Intercalation of Rhodamine B Dye into Zinc-Aluminum Layered Double Hydroxides: Structural, Textural, and Morphological Insights

Abstract

This research reports of Zinc-Aluminium layered double hydroxide material (ZAL) intercalated with the organic dye rhodamine b (ZARB) through a co-precipitation technique. The intercalation of ZAL with rhodamine b (RB) was conducted at various concentrations of rhodamine b ranging from 0.025 to 0.6 M, at a pH of 7.0 ± 0.5, and with an aging time of 18 h. ZAL and ZARB were characterized using PXRD, FTIR-ATR, BET, and SEM-EDX to confirm the intercalation of guest ions into the interlayer of the lamellar structure. The overall PXRD pattern of ZAL and the optimal concentration of ZARB at 0.2 M demonstrated an expansion of basal spacing from 8.9 to 11.0 Å, indicating successful intercalation of the ZAL compound with RB. The FTIR-ATR spectrum of ZAL and ZARB at 0.2 M exhibited peaks at 3,375 cm⁻¹ (O-H), 1,617 cm⁻¹ (C=C), 1,097 cm⁻¹ (C-O), 758 and 608 cm⁻¹ (Zn-OH and Al-OH), while small peaks at 1,334 cm⁻¹ (N-O) indicated that RB was intercalated between the layered structure. The spatial orientation of ZARB at 0.2 M exhibited an interlayer region value of 6.19 Å for the ZAL nanocomposites. BET analysis revealed that ZAL and ZARB exhibited Type IV nitrogen adsorption-desorption isotherms with H1 hysteresis loops. ZAL surface area was 5.19 m²g⁻¹, BJH desorption pore volume is 0.0238 cm³g⁻¹ and BJH average pore diameter is 18.05 nm. Upon modification with RB, ZARB surface area increased to 14.30 m²g⁻¹, BJH desorption pore volume to 0.0538 cm³g⁻¹ and BJH average pore diameter is 20.27 nm. SEM-EDX morphology of ZAL revealed aggregated hexagonal plate-like with non-uniform sizes and shapes. Upon intercalation with RB into the layered double hydroxide, the structure formed flaky plate-like particles with a higher surface area. These results demonstrate the effective intercalation of RB into the ZAL framework, resulting in a nanocomposite with modified structural and morphological properties.

HIGHLIGHTS

• Successful intercalation of Rhodamine B (RB) into zinc-aluminum layered double hydroxide (ZAL) was achieved at an optimal concentration of 0.2 M, with basal spacing expansion from 8.9 to 11.0 Å confirmed by PXRD and FTIR-ATR.
• BET analysis showed a significant increase in surface area (from 5.19 to 14.30 m²/g) and porosity upon intercalation, indicating improved textural properties of the resulting ZARB nanocomposite.
• Morphological transformation was observed via SEM-EDX, where ZAL’s hexagonal plate-like structure changed to flaky plate-like particles with higher surface area after intercalation.
• Spatial modeling suggested a vertical orientation of RB anions within the interlayer region (6.19 Å), consistent with the intercalation-induced structural changes.
• ZARB nanocomposite demonstrated potential for environmental remediation and sensing applications by effectively encapsulating RB, reducing its leaching and enhancing material stability.

GRAPHICAL ABSTRACT