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• Pulp and paper mill sludge (PPMS) landfill sites have GHG assessment challenges. • GHG fluxes measured by chambers with (F +) and without (F-) a frame were compared. • Flux relationships up to 80 % were shown between F- and F + chambers (the standard) • Correction factors for F- chambers were built to estimate fluxes from F + chambers. • The approach can refine GHG inventories on PPMS landfill sites. Assessments of greenhouse gas (GHG) emissions in managed areas are facing various challenges. A non-flow-through, non-steady-state (NFT-NSS) chamber coupled to a frame permanently inserted into the landfilled substrates is a standard method for quantifying GHG emissions in managed areas, such as pulp and paper mill sludge (PPMS) landfill sites. Frequent measurements are needed to minimize uncertainties on GHG emission factors at the landfill site scale. However, maintaining a frame inserted into the substrates for a long time period is often impossible due to landfilling management operations. Therefore, GHG measurements using NFT-NSS chambers placed directly on substrates' surface could be an interesting option. Our objectives were to determine the relationships between CO 2 , CH 4 , and N 2 O fluxes measured with (F +) and without (F-) a frame inserted in the substrates' surface and to develop correction factors for fluxes measured without a frame. Measurements were made at different PPMS landfill sites in the province of Québec, Canada. Stronger GHG flux relationships were observed at the provincial (across sites) than the specific site scale: the variance in GHG fluxes from F- chambers explained up to 80 % of variance in fluxes from F + chambers. The measured CO 2 , CH 4 , and N 2 O fluxes in F- chambers were on average 53, 78, and 63 % lower, respectively, than those estimated by the models at provincial scale. The correction factors developed with this approach could greatly extend the number of sites where in situ GHG measurements can be done and would help refining GHG inventories at the provincial and national levels. [ABSTRACT FROM AUTHOR]

Development of low-cost, efficient, and stable oxygen evolution electrocatalysts is crucial for the conversion and storage of renewable energy. Therefore, an effective integrated heterostructure catalyst is needed to achieve a lower overpotential during oxygen evolution process. In this paper, cobalt-zinc bimetallic MOF precursors are used as templates to prepare bimetallic cobalt-based selenides with good oxygen evolution catalytic activity and stability on carbon fiber paper. Due to the high specific surface area and porous structure of the coupling structure of nanorods and polyhedra, and the strong electronic coupling between CoSe 2 and ZnSe on nanorods. CoSe 2 -ZnSe/CP exhibits excellent electrocatalytic activity in 1 M KOH solution. It only requires an overpotential of 275 mV to reach the current density of 10 mA cm-2, and the Tafel slope is 68.9 mV dec-1. In addition, after 12 h of continuous operation of CoSe 2 -ZnSe/CP, the activity decay of the catalyst is negligible. This work provides a method for the design of heterogeneous bimetallic selenide integrated oxygen evolution electrocatalysts. [Display omitted] • The CoSe 2 -ZnSe/CP catalyst is obtained by selenization of MOF precursor at high temperature. • The catalyst has unique nanorod-coupled polyhedral morphology and high specific surface area. • The strong electron coupling between CoSe 2 and ZnSe improves the oxygen evolution activity. • CoSe 2 -ZnSe/CP exhibits low overpotential, high exchange current density and fast kinetics. [ABSTRACT FROM AUTHOR]

Enzymes derived from microbial sources have gained increasing popularity in industrial applications over the past decades. Despite the high production cost, alkaline proteases have wide applications in industries such as tanneries, food production, and detergents. In recent years, there has been a shift towards utilizing natural carbon sources for cultivating microorganisms and extracting proteases in order to reduce production costs. This study aimed to investigate the biochemical and kinetic properties of protease enzymes obtained from Aspergillus niger cultivated in a paper waste medium and compare with the enzyme produced in a basal medium. Glucose is a more favorable carbon source compared to cellulose, so paper waste was pretreated with cellulose-degrading bacteria to convert cellulose into smaller carbohydrates. After the growth of A. niger in basal and combinational media, the enzymatic properties were compared between the extracted enzymes by using casein as substrate. The results demonstrated that A. niger could produce protease enzymes in the paper waste medium similar to the basal medium with more than 5-fold cost saving. The specific activity of the enzymes isolated from the basal and paper waste media was calculated to be 184.95 ± 10.56 U ml−1 and 169.88 ± 11.05 U ml−1, respectively. Carbon sources did not affect the optimum pH and temperature of the protease enzyme, which were found to be 8 and 37 °C, respectively. This study provides valuable insights into the production of alkaline protease from A. niger using a combinational medium (paper waste pretreated by cellulose-degrading bacteria), offering a cost-effective approach for industrial applications. [ABSTRACT FROM AUTHOR]

