Particle Shedding from Cotton and Cotton-Polyester Fabrics in the Dry State and in Washes.

The influence of 3, 10 and 50 washing cycles on the properties of cotton fabric and cotton-polyester blend in plain weave, was investigated in this study. In addition to the analysis of tensile properties in weft and warp directions and thickness, the number of particles produced in the dry state was also measured after 3, 10 and 50 washes. After washing, the entire effluent was analysed by determining the total suspended solids (TSS), the total solids (TS), the pH value and the conductivity. To determine the similarity of the observed wash cycles and properties of all processed samples, hierarchical cluster analysis (HCA) was performed. The fabric changes indicated by total wear in the warp direction after 50 washing cycles compared to unwashed ones amounting to 41.2% for cotton and 30.9% for cotton-polyester blend, may be attributed to the synergy of washing factors and raw material composition. Cotton fabric produced significantly more particles than cotton-polyester fabric in the dry state after the examined washing cycles in all size categories. A smaller number of released particles are in the larger size category >25 µm. The obtained TSS values confirm the degree of loading of the effluent with particulate matter from the analysed fabrics, since the detergent consists of water-soluble components. The HCA dendrograms confirmed that the release of particles during the first washing cycles is mainly determined by the structural properties of fabrics, while in the subsequent cycles the synergistic effect of chemical, mechanical and thermal effects in the interaction with the material prevailed.

Extending the Protection Ability and Life Cycle of Medical Masks through the Washing Process.

The reuse of decontaminated disposable medical face masks can contribute to reducing the environmental burden of discarded masks. This research is focused on the effect of household and laboratory washing at 50 °C on the quality and functionality of the nonwoven structure of polypropylene medical masks by varying the washing procedure, bath composition, disinfectant agent, and number of washing cycles as a basis for reusability. The barrier properties of the medical mask were analyzed before and after the first and fifth washing cycle indirectly by measuring the contact angle of the liquid droplets with the front and back surface of the mask, further by measuring air permeability and determining antimicrobial resistance. Additional analysis included FTIR, pH of the material surface and aqueous extract, as well as the determination of residual substances-surfactants-in the aqueous extract of washed versus unwashed medical masks, while their aesthetic aspect was examined by measuring their spectral characteristics. The results showed that household washing had a stronger impact on the change of some functional properties, primarily air permeability, than laboratory washing. The addition of the disinfectant agent, didecyldimethylammonium chloride, contributes to the protective ability and supports the idea that washing of medical masks under controlled conditions can preserve barrier properties and enable reusability.

Biopolymer Textile Structure of Chitosan with Polyester.

The research deals with functionalization of a standard polyester fabric with biopolymer chitosan, whose premises are multifunctional and favour ecological effects. Due to the incompatibility of synthetic and natural polymers, the chitosan treatment was preceded by alkaline hydrolysis with sodium hydroxide with the addition of cationic and anionic surfactants as promoters. Compatibility of the chitosan with untreated and alkali-hydrolyzed fabrics was performed by analysis of mechanical and physico-chemical properties. The number of characterisation procedures performed required the use of hierarchical cluster analysis (HCA) to identify homogeneous groups or clusters in which similarities and differences between samples are visible. Almost all applied methods and evaluation parameters have shown that alkaline hydrolysis of polyester fabric has the best potential for functionalization with chitosan. Therefore, the addition of surfactants as promoters during alkaline hydrolysis is not necessary in the pretreatment process phase.

Particle Characterization of Washing Process Effluents by Laser Diffraction Technique.

The dominant type of polymer particles in water, sediment, and various organisms partly derives from natural and synthetic fibres released in the washing process. Pollution of aquatic recipients with these particles poses an interdisciplinary problem throughout the world. Wastewater from washing represents a dispersion system with different particle sizes that is also loaded with the source of the particles. Due to this complex system, the qualification and quantification of this type of pollution is difficult. In this paper, the laser diffraction technique was applied to characterize particles in effluents from washing and rinsing materials made of a mixture of cotton and polyester. The results obtained through the analysis prove that the laser diffraction technique is acceptable for the characterization of a composite effluent sample. The advanced statistical technique of multivariate analysis confirmed the interrelationship of the parameters of this complex dispersion system.

Carboxymethyl Cellulose and Carboxymethyl Starch as Surface Modifiers and Greying Inhibitors in Washing of Cotton Fabrics.

This research is focused on cellulose and starch derivatives, carboxymethyl cellulose (CMC) and carboxymethyl starch (CMS), added to the detergent in washing reference cotton fabric in soft and hard water at 40, 60 and 90 °C. The applied polymers were analyzed through the potential of surface cellulose modification and inhibition of stain transfer from standard stain donors to modified and initial cotton fabrics. The surface modification of the cotton fabrics, characterized by the zeta potential and amounts of deposits, was coupled with the cluster analysis as well as a whiteness assessment. The obtained results of the zeta potential and degree of whiteness of the reference cotton fabrics before and after washing showed differences between CMC and CMS. The appropriateness of the cluster analysis was confirmed in assessing the potential of applied polymers for surface modification of cotton fabrics and greying inhibition.

Removal Efficiency of COD, Total P and Total N Components from Municipal Wastewater using Hollow-fibre MBR.

The membrane bioreactor (MBR) integrates well within the conventionally activated sludge system regarding advanced membrane separation for wastewater treatment. Over the last decade, a number of MBR systems have been constructed worldwide and this system is now accepted as a technology of choice for wastewater treatment especially for municipal wastewater. The aim of this work was to investigate and compare submerged MBR with conventionally-activated sludge system for the treatment of municipal wastewater in Maribor, Slovenia. It can be concluded from the results, that the efficiencies being determined by the parameters were satisfied, such as, chemical oxygen demand, total phosphorous, and total nitrogen, which were 97%, 75%, and 90%, respectively. The efficiencies of ultrafiltration membrane for the same parameters were also determined, and compared with biological treatment. The results of this analysis show an additional effect regarding an improvement in the quality of the permeate but primary treatment is also very important. For successfully application of MBR system smaller grid for primary treatment is needed.