Tarek M. Madkour

A review on the structure, properties, sustainability, and life cycle analysis of basalt fiber composites, emerging as a major sustainable alternative to traditional synthetic reinforcements such as glass and carbon fibers. Basalt fibers (BFs) are high-performance mineral fibers derived from volcanic rock with a high silica content. These fibers exhibit superior mechanical strength, excellent chemical resistance, and exceptional thermal stability across a broad temperature range. This review explores the multi-sectoral applications of basalt fibers, particularly within the energy and chemical industries. Specific focus is placed on their role as reinforcing agents in concrete and polymer matrix composites, where they provide enhanced durability and corrosion resistance. Central to this discussion is the environmental profile of basalt fibers. We evaluate recent life cycle assessments (LCAs) that compare the environmental gains of BF-reinforced structures. The analysis extends beyond environmental metrics to include the economic and social pillars of sustainability, highlighting basalt’s cost-effectiveness in corrosive environments and its safety as a non-carcinogenic material. This review concludes that basalt fibers offer a significant “green” advantage, encouraging wider industrial adoption.

Asphalt pavement production accounts for approximately 1.5% of global carbon emissions, underscoring the need for sustainable binder modification strategies that enhance performance without compromising durability. Existing studies on eco-friendly asphalt modifiers remain largely fragmented, limiting cross-comparison and mechanistic understanding. This study develops a unified, multi-scale experimental framework to comparatively evaluate waste-derived polymers and geopolymer-based modifiers under identical processing and testing conditions. Five modifiers, crumb rubber (CR), low-density polyethylene (LDPE), a combination of CR/LDPE, fly ash (FA), and metakaolin–silica fume (MK–SF) geopolymers, were assessed alongside a commercial fiber elastomer modifier (VIATOP), using two virgin binders from Egyptian refineries to capture source dependency, resulting in twelve modified systems. Binder behavior was evaluated through integrated microstructural (SEM), chemical (FTIR and CI + SI indices), thermal and photochemical (TGA and UV–Vis), and rheological (viscosity and performance grading) analyses. Results show that geopolymer modifiers provided the most consistent improvements across scales, reducing chemical aging indices, increasing decomposition onset temperatures by approximately 10–20 °C, suppressing UV-induced aromatic growth, and maintaining workable viscosities (< 500 cP at 135 °C) with moderate Performance Grade (PG) enhancement ( ≈ + 2–4 °C). Crumb rubber offered balanced performance, yielding moderate PG increases ( ≈ + 4–5 °C) with improved aging resistance. In contrast, LDPE and VIATOP produced the largest PG increases (up to ≈ + 10–13 °C) but exhibited poorer dispersion, higher oxidation, and reduced thermal and UV stability, indicating short-term stiffening rather than long-term durability. The hybrid CR/LDPE combination showed intermediate, partially synergistic behavior. Overall, the study demonstrates that rheological gains alone are insufficient indicators of durability and highlights the decisive role of base binder chemistry. The proposed framework provides quantitative, transferable design guidance for selecting sustainable asphalt modifiers that balance stiffness, durability, and aging resistance.

Ion transport and storage in porous materials play a vital role in numerous energy storage and conversion technologies, such as batteries, capacitors, and fuel cells. In this study, molecular dynamics simulations are used to investigate the structure–property–function relationship of lithium and sodium ion transport and storage in highly porous and π-conjugated Aza-linked covalent organic frameworks (COFs). The simulations reveal that the diffusion coefficients of free lithium ions are significantly higher than those of free sodium ions across all of the COF structures, highlighting the influence of ion size on mobility in the absence of solvent molecules. The presence of nitrogen atoms in the imidazole and phenazine rings of the framework of BCOF-1, referred to throughout this article as Aza-COF, was found to significantly decrease the diffusion coefficients of the metal ions due to the significant electrostatic attraction between the ions and the lone pairs of the nitrogen atoms. Replacing the nitrogen atoms with carbon atoms led to increased diffusion coefficients, suggesting that the lone pairs and π-electrons of the frameworks play critical roles in ion binding. Pore decoration of the frameworks with glycol side chains dramatically reduced ion mobility due to increased electrostatic interactions. This indicates that the ether groups in these side chains create a more restrictive environment for ion movement. Overall, the simulations reveal that the electronic properties and chemical functionality of the pore walls, the free volume of the pores, and the solid-state packing of the COF structure significantly impact the ion transport and storage within the framework. This understanding paves the way for the rational design of new COF materials with tailored ion transport and storage properties for potential use as electrodes and solid-state electrolytes in sustainable batteries.

