Search

This study investigates the production of biochar from fresh wood shavings (B-WSF) and used wood shavings (B-WSU–animal litter) biomass through pyrolysis at 450 °C and explores its potential for NO2 adsorption at different temperatures from 22 °C to 250 °C. The biochars' thermal stability, elemental composition, mineral content, textural properties, and surface chemistry were comprehensively analyzed using various techniques, including thermogravimetric analysis (TGA), ultimate analysis, proximate analysis, mineral composition analysis, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and NO2 adsorption experiments. The results indicate that biochars derived from WSF and WSU biomass possess high stability and exhibit significant changes in their elemental composition, surface functional groups, and textural properties compared to the raw biomass. The biochars demonstrated substantial NO2 adsorption capacities and reduction, with B-WSU biochar exhibiting higher adsorption capacity attributed to its higher specific surface area, mineral content, and functional groups. In addition, the results reveal distinct patterns in NO2 adsorption and NO release, with temperature playing a pivotal role in the process. At lower temperatures, NO2 adsorption on both biochars exhibits gradual increases, while higher temperatures facilitate immediate adsorption and subsequent reduction to NO. The adsorption of NO2 increased with increasing adsorption temperature, with B-WSU biochar achieving a maximum adsorption capacity of 43.54 mg/g at 250 °C, compared to 9.62 mg/g for B-WSF biochar. Moreover, XPS analysis revealed alterations in surface functional groups upon NO2 exposure, indicating enhanced surface oxidation and formation of nitrogen-containing species. In addition, differences in surface heterogeneity and mineral content influence NO2 adsorption behavior between the biochar samples. These findings highlight the potential of WSF biomass-derived biochar as an effective adsorbent for NO2 removal, offering insights into its application in air pollution mitigation strategies. The mechanism of NO2 adsorption involves chemisorption on oxygen-containing functional groups and physical adsorption, facilitated by the high specific surface area and pore volume of the biochar. Furthermore, the rich mineral content in B-WSU biochar explains its high adsorption capacity, demonstrating the potential for valorization of waste materials in the circular economy. [ABSTRACT FROM AUTHOR]

The growing energy consumption and the need for a circular economy have driven considerable interest in the anaerobic digestion (AD) of organic waste, offering potential solutions through biogas and digestate production. AD processes not only have the capability to reduce greenhouse gas emissions but also contribute to the production of renewable methane. This comprehensive review aims to consolidate prior research on AD involving different feedstocks. The principles of AD are explored and discussed, including both chemical and biological pathways and the microorganisms involved at each stage. Additionally, key variables influencing system performance, such as temperature, pH, and C/N ratio are also discussed. Various pretreatment strategies applied to enhance biogas generation from organic waste in AD are also reviewed. Furthermore, this review examines the conversion of generated digestate into biochar through pyrolysis and its utilization to improve AD performance. The addition of biochar has demonstrated its efficacy in enhancing metabolic processes, microorganisms (activity and community), and buffering capacity, facilitating Direct Interspecies Electron Transfer (DIET), and boosting CH4 production. Biochar also exhibits the ability to capture undesirable components, including CO2, H2S, NH3, and siloxanes. The integration of digestate-derived biochar into the circular economy framework emerges as a vital role in closing the material flow loop. Additionally, the review discusses the environmental benefits derived from coupling AD with pyrolysis processes, drawing on life cycle assessment investigations. Techno-economic assessment (TEA) studies of the integrated processes are also discussed, with an acknowledgment of the need for further TEA to validate the viability of integrating the biochar industry. Furthermore, this survey examines the techno-economic and environmental impacts of biochar production itself and its potential application in AD for biogas generation, aiming to establish a more cost-effective and sustainable integrated system. [ABSTRACT FROM AUTHOR]

In the context of sustainable solutions, this study examines the pyrolysis process applied to corn cobs, with the aim of producing biochar and assessing its effectiveness in combating air pollution. In particular, it examines the influence of different pyrolysis temperatures on biochar properties. The results reveal a temperature-dependent trend in biochar yield, which peaks at 400 °C, accompanied by changes in elemental composition indicating increased stability and extended shelf life. In addition, high pyrolysis temperatures, above 400 °C, produce biochars with enlarged surfaces and improved pore structures. Notably, the highest pyrolysis temperature explored in this study is 600 °C, which significantly influences the observed properties of biochars. This study also explores the potential of biochar as an NO2 adsorbent, as identified by chemical interactions revealed by X-ray photoelectron spectroscopy (XPS) analysis. This research presents a promising and sustainable approach to tackling air pollution using corn cob biochar, providing insight into optimized production methods and its potential application as an effective NO2 adsorbent to improve air quality. [ABSTRACT FROM AUTHOR]