Plasma technology in wool

The textile industry processes a large quantity of fibres obtained from various animals of which wool is commercially the most important. However, it has some technical problems which affect the quality and performance of the finished products such as felting shrinkage, handle, lustre, pilling and dyeability. These problems may be attributed mainly to the presence of wool scales on the fibre surface. The scales are relatively hard and have sharp edges which are responsible for causing fibre directional movement and shrinkage during felting. Furthermore, the scales also serve as a barrier for diffusion processes which will adversely affect the sorption behaviour. In recent years, there has been an increase in the modification of wool surface scales by physical means such as mechanical, thermal and ultrasonic treatments, and chemical methods such as oxidation, reduction, enzyme and ozone treatments which can solve the felting and sorption problems to a certain extent. Hitherto, chemical treatments are still the most commonly used descaling methods in the industry.

Owing to the effect of pollution caused by various chemical treatments, physical treatments such as plasma treatment have been introduced recently as they are capable of achieving a similar descaling effect. Since the 1960s, scientists have successfully exploited plasma techniques in materials science. The plasma technologies have been fully utilised to improve the surface properties of fibres in many applications. The fibres that can be modified by plasmas include almost all kinds of fibre such as textile fibres, metallic fibres, glass fibres, carbon fibres, fabrics and other organic fibres.

Plasma-treated wool has different physical and chemical properties when compared with the untreated one. The changes in fibre properties alter the performance of the existing textile processes such as spinning, dyeing and finishing to produce a series of versatile wool products with superior quality. Therefore, the aim of this monograph is to give a critical appreciation of the latest developments of plasma treatment of wool. In this monograph, different surface treatments of wool including plasma treatment will be precisely described. Since plasma treatment can be used to alter material surfaces by removing outer layers, thus the method of generation of plasma and the reaction mechanisms between material surface and plasma species will be highlighted in this monograph. Similar to other chemical reactions, the factors such as (i) the nature of gas used, (ii) gas flow rate, (iii) system pressure and (iv) discharge power affecting the final results of plasma treatments will be described.

The main content of this monograph includes the application of plasma treatment on wool under different industrial conditions such as dyeing and shrinkproofing processing which will be reported and discussed respectively. In addition, the common analytical methods such as Scanning Electron Microscopy, X-ray Photoelectron Spectroscopy and Fourier Transform Infrared Spectroscopy with Attenuated Total Internal Reflectance mode analysis employed for characterising the surface properties of plasma-treated wool will be discussed. Based on the surface characterisation results, more details about the mechanism of plasma treatment that affects the wool processing such as dyeing and shrinkproofing can be explored.

In the latter part of the monograph, the serviceability of plasma-treated wool fabrics is discussed and the possibility of applying the plasma-treated wool fabric to industrial use is evaluated based on standard performance specification, e.g. ASTM. The fabric performance in terms of tailorability and sewability are also discussed with reference to the Kawabata Evaluation System for Fabric (KES-F) results. As the plasma process is a “dry” process, i.e. the water used in the plasma system can be recycled, thus it can solve the industrial effluent problem resulting in providing an effective means for the modification of wool fabrics.     

Developments in functional finishing of cotton fibres – wrinkle-resistant,flame-retardant and antimicrobial treatments