Environmentally friendly nanoporous gels are tailor-designed and employed in the adsorption of toxic organic pollutants in wastewater. To ensure the maximum adsorption of the contaminant molecules by the gels, molecular modeling techniques were used to evaluate the binding affinity between the toxic organic contaminants such as methylene blue (MB) and Congo red (CR) and various biopolymers. To generate nanopores in the matrix of the polymeric gels, salt crystals were used as porogen. The pores were then used to accommodate catalytic nickel (Ni⁰) nanoparticles. Under UV irradiation, the nanoparticles demonstrated the effective adsorption and photocatalytic degradation of both the methylene blue and Congo red dyes, achieving removal efficiencies of up to 90% for MB and 80% for CR. The thermodynamic analysis suggested a spontaneous endothermic dissociative adsorption mechanism, which implies the oxidative catalytic degradation of the dyes. The kinetic modeling suggested a pseudo-second-order model, while the model for intra-particle diffusion revealed that Congo red diffuses faster than methylene blue. MB adsorption followed a Langmuir isotherm, while CR adsorption followed a linear isotherm. The results confirm that dye molecules initially undergo physisorption and subsequent dissociative adsorption. The products of the catalytic degradation of methylene blue continue to be absorbed on the surface of the nanoparticles, while those of Congo red switch to preferential desorption.

Novel functionalized and/or grafted crosslinked chitosan adsorbents were synthesized and used to remove several toxic heavy metal ions such as nickel, lead, chromium, and cadmium ions from contaminated water. The chitosan biopolymer was functionalized by maleic anhydride (CS_MA) acting also as a crosslinking agent. Glutaraldehyde-crosslinked chitosan (CS_GA) grafted with poly(methyl methacrylate) (CS_MMA) was also synthesized. The synthesized adsorbents were characterized using a variety of analytical techniques such as SEM, TGA, and FTIR, which confirmed their chemical structures and morphology. The adsorption capacity of the adsorbents was analyzed under various conditions of contact time, adsorbent dose, initial concertation, temperature, and pH and evaluated against those of pure chitosan (CS) and the crosslinked chitosan(CS_GA). The ultimate removal conditions were 0.5 g/100 mL adsorbent dose, an initial metal ion concentration of 50 ppm, a temperature of 45 °C, and pH 9. CS_MMA had the highest removal percentages for all metal ions, ranging from 92% to 94%. The adsorption was demonstrated to fit a pseudo-first-order model that followed a Langmuir adsorption isotherm. The results highlight the capacity of the synthesized polymers to efficiently remove major toxic contaminants at low cost from contaminated water, present especially in low-income areas, without harming the environment.

Novel functionalized and/or grafted crosslinked chitosan adsorbents were synthesized and used to remove several toxic heavy metal ions from contaminated water efficiently and selectively. The chitosan biopolymer was functionalized by maleic anhydride (CS_MA), which also acted as a crosslinking agent. Separately, Glutaraldehyde-crosslinked chitosan (CS_GA) was grafted with poly(methyl methacrylate) (CS_MMA). The synthesized adsorbents were used to adsorb and remove heavy metal ions from contaminated water. The metal ions were nickel, lead, chromium, and cadmium. The adsorption capacity of the adsorbents was analyzed under various conditions of contact time, adsorbent dose, initial concertation, temperature, and pH and evaluated against those of pure chitosan (CS) and the crosslinked one (CS_GA). The ultimate conditions for the ions removal were 0.5g/100ml adsorbent dose, an initial metal ion concentration of 50 ppm, a temperature of 45oC, and a pH 9. CS_MMA, which had the highest removal percentages for all metal ions, ranging from 92% to 94%. The adsorption was demonstrated to fit a pseudo-first-order model that followed a Langmuir adsorption isotherm. The results highlight the capacity of the synthesized polymers to efficiently remove major toxic contaminants at low cost from contaminated water, present especially in low-income areas, without harming the environment.

