Preparation of a sepiolite/Cu-BDC nanocomposite and its application as an adsorbent in respirator cartridges for H2S removal

Abstract

A newly developed Cu-BDC MOF nanocomposite based on natural sepiolite (Sep) was prepared and characterized using XRD, SEM, EDS, BET, and FTIR techniques. The surface areas of the sepiolite and the Sep/Cu-BDC nanocomposite were obtained as 105.5 m² g⁻¹ and 270.5 m² g⁻¹ with average micropore volumes of 0.39 and 0.32 cm³ g⁻¹, respectively. The Sep/Cu-BDC nanocomposite was prepared from the Cu-BDC metal–organic framework with values of 10, 25, and 40% by weight. The synthesized nanocomposite was tested to estimate the adsorption capacity and breakthrough time under various temperature, humidity, and concentration conditions using a designed setup. The aeroqual S500 direct-reading sensor with 0.01 ppm accuracy was used to measure the exact amount of hydrogen sulfide gas (H₂S). The produced Sep/Cu-BDC nanocomposites had an extremely high adsorption capacity compared to the primary sepiolite. Among the different adsorbents, the Sep/Cu-BDC (25 wt%) nanocomposite exhibited the highest adsorption capacity of 55.13 mg g⁻¹ (SD = 0.70) and breakthrough time of 46.32 min (SD = 1.53), respectively. Also, the amount of adsorption and breakthrough time of H₂S were decreased with increasing moisture and concentration. The pressure drop was also increased slightly. The nanocomposite with 40 wt% of Cu-BDC showed a significant decrease in the adsorption capacity and breakthrough time of H₂S. The Sep/Cu-BDC adsorbent was regenerated using thermal regeneration at 190 °C in N₂ flow for 4 h, and the results showed that the adsorbent could be used for three consecutive cycles exhibiting excellent recyclability and thermal stability.