Discussion on key issues of carbon footprint accounting for bast fiber textiles.

Bast fiber textiles have become increasingly popular as a sustainable alternative in recent years. Although the carbon emissions of bast fiber textiles have been studied using life cycle assessment method, there is a lack of comprehensive literature analyzing and summarizing the results. This study reviews the current state of research on the carbon emissions of bast fiber textiles. Compared to other plant fibers, there are fewer studies on the carbon footprint or life cycle assessment of bast fiber textiles, and these studies lack a comprehensive "cradle to grave" or "gate to grave" analysis. In addition, inconsistencies exist in the allocation methods used for carbon footprint assessments. This study suggests a combination of physical and economic allocation to conduct a more accurate environmental impact assessment of bast fiber textiles. On the basis of the above review, this study modularizes the process of the entire life cycle of textiles and analyzes the carbon sequestration and emission characteristics to determine the main considerations for carbon footprint assessment. The carbon sequestration effect of bast fiber textiles should be analyzed at the raw material extraction stage and at the end-of-life stage. Oxygen release and consumption are also considered as additional factors to be quantified and analyzed in this study. In the future, the modular method should be used for all carbon footprint evaluation reports for bast fiber textiles. This method helps to comprehensively quantify and evaluate the carbon footprint of bast fiber textiles throughout their entire life cycle. It can provide recommendations for green design, green production and sustainable consumption.

A systematic review of the life cycle environmental performance of cotton textile products.

The production of cotton textiles involves cotton cultivation, ginning, spinning, weaving, knitting, dyeing, finishing, cutting and sewing. It consumes large quantities of freshwater, energy and chemicals, causing serious environmental impacts. The environmental impacts of cotton textiles have been studied extensively through various methods. However, little literature comprehensively summarizes current status of researches on environmental impact of cotton clothing comprehensively and identifies common problems to further study. To fill this gap, this study collates published results on the environmental performance of cotton clothing based on different environmental impact assessment methods, i.e., life cycle assessment, carbon footprint, and water footprint. Apart from the environmental impact results, this study also discusses the key issues when assessing the environmental impact of cotton textiles, such as data collection, carbon storage, allocation methods, and the environment benefits brought by recycling. In the production process of cotton textile products, there will be other co-products with economic value so that the environmental impact should be allocated. The economic allocation method is the most widely used method in the existing researches. In the future, considerable efforts are required to construct the accounting modules which consist of multiple modules, each representing a production process of cotton clothing and including an inventory of inputs under that process, such as cotton cultivation (water, fertilizer, pesticides), and spinning (electricity). It can ultimately be used to flexibly invoke one or more modules to calculate the environmental impact of cotton textiles. Moreover, returning carbonized cotton straw to the field can retain about 50 % of carbon, thus having a certain potential for carbon sequestration.

Constructing Sandwich-Structured Poly(vinyl alcohol) Composite Films with Thermal Conductive and Electrical Performance.

With the miniaturization and high integration development in microelectronic devices, the problem of heat dissipation has attracted widespread attention. Highly thermal conductive and electrical insulation polymer composites show great advantages to solve the problems of heat dissipation. Nevertheless, the fabrication of polymer composites with both excellent thermal conductivity and electrical performance is still a great challenge. Herein, to coordinate the thermal and electrical properties of the composite film, the sandwich-structured poly(vinyl alcohol) (PVA)/boron phosphide (BP)-boron nitride nanosheet (BNNS) composite films were prepared, with the PVA/BP composite film as the top and bottom layers and the BNNS layer as the middle layer. When the filler loading was 31.92 wt %, the sandwich-structured composite films showed excellent in-plane thermal conductivity (9.45 W·m-1·K-1), low dielectric constant (1.25 at 102 Hz), and excellent breakdown strength. In the composite film, the interconnected BP particles and BNNS layer formed several heat dissipation pathways to increase the thermal conductivity, while the insulated BNNS layer hampered the electron transformation to enhance the electrical resistivity of films. Therefore, the PVA/BP-BNNS composite films showed a potential application in heat dissipation of high power electronic devices.

