Recent advances in kaolinite-based material for photocatalysts

Management of trihalomethanes in water by ZnO@kaolinite composite: integrated experimental and modeling studies

The adsorption of trihalomethanes (THMs) from drinking water was investigated in the current study through comparison studies of kaolinite and ZnO@kaolinite nanocomposites. The clay structural network's successful immobilization on the zincite hexagonal structure of ZnO nanoparticles' lattice layers was verified by the SEM/EDX analysis. Under the optimum conditions, the maximum removal of THMs was achieved by kaolinite and ZnO@kaolinite nanocomposites after 60 min. The adsorption performance of the ZnO@kaolinite nanocomposites was greater than that of kaolinite because the former had a larger surface area than the latter. The Freundlich isotherm model best matched the adsorption experimental data, which also reveals the existence of multilayer adsorption on a diverse surface with the greatest correlation (R2 = 0.956 and 0.954, respectively) for both nanoadsorbents using the pseudo-first-order (PFO), pseudo-second-order (PSO), mixed 1, 2-order (MFSO), and intraparticle diffusion (IPD) models. The mechanism by which THMs in drinking water adsorb onto nanoadsorbents was examined. This revealed that both intraparticle and film diffusion were involved in the adsorption process. Kaolinite and ZnO@kaolinite nanocomposites can be used in water treatment to remove THMs due to their great recyclable and reusable properties, even after six cycles.

Progress and future prospects of hemostatic materials based on nanostructured clay minerals

The occurrence of uncontrolled hemorrhage is a significant threat to human life and health. Although hemostatic materials have made remarkable advances in the biomaterials field, it remains a challenge to develop safe and effective hemostatic materials for global medical use. Natural clay minerals (CMs) have long been used as traditional inorganic hemostatic agents due to their good hemostatic capability, biocompatibility and easy availability. With the advancement of science, technology and ideology, CM-based hemostatic materials have undergone continuous innovations by integrating new inspirations with conventional concepts. This review systematically summarizes the hemostatic mechanisms of different natural CMs based on their nanostructures. Moreover, it also comprehensively reviews the latest research progress for CM-based hemostatic hybrid and nanocomposite materials, and discusses the challenges and developments in this field.

Mint leaves (Mentha arvensis) mediated CaO nanoparticles in dye degradation and their role in anti-inflammatory, anti-cancer properties

In ancient times, herbal plants were considered one of the greatest gifts from nature that human beings could receive, and about 80% of these plants have medicinal uses. In traditional medicine, Mentha arvensis, commonly known as mint, has many applications, and in the present study, the mint leaf extract has been used to synthesis nanoparticles using the mint leaf extract as a biosource for the extraction of nanoparticles. In addition to having a wide range of applications in various fields, calcium oxide (CaO) nanoparticles are also considered to be safe for human use. In order to assess the characteristics of the abstracted CaO nanoparticles, UV-visible absorption spectrophotometers, Fourier Transform Infrared spectrophotometers (FTIR), Scanning Electron Microscopes (SEMs), Dynamic Light Scattering (DLS), and X-ray Diffraction Spectrophotometers (XRDs) were used. By conducting a protein denaturation assay and nitric oxide scavenging assay, mint leaf mediated CaO nanoparticles were evaluated for their therapeutic applications. MTT assays were used to prove that the CaO nanoparticles mediated by mint leaf had anti-cancer properties. By examining the ability of mint leaf mediated CaO nanoparticles to degrade various dyes such as methyl red, methyl orange, and methylene blue, which are the most used azo dyes in textile industries resulting in water contamination, the ability of these nanoparticles to act as a photocatalytic agent was examined.

A fully quantum-mechanical treatment for kaolinite

Neural network potentials for kaolinite minerals have been fitted to data extracted from density functional theory calculations that were performed using the revPBE + D3 and revPBE + vdW functionals. These potentials have then been used to calculate the static and dynamic properties of the mineral. We show that revPBE + vdW is better at reproducing the static properties. However, revPBE + D3 does a better job of reproducing the experimental IR spectrum. We also consider what happens to these properties when a fully quantum treatment of the nuclei is employed. We find that nuclear quantum effects (NQEs) do not make a substantial difference to the static properties. However, when NQEs are included, the dynamic properties of the material change substantially.

