Circularizing PET-G Multimaterials: Life Cycle Assessment and Techno-Economic Analysis.

The recycling of multimaterials such as payment or access cards poses significant challenges. Building on previous experimental work demonstrating the feasibility of chemically recyclable payment cards made from glycol-modified poly(ethylene terephthalate) (PET-G), we use life cycle assessment and techno-economic analysis to investigate two chemical recycling scenarios and evaluate their potential environmental and economic benefits. Recovering all components from the depolymerized products (Scenario 1) achieves substantial environmental benefits across most categories, reducing global warming by up to 67% compared to only recovering major components (Scenario 2). However, the environmental benefits in Scenario 1 incur 69% higher total annualized costs, causing its profitability to be dependent on a minimum selling price of £13.4/kg for cyclohexanedimethanol and less than a 10% discount rate. In contrast, Scenario 2 is less sensitive to discount rate variation and thus a lower risk and more economically feasible option, albeit less environmentally sustainable.

Non-equilibrium potentiometric sensors integrated with metal modified paper-based microfluidic solution sampling substrates for determination of heavy metals in complex environmental samples.

Metal modified paper-based substrates were utilized for microfluidic paper-based solution sampling coupled with Pb2+-ion selective electrodes (ISEs) with the aim of controlling the super-Nernstian response which usually occurs when using unmodified paper substrates. Potentiometric responses of Pb2+-ISEs coupled with gold, platinum and palladium coated paper substrates were investigated. Potentiometric response time was found to be predominantly dependent on the thickness of metallic layer deposited at the paper substrates. Paper-based substrates coated on both sides with 38 nm gold layers were found to be the most advantageous in controlling the super-Nernstian response of ISEs at non-equilibrium conditions. Durability studies indicated that the lifetime of Pb2+-ISEs could be doubled when used with paper-based substrates in complex environmental samples with high solid-to-liquid content. Determination of lead in real samples using metal modified paper substrates coupled with Pb2+-ISEs was validated by inductively coupled plasma optical emission spectrometry (ICP-OES). Detailed life cycle assessments were performed for model screen printed potentiometric sensors with and without metal modified paper-based solution sampling substrates. The results confirmed that the use of modified paper substrates demonstrated lower environmental impact per potentiometric measurement of Pb2+-ISE in prepared simulated environmental sample as compared to sensors without the use of paper substrates.

Technical and environmental assessment of laboratory scale approach for sustainable management of marine plastic litter.

Laboratory scale recycling of marine plastic litter consisting of polyethylene terephthalate (PET) bottle sorting, pyrolysis and chemical vapor deposition (CVD) was conducted to identify the technical and environmental implications of the technology when dealing with real waste streams. Collected seashore and underwater plastics (SP and UP, respectively) contained large quantities of PET bottles (33.2 wt% and 61.4 wt%, respectively), suggesting PET separation was necessary prior to pyrolysis. After PET sorting, marine litter was converted into pyrolysis oil and multi-walled carbon nanotubes (MWCNTs). Water-based washing of litter prior to pyrolysis did not significantly change the composition of pyrolysis products and could be avoided, eliminating freshwater consumption. However, distinct differences in oil and MWCNT properties were ascribed to the variations in feedstock composition. Maintaining consistent product quality would be one of challenges for thermochemical treatment of marine litter. As for the environmental implications, life cycle assessment (LCA) demonstrated positive benefits, including improved climate change and fossil depletion potentials. The highest positive environmental impacts were associated with MWCNT production followed by pyrolysis oil and PET recovery. The benefits of proposed approach combining PET sorting, pyrolysis and CVD allowed to close the waste loop by converting most of the marine litter into valuable products.

Environmental footprint of voltammetric sensors based on screen-printed electrodes: An assessment towards "green" sensor manufacturing.

Voltammetric sensors based on screen-printed electrodes (SPEs) await diverse applications in environmental monitoring, food, agricultural and biomedical analysis. However, due to the single-use and disposable characteristics of SPEs and the scale of measurements performed, their environmental impacts should be considered. A life cycle assessment was conducted to evaluate the environmental footprint of SPEs manufactured using various substrate materials (SMs: cotton textile, HDPE plastic, Kraft paper, graphic paper, glass, and ceramic) and electrode materials (EMs: platinum, gold, silver, copper, carbon black, and carbon nanotubes (CNTs)). The greatest environmental impact was observed when cotton textile was used as SM. HDPE plastic demonstrated the least impact (13 out of 19 categories), followed by ceramic, glass and paper. However, considering the end-of-life scenarios and release of microplastics into the environment, ceramic, glass or paper could be the most suitable options for SMs. Amongst the EMs, the replacement of metals, especially noble metals, by carbon-based EMs greatly reduces the environmental footprint of SPEs. Compared with other materials, carbon black was the least impactful on the environment. On the other hand, copper and waste-derived CNTs (WCNTs) showed low impacts except for terrestrial ecotoxicity and human toxicity (non-cancer) potentials. In comparison to commercial CNTs (CCNTs), WCNTs demonstrated lower environmental footprint and comparable voltammetric performance in heavy metal detections, justifying the substitution of CCNTs with WCNTs in commercial applications. In conclusion, a combination of carbon black or WCNTs EMs with ceramic, glass or paper SMs represents the most environmentally friendly SPE configurations for voltammetric sensor arrangement.

