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Use of three detemplation schemes (calcination, extraction and H2O2 treatment) led to materials with different structures and surface chemistry (content of silanol groups), which affected their adsorption performance towards l-histidine.

This paper focuses on the development and detailed characterisation of a novel hybrid sol-gel material derived from 3-glycidoxypropyltrimethoxysilane (GPTMS) and ethyltriethoxysilane (ETEOS). The material has been doped with a fluorescent pH-sensitive dye, modified 8-hydroxy-1,3,6-pyrene trisulfonic acid (HPTS) and its application as a high-performance optical ratiometric pH sensor has been demonstrated. The optimum sol-gel-based material composition has been characterised using atomic force microscopy (AFM), scanning electron microscopy in combination with energy dispersive X-ray spectroscopy (SEM-EDX), thermal gravimetric-infrared (TGA-IR) analysis, Fourier transform infrared (FT-IR) and Raman spectroscopy, solid state 29 Si and 13 C nuclear magnetic resonance (NMR). AFM and SEM images demonstrated a high degree of homogeneity of the pH films. FT-IR, Raman and NMR results have shown that hydrolysis and condensation reactions were almost completed and extensive crosslinking occurred in the final material. They also revealed that an opening of the epoxy ring in GPTMS took place which was key to optimum pH response. The pH sensor produced using the hybrid material compares very well with the current state-of-the-art and exhibits very good reversibility, reproducibility, stability, short response time and no leaching. The dynamic range extends from pH 5.0 to 8.0 which is compatible with bioprocessing, environmental and clinical monitoring applications.

A widely distributed mineral, serpentine, obtained from Wadi Ghadir (Eastern Desert in Egypt) was studied as a potential naturally and abundantly available source for the synthesis of an efficient adsorbent for aquatic remediation applications. A novel nanocomposite was synthesized after the exfoliation of the layered structure of serpentine by hydrogen peroxide treatment (serpentine (SP)), followed by decoration with magnetic Fe3O4 nanoparticles (MNP). The goal behind the utilization of the latter phase was to increase the environmental remediation capability and to incorporate magnetic properties at the final adsorbent, toward a better separation after the use. The fabricated composite (MNP/SP) was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). The composite’s potential adsorption application toward the removal of two cationic dyes, methylene blue (MB) and malachite green (MG), was investigated. The observed adsorption kinetics was fast, and the highest uptake was observed at pH = 8, with the capacities to reach 162 and 176 mg g−1 for MB and MG, respectively, values significantly higher than various other materials tested against these two cationic dyes. Compared to hydrogen peroxide-treated serpentine, the removal efficiency of the composite was higher by 157 and 127% for MB and MG, respectively. The MB and MG were adsorbed because of the favorable electrostatic interactions between MNP/SP active sites and the cationic dyes. The close value capacities suggest that the difference in chemistry of the two dyes does not affect the interactions, with the later occurring via the dyes’ amine functionalities. With increasing ionic strength, the adsorption of the studied basic dyes was slightly decreased, suggesting only partial antagonistic ion effect. The sorbent can be easily regenerated and reused without significant deterioration of its adsorption efficiency, which makes MNP/SP a promising adsorbent for the removal of hazardous pollutants from aquatic environments.

Highly porous carbon textiles were modified by impregnation with urea, thiourea, dicyandiamide, or penicillin G, followed by heat treatment at 800 °C. This resulted in an incorporation of nitrogen or nitrogen and sulfur heteroatoms in various configurations to the carbon surface. The volume of pores and, especially, ultramicropores was also affected to various extents. The modified textiles were then used as adsorbents of formaldehyde (1 ppmv) in dynamic conditions. The modifications applied significantly improved the adsorptive performance. For the majority of samples, formaldehyde adsorption resulted in a decrease in the volume of ultramicropores. The enhancement in the adsorption was linked not only to the physical adsorption of formaldehyde in small pores but also to its reactivity with sulfonic groups and amines present on the surface. Water on the surface and in challenge gas decreased the adsorptive performance owing to the competition with formaldehyde for polar centers. The results collected show that the S- and N-modified textiles can work as efficient media for indoor formaldehyde removal.