Sustainable food waste management: synthesizing engineered biochar for CO2 capture

Humanity needs innovative ways to combat the environmental burden caused by food waste, which is one of the critical global issues. We proposed food waste-derived engineered biochar (FWDEB) for CO2 capture from a life cycle perspective. FWDEB samples were prepared by carbonization and chemical activation for CO2 adsorption. FW400-KOH600(2), carbonized at 400 °C and then activated at 600 °C with a KOH/biochar mass ratio of 2, presented the best CO2 adsorption capacities of 4.06 mmol g–1 at 0 °C (1 bar) and 2.54 mmol g–1 at 25 °C (1 bar) among all prepared samples. The CO2 uptake at 25 °C (1 bar) was affected by both micropore volume and surface area limited by narrow micropores less than 8 Å. Basic O- and N-functional groups were generated during the KOH activation, which are beneficial for enhancing the FWDEB-based CO2 adsorption. Moreover, a life cycle assessment was implemented to quantify the potential environmental impacts of FW400-KOH600(2), indicating that negative net global warming potential could be achieved using the FWDEB-based CO2 capture approach. Owing to the environmental benefits, we highlighted its potential as a promising technical route to mitigate climate change and achieve a waste-to-resource strategy

Prediction of Soil Heavy Metal Immobilization by Biochar Using Machine Learning

Biochar application is a promising strategy for the remediation of contaminated soil, while ensuring sustainable waste management. Biochar remediation of heavy metal (HM)-contaminated soil primarily depends on the properties of the soil, biochar, and HM. The optimum conditions for HM immobilization in biochar-amended soils are site-specific and vary among studies. Therefore, a generalized approach to predict HM immobilization efficiency in biochar-amended soils is required. This study employs machine learning (ML) approaches to predict the HM immobilization efficiency of biochar in biochar-amended soils. The nitrogen content in the biochar (0.3–25.9%) and biochar application rate (0.5–10%) were the two most significant features affecting HM immobilization. Causal analysis showed that the empirical categories for HM immobilization efficiency, in the order of importance, were biochar properties > experimental conditions > soil properties > HM properties. Therefore, this study presents new insights into the effects of biochar properties and soil properties on HM immobilization. This approach can help determine the optimum conditions for enhanced HM immobilization in biochar-amended soils

Sustainability-inspired upcycling of waste polyethylene terephthalate plastic into porous carbon for CO2 capture

In addition to climate change, plastic pollution is widely recognized as one of the most severe environmental concerns. Waste plastic-derived advanced materials for carbon capture provide promising solutions to these environmental issues. However, the environmental sustainability and economic feasibility of such a novel approach are still unclear for it to be implemented on an industrial scale globally. As synthesis routes differ in terms of their environmental impact and economic feasibility, we synthesized three waste polyethylene terephthalate (PET) plastic-derived porous carbons (PET6-CO2-9, PET6-K7, and PET6-KU7) using physical and chemical activation routes. The resulting porous carbons exhibited high CO2-capture capacities. Based on techno-economic and life-cycle assessments of the scaled-up industrial processes, we showed that the physical CO2 activation approach performs the best in the reduction of carbon emissions, providing the possibility for carbon neutrality while exhibiting financial viability (net present value of at least euro19.22 million over the operating life of the project). Owing to the environmental benefits and economic feasibility of this approach, we highlighted its potential as a multifunctional alternative to conventional CO2 absorption and plastic waste management technologies