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Formaldehyde is a common indoor air pollutant with hazardous effects on human health. This study investigated the efficiency of biocarbon (BC) functionalized with variable contents of MnO2 for formaldehyde removal in ambient conditions via integrated adsorption-photocatalytic degradation technology. The sample with the highest formaldehyde removal potential was used to prepare a functional coating made of acrylic binder mixed with 20 wt% of the particles and applied on beech (Fagus sylvatica L) substrate. SEM images showed that MnO2 was deposited around and inside the pores of the BC. EDX spectra indicated the presence of Mn peaks and increased content of oxygen in the doped BC compared to pure BC, which indicated the successful formation of MnO2. Raman spectra revealed that the disorder in the BC's structure increased with increasing MnO2 loadings. FTIR spectra of BC–MnO2 samples displayed additional peaks compared to the BC spectrum, which were attributed to MnO vibrations. Moreover, the deposition of increased MnO2 loadings decreased the porosity of the BC due to pores blockage. The BC sample containing 8 % Mn exhibited the highest formaldehyde removal efficiency in 8 h, which was 91 %. A synergetic effect between BC and MnO2 was observed. The formaldehyde removal efficiency and capacity of the coating reached 43 % and 6.1 mg/m2, respectively, suggesting that the developed coating can be potentially used to improve air quality in the built environment.

In this study, we investigated the impact on surface topography and micro-mechanical properties of polyvinyl alcohol (PVA) thin films when loaded with hardwood-derived biocarbon particles (BCP). The PVA/BCP composites were prepared with the conventional film casting method, after varying BCP concentrations of 6, 8, 10, 12, and 20 wt% were added to the PVA solution. Atomic force microscopy (AFM) investigations and nanoindentation tests were performed. The average roughness of the thin films increased with the increase in BCP content. The alternation between dark and light patterns observed in the AFM images showed an irregular surface topography with alternating high peaks and deep valleys. The skewness and kurtosis parameters showed that the different dispersion degrees of the BCP within the PVA matrix influenced the composites' surface roughness. The micro-mechanical properties of the thin film composites depended on the BCP type and concentration. Films reinforced with red oak-derived BCP had higher hardness and Young's modulus compared to films reinforced with willow SV1 and yellow-poplar BCP, which was attributed to the high carbon content and low ash content of red oak BCP. We argue that these results may be extrapolated to other types of BCP-reinforced thin films and can significantly contribute to enabling more efficient methods and protocols for reinforcing polymers with hardwood biocarbon.

Mishandling of waste plastics and biomasses is a major global concern. Every year, around 380 million tonnes of plastic are produced, with only 9% being recycled, leading to widespread pollution. Similarly, waste biomass generation from agricultural and forestry sectors accounts for 140 billion metric tonnes, in addition to 2.01 billion tonnes from municipal solid waste. This review paper addresses the gap regarding the integration of 3D printing, upcycling of recycled plastics, and the utilization of waste biomass in sustainable composites. 3D printed parts from recycled plastic have shown comparable mechanical properties compared to virgin materials, which have been further improved by the addition of waste biomass-derived fillers. The paper acknowledges that different printing parameters have substantial influence on the strength, ductility, crystallinity, and dimensional accuracy of printed parts. Therefore, optimizing these parameters becomes crucial for achieving improved mechanical performance. Moreover, incorporating reinforcing agents, stabilizers, chain extenders, compatibilizers, and surface modifiers in plastic recycling and 3D printing presents an excellent opportunity to enhance mechanical properties, thermal stability, adhesion, and dimensional stability. Additionally, the review identifies research gaps and proposes the integration of machine learning and artificial intelligence for enhanced process control and material development, further expanding the possibilities in this field.

Sustainable hybrid fillers including biocarbon (BioC) and recycled carbon fibers (rCF) are used to reinforce the polyphenylene sulfide (PPS). The PPS biocomposites were compared with the conventional talc filled counterparts. The PPS/BioC/rCF biocomposites have comparable specific mechanical properties and thermal stability to the PPS/talc/rCF composites. However, the former has higher content of sustainable fillers, which provides better energy saving and emission reduction properties. The biocomposites filled with BioC/rCF showed a similar degradation process as talc/rCF counterparts during the heat aging process. This study can help open high-end application options (e.g. Electric Vehicle (EV) parts) of PPS composites reinforced by sustainable carbon fillers.

Agricultural wastes are presently being used as animal feed or incinerated, yet they have the potential to become eco-friendly, value-added products. Converting agricultural waste into biocarbon material is one of the current advancements in their valorization. Biocarbons exhibit a wide range of application potential. The physical and chemical properties of biocarbons produced from agricultural feedstock differ based on pyrolysis conditions, in which the pyrolysis temperature plays a vital role. In this study, almond shell biomass was carbonized at three different temperatures: 300, 500, and 700 °C. The resulting biocarbons were analyzed to understand the influence of pyrolysis temperature on physicochemical characteristics. The carbon content in almond shells rose from 47% in the raw biomass to 75% in the biocarbon obtained at 700 °C. TGA-FTIR spectra indicated the release of volatiles such as CO2, hydrocarbons, carbonyl groups, and ethers, the release of which increased with increasing temperature. Further, the increased pyrolysis temperature improved the thermal stability of almond shell derived biocarbons. The deconvoluted ID/IG ratios of Raman peaks were calculated to 1.274 and 1.012 for the biocarbons obtained at 500 and 700 °C, respectively, indicating a trend of increasing trubostratic carbons with increasing pyrolysis temperature. The biocarbon produced at 700 °C was 53 times more electrically conductive than biocarbon produced at 500 °C, likely due to the high carbon content and increased structural ordering of the carbons.

