Preparation of Viscose Fibres Stripped of Reactive Dyes and Wrinkle-Free Crosslinked Cotton Textile Finish

The chemical recycling of cellulosic fibres may represent a next-generation fibre–fibre recycling system for cotton textiles, though remaining challenges include how to accommodate fibre blends, dyes, wrinkle-free finishes, and other impurities from finishing. These challenges may disrupt the regeneration process steps and reduce the fibre quality. This study examines the impact on regenerated viscose fibre properties of a novel alkaline/acid bleaching sequence to strip reactive dyes and dimethyloldihydroxyethyleneureas (DMDHEU) wrinkle-free finish from cotton textiles. Potentially, such a bleaching sequence could advantageously be integrated into the viscose process, reducing the costs and environmental impact of the product. The study investigates the spinning performance and mechanical properties (e.g., tenacity and elongation) of the regenerated viscose fibres. The alkaline/acid bleaching sequence was found to strip the reactive dye and DMDHEU wrinkle-free finish from the cotton fabric, so the resulting pulp could successfully be spun into viscose fibres, though the mechanical properties of these fibres were worse than those of commercial viscose fibres. This study finds that reactive dyes and DMDHEU wrinkle-free finish affect the viscose dope quality and the regeneration performance. The results might lead to progress in overcoming quality challenges in cellulosic chemical recycling.     

Characterization and pyrolysis of Chlorella vulgaris and Arthrospira platensis: potential of bio-oil and chemical production by Py-GC/MS analysis

Environmental Science and Pollution Research - Biofuels have been seen as potential sources to meet future energy demand as a renewable and sustainable energy source. Despite the fact that the...     

Volatile nanoparticle formation and growth within a diluting diesel car exhaust

A major source of particle number emissions is road traffic. However, scientific knowledge concerning secondary particle formation and growth of ultrafine particles within vehicle exhaust plumes is still very limited. Volatile nanoparticle formation and subsequent growth conditions were analyzed here to gain a better understanding of "real-world" dilution conditions. Coupled computational fluid dynamics and aerosol microphysics models together with measured size distributions within the exhaust plume of a diesel car were used. The impact of soot particles on nucleation, acting as a condensational sink, and the possible role of low-volatile organic components in growth were assessed. A prescribed reduction of soot particle emissions by 2 orders of magnitude (to capture the effect of a diesel particle filter) resulted in concentrations of nucleation-mode particles within the exhaust plume that were approximately 1 order of magnitude larger. Simulations for simplified sulfuric acid-water vapor gas-oil containing nucleation-mode particles show that the largest particle growth is located in a recirculation zone in the wake of the car. Growth of particles within the vehicle exhaust plume up to detectable size depends crucially on the relationship between the mass rate of gaseous precursor emissions and rapid dilution. Chassis dynamometer measurements indicate that emissions of possible hydrocarbon precursors are significantly enhanced under high engine load conditions and high engine speed. On the basis of results obtained for a diesel passenger car, the contributions from light diesel vehicles to the observed abundance of measured nucleation-mode particles near busy roads might be attributable to the impact of two different time scales: (1) a short one within the plume, marked by sufficient precursor emissions and rapid dilution; and (2) a second and comparatively long time scale resulting from the mix of different precursor sources and the impact of atmospheric chemistry.     

Application of chemical oxidation to remediate HCH-contaminated soil under batch and flow through conditions

