De d8 advance

The functional groups of the adsorbent generated at each step to confirm the synthesis were measured by the Fourier-transform infrared (FT-IR) spectroscopy (Perkin Elmer Spectrometer 100, Waltham, MA, USA). The crystallinity of synthesized graphene oxide and coating layer of each synthesis step were confirmed using X-ray diffractometer (XRD, Bruker DE/D8 Advance, Bruker, Karlsruhe, Germany). The thermal stability of GO:PANI, GO:PANI/ZNRs, and GO:PANI/ZNRs/ZIF−8 were evaluated by thermogravimetric analyzer (TGA, TG209 F1 Libra, Netzsch, Selb, Germany).
The specific surface area, pore size distribution, and N₂ adsorption-desorption isotherm of GO:PANI/ZNRs and GO:PANI/ZNRs/ZIF−8 were observed by the Brunauer–Emmet–Teller (BET, 3flex, Micromeritics, Norcross, GA, USA). The morphology of GO:PANI, GO:PANI/ZNRs, and GO:PANI/ZNRs/ZIF−8 was characterized using field emission-scanning electron microscope (FE-SEM, JSM-6700F, JEOL Ltd., Tokyo, Japan).

The attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra of sodium alginate, α-TCP and dried hybrid gels (10:1, 2:1 and 1:10 in w/w) were recorded using an ATR-FTIR spectrometer (Model: Travel IR, Smiths Detection, Edgewood, WI, USA). The wavelength range of spectra were 650–4000 cm⁻¹. The surface morphology of α-TCP and the dried hybrid gels (10:1, 2:1 and 1:10) were observed using scanning electron microscopy (Model: SEM, TESCAN VEGA3, Tescan, Seoul, Korea). The particle size of α-TCP was determined using a laser diffraction particle size analyzer (Model: LS I3 320, Beckman Coulter, Brea, CA, USA) at solid state. The powder X-ray diffraction (XRD) analysis of α-TCP was carried out using X-ray diffractometer (Model: Bruker DE/D8 Advance, Bruker AXS GmbH, Karlsruhe, Germany). The step size was 0.02°, time per step was 0.1 s. The range of 2θ was 5°–80°. The calcium content of the Alg-α-TCP (10:1, 2:1 and 1:10) hybrid gels was measured by inductively coupled plasma mass spectrometry (ICP-MS) (Model: iCAP Q, ThermoFisher Scientific, Bremen, Germany).