A novel adsorbent–contaminant system was investigated for its ability to remove a contaminant of emerging concern, diclofenac potassium, from contaminated water. Bio-based crosslinked chitosan beads functionalized with poly(itaconic acid) side chains were examined for their potential to remove the emerging contaminant. To evaluate the impact of the polymeric microstructure on its adsorptive capacity, several adsorbent samples were prepared using different combinations of initiator and monomeric concentrations. Fourier Transform Infrared (FTIR) analysis confirmed the crosslinking of the chitosan chains and the incorporation of the carboxylic groups on the surface of the final chitosan beads. After the grafting copolymerization process, an additional peak at 1726 cm⁻¹ corresponding to the carboxylic C=O groups of the grafted chains appeared, indicating the successful preparation of poly(IA)-g-chitosan. Thermal stability studies showed that the grafting copolymerization improved the thermal stability of the beads. X-ray and Scanning Electron Microscopy confirmed the successful grafting of the itaconic acid on the surface of the beads. The study revealed that the higher the initiator concentration, the greater the number of side chains, whereas the higher the monomeric concentration, the longer the length of these side chains. The adsorption mechanism involved hydrogen bonding to the carboxylic groups of the grafted chains along with n-π* stacking interaction between the amino group of the chitosan and the aromatic rings of diclofenac potassium. The adsorption efficiencies of diclofenac potassium onto the grafted beads were significantly improved compared to the unfunctionalized chitosan beads, reaching values above 90%. The removal efficiency of grafted chitosan increased with an increase in the concentration in the range of 10–30 ppm and then flattened out in the range of 30–50 ppm. The removal efficiencies of 1–50 ppm of DCF ranged between about 75% and 92% for the grafted chitosan and 30–45% for the crosslinked chitosan. Rapid adsorption occurred within 20 min for all grafted sample combinations, and the adsorption kinetics followed a pseudo-second-order model with q_e values ranging from 28 to 44.25 g/mg and R² values greater than 0.9915. The results highlight the potential of grafted chitosan beads in removing emerging contaminants from contaminated water without harming the environment.

The emerging pharmaceutical contaminants diclofenac (DCF) and salicylic acid (SA) pose potential hazards to humans and living organisms due to their persistence in water environments. In this work, the conductive polymers polypyrrole (PPY) and polyaniline (PANI) were successfully coated on cotton fabrics, as confirmed by FTIR and SEM measurements. The coated fabrics efficiently removed DCF at pH 5.3 and SA at pH 4, with removal efficiencies that exceeded 90% and 70%, respectively. Adsorption was rapid for most of the tested contaminant–fabric systems and reached equilibrium within 20–30 min. The best adsorption performance for both contaminants was shown on the PPY-coated fabrics, which yielded adsorption capacities of about 65 and 21 mg/g for DCF and SA, respectively. This could be explained by molecular modeling simulations, which mostly estimated higher total cohesive energy densities for adsorption on the PPY-coated fabrics than on the PANI-coated ones. The adsorption mechanism involved both coulombic electrostatic attractions and non-coulombic van der Waals and π-π stacking. The fabrics could be reused for three adsorption–desorption cycles. Immobilization of the conductive polymers on cotton fabrics provides a facile method for their handling and collection during adsorption and regeneration cycles while maintaining their multi-functionality in adsorbing different contaminants.