Biodegradation of cotton and cotton/polyester fabrics impregnated with Ag/TiO2 nanoparticles in soil.

This study discusses the biodegradation behavior of cotton and cotton/PET fabrics impregnated with Ag/TiO2 nanoparticles in soil. Biodegradation behavior was evaluated by standard test method ASTM 5988-03 based on determination of percentage conversions of carbon content to CO2 as well as by soil burial test and enzymatic hydrolysis with cellulase where the extent of biodegradation was estimated by the calculation of fabric weight loss. The morphological and chemical changes of fibers during biodegradation process were analyzed by SEM and FTIR spectroscopy, respectively. The results obtained by all applied methods suggested that Ag/TiO2 nanoparticles hindered the biodegradation of investigated cotton and cotton/PET fabrics. Soil burial test indicated faster biodegradation of the impregnated blend compared to impregnated cotton fabric which is attributed to smaller amount of fabricated Ag nanoparticles on the blend proved by AAS measurement. Similar trend was established by enzymatic hydrolysis of cotton fibers. Severe damage of cotton fibers in both fabrics due to biodegradation process was confirmed by SEM. However, the cotton fiber damage occurred to a lesser extent in the samples that were impregnated with Ag/TiO2 nanoparticles. PET fibers remained intact which was also indicated by FTIR analysis.

Sonophotocatalytic degradation of dye C.I. Acid Orange 7 by TiO2 and Ag nanoparticles immobilized on corona pretreated polypropylene non-woven fabric.

This study discusses the possibility of using corona pre-treated polypropylene (PP) non-woven fabric as a support for immobilization of colloidal TiO2 and Ag nanoparticles in order to remove dye C.I. Acid Orange 7 from aqueous solution. Dye removal efficiency by sonocatalysis, photocatalysis and sonophotocatalysis was evaluated on corona pre-treated fabric loaded with TiO2 nanoparticles, corona pre-treated fabric double loaded with TiO2 nanoparticles and corona pre-treated fabrics loaded with TiO2 nanoparticles before and after deposition of Ag nanoparticles. In addition, the stability of PP non-woven fabric during these processes was investigated. The substrates were characterized by SEM, EDX and AAS analyses. The change of the dye concentration was evaluated by UV-VIS spectrophotometry. Unlike sonocatalysis and photocatalysis, complete dye removal from both solution and non-woven fabric was obtained already after 240-270 min of sonophotocatalysis. Corona pre-treated PP non-woven fabric loaded with Ag nanoparticles prior to deposition of TiO2 nanoparticles provided excellent degradation efficiency and superior reusability. Sonophotocatalytic degradation of dye in the presence of all investigated samples was the most prominent in acidic conditions. Although this nanocomposite system ensured fast discoloration of dye solution, TOC values of water measured after sonophotocatalysis were not satisfactory because of PP degradation. Therefore, it is suggested to include TOC evaluation in each case study where different supports for TiO2 nanoparticles are used since these nanoparticles may guarantee the dye removal from solution but the stability of support could be problematic causing even more serious environmental impact.

Superglide at an internal incommensurate boundary.

The intriguing possibility of frictionless gliding of one solid surface on another has been predicted for certain incommensurate interfaces in crystals, based on Aubry's solution to the Frenkel-Kontorova model of a harmonic chain in a periodic potential field. Here we test this prediction for grain boundaries by comparing atomistic simulations with direct experimental observations on the structure and load-deformation behavior of gold nanopillars containing a root-two incommensurate grain boundary. The simulations show supergliding at this boundary limited by finite-size effects which cause edges to act as defects of the incommensurate structure. Structural relaxation at the edges generates stacking faults, dislocations, and asymmetric surface steps. These features as well as the related load-displacement behavior are replicated by experimental observations on the compression of nanopillars using a quantitative nanoindentation device inside a transmission electron microscope. The good agreement between the observed and predicted behavior suggests that incommensurate interfaces could play an important role in the deformation of polycrystalline materials.