Since the start of the global COVID-19 pandemic, extensive quantities of face masks have been used and discarded. Most of these masks end up in landfills, causing a high environmental impact and no ...benefits. However, there are alternative ways to deal with this waste in a more sustainable way. For example, valorisation of face masks through pyrolysis has received special attention because it offers efficient application to produce a liquid oil that can be used as a diesel substitute and a solid char that can be used as an activated carbon substitute after activation. In this context, this study applies the Life-Cycle Assessment methodology to quantify and analyse the environmental impacts of different treatment scenarios based on the pyrolysis of surgical masks and FFP2 masks. It also compares their environmental performance with the conventional practice of landfilling. The scenarios studied include both thermal and catalytic pyrolysis by using sepiolite, a low-cost material abundant in Spain. Data on the pyrolysis process were obtained from laboratory experiments. It was found that the use of the produced oil as a diesel substitute very significantly reduces the environmental impact in all pyrolysis scenarios. Consequently, the pyrolysis of face masks can reduce the environmental impact caused by the treatment of this waste material. Furthermore, the thermal pyrolysis performs environmentally better than the catalytic pyrolysis. In all scenarios, freshwater ecotoxicity and marine ecotoxicity are the environmental impact categories that cause the highest environmental impact overall.
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•Large amounts of face masks were used and discarded during the COVID-19 pandemic.•Current options for managing this waste are costly and have environmental impacts.•Thermal and catalytic pyrolysis of face masks is proposed as a sustainable option.•We analyse the environmental impact of the pyrolysis using Life-Cycle Assessment.•Thermal pyrolysis has a better environmental performance than catalytic pyrolysis.
Nowadays, the environmental challenges associated with plastics are becoming increasingly prominent, making the exploitation of alternatives to landfill disposal a pressing concern. Particularly, ...polyvinyl chloride (PVC), characterized by its high chlorine content, poses a major environmental risk during degradation. Furthermore, PVC recycling and recovery present considerable challenges. This study aims to optimize the PVC pyrolysis valorization process to produce effective adsorbents for removing contaminants from gaseous effluents, especially CO2. For this purpose, PVC waste was pyrolyzed under varied conditions, and the resulting solid fraction was subjected to a series of chemical and physical activations by means of hydroxides (NaOH and KOH) and nitrogen. Characterization of the PVC-based activated carbons was carried out using surface morphology (SEM), N2 adsorption/desorption, elemental analysis, and FTIR, and their capacity to capture CO2 was assessed. Finally, neuro-fuzzy models were developed for the optimization of the valorization technique. The resulting activated carbons exhibited excellent CO2 adsorption capabilities, particularly those activated with KOH. Optimal activation conditions include activations at 840 °C with NaOH at a ratio of 0.66 and at 760 °C using either NaOH or KOH with ratios below 0.4. Activations under these experimental conditions resulted in a significant increase in the adsorption capacity, of up to 25%, in the resulting samples.
In this work, first, the two-phase olive mill solid waste was characterized in terms of its physical–chemical properties, which can be useful for its use in pyrolysis units. Then, its behavior on ...pyrolysis processes was studied by dynamic thermogravimetry and derivate thermogravimetry. For the simulation of pyrolysis processes a kinetic model including three independent parallel reactions was used. The characterization results showed that the solid presents a size distribution with about 66% of particles >1.00mm, while the percentage of fines (<0.250mm) is only of 1.50%. The moisture content is very high (around 70%), being one of the main characteristics of the solid that makes its direct use as a fuel difficult. However, the low sulfur value (<0.1%) is very suitable from the environmental point of view, reducing SO2 emissions. The results of the proximate analysis are within the range of most biomass waste and the gross calorific value obtained was 4897kcal/kg. The thermal decomposition in an inert atmosphere can be modeled by separate decomposition of each of the three fractions which constitute the material. The results of both, physical–chemical characterization and thermogravimetric study show that the two-phase olive mill solid waste could be treated in energy recovery installations.
•The physical-chemical characterization of the solid is required for use as fuel.•The solid has a physic-chemical characteristics suitable for use as fuel.•Pyrolysis can be modeled by separate decomposition of fractions of the material.•Two-phase olive mill solid waste could be treated in energy recovery installations.
In this study, an encapsulated purified bentonite/sodium alginate composite (PB/SA) was successfully prepared by solution intercalation and ionic crosslinking using calcium chloride. The PB/SA ...adsorbent was characterised by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer-Emmett-Teller method (BET) from N
2
adsorption-desorption isotherm at 77 K, thermogravimetric analysis (TGA), and the point of zero charge (pH
PZC
). Adsorption efficiency of PB/SA was studied by using methylene blue dye (MB) in batch, recirculating and continuous systems. The effect of certain parameters on the adsorption capacity in the different systems was investigated. The results from batch study showed that MB removal increased with increasing adsorbent dose and pH solution. The test of operating parameters in continuous system, such as the bed height and the adsorbate flow rate, showed that MB removal increases at lower flow rate (2 mL/min) and higher bed height (2.4 cm). Kinetics modelling shows that the adsorption of MB onto PB/SA in batch and recirculating processes was well described by the pseudo-first-order model with high coefficient correlation R
2
(0.99). Regarding results from isotherms, the MB adsorption follows the Langmuir isotherm with R
2
exceeding 0.99 justifying monolayer and homogeneous adsorption. In addition, when comparing batch and recirculating processes, we observed that for a range of initial concentrations from 10 to 100 mg/L, the maximum adsorbed amounts were found to be 100 mg/g and 86.6 mg/g respectively for batch and recirculating systems. However, these values are higher in isotherms modelling because the results were fitted and compared only for low concentrations without the equilibrium lines. Hence, PB/SA beads can be a promising material for enhancing the elimination of dyes from an aqueous solution in different adsorption processes.