Natural fibres, especially cotton, are still the most important kinds of fibres because of their numerous advantages such as high tensile strength, good abrasion resistance, high moisture absorption, quick drying and absence of static problems. However, cotton has poor elasticity and resilience, i.e. poor wrinkle recovery property. It is weakened easily by acids and resin chemicals used in finishing processes. In addition, fabrics made from untreated cotton fibres burn easily with a high flame velocity and are prone to being attacked by mildew and bacteria. Reducing wrinkling, flammability and microbial attacks of cotton fibre have been the major challenge facing the textile industry. The aim of this paper is to provide an overview of the current status of developments in functional finishing of cotton fabrics. Functional finishing agents, especially cross-linking agents, are embedded in cotton fabrics with the aid of acid catalysts, followed by drying and curing at high temperatures. The treated cotton fabrics often suffer from decrease in tensile strength, tear strength, abrasion resistance and sewability with a stiff, harsh and uncomfortable feel. Moreover, chemicals present in finishing agents react in the curing process to form some residues, which may even release free formaldehyde, which is of carcinogenic nature. The amount of formaldehyde remaining in the finished product depends largely on the amount and kind of finishing agents and catalysts used, as well as the curing conditions. Over the last decade, there have been many changes in the textile industry. The importance of environmental issues, which influence the direction of chemical finishing and reshaping the types of speciality chemicals used in textile wet processing, is a dominant theme in the market. Apart from the trend towards the use of environment-friendly chemical finishes, chemicals are being specially formulated for ease of application and high quality finishing. In this paper, the latest developments in textile functional finishing of cotton fabrics are critically reviewed and precisely described. The use of plasma surface treatment is one of the easiest and the most efficient ways to improve post-finishing of cotton fabrics. In general, the active species produced in plasma carry high energy to promote surface functionalisation reactions causing a sputtering or etching effect on cotton fabrics. The altered surface characteristics can still retain inherent advantages of cotton substrates and enhance material properties by incorporating with a large variety of chemically active functional groups. Furthermore, it may be necessary to add a suitable co-reactant to enhance the performance of chemical finishing and minimise the side effects. Recently, some finishing formulations involving catalytic effects induced by co-reactants have been developed. The aim of this paper is to critically and comprehensively examine the existing developments in textiles functional finishing, with special focus on wrinkle-resistant, flame-retardant and anti-microbial finishing of cotton fabrics. In addition, further developments of these finishing processes are discussed.     

Amine treatment of polyvinyl chloride/wood flour composites

Ethanolamine and L ‐arginine treated wood flour were added to polyvinyl chloride (PVC) in order to improve the interphase between PVC and wood. The influence of the treatment on pH‐value changes and nitrogen fixation of the wood and mechanical properties of the composite were evaluated. The treatments changed the pH of wood from acidic to basic. The highest nitrogen fixation was measured for monoethanolamine and L ‐arginine treated wood flour at high concentrations. Tensile strength, elongation at break, and unnotched impact strength were improved by ethanolamine and L ‐arginine treatments considerably. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Degradation of carbamazepine in environmentally relevant concentrations in water by Hydrodynamic-Acoustic-Cavitation (HAC)

The antiepileptic drug carbamazepine is one of the most abundant pharmaceuticals in the German aquatic environment. The effect of low carbamazepine concentrations (1-50 μg L⁻¹) is discussed controversially, but ecotoxicological studies revealed reproduction toxicity, decreased enzymatic activity and bioaccumulation in different test organisms. Therefore, as a preventive step, an efficient and cost-effective technique for wastewater treatment plants is needed to stop the entry of pharmaceuticals into the aquatic environment. Cavitation, the formation, growth, and subsequent collapse of gas- or vapor-filled bubbles in fluids, was applied to solve this problem. The technique of Hydrodynamic-Acoustic-Cavitation was used showing high synergistic effect. Under optimized conditions carbamazepine (5 μg L⁻¹) was transformed by pseudo-first order kinetics to an extent of >96% within 15 min (27% by hydrodynamic cavitation, 33% by acoustic cavitation). A synergistic effect of 63% based on the sum of the single methods was calculated. Carbamazepine concentrations were monitored by a sensitive and selective immunoassay and after 60 min no known metabolites were detectable by LC-MS/MS.     

Effect of supplementation of two sources and two levels of copper on lipid metabolism in Nellore beef cattle

This study was conducted with 35 Nellore beef cattle to determine the effect of supplementation of two levels and two copper sources (organic and inorganic) on metabolism of lipids and cholesterol of meat. The five treatments used were: Control: without copper supplementation, I10 or I40: 10 or 40 mg/kg DM (as Cu sulfate), O10 or O40: 10 or 40 mg/kg DM (as Cu proteinate). In general, the copper supplementation changed the fatty acid profile of meat (p<0.05), with a higher proportion of unsaturated fatty acids and reduction of saturated fatty acids. There was no effect of supplementation on blood cholesterol and triglycerides, however; in general, there was a reduction in cholesterol concentration in the L. dorsi (p<0.05) compared to the control treatment through the reduction (p<0.05) in the concentrations of GSH and GSH/GSSG ratio. The Cu supplementation did have an influence on metabolism of lipids. The production of healthier meat is beneficial to public health by reducing the risk of cardiovascular disease.     

