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.     

基于耦合模型的安徽经济与环境协调发展分析

构建了经济发展与生态环境评价指标体系，选用耦合协调度模型计算2010—2019年安徽省不同区域经济发展与生态环境的耦合协调度，并采用灰色关联度法计算评价指标与耦合协调度的关联系数。研究结果表明：全省经济发展与生态环境的耦合协调度整体呈改善趋势，耦合协调度集中分布在0.393~0.765，基本处于良好协调或低水平协调阶段。全省不同区域的生态环境指数均大于经济发展指数。省会城市、沿江江南地区耦合协调度高于江淮之间和淮河以北地区。工业"三废"排放量、环境质量、环境污染治理力度是影响经济发展与生态环境耦合协调度的重要因素，建议通过改善这些方面进一步提升经济与环境的耦合协调度水平。     

巢湖底泥磷的释放模拟实验研究

在实验室条件下，模拟了DO控制、pH值调节、温度调节、水动力条件等，进行了底泥释磷实验。实验表明：（1）厌氧条件下，底泥中的磷向水体释放，且释放强度随pH值的升高而升高。好氧条件下，底泥非但没有向水体释放磷，反而从水体中吸附磷，呈“负释放”状态；且pH值越低，“负释放强度”越大。（2）温度升高有利于底泥中磷的释放，最大释放强度随温度的升高而提前。（3）搅动条件下的底泥磷释放量大于静置条件下的底泥磷释放量。（4）微生物对磷释放有明显的影响。从本次模拟实验结果看，体系温度升高、减少溶解氧、提高pH以及施以水动力作用，均可使底泥中的磷释放量增加，在常温（25℃）、厌氧、pH=7.5条件下，底泥中磷向水体的释放量将增加17％左右。     

齿形零件的冷摆辗成形

介绍了摆辗成形工艺的基本原理,综述了齿形零件冷摆辗精密成形和摆动辗压设备研制的概况.指明用压力加工方法,特别是冷摆辗工艺.加工精密齿形可提高零件机械性能,节能节材.     

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.     

地下水环境影响评价导则执行过程中遇到的问题及建议

对中国各地区地下水的水质情况进行了调查,分析了地下水环境管理和保护工作中的问题,指出地下水污染防治工作的重要性、迫切性。对《环境影响评价技术导则地下水环境》(HJ 610-2011)的工作等级划分、环境影响识别、环境现状调查、影响评价及污染防治等内容进行了简要介绍,汇总了评价导则执行后,对各类项目进行地下水评价过程中遇到的困难和问题,并在对各种问题进行分析的基础上,提出了有针对性的解决方法和建议。     

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.