Bagasse from sugarcane, a waste material, has been studied as a biosorbent for removing lead from aqueous solutions in batch systems. In this study, bagasse was modified by sulphuric acid to enhance ...sorption capacity for lead and the origin of the enhancement was investigated by observing the change in surface functional group concentrations and the lead sorption behaviours. The untreated and treated bagasse was characterized by elemental analysis, SEM, FTIR and potentiometric titrations. Titrations revealed two different types of sites present on both solid wastes that probably correspond to carboxyl and amine groups. Sorption isotherm test showed that equilibrium sorption data were better represented by Langmuir model than the Freundlich model. The sorption capacities for lead of untreated bagasse and bagasse treated by H
2SO
4 were 6.366 and 7.297
mg/g, respectively at 25
°C and pH 5.
Nowadays, the environmental challenges associated with plastics are becoming increasingly prominent, making the exploitation of alternatives to landfill disposal a pressing concern. Particularly, ...polyvinyl chloride (PVC), characterized by its high chlorine content, poses a major environmental risk during degradation. Furthermore, PVC recycling and recovery present considerable challenges. This study aims to optimize the PVC pyrolysis valorization process to produce effective adsorbents for removing contaminants from gaseous effluents, especially COsub.2. For this purpose, PVC waste was pyrolyzed under varied conditions, and the resulting solid fraction was subjected to a series of chemical and physical activations by means of hydroxides (NaOH and KOH) and nitrogen. Characterization of the PVC-based activated carbons was carried out using surface morphology (SEM), Nsub.2 adsorption/desorption, elemental analysis, and FTIR, and their capacity to capture COsub.2 was assessed. Finally, neuro-fuzzy models were developed for the optimization of the valorization technique. The resulting activated carbons exhibited excellent COsub.2 adsorption capabilities, particularly those activated with KOH. Optimal activation conditions include activations at 840 °C with NaOH at a ratio of 0.66 and at 760 °C using either NaOH or KOH with ratios below 0.4. Activations under these experimental conditions resulted in a significant increase in the adsorption capacity, of up to 25%, in the resulting samples.
La contaminación de las aguas residuales con metales pesados presenta hoy en día un gran problema para el Medio Ambiente. El uso extensivo del níquel para la fabricación de productos requeridos por ...la sociedad actual ha provocado la contaminación del aire, suelo y agua. Uno de los objetivos de este trabajo es evaluar los vertidos de níquel presentando información cuantitativa de emisiones industriales de este metal en España, recopilada de la base de datos más relevante a nivel europeo, el European Pollutant Release and Transfer Registrer (E-PRTR). A continuación, se realizaron pruebas para la eliminación de níquel mediante biosorción, seleccionando como biosorbente la cáscara de piña piñonera, que tiene la ventaja de ser un residuo agrícola muy abundante en Andalucía de bajo o nulo coste. Se estudiaron las variables que intervienen en el proceso (tamaño de partícula, pH, etcétera), determinando su influencia en el mismo.
This is a multicenter prospective observational study that included a large cohort (n = 397) of allogeneic (allo‐HSCT; (n = 311) and autologous (ASCT) hematopoietic stem cell transplant (n = 86) ...recipients who were monitored for antibody detection within 3–6 weeks after complete severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) vaccination from February 1, 2021, to July 20, 2021. Most patients (n = 387, 97.4%) received mRNA‐based vaccines. Most of the recipients (93%) were vaccinated more than 1 year after transplant. Detectable SARS‐CoV‐2‐reactive antibodies were observed in 242 (78%) of allo‐HSCT and in 73 (85%) of ASCT recipients. Multivariate analysis in allo‐HSCT recipients identified lymphopenia < 1 × 109/ml (odds ratio OR 0.33, 95% confidence interval 95% CI 0.16–0.69, p = .003), active graft versus host disease (GvHD; OR 0.51, 95% CI 0.27–0.98, p = .04) and vaccination within the first year of transplant (OR 0.3, 95% CI 0.15–0.9, p = .04) associated with lower antibody detection whereas. In ASCT, non‐Hodgkin's lymphoma (NHL; OR 0.09, 95% CI 0.02–0.44, p = .003) and active corticosteroid therapy (OR 0.2, 95% CI 0.02–0.87, p = .03) were associated with lower detection rate. We report an encouraging rate of SARS‐CoV‐2‐reactive antibodies detection in these severe immunocompromised patients. Lymphopenia, GvHD, the timing of vaccine, and NHL and corticosteroids therapy should be considered in allo‐HSCT and ASCT, respectively, to identify candidates for SARS‐CoV‐2 antibodies monitoring.
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