The adsorption and desorption characteristics of cadmium (Cd) in uncontaminated soils have been investigated in numerous studies. However, similar studies on Cd-polluted soils from different sources, which exhibit complex physicochemical characteristics and internal interactions between Cd and the soil particles, are scarce. Therefore, in order to elucidate the adsorption and desorption characteristics of Cd in Cd polluted soils, six representative Cd-contaminated paddy soil samples were collected from farmlands in the vicinity of a steel plant (Soil 1), a smelter (Soil 2), a thermal power plant (Soil 3), two mining areas (Soil 4, the Dabaoshan mine, Shaoguan; Soil 5, a lead-zinc mine located at Lechang), and a paddy field irrigated with sewage at Zhongshan (Soil 6) in Guangdong Province, China. The analysis of the six soil samples showed that Cd adsorption fitted well to pseudo-second order as well as pseudo-first order kinetics; however, the pseudo-second order equation showed a better fit (R² = 0.860–0.962), while Elovich and intraparticle kinetic models fitted the adsorption kinetics poorly. Further, the adsorption isotherms fitted well to both the Langmuir and Freundlich models, with the Freundlich model showing a better fit (R² = 0.96–0.98). The following order was observed for the Cd(II) adsorption amount and rate: S5 > S6 > S1 > S3 > S2 > S4; meanwhile, the desorption amount and rate followed the opposite trend. Furthermore, the pH and soil organic matter were identified as the soil characteristics with the most significant impact on the adsorption and desorption behaviors of Cd(II) in the Cd-polluted soils.

With the intensification of anthropogenic activities, cultivated soils in many regions have become increasingly contaminated with heavy metals (HMs), generating substantial quantities of biomass carrying HM burdens. Conventional disposal pathways, such as direct incineration or returning biomass to farmland, may re-release HMs and create additional environmental risks. This review summarizes the dry and wet pyrolysis treatment of HM-contaminated biomass, with an emphasis on HMs' migration, post-treatment stabilization, and product utilization pathways. To strengthen the field-level perspective of the review, a bibliometric analysis of the 2001–2025 literature was incorporated to identify major hotspots, conceptual structures, and emerging directions. The available evidence indicates that slow pyrolysis offers a promising route to reduce the HM risk while creating carbon-rich products with potential applications in soil amendment, adsorption, catalysis, electrochemical materials, metal recovery, and energy recovery.