In this study, material characterization and a cradle-to-gate life cycle assessment methodology are applied to examine how the addition of biochar as a filler in recycled plastics (rHDPE) influences material properties and environmental burdens. Environmental impacts for these composites are then compared to biochar fillers in virgin HDPE and bio-based polylactic acid (PLA) and polyhydroxybutyrate (PHB). At 40% biochar addition to rHDPE, biochar increased the tensile strength by 45%, stiffness by 126% and flexural storage modulus by 79% but resulted in a more brittle material. Biochar addition detrimentally affects the thermal degradation of both PLA and PHB, resulting in reduced mechanical properties. Increased biochar loading linearly reduced the global warming potential of all plastics relative to neat plastic by up to 3.3 kg CO2 eq. per kg of composite, with a dual benefit of reducing the amount of plastic used and creating a net-uptake of carbon in the biochar. Similarly, biochar decreased the fossil fuel depletion of PLA, PHB, and HDPE, but additional transportation-related emissions and the low fossil fuel depletion for neat rHDPE caused biochar addition to increase fossil fuel depletion for rHDPE. While changes in material application and end-of-life were outside the scope of this study, biochar is expected to provide further end-of-life benefits to the biodegradable PHB or PLA. Importantly, this study demonstrates that biochar can be applied to produce carbon-neutral composite materials when added to a wide variety of plastics and demonstrates the potential of biochar to reduce the environmental impacts of plastic materials.

This study investigates biochar, a carbon-based material produced via pyrolysis, as a filler in two plastics: biodegradable plastic polylactic acid (PLA) and recycled high-density polyethylene (HDPE). Specifically, we examine biochar derived from post-consumer food waste as a method to reuse this large waste stream. We find that pyrolysis of this inhomogeneous waste at 900 °C forms biochar with a graphitic structure and electrical conductivity similar to carbon black. Biochar addition impacts the properties of HDPE and PLA differently, with reduced thermal stability in PLA and only minor impacts on the thermal and mechanical properties of HDPE. In both polymers, agglomeration of biochar particles results in low electrical conductivity of the composites. This study highlights a loss of thermal stability in PLA with the addition of biochar as a critical roadblock to applying biochar as a filler in PLA. We propose that inorganic compounds in the biochar catalyze the thermal degradation of PLA, resulting in shorter PLA chains and reducing the composite’s mechanical properties. An important finding of this work is that food-waste-derived biochar increased the degradation rate of PLA under composting conditions, with almost twice the mass loss after 40 days in samples with high biochar loading compared to neat PLA. This study highlights both the promise and challenges of utilizing biochar as a filler in PLA and HDPE. If particle dispersion and thermal stability with PLA can be addressed, biochar has the potential for reuse of a high environmental impact waste stream for a wide range of applications.

This research work focuses on the utilization of waste ocean plastics with waste agro-industrial pyrolyzed biomass to develop complex shaped value-added prototypes through additive manufacturing. Fused Filament Fabrication (FFF)-based three-dimensional (3D) printing of recycled HDPE/PP blends was challenging due to significant warpage-related problems during printing. Reinforcing these blend plastics with fillers played a significant role in the efficient 3D printing of complex-shaped objects. In this research, a blend of these recycled HDPE (70%) (rHDPE) and recycled PP (30%) (rPP) collected from the ocean shores was reinforced with pyrolyzed soy hulls-based biocarbon (20%) to fabricate filaments employed for developing specimens through injection molding as well as FFF-based 3D printing. The design of experiments (DOE) using Taguchi method was performed to determine the optimized 3D printing parameters to obtain the defect-free printed specimens. The results suggested that the injection-molded samples showed better mechanical properties as compared with 3D printed samples. However, an improvement (34%) in Young's modulus of the 3D printed rHDPE/rPP (70/30) blend was observed in comparison with injection-molded counterparts. The 3D printed rHDPE/rPP/20% Biocarbon composite showed an improvement of ∼11 and ∼15% in Young modulus and flex modulus, respectively as compared to rHDPE/rPP. Combining ocean plastics and agro-industrial wastes could generate value-added products that would contribute to the circular economy approach for sustainable product development for different applications such as prototyping and automotive, while helping to protect ocean marine life. Two prototypes, elliptical gears with shaft and spectacle frame, have also been developed by using sustainable recycled HDPE/PP-based composites.

Oxidative acid treatments of biochar produced from Miscanthus were performed in this study using nitric acid, sulfuric acid, and a mixture of both. The structural and morphological changes of the acid-treated biochar were investigated using Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), Raman spectroscopy, organic elemental analysis and energy-dispersive X-ray spectroscopy (EDS). Improved surface functionality of the treated biochars was observed in their respective FT-IR spectra through the presence of nitro and carboxylic acid functional groups. SEM-EDS and elemental analysis revealed a large increase in the oxygen to carbon ratio in the biochar, which was evidence of chemical oxidation from the acid treatment. Further, TGA study showed the reduced thermal stability of acid-treated biochar over 200°C due to the increased oxygen content. Acid treatments also influenced the graphitic structure of the biochar, as observed in the Raman spectra. The results suggest that biochar can be successfully functionalized for composite applications and provide a sustainable alternative to petroleum-based carbon additives., (Copyright © 2016 Elsevier B.V. All rights reserved.)