Kaolinite clay mineral with a layered silicate structure is an abundant resource in China. Due to its advantages of excellent stability, high specific surface area and environmental friendliness, kaolinite is widely used in environment decontamination. By using kaolinite as a carrier, the photocatalytic technology in pure photocatalysts of poor activities, narrow spectral responses, and limited electron transport can be overcome, and the nano-Ag disinfectant’s limitation of the growth and aggregation of nanoparticles is released. Moreover, pure kaolinite used as an adsorbent shows poor surface hydroxyl activity and low cation exchange, leading to the poor adsorption selectivity and easy desorption of heavy metals. Current modification methods including heat treatment, acid modification, metal modification, inorganic salt modification, and organic modification are carried out to obtain better adsorption performance. This review systematically summarizes the application of kaolinite-based nanomaterials in environmental decontamination, such as photocatalytic pollutant degradation and disinfection, nano silver (Ag) disinfection, and heavy metal adsorption. In addition, applications on gas phase pollutant, such as carbon dioxide (CO₂), capture and the removal of volatile organic compounds (VOCs) are also discussed. This study is the first comprehensive summary of the application of kaolinite in the environmental field. The review also illustrates the efficiency and mechanisms of coupling naturally/modified kaolinite with nanomaterials, and the limitation of the current use of kaolinite.

The K-feldspar mineral is an insoluble potassium resource with a high potassium content and the most extensive and abundant reserves. To address the insufficient supply of soluble potassium fertilizers in China, the application of appropriate processing methods to extract potassium from K-feldspar and transform it into a soluble potassium fertilizer is of great significance. To date, various techniques have been developed to extract potassium from K-feldspar and produce a soluble potassium fertilizer. This review summarizes the main methods, i.e., the hydrothermal, high-temperature pyrolysis, microbial decomposition, and low-temperature methods, for potassium extraction from K-feldspar. The mechanisms, efficiencies, impact parameters, and research progress of each potassium extraction method are comprehensively discussed. This study also compares the merits and drawbacks of the individual methods in terms of potassium extraction efficiency and practical operating conditions. The species of additives, reaction temperature, reaction time, particle size of K-feldspar, and dosage of additives significantly affected the potassium extraction efficiency. Moreover, the combination of different methods was very effective in improving the potassium extraction efficiency. This review elaborates the research prospects and potential strategies for the efficient utilization of the K-feldspar mineral as a fertilizer resource.

It is attractive to explore practical approaches to optimize the photodegraded NO property of TiO ₂ . Herein, a typical Z -shaped heterojunction C-TiO ₂ /rGO composed of carbon-doped TiO ₂ and reductive graphene oxide (rGO) was constructed to optimize the NO removal efficiency through an in situ one-pot hydrothermal process with glucose as reductant and dopant. The C-TiO ₂ /rGO (0.11%) composite displays a remarkable NO removal performance of 40.6% under visible light illumination. It was found that the C-TiO ₂ nanoparticles were tightly attached to the rGO sheets and had strong interactions with rGO, which induced a positive impact on not only the light absorption and photo-generated charge separation but also the NO adsorption and reactive oxygen species formation, resulting in boosted photodegrade NO activity. As to the photodegrade NO process over the C-TiO ₂ /rGO, the HO ^• and O ₂ ^•− were the dominant radicals, of which the O ₂ ^•− radical originated from the interactions between C-TiO ₂ and rGO. We proposed a Z -scheme mechanism to illuminate the advanced photocatalytic activity of C-TiO ₂ /rGO. This work affords an approach to developing effective photocatalysts in the NO purification field.