Evans Suter

Cadmium contamination of water poses serious environmental and public-health risks, creating a need for efficient, reusable, and readily recoverable treatment materials. This study developed a magnetic PA6/CNCs–Fe₃O₄ composite from waste polyamide 6 (PA6), cellulose nanocrystals (CNCs), and Fe₃O₄ for Cd(II) removal from aqueous solution. The composite was prepared via in situ co-precipitation and characterised using SEM–EDS, FTIR, XRD, BET, zeta-potential analysis, and VSM. Characterisation confirmed composite formation, retention of the crystalline magnetite phase, mesoporosity, and the presence of Fe₃O₄ nanoparticles, with sufficient magnetic responsiveness for effective separation. Batch experiments evaluated the effects of pH, contact time, initial Cd(II) concentration, adsorbent dosage, and temperature. Under selected conditions of pH 5.0, an initial Cd(II) concentration of 18.97 mg L⁻ ¹ , a contact time of 120 min, an adsorbent dosage of 1.0 g L⁻ ¹ , and 298 K, the composite achieved an adsorption capacity of 18.62 mg g⁻ ¹ and a removal efficiency of 98.15%. The pseudo-second-order model best described the kinetic data. The linearised Langmuir model yielded a maximum adsorption capacity of 39.68 mg g⁻ ¹ , whereas the nonlinear Sips model provided the closest fit on the untransformed scale. Apparent Gibbs free-energy changes ranged from − 21.75 to − 28.38 kJ mol⁻ ¹ , indicating favourable adsorption. The composite retained 86.30% removal efficiency after five adsorption–desorption cycles, demonstrating its potential as a reusable, magnetically recoverable adsorbent for Cd(II)-contaminated water.

Silver nanoparticles have gained worldwide attention in the scientific community due to their high antimicrobial activity. However, they tend to agglomerate and lose their shape and properties, thus capping agents necessary to protect their shapes, sizes, and properties. To enhance their antimicrobial activity, this research aimed to cap silver nanoparticles with cellulosic matrices from wheat straws. The wheat straw was delignified with 6% HNO_3, and the residual was treated with 1% NaOH and NaClO: CH₃COOH (1:1), then used to synthesize cellulose nanocrystals via acid hydrolysis. AgNPs were incorporated into the CPC and CNCs by in-situ synthesis using NaHB₄ as the reducing agent. Fourier Transform Infrared, Scanning Electron Microscopy, and X-ray diffraction were used to investigate their features. The findings exhibited crystallinity increased with subsequent treatments, according to XRD analysis. Ultraviolet-visible, FTIR, TEM, and XRD analysis confirmed the capping of AgNPs onto the cellulosic materials. Antibacterial activity against Staphylococcus aureus and Escherichia coli, with CNCs-AgNPs composite, exhibited higher activity compared to CPC-AgNPs composite due to the increased surface area and excellent binding on the surface of the composite.

Iron is a ubiquitous element found on Earth's crust, existing in various forms, such as Magnetite (Fe₃O₄) and Hematite (α-Fe₂O₃). Magnetic iron oxide nanoparticles (MIONPs) have become increasingly popular because they possess unique properties such as high surface area to volume ratio, super-paramagnetic properties, photocatalytic properties, and economical synthesis methods. This study produced MIONPs using the co-precipitation method, stabilized by a molybdenum magnet. Two soluble iron salts (FeCl₃.6H₂O and FeSO₄.7H₂O) were reacted with 5N NH₄OH solution at 80 °C in a nitrogen atmosphere. The MIONPs had a high saturation magnetization of 74.2emu/g, good crystallinity with crystalline spinel structured magnetite phase of iron oxide, high thermal stability depicted by 2.09 wt. % weight loss, and small particle sizes (6-25 nm). FTIR revealed a high-intensity peak at 546.28 cm^-1, attributed to the Fe-O stretching bond. Furthermore, the study showed that the co-precipitation method could be used to produce nanoparticles with a wide range of properties that could be used for various applications. It is a promising solution for producing stabilized magnetic nanoparticles since it uses non-toxic reagents and a straightforward, secure technique. Therefore, it may be used to synthesize nanoparticles for targeted treatment, magnetic resonance imaging, drug delivery, water treatment purposes and environmental remediation.

This work reports on the structural modification of cellulosic materials with magnetic iron oxide nanoparticles through the co-precipitation method. Cellulose is one of the most abundant natural polymers with chemical variability brought about by the presence of several hydroxyl groups, allowing its surface modifications through the insertion of several chemical groups to impact its cellulosic characteristics. Thus, the objective of this study was to synthesize magnetic iron oxide nanoparticles (MNPs) through co-precipitation, followed by in situ incorporation of MNPs onto chemically purified cellulose (CPC) and cellulose nanocrystals (CNC). The composites were characterized for thermal properties using TGA, molecular structure using FTIR, surface morphology using SEM, elemental composition using electron dispersion spectroscopy (EDS), and crystallinity using XRD. The prepared composites presented improved crystal, thermal, and surface properties. CNC-MNPs and CPC-MNPs bore particle sizes of 26.94 and 37.72 nm, respectively, whereas MNPs’ particle size was 10.3 nm. EDS analysis indicated that Fe, C, and Cl were the main elements present in the composites. Surface modification of the cellulosic materials presented excellent sorption surface properties and can be used in several industrial processes, such as wastewater purification, air filtration, and various environmental remediation processes.