C@TiO2 core-shell adsorbents for efficient rhodamine B adsorption from aqueous solution

In the present work, C@TiO2 core-shell adsorbents were successfully prepared and the adsorption capacities for rhodamine B (RB) were investigated at different conditions. The adsorbents were prepared by first in-situ hydrolysis and deposition of TBOT on the surface of ZIF-8 nanoparticles to obtain ZIF-8@titania gel, and then carbonization. XRD, SEM, TEM, and N-2 adsorption-desorption techniques were employed to characterize the adsorbents. The results showed that the adsorbents were comprised of TiO2 shell and carbon core. Large surface area and hierarchical pores, which were different from ZIF-8 derived porous carbon, were generated due to the less contraction of carbon during carbonization when robust TiO2 shell covered on the surface. The highest adsorption capacity for RB was 298 mg/g on C@TiO2. Apart from the hierarchical pores and large surface area, the low surface charge of C@TiO2 core-shell adsorbents was also observed, which also contributed to the high adsorption capacity for cationic dyes. The reuse experiments showed that the adsorbents maintained the high adsorption capacity after 5 cycles. The high stability is crucial for practical application.