Silver nanoparticles (Ag-NPs) readily transform in the environment, which modifies their properties and alters their transport, fate, and toxicity. It is essential to consider such transformations when assessing the potential environmental impact of Ag-NPs. This review discusses the major transformation processes of Ag-NPs in various aqueous environments, particularly transformations of the metallic Ag cores caused by reactions with (in)organic ligands, and the effects of such transformations on physical and chemical stability and toxicity. Thermodynamic arguments are used to predict what forms of oxidized silver will predominate in various environmental scenarios. Silver binds strongly to sulfur (both organic and inorganic) in natural systems (fresh and sea waters) as well as in wastewater treatment plants, where most Ag-NPs are expected to be concentrated and then released. Sulfidation of Ag-NPs results in a significant decrease in their toxicity due to the lower solubility of silver sulfide, potentiall...

Environmental Transformations of Silver Nanoparticles: Impact on Stability and Toxicity

The concept of thermoregulating textiles capable of providing personal thermal management property (PTM) has attracted significant attention in recent years. It is considered as an emerging approach to promote the comfort and general well-being of wearers and also to mitigate the energy consumption load for indoor living space conditioning. Regulating the heat exchange between human body and environment has been the core subject of many studies on introducing the PTM functionality to textiles. This work provides an overview of the latest literature, summarizing the recent innovations and state-of-the-art approaches of controlling the heat gain and loss of textiles. To this end, methods to control the fundamental aspects of heat gain and loss of fabrics such as using near-infrared reflective materials and conductive nanomaterials, designing photonic structures of fabrics, and engineering nanoporous structures for passive cooling and heating effects will be discussed. Moreover, specific attention is given t...

Advanced Functional Fibrous Materials for Enhanced Thermoregulating Performance.

Functional nanofibers embedded into textiles for durable antibacterial properties

The main purpose of this work was to obtain durable antimicrobial cotton textiles functionalized with l-cysteine (Cys) and silver nanoparticles (Ag NPs). Cys molecules were covalently linked to cotton fibers via esterification with the cellulose hydroxyl groups, and the Ag NPs tightly adhered to the fiber surface via coordination bonds with the Cys thiol groups. As a result, the Ag NPs coating on the cotton fabric showed an excellent antibacterial function with an outstanding laundering durability. Even after 90 consecutive laundering tests, the modified cotton fabrics still showed satisfactory bacterial reduction rates against both Staphylococcus aureus and Escherichia coli, and the rates were are all higher than 94%. These findings will allow for broader applications of antimicrobial cotton textiles with a decreased safety risk and lower environmental impact due to the Ag NPs.

Silver-based, single-sided antibacterial cotton fabrics with improved durability via an l-cysteine binding effect

The room temperature electron reduction for the preparation of silver nanoparticles on cotton with high antimicrobial activity.

A major challenge in nanotechnology is that of determining how to introduce green and sustainable principles when assembling individual nanoscale elements to create working devices. For instance, textile nanofinishing is restricted by the many constraints of traditional pad-dry-cure processes, such as the use of costly chemical precursors to produce nanoparticles (NPs), the high liquid and energy consumption, the production of harmful liquid wastes, and multistep batch operations. By integrating low-cost, scalable, and environmentally benign aerosol processes of the type proposed here into textile nanofinishing, these constraints can be circumvented while leading to a new class of fabrics. The proposed one-step textile nanofinishing process relies on the diffusional deposition of aerosol NPs onto textile fibers. As proof of this concept, we deposit Ag NPs onto a range of textiles and assess their antimicrobial properties for two strains of bacteria (i.e., Staphylococcus aureus and Klebsiella pneumoniae). The measurements show that the logarithmic reduction in bacterial count can get as high as ca. 5.5 (corresponding to a reduction efficiency of 99.96%) when the Ag loading is 1 order of magnitude less (10 ppm; i.e., 10 mg Ag NPs per kg of textile) than that of textiles treated by traditional wet-routes. The antimicrobial activity does not increase in proportion to the Ag content above 10 ppm as a consequence of a "saturation" effect. Such low NP loadings on antimicrobial textiles minimizes the risk to human health (during textile use) and to the ecosystem (after textile disposal), as well as it reduces potential changes in color and texture of the resulting textile products. After three washes, the release of Ag is in the order of 1 wt %, which is comparable to textiles nanofinished with wet routes using binders. Interestingly, the washed textiles exhibit almost no reduction in antimicrobial activity, much as those of as-deposited samples. Considering that a realm of functional textiles can be nanofinished by aerosol NP deposition, our results demonstrate that the proposed approach, which is universal and sustainable, can potentially lead to a wide number of applications.

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Scalable and Environmentally Benign Process for Smart Textile Nanofinishing

In this paper, an aerosol-based process is shown for imparting antibacterial property to textiles. Metal nanoparticles (copper and silver) are produced by means of DC electrical discharges (glow and arc) between two electrodes in nitrogen at ambient pressure and passed through textile fabrics (cotton, polyester and lyocell) which act as filter media. The particle retention efficiency of the fabrics is measured in dependence of particle size and face velocity. The antibacterial performance of the fabrics treated with metal nanoparticles and its durability to wash is assessed according to industry standards. Loads of about 200 ppm (2x10-2 %wt.) of nanoparticles of copper or silver give strong antibacterial property but the colour and hand feeling of the fabrics are significantly affected. Nanosilver loads in the order of 50 ppm (5x10-3 %wt.) impart comparably high antibacterial property to the fabrics with no visible impact on colour and hand touching, and wash fastness is proven for 10 washes. Small silver nanoparticles (<5 nm) result in much less release of silver to wash water, with respect to larger nanoparticles (>20 nm).

/pdf/a-sustainable-route-for-antibacterial-nanofinishing-of-ubl7yqk2h8.pdf

A Sustainable Route for Antibacterial Nanofinishing of Textiles

In this paper, an aerosol-based process is proven for imparting antibacterial property to textiles. Nanoparticles of copper and silver are produced by means of glow discharge between two electrodes in nitrogen at atmospheric pressure and passed through fabrics of cotton and polyester which act as filter media. The bactericidal performance of the nanofinished fabrics is assessed against Gram-positive Staphylococcus aureus and Gramnegative Klebsiella pneumonia bacteria. Nanoparticle loads of about 0.3 g/m2 (~ 0.2 wt %) give strong antibacterial activity to the fabrics regardless of particle composition and size. Higher loads do not enhance the bactericide property but affect the colour and hand feel of the fabrics. Cotton and polyester fabrics with low loads (<0.3 g/m2) of small silver nanoparticles (<10 nm) show different bactericidal behaviour. Polyester fabrics attain good antibacterial activity for SA and KP, which is retained (KP) or decreases (SA) after washing. Cotton fabrics show hardly bactericidal property but, in some cases, it increases after washing. (Less)

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María Blanes

Papers

Scalable and Environmentally Benign Process for Smart Textile Nanofinishing

A Sustainable Route for Antibacterial Nanofinishing of Textiles

A Green Dry Route for Antibacterial Nanofinishing of Textiles