Qi Wei

The construction of semiconductor heterojunctions offers a promising route to markedly enhanced photocatalytic performance. A template-based and electrostatic self-assembly strategy was employed to synthesize the mesoporous g-C₃N₄/MXene photocatalyst, integrating melamine-derived g-C₃N₄ with a MXene secondary phase. MXene layers were inserted between g-C ₃ N ₄ layers to construct a special stacked sandwich structure called 2D/2D heterostructure. The mesoporous g-C ₃ N ₄ /MXene composite delivers markedly superior photoelectrochemical performance to bare mesoporous g-C ₃ N ₄ . With 10 wt % MXene, the as-prepared g-C ₃ N ₄ /MXene attains its maximum BET surface area of 43.19 m ² g ^− 1 and simultaneously delivers the highest photocatalytic activity. After 120 min of visible-light irradiation it degrades 98.6% of methyl orange and 97.2% of rhodamine B, while retaining excellent cyclic stability. The construction of heterojunction between MXene and mesoporous g-C ₃ N ₄ can significantly reduce the band gap of g-C ₃ N ₄ , causing redshift of the UV-vis absorption edge, and effectively improve the separation efficiency of photogenerated electron-hole pairs during photoresponse. After cyclic testing, the degradation efficiency showed no significant decline, demonstrating excellent catalytic stability. These findings synthesize an economical, versatile, and efficient mesoporous g-C ₃ N ₄ /MXene photocatalyst, which can be used to eliminate pollutants in industrial wastewater streams and improve environmental sustainability.

As a kind of volatile organic compound (VOC), methyl tert-butyl ether (MTBE) is hazardous to human health and destructive to the environment if not handled properly. MTBE should be removed before the release of wastewater. The present work supported the methyl-modified silica layer (MSL) on porous α-Al₂O₃ ceramic membranes with methyltrimethoxysilane (MTMS) as a precursor and pre-synthesized mesoporous silica microspheres as dopants by the sol-gel reaction and dip-coating method. MTMS is an environmentally friendly agent compared to fluorinated alkylsilane. The MSL-supported Al₂O₃ ceramic membranes were used for MTBE/water separation by pervaporation. The NMR spectra revealed that MTMS evolves gradually from an oligomer to a highly cross-linked methyl-modified silica species. Methyl-modified silica species and pre-synthesized mesoporous silica microspheres combine into hydrophobic mesoporous MSL. MSL makes the α-Al₂O₃ ceramic membranes transfer from amphiphilic to hydrophobic and oleophilic. The MSL-supported α-Al₂O₃ ceramic membranes (MSL-10) exhibit an MTBE/water separation factor of 27.1 and a total flux of 0.448 kg m⁻² h⁻¹, which are considerably higher than those of previously reported membranes that are modified by other alkylsilanes via the post-grafting method. The mesopores within the MSL provide a pathway for the transport of MTBE molecules across the membranes. The presence of methyl groups on the external and inner surface is responsible for the favorable separation performance and the outstanding long-term stability of the MSL-supported porous α-Al₂O₃ ceramic membranes.

The potential possibility of blast furnace slag as a low-cost adsorbent to remove lead ions from wastewater was investigated in detail in the present work. Both single factor experiment and orthogonal experiment were performed to reveal the effect of pH, adsorption temperature, contact time and initial concentration of lead ions on the adsorption performance of pristine slag. In order to make clear the correlation between the lead ion adsorption performance and the structure of slag, solid state nuclear magnetic resonance (NMR) was conducted to reveal the network structure and X-ray fluorescence (XRF) was used to calculate the nonbridging oxygen in the network-forming tetrahedra. For the purpose of improving the adsorption performance, γ-aminopropyltriethoxysilane (APTES) was adopted to modify the slag via post-grafting method. The results show that the slag is predominately composed of SiO₂, Al₂O₃, CaO and MgO, exhibiting an amorphous network structure based on SiO₄ and AlO₄ tetrahedra. The conditions for adsorption can be optimized as follows: a pH of 7, an adsorption temperature of 60 °C, a contact time of 120 min and an initial lead ion concentration of 40 mg·L⁻¹. Under the optimal conditions, a removal rate of 99.98% and an adsorption capacity of 49.99 mg·g⁻¹ are obtained for the pristine slag. The adsorption complies with the Langmuir model thermodynamically and conforms to the pseudo-second order model kinetically. It is noted that aminopropyl-modification has considerably enhanced the removal rate of lead ions from 20.71 to 64.32% and the adsorption capacity from 29.01 to 96.48 mg·g⁻¹ since amino groups (-NH₂) are more inclined to form a complex with lead ions than hydroxyl groups due to the higher nucleophilicity of amino groups than that of hydroxyl groups. However, it is necessary to develop more low-cost modification agents in the future work.

Blast furnace slag has good adsorption performance and can be used to adsorb heavy metal ions in waste liquid. It’s worth studying whether the blast furnace slag absorbing heavy metal ions will pose a potential threat to the environment during the process when used in cement-based materials.This paper has studied the leaching amount of copper ions in the blast furnace slag-cement system was analyzed, and analyzed the leaching kinetics of copper ions. The results showed that the leaching amount of copper ions in the blast furnace slag-cement system that adsorbed copper ions basically met the national standard, and the solidified body age was 28 days,blast furnace slag content 30% is the smallest condition for the amount of copper ion leaching.The leaching model of copper ions in the blast furnace slag-cement system is the Elovich equation, which is a heterogeneous diffusion process. The longer the curing age is the slower the leaching process is completed and do not cause environmental pollution during long-term use.