In this work, natural palygorskite clay was coupled with TiO2 (anatase) nanocrystals to obtain nanocomposites, in order to be tested as photocatalysts for outdoor and indoor air de-pollution. Three types of palygorskite, i.e., untreated (P) and metal treated, namely Zn-modified (Zn-P) and Cu-modified (Cu-P) palygorskite, were firstly synthesized. Afterward, these three kinds of samples were loaded with 70 wt% TiO2 nanoparticles, using hydrothermal treatment with titanium isopropoxide, abbreviated as P-TiO2, Zn-P-TiO2 and Cu-P-TiO2 nanocomposites, respectively. The nanostructure of all samples was gingerly characterized using a series of spectroscopic and microscopy techniques, including XRD, XPS, ATR-FTIR, TEM, BET and DRS. The photocatalytic performance of the nanocomposites to the decomposition of air pollutants was evaluated in the oxidation of NOx and acetaldehyde under both UV and visible light illumination, while a direct comparison to the corresponding photocatalytic performance of the reference TiO2 photocatalyst (P25) was also made. The results showed that the nanocomposites can be significantly more effective than P25 in the oxidation of NOx under UV light (∼3 times higher) and acetaldehyde under visible light (∼2 times higher). The recorded activities, as well as the lower TiO2 demand, make the palygorskite-based nanocomposites very promising catalysts for both outdoor (NOx) and indoor (acetaldehyde) air purification. 

Synthesis of Zn/Cu metal ion modified natural palygorskite clay – TiO2 nanocomposites for the photocatalytic outdoor and indoor air purification

In this work, natural palygorskite clay was coupled with TiO2 (anatase) nanocrystals to obtain nanocomposites, in order to be tested as photocatalysts for outdoor and indoor air de-pollution. Three types of palygorskite, i.e., untreated (P) and metal treated, namely Zn-modified (Zn-P) and Cu-modified (Cu-P) palygorskite, were firstly synthesized. Afterward, these three kinds of samples were loaded with 70 wt% TiO2 nanoparticles, using hydrothermal treatment with titanium isopropoxide, abbreviated as P-TiO2, Zn-P-TiO2 and Cu-P-TiO2 nanocomposites, respectively. The nanostructure of all samples was gingerly characterized using a series of spectroscopic and microscopy techniques, including XRD, XPS, ATR-FTIR, TEM, BET and DRS. The photocatalytic performance of the nanocomposites to the decomposition of air pollutants was evaluated in the oxidation of NOx and acetaldehyde under both UV and visible light illumination, while a direct comparison to the corresponding photocatalytic performance of the reference TiO2 photocatalyst (P25) was also made. The results showed that the nanocomposites can be significantly more effective than P25 in the oxidation of NOx under UV light (∼3 times higher) and acetaldehyde under visible light (∼2 times higher). The recorded activities, as well as the lower TiO2 demand, make the palygorskite-based nanocomposites very promising catalysts for both outdoor (NOx) and indoor (acetaldehyde) air purification.

Pharmaceutical grade bentonite, containing a high amount of montmorillonite, enriched with zinc (Zn) or copper (Cu) (ZnBent and CuBent, respectively) was used as the main component for the creation of formulations for cutaneous use and tested for their antimicrobial capacity. Bentonite (Bent) with added phenoxyethanol (PH) as a preservative and unmodified bentonite were used as control groups. The mineralogical composition, structural state, and physical or chemical properties, before and after the modification of the samples, were characterized utilizing X-ray Diffraction Analysis (XRD), Fourier-Transform Infrared Spectroscopy (FTIR) and X-ray Fluorescence (XRF) techniques, and Scanning Electron Microscope-Energy Dispersive Spectroscopy (SEM, SEM-EDS) analyses. In addition, the profile of zinc and copper concentration from two types of surfaces ZnBent and CuBent, and into Phosphate-Buffered Saline (PBS) are discussed. Finally, the formulations in the form of basic pastes were challenged against bacteria, molds, and yeasts, and their performance was evaluated based on the European Pharmacopeia criteria. The Cu-modified bentonite performed excellently against bacteria and yeasts, while the Zn-modified bentonite only showed great results against yeasts. Therefore, Cu-modified bentonite formulations could offer antimicrobial protection without the use of preservatives.

/pdf/the-antimicrobial-properties-of-modified-pharmaceutical-imnihehjaf.pdf

The Antimicrobial Properties of Modified Pharmaceutical Bentonite with Zinc and Copper.

Clay minerals are often used due to their high adsorption capacity, which has sparked interest in their biological applications to stabilize drugs and pharmaceutical products. This research aims to summarize information about the stability of drugs, cosmetics, dermocosmetics, and pharmaceutical compounds incorporated in the structure of different clay minerals. The databases used to search the articles were Web of Science, Scopus, PubMed, and Science Direct. Photostabilization of these compounds is reviewed and its importance demonstrated. For biological applications, the increase in solubility and bioavailability of clay minerals has proven useful for them as drug carriers. While their natural abundance, low toxicity, and accessible cost have contributed to classical applications of clay minerals, a wide range of interesting new applications may be facilitated, mainly through incorporating different organic molecules. The search for new functional materials is promising to challenge research on clay minerals in biological or biotechnological approaches.

/pdf/clays-as-vehicles-for-drug-photostability-2pam0hvm.pdf

Clays as Vehicles for Drug Photostability

Preliminary characterization and potential use of different clay materials from North-Eastern Morocco in the ceramic industry

Six pharmaceutical pastes were prepared using chemically modified kaolin and talc powders. Tests were conducted to determine their structural and chemical characteristics as well as their antimicrobial protection, thus rendering them suitable for cosmetic and pharmaceutical uses. Kaolin and talc were treated chemically via the cation exchange method to load the clay particles with copper and zinc ions, two cations well known for their antimicrobial properties. Mineralogical analyses were conducted by using X-ray diffraction (XRD) before and after the modification, confirming the mineralogical purity of the samples. Scanning electron microscopy was also used in conjunction with energy dispersed spectroscopy (SEM-EDS) to obtain chemical mapping images, revealing the dispersion of the added metals upon the clay minerals surfaces. Moreover, chemical analysis has been performed (XRF) to validate the enrichment of the clays with each metal utilizing the cation exchange capacity. All modified samples showed the expected elevated concentration in copper or zinc in comparison to their unmodified versions. From the X-ray photoelectron spectroscopy (XPS), the chemical state of the samples’ surfaces was investigated, revealing the presence of salt compounds and indicating the oxidation state of adsorbed metals. Finally, the resistance of pastes in microbial growth when challenged with bacteria, molds, and yeasts was assessed. The evaluation is based on the European Pharmacopeia (EP) criteria.

https://www.mdpi.com/1996-1944/14/5/1173/pdf

Martin Barlog

Papers

The Antimicrobial Properties of Modified Pharmaceutical Bentonite with Zinc and Copper.

Evaluation of the Antimicrobial Protection of Pharmaceutical Kaolin and Talc Modified with Copper and Zinc.