Particle size, one of the predominant factors that affect the adsorption capacity of biochar, has been widely investigated. However, correlative studies on a coexistence system containing various ions together with differentiated particle sizes are scarce. In this study, samples of municipal solid waste (sludge) biochar (SB) with different particle sizes were separated and examined for the adsorption performance in bi-cation (Pb²⁺/Zn²⁺) and multi-ion (Pb²⁺, Zn²⁺ and Cl^–) systems. The results showed that the adsorption capacity is influenced by both particle size and ion configurations. The effective stabilization ability of a small size group can be attributed to the most non-bioavailable fraction. Meanwhile, the acidic soluble and non-bioavailable fraction of Pb²⁺/Zn²⁺ reached more than 90%. The mixed adsorption experiment showed that Pb²⁺ would compete for the adsorption sites of biochar with Zn²⁺, and Cl^– intervention could improve the adsorption of Pb²⁺ (2.33–6.93%) and Zn²⁺ (16.52–18.01%) on biochar. Further, X-ray diffraction spectra and phosphorus concentration dynamics and kinetics simulations revealed that more abundant active sites in the formatted pyromorphite were able to be exposed in the presence of Cl^–. The small-size portion of SB therefore exhibited excellent potential for the long-term heavy metal remediation under practical conditions of multi-ion systems in an actual environment.

Solar-driven steam generation as a potential green technology has attracted extensive attention to solve the freshwater scarcity crisis. Photothermal materials as the key section of solar steam generation have been widely reported. However, there is still a challenge in developing easily prepared, environmental-friendly, and low-cost materials. Herein, the simple, scalable, and porous carbonized cotton was prepared as an evaporator to enhance solar-based evaporation, which has excellent light absorption ability in the range of the full spectrum (300–2,500 nm). Benefiting from 95% solar absorption and the pores between the cellulose tubes, the carbonized cotton heated by plate carbonization reaches a steam generation rate of 0.8 kg m⁻² h⁻¹, which is about 5 times that of untreated cotton. Compared with tube furnace carbonization, flat plate heating carbonization of cotton requires lower equipment requirements and does not need nitrogen protection and cleaning tar, and the photothermal conversion efficiencies of both are similar. In addition, carbonized cotton as an evaporator was heated up rapidly under 1 sun irradiation and reached a stable temperature in 20 s, greatly improving the photothermal conversion rate. Therefore, plate heating carbonized cotton provides a good idea for preparing solar photothermal conversion materials and a novel strategy for simplifying the production of biomass thermal evaporators.

Developing modern circular agriculture is one of the important ways to promote agricultural sustainable development, facilitating the achievement of the Sustainable Development Goals adopted by the United Nations. However, when agricultural production operators constructed particular systems, they often lacked accurate data support and parameter matching. Consequently, problems such as unknown input and output, low circulation efficiency, and lack of comprehensive evaluation occurred, increasing challenges for efficient circulation of the systems. Therefore, based on sufficient data collection and field investigation, this research integrated emergy analysis and life cycle assessment to conduct sustainability evaluation on the modern Straw–Sheep–Cropland agro-pastoral circular system. Then the system was optimized by means of coupling parameter adjustment and key technology regulation. The results showed that the whole system required lower total emergy input after optimization. And the total weighted value of potential environmental impacts of the optimized system was 47.12% of that of the original system. Meanwhile, annual environmental service emergy in air, water, and soil was reduced significantly compared with the original one. In general, the optimized system had good performance in reduction, reuse, and controllability, so its sustainability was also high. This research formed a systematic method suitable for evaluating and optimizing the modern agro-pastoral circular system, which provided accurate guidance for the scientific construction and sustainable development of circular agriculture systems.

The ridge culture place planting system (RCPPS) is a promising technique for planting rapeseed that can promote the growth of rapeseed by late rice stubble, which has been widely adopted in the Yangtze River delta. To determine the optimum planting date for rape (Brassica napus L.) forage and grain yield in an intensive rice–rape rotation system, a field experiment was conducted with five transplantation dates (from 20 October to 30 November at 10 day intervals) in RCPPS. The forage/grain yield, nutrition, and growth parameters were analyzed. At podding, rape biomass yield was highest, and no significant differences were found among treatments. It was around 12.0% crude protein, 11.4% ether extract, 38.8% neutral detergent fiber, and 34.9% acid detergent fiber. In the treatments of 20 and 30 November, crude protein content increased and acid detergent fiber content decreased significantly. Compared with 20 October, the grain yield of rape transplanted in November decreased significantly by 17.2% to 22.5%. The grain yield was significantly correlated with the number of secondary branches, pods, and seeds. At the final flowering stage, rape transplanted in November had noticeably reduced leaf growth, rhizome width, and yield than 20 and 30 October. Overall, for multiple uses of rapeseed in the Yangtze River delta belt with RCPPS, it is optimal to plant in mid to late November for forage use with higher nutritional value, being coordinated with the previous rice crop, whereas late October is the appropriate planting time to obtain a higher grain yield.