Fernando Machado Machado

Balancing melt processability with stiffness and heat resistance remains a central challenge for PA6 nanocomposites. Here, graphene oxide (GO) was synthesized by a modified Hummers method and incorporated into PA6 via a hybrid route (solution‐made masterbatch, melt dilution and injection molding) at 0.1–2.0 wt%. Melt rheology at 240°C shows higher zero‐shear viscosity and stronger shear thinning, while SAOS and Cole–Cole plots reveal the development of a GO‐induced network. Capillary rheometry over 80–11,500 s ⁻¹ indicates viscosity convergence to Pa s for all compositions, confirming preserved moldability. By tracking / before and after injection molding, we show that the second melt‐processing step relaxes, but does not destroy, the filler‐induced network and shifts the onset of rheological percolation to around 2 wt% GO. In the solid state, DMA and HDT demonstrate a increase of ≈6°C–8°C, a 21% rise in HDT (80.8°C–97.7°C) and higher rubbery modulus, whereas tensile tests reveal up to +22% yield stress and +59% ultimate strength at 2 wt% GO, at the cost of reduced ductility. Correlating unified rheological parameters with HDT and tensile data yields a concise rheology‐to‐performance map, with an optimum near 1 wt% GO. The results link injection relevant melt signatures to molded part performance, targeting electrical connector housings.

This investigation outlines the synthesis of activated biochar from peach stone biomass (ABPS) using a single‐step microwave‐assisted pyrolysis process. The resulting ABPS adsorbent was characterized using IEP, pH _PZC , scanning electron microscopy (SEM), N ₂ adsorption/desorption, and Fourier transform infrared (FTIR) techniques. Interactions between ABPS and the analgesic paracetamol (PAR) were also evaluated. The ABPS exhibited a surface area of 652 m ² g ⁻¹ and was rich in oxygen‐based functional groups. The Avrami nonlinear kinetic model best described the adsorption kinetics, indicating rapid adsorption with t ₀ . ₉₅ = 2.381 min. The Liu nonlinear model best explained the adsorption isotherms, with a maximum adsorption capacity ( Q _max ) of 150.2 mg g ⁻¹ . Thermodynamic and spectroscopic analyses indicated that the adsorption process was endothermic and spontaneous, exhibiting physisorption characteristics (ΔH = 36.37 kJ mol ⁻¹ ). The proposed adsorption mechanism involved pore filling, hydrogen bonding, π–π interactions, and van der Waals interactions in the ABPS–PAR system. The adsorption performance of activated biochar derived from peach stones highlights its potential as an effective carbon‐based adsorbent for paracetamol removal from wastewater. In addition to its high removal efficiency, the biochar demonstrated excellent reusability, maintaining high performance after three adsorption–desorption cycles, reinforcing its applicability in sustainable water treatment processes.

Environmental pollution, stemming from the disposal of contaminants, poses severe threats to ecosystems and human health. The emergence of a new class of pollutants, termed emerging contaminants (ECs), in soil, water, and air has raised global concerns, aligning with the UN 2030 Agenda’s Sustainable Development Goals. Aerogels, three-dimensional structures with high porosity and low density, offer promise in addressing this issue. Cellulose-based aerogels, derived from abundant, renewable, and biodegradable sources, particularly stand out for their potential in adsorption applications. However, challenges arise in water and wastewater treatment due to cellulose aerogel’s inherent hydrophilicity. To overcome this limitation, incorporating new components and employing modification processes becomes essential. This article explores the production phases and diverse modifications of cellulose aerogels, aiming to enhance their adsorption capabilities for various environmental contaminants. By addressing hydrophilicity issues and developing stable composites, cellulose aerogels can contribute significantly to efficient and sustainable solutions in the quest for cleaner ecosystems and improved human health.

This study reported a one-spot preparation of magnetic composite carbon (MCC@Fe) from microcrystalline cellulose (MC). The pure cellulose was impregnated in iron (III) chloride solution and carbonized at 650 °C. The MCC@Fe composite adsorbent underwent various characterization techniques. XRD identified nanostructured Fe₃O₄ particles with an average crystallite size of 34.3 nm embedded in the core subunits of the material. FESEM images indicated a rough and irregular surface, with some cavities along its surface, incorporating Fe₃O₄ nanoparticles, while EDS analysis confirmed the presence of elements like Fe, C, and O. Notably, combining thermal and chemical treatments produces a composite with more pores and a high specific surface area (500.0 m² g⁻¹) compared to MC (1.5 m²/g). VSM analysis confirmed the magnetic properties (0.76 emu/g), while the Hydrophobic Index (HI) showed that MCC@Fe was hydrophobic (HI 1.395). The adsorption studies consisted of kinetic, mass transfer, equilibrium, and thermodynamics studies. Kinetic study of the adsorption of paracetamol on MCC@Fe composite proved to be rapid, and the time necessary for covering 95% of the surface (t_0.95) was lower than 27 min following the fractal-like pseudo-first-order model (FPFO). Liu’s isotherm proved to be the most appropriate for understanding the adsorption equilibrium. Remarkably, the maximum sorption capacity (Q_max) of paracetamol was 34.78 mg g⁻¹ at 45 °C. The ΔH° value (+27.00 kJ/mol) and the negative ΔG° values were consistent with the physisorption mechanism and favorable process. Furthermore, the mass transfer mechanism showed that the transfer is governed by the intraparticle diffusion model, with surface diffusion being the rate-limiting step when considering the Biot number greater than 100. This research displayed a single-route production of inexpensive magnetic nano adsorbents capable of efficiently eliminating paracetamol from aqueous environments.

The presence of pharmaceuticals in wastewater resulting from human activities has driven researchers to explore effective treatment methods such as adsorption using activated carbon (AC). While AC shows promise as an adsorbent, further studies are essential to comprehend its entire interaction with pharmaceuticals. This article investigates the adsorption of potassium diclofenac (PD) onto AC using experimental and modeling approaches. Batch adsorption studies coupled with Fourier transform infrared spectroscopy (FTIR) were employed to clarify the adsorption mechanism of PD on AC. Various kinetic and isotherm adsorption models were applied to analyze the adsorbent-adsorbate interaction. The kinetics were best described by Avrami's fractional order (AFO) nonlinear model. Also, the intraparticle diffusion (IP) model reveals a three-stage adsorption process. The experimental equilibrium data fitted well with the three-parameter nonlinear Liu model, indicating a maximum adsorption capacity (Q_max) of 88.45 mg g⁻¹ and suggesting monolayer or multilayer adsorption. Thermodynamic analysis showed favorable adsorption (ΔG° < 0), with an enthalpy change (ΔH° = -30.85 kJ mol^–1) characteristic of physisorption involving hydrogen bonds and π-π interactions. The adsorption mechanism was attributed to forming a double layer (adsorbate-adsorbent and adsorbate–adsorbate).