Co-pyrolysis is considered a very promising technology for the treatment of solid wastes as it can rapidly realize the volume reduction of raw materials and obtain high value-added products. To realize the resource utilization of newly emerging solid wastes in relation to edible fungi residue and waste plastics, mushroom residue (MR), a representative of edible fungi residue, was co-pyrolyzed with waste plastic bags (PE), waste plastic lunch boxes (PP), and waste plastic bottles (PET). The thermal behavior and pyrolysis kinetics of the mixtures were investigated. It was found that the softening of the plastics in the mixtures led to an increase in the initial pyrolysis temperature of MR by 2–27 °C, while the pyrolytic intermediates of MR could greatly promote the decomposition of the plastics, resulting in a decrease in the initial pyrolysis temperatures of PE, PP, and PET in the mixtures by 25, 8, and 16 °C, respectively. The mixture of MR and PE (MR/PE) under different mixture ratios showed good synergies, causing the pyrolysis peaks attributed to MR and PE to both move towards the lower temperature region relative to those of individual samples. The increase in heating rate led to enhanced thermal hysteresis of the reaction between MR and PE. The strength of the interaction between plastics and MR based on mass variation was subject to the order PE > PP > PET. The pyrolysis activation energies of MR, PE, PP, and PET calculated from kinetic analysis were 6.18, 119.05, 84.30, and 74.38 kJ/mol, respectively. The activation energies assigned to MR and plastics were both reduced as plastics were introduced to co-pyrolyze with MR, indicating that MR and plastics have a good interaction in the co-pyrolysis process. This study provides theoretical and experimental guidance for the resource utilization of agricultural solid wastes via thermochemical conversion.

Due to its high carbon content, lignin, particularly for lignin-containing solid waste, is considered an excellent raw material for the preparation of carbon materials like biochar. To produce high-quality lignin-based biochar (LGBCs), lignin extracted from black liquor was employed to prepare biochar at various pyrolysis temperatures (300~600 °C). The physicochemical properties of LGBCs were assessed using scanning electron microscopy, N₂ adsorption/desorption, Fourier transform infrared spectroscopy, Raman spectroscopy, and X-ray diffraction. Furthermore, the adsorption capability and potential mechanism of LGBCs in removing Cd(II) were investigated as well. The results indicate that LGBCs produced at higher pyrolysis temperatures exhibit rougher surfaces and more developed pore structures, which facilitate the exposure of numerous active adsorption sites. The adsorption of Cd(II) by LGBCs generally follows the order of LG-300C < LG-400C < LG-500C < LG-600C. According to the Langmuir adsorption isotherm model, the theoretical maximum adsorption capacity of LG-600C for Cd(II) is calculated to be 18.54 mg/g. Adsorption mechanism analysis reveals that the complexation interaction, dependent on the surface functional groups, plays a crucial role in the adsorption of Cd(II) by LGBCs prepared at higher pyrolysis temperatures. This study demonstrates that, by controlling the pyrolysis temperature during biochar preparation, high-quality lignin-based biochar can be readily obtained.

This study synthesized biochar through a one-pot pyrolysis process using IALG as the raw material. The physicochemical properties of the resulting biochar (IALG-BC) were characterized and compared with those of biochar derived from acid-treated lignin with the ash component removed (A-IALG-BC). This study further investigated the adsorption performances and mechanisms of these two lignin-based biochars for Pb(II). The results revealed that the high ash content in IALG, primarily composed of Na, acts as an effective catalyst during pyrolysis, reducing the activation energy and promoting the development of the pore structure in the resulting biochar (IALG-BC). Moreover, after pyrolysis, Na-related minerals transformed into particulate matter sized between 80 and 150 nm, which served as active adsorption sites for the efficient immobilization of Pb(II). Adsorption results demonstrated that IALG-BC exhibited a significantly superior adsorption performance for Pb(II) compared to that of A-IALG-BC. The theoretical maximum adsorption capacity of IALG-BC for Pb(II), derived from the Langmuir model, was determined to be 809.09 mg/g, approximately 40 times that of A-IALG-BC. Additionally, the adsorption equilibrium for Pb(II) with IALG-BC was reached within approximately 0.5 h, whereas A-IALG-BC required more than 2 h. These findings demonstrate that the presence of inorganic mineral components in IALG plays a crucial role in its resource utilization.