Carbon paper is one of the most widely used gas diffusion layer substrate materials due to its stable performance, relatively low cost, and easy for subsequent processing. Water-soluble phenolic resin, which is more ecologically friendly than alcohol-soluble phenolic resin, was used to prepare carbon paper as the precursor of the carbon matrix. And the effect of different resin solution concentrations on the properties of carbon paper was explored. The results showed that the graphitization, electrical conductivity and mechanical properties of carbon paper increased with the increase of resin solution concentration. When the concentration of resin solution was 20 wt%, the performance of carbon paper was relatively optimal. The graphitization of the carbon paper reached 65.45%, the porosity reached 80.74%, the resistance value at 1 MPa pressure was only 7.61 mΩ cm2, the tensile strength was 1.57 MPa, and the elastic modulus was 1210.98 MPa. [ABSTRACT FROM AUTHOR]

Carbon paper as a macroporous substrate of gas diffusion layer in proton exchange membrane fuel cells directly impacts the output performance of cells. In this study, we present a straightforward strategy to improve the overall performance of carbon paper by mixing short/long (6mm/10 mm) chopped carbon fibers at an optimal concentration of phenolic resin. The results show that incorporating longer carbon fibers can increase the porosity, conductivity, gas flux, and mechanical properties of carbon paper. The membrane electrode assembly achieved a peak power density of 1182.61 mW cm−2 at 60% RH using carbon paper with a long carbon fiber content of 40 wt% and an impregnation concentration of 10 wt%. This outperforms commercially available carbon paper. Based on electrochemical impedance spectroscopy results, it was confirmed that our carbon paper had a lower mass transfer resistance of only 32.17 mΩ cm−2 under conditions of 2 A cm−2 and 60% RH. This was due to its sparser three−dimensional network-like pore structure which was created by mixing different lengths (6mm/10 mm) of carbon fibers. This work provides new insights into preparing high−performance carbon papers. • The nature of carbon paper is regulated by mixing short/long (6mm/10 mm) CFs ratio. • The long carbon fiber contents of 20–40 wt% present better physical properties. • The optimal carbon papers can mitigate mass transfer resistance. • MEA composed of the optimal CP shows a higher power density than commercial CP. [ABSTRACT FROM AUTHOR]

A facile method is proposed in this work to prepare a carbon paper (CP) with outstanding properties by doping boron to catalyze graphitization at lower temperature. Boron was introduced into CP by impregnating carbon fiber preform into a boron/phenolic resin/ethanol solution, and then CP was obtained after the consecutive procedures of hot pressing, carbonization, and graphitization. Morphology, microstructure, composition, and physical properties of the doped and undoped CPs were thoroughly investigated via various techniques to exam the effects of boron concentration and graphitization temperature. Furthermore, the boron doped CP was fabricated into fuel cell gas diffusion layer (GDL) and membrane electrode assembly (MEA) to evaluate its performance through the single cell performance. The findings indicated CP doping with 2 wt% boron could lower the graphitization temperature by at least 200 °C. The B-doped GDL had a higher power density in comparison with the undoped GDLs made in our lab or from the commercial brands. • The innovative preparation method for carbon paper with high conductivity. • The effect of boron concentration and graphitization temperature on carbon paper. • The single cell performance of B-doped gas diffusion layer. [ABSTRACT FROM AUTHOR]

The solar photocatalytic degradation of pulp and paper mill wastewater has been reported by several scientists. However, this is the first time we are reporting for solar photocatalytic hydrogen production from pulp and paper mill wastewater and simultaneous degradation of pollutants. In this work, CuO based photocatalysts and novel square type photocatalytic reactor of 5 L capacity were used. The result shows that the prepared photocatalysts are solar active, efficient in hydrogen recovery and pollutant degradation from the pulp and paper wastewater. The effects of catalyst loading, sacrificial agent, pollutant removal efficiency and stability check were investigated. At 0.25 g/L of CuO/Fe 2 O 3 , 0.2 M of sacrificial agent (Na 2 SO 3 2−) and hydrogen yield of 1000 mL from 1000 mL of wastewater was achieved. The removal efficiency of TSS, TDS, BOD, COD, turbidity and TOC are around 70, 50, 60, 65, 70 and 45% respectively. Reusability study revealed that CuO/Fe 2 O 3 was chemically stable and could be reused successively (five cycles) without significant changes in its photoactivity and intrinsic properties. [Display omitted] • Visible light active CuO mixed with novel metal oxides were employed. • Hydrogen recovery from black liquor, paper mill wastewater were 1000 mL/h/L and 850 mL/h/L. • Efficiency of degradation of pulp & paper wastewater chemicals were around 50–70%. • AcHieved high recovery of hydrogen from pulp & paper wastewater. [ABSTRACT FROM AUTHOR]

