In this study, a facile and low-cost method for biochar (CLB) preparation from vegetable waste (cauliflower leaves) was developed at a low temperature (120 °C) in the air atmosphere. The prepared mechanism, adsorption mechanism, and performance of CLB for Cu(II) and Pb(II) sorption were investigated using Scanning electron microscopy- energy dispersive X-ray spectroscopy(SEM-EDS), X-ray diffraction(XRD), Fourier transform infrared spectroscopy(FTIR), and a series of sorption experiments. Then the CLB was subjected to single and double element sorption studies to examine the effect of pH value on the Cu(II)/Pb(II) sorption capacities and then competitive sorption priority. There are both more hydroxyl (–OH) and carboxyl (–COOH) functional groups on the surface of CLB compared to those from control (without H₃PO₄ impregnation), resulting in more ion exchanges and complexation reaction for CLB with Cu(II) and Pb(II). Besides, the phosphorus-containing groups (e.g., P = OOH, P = O.), which newly formed with H₃PO₄ impregnation, could also enhance sorption, especially for Pb(II), this way leaded to its adsorption and precipitation as Pb₅(PO₄)₃OH crystals. The performance of maximum adsorption capacities of CLB toward Cu(II) and Pb(II) were 81.43 and 224.60 mg/g, respectively. This sorption was slightly pH-dependent, except that the sorption capacity improved significantly as the pH value of the solution increased from 2 to 4. Competitive sorption experiment confirmed that Pb(II) had a higher sorption priority than Cu(II).

In buildings with the solar heat collection/insulation energy-saving window (SHC/IESW), when the insulation device is placed at night in winter, a double-wall structure façade (DSF) is formed between the glass and the insulation curtain, and the existence of air inlet and outlet leads to cold air penetration. In this paper, the Nusselt number (Nu) correlation and convective heat transfer coefficient (CHTC) of the cavity in SHC/IESW were calculated through an experiment combined with a theoretical analysis. Then, numerical simulation was performed on the fluid dynamics and thermal characteristics caused by air convection in an asymmetrically heated cavity under uniform heat flow conditions, to optimize the SHC/IESW structure and analyze its heat transfer mechanism to solve the problem of convection heat transfer between plates under cold air infiltration. Using the calculation formulas obtained from the experiment, the heat transfer coefficient of SHC/IESW is 1.71 W·m⁻²·K⁻¹. The numerical simulation results showed that with the increase of air layer thickness, the outlet temperature, the average air velocity of the cavity, and the surface temperature of thermal insulation curtain all decrease; with the increase of inlet width, the outlet temperature and the surface temperature of thermal insulation curtain decreases significantly, while the average air velocity of cavity increases. It can help to weaken the convective heat transfer in the cavity and thus, reduce the total heat transfer coefficient to 1.28 W·m⁻²·K⁻¹ when the air layer thickness is 12 mm and the inlet width is 1 mm.