Figure 3: Morphological characterization of unsupported sorbent. Shown here are representative nitrogen sorption isotherms A and pore size distributions B for the sorbent when synthesized as a monolith black and when synthesized as a thick film red Figure 4: Water vapor permeation.
Results from water vapor permeation analysis are presented for the complete CuDIX porphyrin functionalized sorbent on cotton fabric black. Cotton fabric only red and cotton fabric with only the sorbent component blue are presented for comparison. Permeation of CEES through a complete porphyrin functionalized sorbent coating on cotton fabric is presented black. Fabric only red and fabric with only the sorbent component blue are presented for comparison. The inset provides a zoomed view of the initial breakthrough period for the three materials. Here, we have shown that the microwave-initiated deposition of TEOS can be used to prepare fabric for subsequent deposition of a porous organosilicate sorbent.
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The approach leads to loading of the fabric with 1. Analysis of the coated fabric by nitrogen adsorption indicated deposition of a porous coating with significant differences between the full treated material and that of the initiated fabric. The surface area was, however, less than that observed for a similarly composed material synthesized as a monolith.
Initial breakthrough for the porphyrin functionalized treated fabric occurred at 2 min; initial breakthrough the cotton fabric was at 0. This reduction in chemical permeation was achieved with little impact on the water vapor transport of the fabric. The deposited sorbent is not a continuous thin film. The approach produces a coating that is more closely conformal to the yarn of the fabric. As a result, reduction to permeation is limited by the weave of the fabric. Here, a light-weight cotton fabric is used as the support material.
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The microwave initiation is suitable for use on other fabrics that provide amine or hydroxyl groups for modification. A more densely woven fabric, such as the nylon and cotton blend used in the US Army Combat Uniform ACU , would produce greater reduction to target transport simply on the basis of reduction in void spaces within the weave. A densely woven fabric used as a shelter material would provide similar advantages.
Recalling that the sorbent treatment is not limited to the surface of the fabric, a material providing some depth in the manner of a fleece or heavy knit fabric would also be expected to produce additional reductions in permeation. This concept would also apply to the three-dimensional pleated materials used in air filtration. The treatment outlined here is not limited to use on traditional fabrics.
It provides the potential for modification of the paper, layered, and pleated materials more typically applied in filtration approaches as well as nonwoven textiles. In some cases, the conditions described here may need to be gentled to maintain the integrity of the supporting material. Reducing the concentration of the base ammonium hydroxide may be necessary, as in the case of polyethylene fabrics. Shortening the duration of the microwave period may be necessary to avoid scorching paper materials. Some synthetic fabrics, polypropylene for example, require reduction in the drying temperatures used.
Changes to sol aging temperatures and durations should be avoided as these conditions have significant impact on the morphology of the resulting sorbent. Ethanol may be substituted for methanol in the dip coating sol. This is encouraged when scaling up a synthesis and using a larger volume of sol, because ethanol presents a lesser health hazard. The sol can be diluted considerably with alcohol, e. Relative amounts of reactants and solvent can also be multiplied to prepare a sol for generation of larger samples of coated materials.
The degree of dilution or concentration of a sol may impact the resulting mass loading of sorbent material on a particular fabric. Multiple cycles of dipping into a sol mixture should also lead to changes in total loading. Optimization of the deposition approach for other support materials is ongoing.
Modification of the ACU nylon and cotton blend fabric is of particular interest for a daily wear solution providing baseline chemical protection as are jersey knit based materials. The deposition of other sorbent materials is also being explored. The diethylbenzene bridged sorbents developed for capture of pesticide targets, for example, use a sol preparation that differs from the one described here 17 , 20 , 27 and catalysis is based on a different porphyrin. Finally, evaluation of the fabric supported materials against aerosol, liquid, and vapor targets is ongoing.
The views expressed here are those of the authors and do not represent those of the U. Navy, the U. Department of Defense, or the U. You must be signed in to post a comment. Please sign in or create an account. This content is Open Access. A verification has been sent to. Please check your email and follow the link to activate your 10 minute JoVE trial.
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Caution: Tetraethyl orthosilicate is flammable and toxic. To initiate the sample, submerge fabric substrate fully in the TEOS mixture and remove to a glass, microwave safe dish. NOTE: The fabric used here was a light weight, unbleached cotton obtained from a specialty crafts and fabrics retailer. The described process is suitable to a wide range of fabrics with the limitation that they must have available hydroxyl or amine groups 5.
The size of the dish is not important provided the cloth can lie flat within it. Microwave the saturated fabric sample using 1, W for 30 s. Caution: Fabric sample and dish will be hot following treatment. Microwave samples with sufficient ventilation and avoid inhalation of resulting vapors.
Repeat soaking and microwave treatment for a total of three cycles. Use immediately. Once dry, the fabric can be stored under ambient conditions. NOTE: The oven used here was a gravity oven, but any oven of sufficient size is suitable for drying the materials. Preparation of Sol for Dip Coating To prepare the sol, mix 1. Caution: 1,2-Bis trimethyoxysilyl ethane is flammable and toxic.
Avoid skin contact and inhalation. Mesitylene is flammable and toxic. Add 2. Seal the container and stir at rpm. Caution: Methanol is flammable and toxic and may present other health hazards. NOTE: In variations of this deposition, ethanol may be used in place of the methanol of this protocol. Additional information is provided in the Discussion. When the stirred solution appears homogeneous, add 6. Caution: Nitric acid is corrosive and can cause skin, eye, and respiratory system irritation.
Continuing stirring the mixture for 6 h. NOTE: The mixture is stable overnight at this point, but only in the absence of evaporation.
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If methanol evaporates during storage, changes to the sol-gel will occur. After curing, the fabric can be stored at ambient temperature, allowing for later extraction. Caution: Ethanol is flammable. NOTE: Ensure the container will tolerate necessary temperatures. Rinse the fabric with additional ethanol.
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Porphyrin Functionalization of Coated Fabrics To functionalize the sorbent material with primary amine groups, prepare a solution of 3-aminopropyltriethoxy silane APS in toluene at 0. Caution: 3-Aminopropyltriethoxy silane is corrosive and toxic. Toluene is flammable, toxic, and a known carcinogen. Submerge fabric in the solution and incubate for 1 h, covered. Rinse the samples thoroughly with toluene. To prepare the copper complex of Deuteroporphyrin IX 2,4 bis ethylene glycol DIX , dissolve 20 mg of the porphyrin in 2 mL dimethyl sulfoxide Caution: Porphyrins may present health hazards; follow recommended precautionary procedures.
Add the porphyrin solution to mL of water with Could urinary retinol be used as a new biomarker of kidney damage?
Trends Anal. Acta, , Ultra-high performance supercritical fluid chromatography in impurity control: Searching for generic screening approach. Khalikova, M. Acta , E-mail: [e-mail].