Bimetallic nanoparticles (BNPs) have attracted much attention recently due to their improved properties compared to monometallic ones. Gold and silver nanoparticles (AuAgNPs) are among the most studied BNPs. Using these particles as powder or dispersion has drawbacks such as ease of aggregation and difficulty separating and recovering from the reaction medium. Therefore, immobilizing these nanoparticles in polymeric matrices, such as cellulose, is appealing. In this context, the present work focused on preparing unmodified cellulose membranes containing AuAgNPs for use as heterogeneous catalysts in reducing the pollutant 4-nitrophenol. Incorporating these nanoparticles into cellulose membranes represents a significant advancement in heterogeneous catalysis. In addition to being eco-friendly, cellulose membranes offer ease of handling and the potential for reusability, which are crucial factors in catalysis. The nanoparticles were prepared in an aqueous medium from the seeded growth of a silver shell around AuNP seeds. Images recorded by transmission electron microscopy showed that the particles have diameters smaller than 100 nm and are core-shell type. The cellulose membrane was prepared by dissolving microcrystalline cellulose in an ionic liquid, followed by a regeneration process using water. Next, the bimetallic nanoparticles were incorporated into the cellulose membrane. The analyses revealed that the membranes contain bimetallic nanoparticles homogeneously distributed in the matrix, and the inductively coupled plasma-optical emission spectroscopy (ICP-OES) showed that the membrane has 0.339 wt % in silver and 0.069% in gold. The membranes produced were efficient heterogeneous catalysts in reducing 4-nitrophenol, used for at least four cycles without loss of efficiency. This material can be easily isolated from the reaction medium, avoiding centrifugation or filtration processes for reuse. This study represents the first use of AuAgNPs supported on nonmodified cellulose membranes as heterogeneous catalysts, marking an advancement in catalysis and material science.

This study focuses on comparing the efficiency of commercially available TiO₂ (P25) with synthesized TiO₂ nanoparticles (TiO₂NP) impregnated in nonmodified cellulose membranes, specifically targeting the degradation of Indigo Carmine (IC) dye. We developed a novel method to enhance the interaction between cellulose and TiO₂, thereby improving efficiency and reusability. This involves dissolving microcrystalline cellulose in 1-butyl-3-methylimidazolium chloride (BMImCl) and dispersing the TiO₂ samples within this solution. The resulting cellulose membrane embedded with TiO₂ nanoparticles (TiO₂NP) exhibited a higher adsorption capacity and greater photocatalytic efficiency against IC compared to that of P25. This improvement is attributed to the larger surface area and increased reactivity of the synthesized TiO₂NPs. Furthermore, the CEL_TiO₂NP membranes demonstrated excellent stability and reusability, maintaining their catalytic efficiency over multiple cycles. This study presents new opportunities for developing efficient, reusable photocatalytic materials for environmental remediation using eco-friendly cellulose.

In the present work a remarkably simple procedure for the elaboration of wet cellulose film containing manganese oxide nanoparticles was developed. The films were produced using a mold made by 3D printing using cellulose dissolved in an ionic liquid, which allows the production of thin and homogeneous films of different shapes, types and designs which cannot be made using conventional techniques. Thanks to this possibility, the final catalytic object can be implemented in specific reactors. Manganese oxide nanoparticles were prepared as a colloidal solution by a redox/sol-gel procedure and then deposited on the cellulose films by wet impregnation. The catalytic film obtained was tested in the decomposition of a dye, indigo carmine (IC), in the absence of light. The influence of the pH of the solution on the decomposition rate was investigated. IC total decomposition was measured after 1-h reaction at pH below 3. At pH = 2, no deactivation of the catalyst was observed even after four decomposition cycles. This work provides a new strategy to design cellulose-based catalysts for dye removal from wastewater.