Closing the loop: Analysis of biotechnological processes for sustainable valorisation of textile waste from the fast fashion industry

The textile industry currently stands as one of the most polluting sectors globally. The proliferation of fast fashion has led to an unprecedented increase in textile production and waste generation, marked by mixed material compositions and significant reduction in the lifespan of each garment. These factors contribute to the creation of complex mixed waste streams, with a majority ending up in landfills. In agreement with international sustainability directives, the textile sector has emerged as a prime candidate for harnessing valuable raw materials from waste. This review specifically targets the transformation of the prevailing linear production model into a more circular one. It focuses on utilizing biotechnological processes to convert textile waste into secondary raw materials to produce platform chemicals and added-value products, able to replace petrochemical-derived materials. The review begins with an extensive analysis of the state-of-the-art and the determination of technically feasible, economically viable, and environmentally sustainable waste valorisation techniques. The focus is on the pre-treatment phases of hydrolysis and fermentation of textile waste to produce industrially promising building blocks. Cotton and cotton-polyester blends, the two most common waste materials in fast fashion, were selected as the primary research materials. Significant variables affecting the efficiency of pre-treatment and hydrolysis methods are identified, highlighting the importance of pre-treatment and the potential use of enzymes for textile hydrolysis. Following the selected studies, the review defines the environmental and economic interests of the projects. These assessments provide essential insights into the sustainability and financial feasibility of the proposed waste valorisation methods

Toxicological profile of calcium carbonate nanoparticles for industrial applications.

Calcium carbonate nanoparticles (CaCO3NPs) derived from CO2 are promising materials for different industrial applications. It is imperative to understand their toxicological profile in biological systems as the human and environmental exposures to CaCO3NPs increases with growing production. Here, we analyse the cytotoxicity of CaCO3NPs synthesized from a CaO slurry on two cell lines, and in vivo on zebrafish (Danio Rerio). Our results demonstrate the CaCO3NPs in vitro safety as they do not cause cell death or genotoxicity. Moreover, zebrafish treated with CaCO3NPs develop without any abnormalities, confirming the safety and biocompatibility of this nanomaterial

Nano CaCO3 particles in cement mortars towards developing a circular economy in the cement industry

Abstract This paper calls into question the effects of incorporating nano calcium carbonate (CaCO3) particles in cement mortars, as they are interesting additive materials already successfully tested as cement nanofiller. These nanoparticles could potentially be prepared through the carbonation route using CO2 from combustion gases from the cement industry. This could enable a circular-economy approach for carbon capture and its re-use within the cement industry, in a sustainable and synergistic manner. In this study, part of the cement content was substituted with commercial nano CaCO3 particles to investigate their effects on the flexural and compressive strength of the resulting cement mortars, after curing for 7 and 28 days. Decreasing the cement content could lead to a reduction in the carbon footprint of cement, which is responsible for approximately 8% of global carbon dioxide emissions. Preliminary results using synthesized CaCO3 particles as nanofillers showed that, after 7 days of curing, mechanical properties of cement mortars improved. This indicates that hydration reaction was accelerated since CaCO3 acts as seeding for this reaction. By contrast, after 28 days of curing, no major improvement was observed. A higher content of calcium carbonate nanoparticles may have reduced the filler effect of these particles due to aggregation phenomena. In the present work, the effects of commercial nano CaCO3 particles on cement hydration were investigated. Mechanical tests showed promising results both after 7 and 28 days of curing. This could lead to the reduction of the carbon footprint of cement manufacturing and produce increasingly better performing building materials. Thus, the development of a circular economy in the cement industry could be achieved

Optimization of BiVO4 photoelectrodes made by electrodeposition for sun-driven water oxidation

In this work, the synthesis of cheap BiVO4 photoanodes for the photoelectrochemical water splitting reaction was optimized via the scalable thin film electrodeposition method. Factors affecting the photoelectrochemical activity, such as the electrodeposition time, the ratio of the Bi-KI to benzoquinone-EtOH in the deposition bath, and the calcination temperature, have been investigated by using the Central Composite Design of Experiments. Pristine monoclinic scheelite BiVO4 photoanodes having a photocurrent density of 0.45 ± 0.05mA/cm2 at 1.23 V vs RHE have been obtained. It was shown that a high photocurrent density is generally dictated by the following physico-chemical properties: a higher crystallite size, optimal thickness and a porous morphology, which give rise to a low charge transfer resistance, low onset potential and a high donor density. Moreover, to the best of our knowledge, this is the first report on the depth profile XPS analysis performed in BiVO4 photoanodes made by electrodeposition technique, from which it was concluded that the surface V species exist as V4+ while the bulk V species are V5+. The V4+ induces a higher amount of surface oxygen vacancies, which was found to be beneficial for the photoactivity

Aftertreatment Technologies for Diesel Engines: An Overview of the Combined Systems

The abatement of the pollutants deriving from diesel engines in the vehicle sector still represents an interesting scientific and technological challenge due to increasingly limiting regulations. Meeting the stringent limits of NOx and soot emissions requires a catalytic system with great complexity, size of units, and number of units, as well as increased fuel consumption. Thus, an after-treatment device for a diesel vehicle requires the use of an integrated catalyst technology for a reduction in the individual emissions of exhaust gas. The representative technologies devoted to the reduction of NOx under lean-burn operation conditions are selective catalytic reduction (SCR) and the lean NOx trap (LNT), while soot removal is mainly performed by filters (DPF). These devices are normally used in sequence, or a combination of them has been proposed to overcome the drawbacks of the individual devices. This review summarizes the current state of NOx and soot abatement strategies. The main focus of this review is on combined technologies for NOx removal (i.e., LNT–SCR) and for the simultaneous removal of NOx and soot, like SCR-on-Filter (SCRoF), in series LNT/DPF and SCR/DPF, and LNT/DPF and SCR/DPF hybrid systems