Carbon footprint assessment of face masks in the context of the COVID-19 pandemic: Based on different protective performance and applicable scenarios.

Widespread concerns have been raised about the huge environmental burden caused by massive consumption of face masks in the context of the COVID-19 pandemic. However, most of the existing studies only focus on the environmental impact associated with the product itself regardless of the actual usage scenarios and protective performance of products, resulting in unrealistic conclusions and poor applicability. In this context, this study integrated the product performance into the existing carbon footprint assessment methodology, with focus on the current global concerns regarding climate change. Computational case studies were conducted for different mask products applicable to the scenarios of low-, medium- and high-risk levels. The results showed that reusable cotton masks and disposable medical masks suitable for low-risk settings have a total carbon footprint of 285.484 kgCO2-eq/FU and 128.926 kgCO2-eq/FU respectively, with a break-even point of environmental performance between them of 16.886, which implies that cotton masks will reverse the trend and become more environmentally friendly after 17 washes, emphasizing the importance of improving the washability of cotton masks. Additionally, the total carbon footprints of disposable surgical masks and KN95 respirators were 154.328 kg CO2-eq/FU and 641.249 kg CO2-eq/FU respectively, while disposable medical masks and disposable surgical masks were identified as alternatives with better environmental performance in terms of medium- and high-risk environments respectively. The whole-life-cycle oriented carbon footprint evaluation further indicated that the four masks have greater potential for carbon emission reduction in the raw material processing and production processes. The results obtained in this study can provide scientific guidance for manufacturers and consumers on the production and use of protective masks. Moreover, the proposed model can be applied to other personal protective equipment with similar properties, such as protective clothing, in the future.

Assessing environmental impact of NOX and SO2 emissions in textiles production with chemical footprint.

Air pollution is a major concern of the new civilized world due to its adverse impact on human health and environment. As typical air pollutants, nitrogen oxide (NOX) and sulfur dioxide (SO2) not only pollute the atmosphere by forming acid rain and particulate matter, but are also harmful to the human respiratory system. Significant emissions of NOX and SO2 in the production phases make the textile industry under enormous environmental pressure. Chemical footprint (ChF) is an effective method for transforming the potential environmental risks of pollutant emissions into an intuitive form of toxicity. In this study, we present a ChF assessment method for NOX and SO2 emissions from textiles production. For this purpose, we adopt the USEtox model and calculate the relevant characterization factors (CFs) by considering the physicochemical properties and toxicity of NOX and SO2. The textile industry in Zhejiang Province, China, is chosen as a case study to demonstrate the feasibility of this proposed ChF assessment methodology. Results indicate that ChF caused by NOX emission in Zhejiang's textile industry is approximately eight times larger than that caused by SO2 emission. The four sub-sectors of Zhejiang's textile industry (textile manufacturing sector; textile wearing apparel, footware, and caps manufacturing sector; leather, fur, feather and related products manufacturing sector; chemical fibers manufacturing sector) also have similar proportional distributions of ChFs. Besides, the textile manufacturing sector has the largest ChF, accounting for 73% of the total ChF caused by NOX and SO2 emissions.

An improved method for assessing environmental impacts caused by chemical pollutants: A case study in textiles production.

The use of chemicals in the textile industry has been widely investigated. This study used an improved method with the USEtox model to assess the environmental impacts of chemical pollutants discharged by the textile industry. The environmental impacts attributed to the discharged chemical pollutants were ranked using a quantity analysis method and a toxicity analysis method. The rankings of the two methods were compared by calculating Spearman's correlation coefficients and outliers. The results showed that the human health and ecological hazards potential were mainly caused by heavy metals. The rankings of the environmental impacts calculated with the quantity analysis method were different from those calculated with the toxicity analysis method. Cadmium, hexachlorobenzene and mercury caused severe human and ecological hazards with a small volume of emissions. Zinc and hexavalent chromium were highly toxic chemical pollutants, which could cause severe human health and ecological hazards potential. These five kinds of chemical pollutants should be preferentially controlled to mitigate the environmental impacts caused by chemical pollutants discharged from the textile industry.

