Amorphous and ordered organosilicas functionalized with amine groups as sorbents of platinum (II) ions

Two groups of amine-functionalized organosilicas have been synthesized: amorphous polysiloxane xerogels (APX) and ordered mesoporous organosilicas (OMO) by co-condensation of tetraethoxysilane and appropriate alkoxysilanes: aminopropyltriethoxysilane and N-[3-(trimethoxysilyl)propyl]ethylenediamine. The obtained materials were characterized by sorption measurements, X-ray diffractometry, elemental analysis, transmission electron microscopy, and scanning electron microscopy. The OMO samples have well developed porous structure—the values of specific surface area are in the range 740–840 m²/g. While the APX samples are less porous having the corresponding values in the range 280–520 m²/g. The sizes of the ordered mesopores of OMO are in the range 5.9–6.5 nm while for the APX they are 2.9–12.1 nm indicating structural differences between both groups of the samples. All samples were tested as the sorbents of Pt(II) ions. The influence of various parameters such as pH, contact time, equilibrium concentration on Pt(II) adsorption ability onto prepared adsorbents was studied in detail. Additionally, the effect of chloride concentration on Pt(II) adsorption was investigated. The values of static sorption capacities were in the range of 32–102 mg_Pt(II)/g and 20–139 mg_Pt(II)/g for OMO and APX series, respectively.