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.

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.

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Raw palygorskite (Pal) samples went under acid (H‐Pal), NaCl (Na‐Pal), and CaCl2 treatment (Ca‐Pal) in order to be examined as ammonium (NH4+) sorbents from aqueous solutions. The samples were characterized by XRD and FT‐IR techniques to examine potential structural differences after modifications, and batch kinetic experiment series were applied to determine the optimal conditions for NH4+ removal. According to thermodynamic analysis, the removal reaction for sodium‐ and calcium‐treated samples was endothermic (ΔΗ0 > 0, 1.65 kJ/mol and 24.66 kJ/mol, respectively), in contrast with the exothermic reactions of raw and acidic‐treated palygorskite samples (ΔΗ0 < 0, −37.18 kJ/mol and −27.56 kJ/mol respectively). Moreover, each sample presented a different order of sorbed ions preference, whereas the strong affinity for Ca2+ sorption was common in all cases since the NH4+ removal inhibited. Nevertheless, a similar pattern was followed for raw and modified samples at isotherm study, rendering the linear form of Freundlich isotherm to express better the NH4+ sorption on palygorskite sample, indicating that it is a heterogeneous procedure. In all cases, the NH4+ maximum uptake was within 15 min using 8 g/L of each sorbent, especially for the Na‐Pal sample, which could reach almost 100% removal of low concentration NH4+. Practitioner Points Modified palygorskite samples were tested for NH4+ removal from aqueous solutions. NaCl‐treated palygorskite had the higher removal efficiency, which could reach almost 100% removal of low concentration NH4+. NH4+ maximum uptake was within 15 minutes using 8 g/L of each sorbent. NH4+ adsorption was an endothermic reaction for NaCl‐ and CaCl2‐treated palygorskite sorbents. NH4+ adsorption was an exothermic reaction for raw and acid‐treated palygorskite sorbents.