In situ catalytic reforming of plastic pyrolysis vapors using MSW incineration ashes.

The valorization of municipal solid waste incineration bottom and fly ashes (IBA and IFA) as catalysts for thermochemical plastic treatment was investigated. As-received, calcined, and Ni-loaded ashes prepared via hydrothermal synthesis were used as low-cost waste-derived catalysts for in-line upgrading of volatile products from plastic pyrolysis. It was found that both IBA and air pollution control IFA (APC) promote selective production of BTEX compounds (i.e., benzene, toluene, ethylbenzene, and xylenes) without significantly affecting the formation of other gaseous and liquid species. There was insignificant change in the product distribution when electrostatic precipitator IFA (ESP) was used, probably due to the lack of active catalytic species. Calcined APC (C-APC) demonstrated further improvement in the BTEX yield that suggested the potential to enhance the catalytic properties of ashes through pre-treatment. By comparing with the leaching limit values stated in the European Council Decision, 2003/33/EC for the acceptance of hazardous waste at landfills, all the ashes applied remained in the same category after the calcination and pyrolysis processes, except the leaching of Cl- from the ESP, which was around the borderline. Therefore, the use of ashes in catalytic reforming application do not significantly deteriorate their metal leaching behavior. Considering its superior catalytic activity towards BTEX formation, C-APC was loaded with Ni at 15 and 30 wt%. The Ni-loading favored an increase in overall oil yield, while reducing the gas yield when compared to the benchmark Ni loaded ZSM catalyst. However, Ni addition also caused the formation of more heavier hydrocarbons (C20-C35) that would require post-treatment to recover favorable products like BTEX.

Heavy Metals Detection with Paper-Based Electrochemical Sensors.

This Feature summarizes recent works in paper-based potentiometry and voltammetry in heavy metal determination. Interactions of paper substrates with heavy metals, influence on the sensing response, and modification methods applied to paper substrates to improve the performance of recently developed electrochemical sensors are discussed. Since the rekindling of interest in paper-based analytical devices, methodologies and electrode designs for heavy metal determinations are highlighted. Promising aspects of the use of these sensors for samples containing solids and the increased versatility of the use of paper in analytics offers the possibility of increased acceptance of these low-cost platforms.

Diagnostics of skin features through 3D skin mapping based on electro-controlled deposition of conducting polymers onto metal-sebum modified surfaces and their possible applications in skin treatment.

Analytical diagnostics of skin features was developed through application of portable and fast skin mapping based on electro-controlled deposition of conducting polymers onto metal-sebum modified surfaces. In this analytical diagnostic technique, the development of skin pattern is based on electropolymerization of conducting polymers within insulating barriers in skin stamp provided by natural sebum to monitor the 3D nature of various skin features. The recorded skin maps reach a µm-level resolution and are proved to be capable of recognition, enhancement, and reproduction of surface outlines of various skin topographies, subsequently assisting dermatological diagnosis. The technique can precisely record skin surface morphology and reflect the vertical dimension information within 10 min and is aimed to assist dermatologists working with patients suffering from skin diseases via recording or monitoring the skin surface conditions. Additionally, successful trials of loading and electro-controlled release of Cu2+ into/from the developed skin patterns reveals its potential to be also utilized for treatment of pathological skin conditions. Based on the developed analytical diagnostic technique, a well-designed 3D printed portable prototype device based on electrosynthesis of the conducting polymer powered by an ordinary battery (1.5 V) was tested and was found to have excellent performance in onsite 3D skin pattern reproduction from live human skin.

Too small to matter? Physicochemical transformation and toxicity of engineered nTiO2, nSiO2, nZnO, carbon nanotubes, and nAg.