Comparison of destructive and nondestructive sampling techniques of retail chicken carcasses for enumeration of hygiene indicator microorganisms

The type of sampling technique used to obtain food samples is fundamental to the success of microbiological analysis. Destructive and nondestructive techniques, such as tissue excision and rinsing, respectively, are widely employed in obtaining samples from chicken carcasses. In this study, four sampling techniques used for chicken carcasses were compared to evaluate their performances in the enumeration of hygiene indicator microorganisms. Sixty fresh chicken carcasses were sampled by rinsing, tissue excision, superficial swabbing, and skin excision. All samples were submitted for enumeration of mesophilic aerobes, Enterobacteriaceae, coliforms, and Escherichia coli. The results were compared to determine the statistical significance of differences and correlation (P < 0.05). Tissue excision provided the highest microbial counts compared with the other procedures, with significant differences obtained only for coliforms and E. coli (P < 0.05). Significant correlations (P < 0.05) were observed for all the sampling techniques evaluated for most of the hygiene indicators. Despite presenting a higher recovery ability, tissue excision did not present significant differences for microorganism enumeration compared with other nondestructive techniques, such as rinsing, indicating its adequacy for microbiological analysis of chicken carcasses.     

An investigation of strong sodium retention mechanisms in nanopore environments using nuclear magnetic resonance spectroscopy

Recent experimental research into the adsorption of various cations on zeolite minerals has shown that nanopore channels of approximately 0.5 nm or less can create an effect whereby the adsorption of ions, especially those that are weakly hydrated, can be significantly enhanced. This enhanced adsorption occurs due to the removal of hydrating water molecules which in turn is caused by the nanopore channel's small size. A new adsorption model, called the nanopore inner-sphere enhancement (NISE) effect, has been proposed that explains this unusual adsorption mechanism. To further validate this model a series of nuclear magnetic resonance (NMR) spectroscopy studies is presented here. NMR spectra were gathered for Na adsorbed on three zeolite minerals of similar chemical composition but differing nanoporosities: zeolite Y with a limiting dimension of 0.76 nm, ZSM-5 with a limiting dimension of 0.51 nm, and mordenite with a limiting dimension of 0.26 nm. The NMR experiments validated the predictions of the NISE model whereby Na adsorbed via outer-sphere on zeolite Y, inner-sphere on ZSM-5, and a combination of both mechanisms on mordenite. The strong Na adsorption observed in these nanoporous minerals conflicts with sodium's general designation as a weak electrolyte.     

A steady-state biofilm model for simultaneous reduction of nitrate and perchlorate, part 1: model development and numerical solution

A multispecies biofilm model is developed for simultaneous reduction of nitrate and perchlorate in the H(2)-based membrane biofilm reactor. The one-dimension model includes dual-substrate Monod kinetics for a steady-state biofilm with five solid and five dissolved components. The solid components are autotrophic denitrifying bacteria, autotrophic perchlorate-reducing bacteria, heterotrophic bacteria, inert biomass, and extracellular polymeric substances (EPS). The dissolved components are nitrate, perchlorate, hydrogen (H(2)), substrate-utilization-associated products, and biomass-associated products (BAP). The model explicitly considers four mechanisms involved in how three important operating conditions (H(2) pressure, nitrate loading, and perchlorate loading) affect nitrate and perchlorate removals: (1) competition for H(2), (2) promotion of PRB growth due to having two electron acceptors (nitrate and perchlorate), (3) competition between nitrate and perchlorate reduction for the same resources in the PRB: electrons and possibly reductase enzymes, and (4) competition for space in the biofilm. Two other special features are having H(2) delivered from the membrane substratum and solving directly for steady state using a novel three-step approach: finite-difference for approximating partial differential and/or integral equations, Newton-Raphson for solving nonlinear equations, and an iterative scheme to obtain the steady-state biofilm thickness. An example result illustrates the model's features.