The Proton Exchange Membrane Fuel Cell (PEMFC) performances are strongly impacted by the compression of the Gas Diffusion Layer (GDL). Despite its fibrous microstructure, this material is usually considered as a continuous medium and characterized with uniform loading. However, the GDL is subjected to a heterogeneous compression onto rib/channel patterns in the fuel cell assembly. In the present study, a complex behavior of the GDL response is experimentally revealed when the material is loaded with a rib/channel pattern, compared to uniform compression. The tests are simulated by finite element modeling using a classical strain-dependent elastic law, using parameters fitted from uniform compression experiments. It is shown that the numerical results do not reproduce the effect of pattern observed experimentally. Hypotheses to interpret these results involve mechanisms at the fiber microscale including fiber fracture, cross-link breakage and fiber rearrangement, which are exacerbated by larger material deformation caused by the heterogeneous loading. • Unexpected impact of rib/channel patterns on GDL compression. • Experimental investigation of the effect of rib/channel width on GDL deformation. • Numerical study with classical model unable to reproduce experimental results. • Interpretations based on mechanisms at the fiber microscale. [ABSTRACT FROM AUTHOR]

• The PBAT/PLA coated paper shows high methane yield under AD condition. • Plastic film residues remain after the digestion of PBAT/PLA coated paper. • The decrease of hydrophobicity for PBAT/PLA bags is due to the formation of PLA monomers. • The bacterial community shows difference between PBAT/PLA coated paper and bags. • Methanoculleus is enriched on the plastic surface under mesophilic AD. Poly (lactic acid) (PLA) and Poly(butylene adipate-co-terephthalate) (PBAT) are two of biodegradable plastics with the highest production capacities in 2021. Bioplastic waste management can be easily integrated with organic waste management, especially when bioplastics are used as food packaging material, since they are potentially biodegradable. The aim of this study was to assess the biodegradability of biodegradable polymer-coated paper (BPCP) and bioplastic bags made from PBAT/PLA blend during mesophilic and thermophilic anaerobic digestion (AD) and to reveal the changes in the physicochemical properties of the bioplastics. BPCP obtained 155 NmL-CH 4 /g VS and 307.3 NmL-CH 4 /g VS under mesophilic and thermophilic conditions, respectively, but left bioplastic film residues. The bioplastic bags did not exhibit significant biodegradation during the AD processes. 1H NMR results indicated that the ratio of PLA to PBAT decreased significantly after AD of the BPCP film and that PLA monomers were formed from the bioplastic bags, leading to a decrease in the hydrophobicity on the surfaces of the materials. Methanoculleus was found to be enriched on the bioplastic surface after mesophilic AD. From the perspective of coupling bioplastic waste management with the food waste management, the incorporation of BPCP into the AD reactor not only enhances system stability and methane production to a greater extent than biodegradable plastic bags but also raises concerns regarding the residual biofilm when utilizing the digestate for direct land applications. [ABSTRACT FROM AUTHOR]

This paper describes the fabrication and characterization of porous SiC ceramics derived from highly-filled preceramic papers. The SiC ceramics were obtained by spark plasma sintering of stacked preceramic papers at temperatures of 2100 and 2200 °C under pressures of 5–60 MPa for 10 min. The microstructure and phase composition were analyzed by scanning electron microscopy and X-ray diffraction, respectively. Gas permeation tests were performed using hydrogen permeation cell at room temperature. It is revealed that the porosity of sintered SiC can be varied from 9 to 45 % depending on the sintering parameters. The shrinkage of the materials during spark plasma sintering occurs in four stages. The linear shrinkage value of the material increases from 7 to 47 % at 2100 °C and from 20 to 50 % for the samples sintered at 2100 and 2200 °C, respectively. Correlation dependencies between porosity and mechanical properties of the fabricated SiC were established. The obtained porous SiC ceramics exhibit high bending strength of 165 MPa and gas permeation flux of 78 molH 2 /m2/s at the porosity of 36 % that make it suitable for ceramic-based membranes. [ABSTRACT FROM AUTHOR]