Engineered nanomaterials (ENMs) refer to a relatively novel class of materials that are increasingly prevalent in various consumer products and industrial applications - most notably for their superlative physicochemical properties when compared with conventional materials. However, consumer products inevitably degrade over the course of their lifetime, releasing ENMs into the environment. These ENMs undergo physicochemical transformations and subsequently accumulate in the environment, possibly leading to various toxic effects. As a result, a significant number of studies have focused on identifying the possible transformations and environmental risks of ENMs, with the objective of ensuring a safe and responsible application of ENMs in consumer products. This review aims to consolidate the results from previous studies related to each stage of the pathway of ENMs from being embodied in a product to disintegration/transformation in the environment. The scope of this work was defined to include the five most prevalent ENMs based on recent projected production market data, namely: nTiO2, nSiO2, nZnO, carbon nanotubes, and nAg. The review focuses on: (i) models developed to estimate environmental concentrations of ENMs; (ii) the possible physicochemical transformations; (iii) cytotoxicity and genotoxicity effects specific to each ENM selected; and (iv) a discussion to identify potential gaps in the studies conducted and recommend areas where further investigation is warranted.

Advances in Antiviral Material Development.

The rise in human pandemics demands prudent approaches in antiviral material development for disease prevention and treatment via effective protective equipment and therapeutic strategy. However, the current state of the antiviral materials research is predominantly aligned towards drug development and its related areas, catering to the field of pharmaceutical technology. This review distinguishes the research advances in terms of innovative materials exhibiting antiviral activities that take advantage of fast-developing nanotechnology and biopolymer technology. Essential concepts of antiviral principles and underlying mechanisms are illustrated, followed with detailed descriptions of novel antiviral materials including inorganic nanomaterials, organic nanomaterials and biopolymers. The biomedical applications of the antiviral materials are also elaborated based on the specific categorization. Challenges and future prospects are discussed to facilitate the research and development of protective solutions and curative treatments.

Processing of flexible plastic packaging waste into pyrolysis oil and multi-walled carbon nanotubes for electrocatalytic oxygen reduction.

Flexible plastic packaging waste causes serious environmental issues due to challenges in recycling. This study investigated the conversion of flexible plastic packaging waste with 11.8 and 27.5 wt.% polyethylene terephthalate (PET) (denoted as PET-12 and PET-28, respectively) into oil and multi-walled carbon nanotubes (MWCNTs). The mixtures were initially pyrolyzed and the produced volatiles were processed over 9.0 wt.% Fe2O3 supported on ZSM-5 (400 °C) to remove oxygenated hydrocarbons (catalytic cracking of terephthalic and benzoic acids) that deteriorate oil quality. The contents of oxygenated hydrocarbons were decreased in oil from 4.6 and 9.4 wt.% per mass of PET-12 and PET-28, respectively, to undetectable levels. After catalytic cracking, the oil samples had similar contents of gasoline, diesel and heavy oil/wax fractions. The non-condensable gas was converted into MWCNTs over 0.9 wt.% Ni supported on CaCO3 (700 °C). The type of plastic packaging influenced the yields (2.4 and 1.5 wt.% per mass of PET-12 and PET-28, respectively) and the properties of MWCNTs due to the differences in gas composition. Regarding the electrocatalytic application, both MWCNTs from PET-12 and PET-28 outperformed commercial MWCNTs and Pt-based electrodes during oxygen evolution reaction, suggesting that MWCNTs from flexible plastic packaging can potentially replace conventional electrode materials.

Prostatic Abscess in a Neonate.

Urinary tract infection (UTI) is the most commonly occurring serious bacterial infection in young infants. Uncircumcised male infants have a higher rate of UTI when compared with circumcised male infants and girls. A prostatic abscess is a very rare clinical variety of UTI, especially in neonates. We present the case of a 15-day-old male neonate who developed a rare variety of urosepsis. The baby was evaluated and found to have a prostatic abscess. Ultrasound of the abdomen showed an enlarged prostate gland with diffuse heterogeneous hypoechogenicity. Magnetic resonance imaging (MRI) of the pelvis showed an enlarged, lobulated prostate with T2 hyperintense signal and T1 hypointense signal and diffusion restriction. The post-contrast images in the pelvis-MRI also showed peripheral rim enhancement suggestive of a prostatic abscess. Urine culture showed growth of methicillin-resistant Staphylococcus aureus (MRSA). The baby was treated with intravenous vancomycin, and pus was drained through a transurethral approach. Phimosis can cause purulence in the prostate. Prostatic abscess usually has a good prognosis in neonates when diagnosed early and appropriate treatment was instituted.

Environmental impact assessment of converting flexible packaging plastic waste to pyrolysis oil and multi-walled carbon nanotubes.