This is the first study describing the chemical oxidation of hexachlorocyclohexanes (HCHs) in contaminated soil under water saturated and unsaturated flow through conditions. Soil contaminated with β-HCH (45 mg kg^?1) and γ-HCH (lindane, 25 mg kg^?1) was sampled from former lindane waste storage site. Efficiency of following treatments was tested at circumneutral pH: H₂O₂ alone, H₂O₂/Fe^II, Na₂S₂O₈ alone, Na₂S₂O₈/Fe^II, and KMnO₄. Experimental conditions (oxidant dose, liquid/solid ratio, and soil granulometry) were first optimized in batch experiments. Obtained results revealed that increasing dose of H₂O₂ improved the oxidation efficiency while in Na₂S₂O₈ system, maximum HCHs were removed at 300 mM. However, oxidation efficiency was slightly improved by Fe^II-activation. Increasing the solid/liquid ratio decreased HCH removal in soil samples crushed to 500 μm while an opposite trend was observed for 2-mm samples. Dynamic column experiments showed that oxidation efficiency followed the order KMnO₄ > Na₂S₂O₈/Fe^II > Na₂S₂O₈ whatever the flow condition, whereas the removal extent declined at higher flow rate (e.g., ~50% by KMnO₄ at 0.5 mL/min as compared to ~30% at 2 mL/min). Both HCH removal and oxidant decomposition extents were found higher in saturated columns than the unsaturated ones. While no significant change in relative abundance of soil mineral constituents was observed before and after chemical oxidation, more than 60% of extractable organic matter was lost after chemical oxidation, thereby underscoring the non-selective behavior of chemical oxidation in soil. Due to the complexity of soil system, chemical oxidation has rarely been reported under flow through conditions, and therefore our findings will have promising implications in developing remediation techniques under dynamic conditions closer to field applications.     

Treatment of hydrocarbon contamination under flow through conditions by using magnetite catalyzed chemical oxidation

Soil pollution by hydrocarbons (aromatic and aliphatic hydrocarbons) is a major environmental issue. Various treatments have been used to remove them from contaminated soils. In our previous studies, the ability of magnetite has been successfully explored to catalyze chemical oxidation for hydrocarbon remediation in batch slurry system. In the present laboratory study, column experiments were performed to evaluate the efficiency of magnetite catalyzed Fenton-like (FL) and activated persulfate (AP) oxidation for hydrocarbon degradation. Flow-through column experiments are intended to provide a better representation of field conditions. Organic extracts isolated from three different soils (an oil-contaminated soil from petrochemical industrial site and two soils polluted by polycyclic aromatic hydrocarbon (PAH) originating from coking plant sites) were spiked on sand. After solvent evaporation, spiked sand was packed in column and was subjected to oxidation using magnetite as catalyst. Oxidant solution was injected at a flow rate of 0.1 mL min^?1 under water-saturated conditions. Organic analyses were performed by GC–mass spectrometry, GC–flame ionization detector, and micro-Fourier transform infrared spectroscopy. Significant abatement of both types of hydrocarbons (60–70 %) was achieved after chemical oxidation (FL and AP) of organic extracts. No significant by-products were formed during oxidation experiment, underscoring the complete degradation of hydrocarbons. No selective degradation was observed for FL with almost similar efficiency towards all hydrocarbons. However, AP showed less reactivity towards higher molecular weight PAHs and aromatic oxygenated compounds. Results of this study demonstrated that magnetite-catalyzed chemical oxidation can effectively degrade both aromatic and aliphatic hydrocarbons (enhanced available contaminants) under flow-through conditions.     

Trends and issues in land and water resources management: Setting the agenda for change

The classical model of a paradigm shift is used to explore changes that are occurring in public lands and water resources management. Recent policy developments suggest that the traditional paradigm, which is characterized by sustained yield, is in the process of being invalidated. While no new paradigm has been fully accepted, the emerging paradigm does appear to be based on two principles: ecosystem management and collaborative decision making. Implementation of these two principles is likely to require extensive revision of traditional management practices and institutions. Failure to address these issues could result in adoption of the rhetoric of change without any lasting shift in management practices or professional attitudes.     

DECISION-MAKING IN THE DEVLOPMENT OF URBAN WATERFRONTS FOR PARK/BUSINESS USE1

Abstract: Opportunities for the development of an amalgam of park and leisure-oriented commercial establishments in urban-core waterfont settings exist in many U.S. cities. Public awareness of the need to enhance the environmental quality of these waterfont areas has resulted in a demand for planning and implementation action. However, the lack of understanding of urban political systems has been an inhibiting factor in the development of this park/ business concept. The major factors that influence the decision-making process leading to the development of urban-core waterfronts for park/business use are identified inthis paper. Understanding this decision-making process can aid project implementation and avoid waste of planning effort in time, dollars, and productivity.