Cu2+ ions adsorption by dense calcium silicate hydrate samples and their catalytic activity

The objective of this study was to synthesize calcium silicate hydrates in dense samples and apply them for the adsorption of copper ions and, later, as a catalyst for the oxidation of volatile organic compounds. At the beginning of the synthesis, semicrystalline calcium silicate hydrate C–S–H(I) and Z-phase were formed, and after long-term synthesis, these compounds recrystallized to gyrolite. It was determined that the duration of the synthesis changed not only the mineralogical composition of the samples but also their density and compressive strength. Calcium silicate hydrates synthesized in dense samples could be applied for the removal of copper ions from the liquid medium; however, the amount of adsorbed copper ions and the efficiency of purification depended upon the properties of both the liquid medium and the duration of synthesis. The results of the methanol oxidation experiments showed that synthetic samples combined with copper ions could be applied as a catalyst. The obtained results were confirmed by X-ray powder analysis, simultaneous thermal analysis, atomic absorption spectroscopy, and chromatography/mass spectrometry.