A solution to low recycling rates of plastic waste is the conversion into multi-walled carbon nanotubes (MWCNTs) that have high value and can create additional revenue for plant operators. The purpose of this study was to perform a life cycle assessment (LCA) of an integrated system that involves flexible packaging plastic waste (FPPW) pyrolysis, oil upgrading, and MWCNTs production. The objectives were to determine the environmental impact of MWCNTs synthesis from non-condensable pyrolysis gases, and to assess the environmental impact of MWCNTs synthesis from different plastic fractions. Integrating MWCNTs synthesis to the plastic pyrolysis process provides various environmental benefits including, reduction of contribution towards climate change, fossil depletion, human toxicity (cancer), and ionizing radiation potentials. Sensitivity analysis of MWCNTs yields provided the range of impacts on the environment and a critical yield of >2% for most impact categories was determined. Comparison of different plastic fractions indicated that using low PET content feedstock had lesser impact on the environment, and demonstrated comparable performance to mixed virgin plastics for most impact categories. The results highlighted the versatility of the integrated pyrolysis process for treating diverse plastic waste fractions with negligible effects from the impurities present in the actual FPPW during thermal processing.

Human exposure and risk assessment of recycling incineration bottom ash for land reclamation: A showcase coupling studies of leachability, transport modeling and bioaccumulation.

Incineration bottom ash (IBA) faces challenges for its sustainable recycling due to the absence of scenario-specific risk assessment. Environmental risk assessment was carried out via a case study incorporating key factors to dominate human exposures during IBA utilization in land reclamation. Three research components echoing respective IBA leaching, exposures, and consequences were performed under a supportive framework to elaborate these interlinked key factors and unveil the potential environmental risks. IBA leachability was firstly investigated using various laboratory standard leaching methods while conducted a large-scale field trial experiment for mutual confirmation, suggesting that maximum leached amounts may be achieved when liquid to solid (L/S) ratio increases to 10. Dilution and transportation models were both developed to discriminate the mitigation of IBA leachate between two periods i.e. during and after land reclamation, suggesting that dilution rather than transportation may dominate the environmental impact for metal exposures. Metal bioaccumulation from a typical mollusk species was performed coupling the calculated dietary safety limits based on Singaporean diet intake for development of the threshold of toxicology concerns on human exposures. With such, IBA benign usage in land reclamation was also conferred in the form of distance and dilution factor.

Environmental perspectives of recycling various combustion ashes in cement production - A review.

Recycling different types of ashes for cement production has gained increasing attentions worldwide in a bid to close the waste loop. It minimizes waste landfilling and meanwhile produces useful secondary materials with reduced costs. Ascribed to the presence of elevated metal concentrations, however, it also receives negative inclination for their reuse. Herein, recycling various combustion ashes, such as municipal solid waste incineration fly ashes (MSWI FA), municipal solid waste incineration bottom ashes (MSWI BA), coal fly ashes (CFA), coal bottom ashes (CBA), blast furnace slags (BFS), biomass ashes (BIOA), sewage sludge ashes (SSA) and different co-combustion ashes (CCA), were comprehensively reviewed, from environmental perspectives combined with statistical data analysis (e.g. bulk components, trace metals, leaching potential, and etc.), to quantitatively explore their feasibility during cement production. It was unveiled that pozzolanic contents were predominant which highly fluctuated in their composition based on the ash type, limiting the replacement at maximum of 5-10 wt%. Considering total metal criteria, heavy metal contents posed challenges as secondary raw materials for blended cements. However, in consideration of metal leaching criteria, exothermic pozzolanic reactions in the second phase of blended cement would sufficiently alleviate their leaching potential, ensuring the environmental feasibility. Apart from the above, treatment costs have to be evaluated in nexus of multiple factors, whereas government policies play significant roles in valorization of recycling ashes. From sustainability perspective, life cycle assessment promises the overall strategy on ash utilization in cement industry.

Hydrolytic and acidogenic fermentation potential of food waste with source segregated feces-without-urine as co-substrate.

This study explored a new approach to enhance VFA productivity from anaerobic co-digestion of food-waste (FW) with source-segregated brown-water (BW) [feces-without-urine]. Effort was made to separate urine and BW from the source (using no-mix-toilet) mainly to expedite further treatment and resource-recovery. Effect of alkaline-pH [B] and acclimatized acidogenic inoculum [C] on acidification efficiency was investigated and compared with raw FW+BW co-digestion [A]. Batch-assay results indicated that VFA productivity persists for 144-h with about 615%, 522% and 376% increase in VFA-COD, respectively for 3-conditions [A-C]; which accounted for 70%, 49% and 58% of CODs input, respectively. High butyric-acid was observed in [A] and [C], followed by acetic, propionic-acids; whereas, abundant acetic-acid (86% of TVFA) was observed in [B], which are the most favorable-forms for methane production or other value-added-products. For 144-h of acidification, this study validated the feasibility of maximizing VFA-yield by 7-12 times compared to FW or BW as a sole-substrate.