Advances in Green Nanocomposites: Design, Characterization and Applications

Nowadays, green nanocomposites are gaining interest in different application fields. The use of the nanotechnology is emerging as a way to facilitate the fabrication of nanomaterials. Nanomaterials with unique physical–chemical properties are being widely applicable in many industrial fields, such as those related to energy and the environment, packaging, cosmetics, tissue engineering, sensors, water remediation, and smart materials. Several nanosized materials are now being investigated by researchers, including carbon-based materials, nanoclay, zeolite, nanofibers, and so on. This Special Issue, titled “Advances in Green Nanocomposites: Design, Characterization and Applications”, focuses on the exploitation of nanotechnologies to design novel green composite materials with advanced properties.

Lagunay et al. [1] investigated the synthesis and characterization of undoped and doped carbon dots (CDs) derived from soybean biomass, as a nitrogen source, through eco-friendly autogenic atmosphere pyrolysis. The manipulation of optical properties was achieved by doping the CDs with potassium chloride (KCl) or zeolite. The inclusion of these doping agents contributed significantly to reducing the size of the resulting CDs from 8.86 ± 0.10 nm for the undoped CDs to 3.09 ± 0.05 and 2.07 ± 0.05 nm for the zeolite and KCl doped CDs. Moreover, doping with zeolite or KCl altered the elemental composition of the CDs, which affected their optical properties, causing changes in bandgap energies and excitation-dependent fluorescence spectra. The results of this research proved the advanced properties of doped CDs that could potentially be applied in environmental sensing and energy-related fields.

Mane et al. [2] focused on improving the supercapacitive capabilities of metal-free graphitic carbon nitride (g-C₃N₄) by incorporating a cationic surfactant such as cetyltrimethylammonium bromide (CTAB). CTAB facilitates the formation of well-defined 2D sheets and preserves the structural integrity of g-C₃N₄ during synthesis. The proposed methodology led to enhanced specific capacitance, cyclic stability, and comparative rate capability in relation to pristine g-C₃N₄, making the modified carbon nitride an interesting material for advanced energy storage applications, especially those related to high-performance supercapacitors.

Li et al. [3] focused on a novel system designed for the removal of micropollutants. The authors prepared a large-sized planar photocatalytic reactive ceramic membrane using the dip-coating method with nitrogen-doped TiO₂ (N-TiO₂-CM) for the purification of tetracycline hydrochloride (TC). The doping of nitrogen allowed them to reduce the bandgap energy of titania, promoting the adsorption of visible LED light, which improved its photocatalytic activity. N-TiO₂ nanoparticles showed a spherical morphology with nanosized dimensions. A water treatment system using LED UVA light was set up, and the TC removal efficiency was 92% after 270 min following treatment with an initial concentration of 20 mg/L. The degradation rate and permeate flux of N-TiO₂-CM were 2.57 and 2.30 times as high as that of the pristine CM, respectively, proving its good self-cleaning features. This study proposed a novel way for facilitating the industrial treatment of water or wastewater and the utilization of solar light by exploiting the properties of doped nanomaterials.

Kiani et al. [4] proposed a novel way of functionalizing charcoal, a low-cost material derived from biomass pyrolysis, as a novel green filler with potential antimicrobial and flame-retardant properties. The proposed methodology is based on an initial oxidation step, performed using H₂O₂ solution, followed by the preparation of oxidized charcoal adducts through a sustainable procedure to uptake ionically quaternary phosphonium salts such as tetraphenyl phosphonium bromide (TPPBr) and dodecyl triphenyl phosphonium bromide (DTPPBr) in an alkaline solution. This form of green modification altered the polarity of carbon material, providing new interesting chemical-modified carbon fillers that could potentially be applied as flame-retardant agents or antimicrobial materials.

Viscusi et al. [5] fabricated a novel green rice milk-based bead through ionotropic gelation to deliver chili pepper extract (PE) as a green herbicide. The effect of PE release from the green hydrogel beads on the growth and proliferation of Cynodon dactylon weed was evaluated. The results of this study show that the fabricated novel biocomposites could be used in systems for releasing waste resources or as green herbicides to inhibit the proliferation of common weeds. The results showed quasi-complete inhibition of weed growth after 12 days, when the soil was covered with the highest amount of PE loaded into beads. The length of the weeds in the absence of the beads reached 12 cm, while the weed length became noticeably shorter as the PE content increased. This study’s results prove that the PE showed a positive response with respect to the inhibition or delaying of weed proliferation.

This Special Issue, “Advances in Green Nanocomposites: Design, Characterization and Applications”, may be considered an interesting reference with respect to the design, fabrication, and application of green nanocomposites with different industrial applications.