Effect of intercalated metal ions on the specific surface area and porosity of dibasic calcium silicate hydrate

This work aims to determine the influence of adsorbed Cu 2+ , Co 2+ , and Cr 3+ ions on the porosity of synthetic calcium silicate hydrate by analyzing nitrogen adsorption and desorption isotherms. The calcium silicate hydrate sample was synthesized under saturated steam pressure at a 175 °C temperature when the duration of isothermal curing was 16 h. The intercalation of Cu 2+ , Co 2+ , or Cr 3+ ions was based on the adsorption experiment at 25 °C temperature. It was obtained that after adsorption 100 mg of metal ions were intercalated in 1 g of the sample. The analysis of nitrogen adsorption-desorption isotherms showed, that the nature of intercalated metal ions strongly affects the specific surface area and porosity of adsorbent. It was calculated that the specific surfaces area of the adsorbent increases during adsorption of Cu 2+ and Co 2+ ions and decreases during adsorption of Cr 3+ ions. During calcination , adsorbent and adsorbent with intercalated Co 2+ ions became non-porous materials, while samples with intercalated Cr 3+ and Cu 2+ ions showed a different tendency. The classification of hysteresis loops and calculations by using the corrected Kelvin equation and Orr et al. scheme revealed that the shape of pores depends on the nature of adsorbate. The obtained results were confirmed by analysis of nitrogen adsorption-desorption isotherms as well as SEM and TEM analysis.