Assessing environmental impact of textile production with water alkalization footprint.

The dyeing process contributes most to the water consumption and wastewater emission associated with the textile industry, leading to water depletion and degradation. The water footprint is an effective concept for evaluating the environmental impact of textile production processes on water bodies, and serves as a reference for practitioners seeking to develop suitable water management strategies. Water degradation can be quantified in terms of several sub-indicators, such as aquatic eutrophication, acidification, and ecotoxicity. However, some processes (such as the production of viscose fiber and dyeing) produce significant quantities of alkaline wastewater that can alkalize the receiving water bodies. In this study, we proposed the concept of water alkalization footprint to assess the potential impact of water alkalization caused by textile production. To achieve this, we constructed an evaluation framework and calculated the relevant characterization factors by considering the mechanisms of chemical reaction. A dyeing mill was selected as a case study to demonstrate the feasibility of the concept. The results indicate that the dyeing of 1 ton of viscose fabric produces a water alkalization footprint of 15.478 kg OH- equiv, and that NaOH in the wastewater from the desizing and dyeing phases was the largest contributor at 97.23%.

Water environmental stress, rebound effect, and economic growth of China's textile industry.

The rapid development of China's textile industry (TI) has led to severe water environmental stress. Water environmental stress of China's TI mainly comes from large quantities of discharged wastewater and chemical oxygen demand (COD). The sustainable development of the TI is realized to achieve the decoupling between economic growth and water environmental stress. This study analyzes the decoupling elasticity results from wastewater discharge and COD discharge, respectively. Decoupling results show that TI's wastewater has strong decoupling from economic growth for three years (2002, 2013-2014) while COD has strong decoupling for six years (2002-2003, 2008, 2010, 2013-2014). The paper further calculates the decoupling elasticity results of the TI's three sub-sectors (manufacture of textile sector, manufacture of textile wearing and apparel sector, and manufacture of chemical fibers (MCF) sector), and calculates the factors that affect wastewater discharge. The decrement and rebound effects of wastewater discharge are analyzed based on calculated results. Decomposition results show that the scale factor is the most significant contributor to wastewater discharge, the intensity factor inhibits wastewater discharge, and the effect of the structure factor is not evident. The decrement effect of TI increases yearly, but the rebound effect shows that the absolute amount of wastewater discharge also increases. The rebound effect has declined since 2012. In the three sub-sectors, MCF's decrement effect is the strongest, and its rebound effect is the weakest, which indicate that MCF is the biggest contributor to the discharge reduction of China's TI.

Blue and grey water footprint of textile industry in China.

Water footprint (WF) is a newly developed idea that indicates impacts of freshwater appropriation and wastewater discharge. The textile industry is one of the oldest, longest and most complicated industrial chains in the world's manufacturing industries. However, the textile industry is also water intensive. In this paper, we applied a bottom-up approach to estimate the direct blue water footprint (WFdir,blue) and direct grey water footprint (WFdir,grey) of China's textile industry at sector level based on WF methodology. The results showed that WFdir,blue of China's textile industry had an increasing trend from 2001 to 2010. The annual WFdir,blue surpassed 0.92 Gm(3)/yr (giga cubic meter a year) since 2004 and rose to peak value of 1.09 Gm(3)/yr in 2007. The original and residuary WFdir,grey (both were calculated based on the concentration of chemical oxygen demand (CODCr)) of China's textile industry had a similar variation trend with that of WFdir,blue. Among the three sub-sectors of China's textile industry, the manufacture of textiles sector's annual WFdir,blue and WFdir,grey were much larger than those of the manufacture of textile wearing apparel, footware and caps sector and the manufacture of chemical fibers sector. The intensities of WFdir,blue and WF(res)dir,grey of China's textile industry were year by year decreasing through the efforts of issuing restriction policies on freshwater use and wastewater generation and discharge, and popularization of water saving and wastewater treatment technologies.