could be a good indicator of where the transition from filtration to consolidation occurs. The pressure along the screw press did not change much in the filtration zone, and it notably increased near the discharge end. When the drainage was very high, the pulp feed increased, causing the pulp axial velocity in the end part to be greater than the screw’s linear advance.

Biomass-derived biochars are studied extensively because of their unique surface properties and efficiency in removing heavy metals from aqueous solution. Power ultrasound pre-treatments are interesting in this context, as they can make significant changes in the physicochemical characteristics of biomass. Herein, we studied their effect on adsorption characteristics of softwood biochar under different conditions of frequency, power, temperature and exposure time of ultrasound. The 40 kHz pre-treated samples exhibited around 0.3 to 0.65 mg/g increase in equilibrium adsorption capacity (Qe) which highly depends on the combination of power versus time and temperature of ultrasound. The isotherm and thermodynamic studies also showed that the mechanical effect of ultrasound plays a vital role in enhancing the surface. Results from this study demonstrated that ultrasound pre-treatment conditions influence the behaviour of biochar towards metal adsorption and ultrasonic pre-treatments can be used as an efficient processing method for biomass residues and the derived products.

Statistical modeling of a screw press was established by using an experimental design based on the screw rotational speed, the pulp feed consistency, the pulp feed suspension freeness, the inlet pressure, and the counter-pressure at the discharge end. The statistical models showed that the screw press outputs for each pulp could be predicted. When including all data in a global model to predict the outputs of the press for any pulp, a global statistical model was found not to be efficient by using just the five fixed parameters. The solution to this problem was to use a multivariate analysis to include more parameters, mainly about the fiber characteristics (crowding factor, fiber length, fiber width, and fines content). By including these fiber properties, the differences between each pulp were more properly analyzed. The multivariate analysis predicted the press outsets very well in a global model by using eight parameters instead of five. The R2 values of the multivariate prediction model were all higher than 0.70 and had the goodness of prediction (Q2¬¬¬) higher than 0.60.