Facile preparation of functionalized poly(amidoamine)s with biocidal activity on wood substrates

Antifungal Agents in Wood Protection—A Review

The biodegradation of wood and wood products caused by fungi is recognized as one of the most significant problems worldwide. To extend the service life of wood products, wood is treated with preservatives, often with inorganic compounds or synthetic pesticides that have a negative impact on the environment. Therefore, the development of new, environmentally friendly wood preservatives is being carried out in research centers around the world. The search for natural, plant, or animal derivatives as well as obtaining synthetic compounds that will be safe for humans and do not pollute the environment, while at the same time present biological activity is crucial in terms of environmental protection. The review paper presents information in the literature on the substances and chemical compounds of natural origin (plant and animal derivatives) and synthetic compounds with a low environmental impact, showing antifungal properties, used in research on the ecological protection of wood. The review includes literature reports on the potential application of various antifungal agents including plant extracts, alkaloids, essential oils and their components, propolis extract, chitosan, ionic liquids, silicon compounds, and nanoparticles as well as their combinations.

Green Extraction of Cellulose Nanocrystals of Polymorph II from Cynara scolymus L.: Challenge for a “Zero Waste” Economy

The increase of agri-food wastes by agriculture and industries is one of the main causes of environmental pollution. Here we propose the recycling of Cynara scolymus L. wastes to obtain polymorph II cellulose nanocrystals (CNC). Two different extraction procedures are compared: (i) Soxhlet extraction in an ethanol/toluene mixture, and (ii) water boiling of the agricultural waste. Both procedures were followed by purification of cellulose fibers through bleaching treatments and extraction of cellulose nanocrystals by acid hydrolysis. CNCs have been extensively characterized by FTIR spectroscopy, electrophoretic light scattering measurements, X-ray powder diffraction methods, transmission electron microscopy, and thermogravimetric analyses. Extracted CNC are rod-like-shaped polymorph IIs with a good crystallinity index, and they are characterized by high hydrogen bonding intensity. The ELS measurements on samples from both procedures show good results regarding the stability of the CNC II sol (ζ < −40 ± 5 mV), comparable to that of the CNC polymorph I. Both polymorph II CNCs show better thermal stability, compared to CNC I. The results show that the easy extraction procedure from agricultural Cynara scolymus L. waste can be used to produce high-quality cellulose nanocrystals as a green alternative to the commonly used synthetic route.

Toxic metal sequential sequestration in water using new amido-aminoacid ligand as a model for the interaction with polyamidoamines

Polyamidoamines are low cost and easily synthesized materials that may find applications in cations sequestration and water treatment. In this paper a new amido-aminoacid ligand containing methionine has been designed as a monomeric model of the corresponding polyamidoamine. The amido-aminoacid ligand has been synthesized in high yield, by reacting acrylamide and methionine via aza-Michael addition in water and mild temperature conditions. The reaction has been monitored by NMR and Raman spectroscopies and the crystal structure has been determined by X-ray diffraction analysis. The coordination ability of the ligand towards Cu²⁺ cations in water, as well as its affinity for Ni²⁺ and Co²⁺ has been studied by potentiometric and spectrophotometric techniques. The divalent metal cations sequestration from water may occur with sequential selection by changing the pH of the solution. The copper complex with two coordinated ligands has been fully characterized in the solid state by single crystal X-ray diffraction. The results are discussed with a view to use these materials in the treatment of water contaminated by toxic transition metal ions.

Resistance to Growth of Molds for Wood Modified with Hydrophobic Hybrid Silica Gel Containing Copper Amine Complexes

Complexation copper with amine provides an effective strategy for fixation copper in wood, while hydrophobic modification improves the dimensional stability of wood. Thus, a combination of complexation and hydrophobization is expected to enhance the efficiency of copper-based biocides. In this study, hydrophobic hybrid silica gel containing copper amine complexes (MACu) was prepared through an in situ sol-gel process in wood using methyltriethoxysilane (MTES), 3-amino-propyltriethoxysilane (APTES), and copper chloride. The resistance to growth of molds for MACu modified wood (Populus tomentosa) was measured according to ASTM D3273-16. A leaching resistance test was carried out in accordance with AWPA E11-16. The results showed that only Aspergillus niger covered the surface of untreated wood blocks and no mold grew on the MACu surface even after the leaching test. MACu xerogel and MACu wood were further characterized by SEM-EDS, FTIR, and XPS. A possible schematic diagram of the reaction mechanism was proposed to explain the high-efficiency anti-mold performance of MACu wood.

Ag-functionalized nanocrystalline cellulose for paper preservation and strengthening

Waste paper is an environmentally friendly source of cellulosic material. Here we propose a new treatment based on nanocrystalline cellulose (CNC) for paper preservation and consolidation. Suspensions of CNC were prepared by sulfuric acid hydrolysis using waste paper as cellulose source (CNC_WP) and compared with CNC from cotton linter (CNC_CL). Both CNCs were obtained with good yield, showing high crystallinity index and comparable morphology, as demonstrated by DLS-ELS, XRD, FTIR, Raman and TEM analyses. CNCs were mixed with silver nanoparticles (CNC/Ag) and their biocidal activity was tested against Escherichia coli and Bacillus subtilis, measuring the minimum inhibitory concentration. CNCs were exploited as treatments for biocidal activity and consolidation on Whatman paper. The presence of silver nanoparticles doesn't affect aesthetic appearance of the original paper and prevents the growth of Aspergillus niger fungus. Mechanical tests demonstrated that the coatings by CNC based products improve stretch and toughness of the paper support.