Structural, elastic, electronic, and optical properties of NaAlSi3O8 and Al4[Si4O10](OH)8 from first-principles calculations

CONTEXT

Based on the first-principles calculations, this paper investigates the structural, elastic, electronic, and optical properties of albite and kaolinite, respectively. It is determined that both of them show structural stability, mechanical stability, and brittleness by calculating formation enthalpy, phonon dispersion, elastic, and mechanically relevant properties. Both materials are insulators with an indirect bandgap. By calculating the TDOS and PDOS, the main characteristics of the electronic structure of NaAlSi₃O₈ come from O-2p and Si-3p states, O-2p, and Al-3p states hybridization, similar to Al₄[Si₄O₁₀](OH)₈. The covalence of Si-O bonds in NaAlSi₃O₈ is greater than Al-O bonds, and the covalent property sequence of Si-O bands in NaAlSi₃O₈ is Si2-O3 > Si1-O4 > Si2-O2 > Si1-O8 > Si1-O6 > Si3-O2 > Si3-O4. The optical anisotropy of NaAlSi₃O₈ and Al₄[Si₄O₁₀](OH)₈ is analyzed.

METHODS

First-principles density functional theory (DFT) calculation was carried out by the CASTEP computer program. The GGA-PW91 exchange-correlation was used. The energy convergence tolerance, the maximum force, and the maximum displacement were set in the calculation.

Efficient wastewater disinfection by raised 1O2 yield through enhanced electron transfer and intersystem crossing via photocatalysis of peroxymonosulfate with CuS quantum dots modified MIL-101(Fe)

Peroxymonosulfate (PMS)-based photocatalysis is a promising alternative approach for wastewater disinfection. Singlet oxygen (¹O₂) is sensitive and efficient for bacterial inactivation. This study developed a ¹O₂-predominated PMS disinfection technique under visible light with CuS quantum dots (QDs) modified MIL-101(Fe) (CSQDs@MF). CuS QDs modification greatly enhanced the ¹O₂ quantum yield by 80% than that of MIL-101(Fe). Photoelectricity and photoluminescence tests demonstrated that both the enhanced electron transfer and energy transfer were responsible for improved ¹O₂ generation in Vis/PMS/CSQDs@MF system. The system took 60 min to inactivate 7.5-log E. coli, and it could be applied in a broad pH and dissolve oxygen range. Bacterial inactivation mechanism suggested that ¹O₂ attacked cell membrane first, then induced oxidative stress, up-regulated intracellular ROS level, eventually broke DNA strand. The system showed good disinfection performance on Gram-positive B. subtilis and fecal coliforms in practical wastewater, implying it is a promising alternative disinfection technology for wastewater treatment.

The Application of Mineral Kaolinite for Environment Decontamination: A Review

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.

Grafting of R4N+-Bearing Organosilane on Kaolinite, Montmorillonite, and Zeolite for Simultaneous Adsorption of Ammonium and Nitrate

Modification of aluminosilicate minerals using a R₄N⁺-bearing organic modifier, through the formation of covalent bonds, is an applicable way to eliminate the modifier release and to maintain the ability to remove cationic pollutants. In this study, trimethyl [3-(trimethoxysilyl) propyl] ammonium chloride (TM) and/or dimethyl octadecyl [3-(trimethoxysilyl) propyl] ammonium chloride (DMO) were used to graft three aluminosilicate minerals, including calcined kaolinite (Kaol), montmorillonite (Mt), and zeolite (Zeol), and the obtained composites were deployed to assess their performance in regard to ammonium (NH₄⁺) and nitrate (NO₃^-) adsorption. Grafting of TM and/or DMO had little influence on the crystal structures of Kaol and Zeol, but it increased the interlayer distance of Mt due to the intercalation. Compared to Kaol and Zeol, Mt had a substantially greater grafting concentration of organosilane. For Mt, the highest amount of loaded organosilane was observed when TM and DMO were used simultaneously, whereas for Kaol and Zeol, this occurred when only DMO was employed. ²⁹Si-NMR spectra revealed that TM and/or DMO were covalently bonded on Mt. As opposed to NO₃^-, the amount of adsorbed NH₄⁺ was reduced after TM and/or DMO grafting while having little effect on the adsorption rate. For the grafted Kaol and Zeol, the adsorption of NH₄⁺ and NO₃^- was non-interfering. This is different from the grafted Mt where NH₄⁺ uptake was aided by the presence of NO₃^-. The higher concentration of DMO accounted for the larger NO₃^- uptake, which was accompanied by improved affinity. The results provide a reference for grafting aluminosilicate minerals and designing efficient adsorbents for the co-adsorption of NH₄⁺ and NO₃^-.