Chiang Mai Journal of Science

In this paper, graphite (GP) has been composited with three different type of layered double hydroxides (LDH) namely NiAl-LDH/GP, CuAl-LDH/GP, and CaAl-LDH/GP by the co-precipitation method. The synthesized composites has been applied as an adsorbent for malachite green (MG) adsorption. The characterization of these materials was characterized using X-ray diffraction, Fourier transform infrared spectroscopy, N2 adsorption desorption isotherms, and scanning electron microscopy. The x-ray powder diffractions of prepared materials showed the typical diffraction pattern of both pristine graphite and LDH. The BET surface of NiAl-LDH/GP, CuAl-LDH/GP, and CaAl-LDH/GP were 21.595 m2/g, 18.830 m2/g, and 27.358 m2/g, respectively. The adsorption characteristic of MG onto the synthesized materials were systematically examined, including the adsorption kinetic, equilibrium, and thermodynamic. The adsorption kinetic of MG onto all the synthesized adsorbents followed the pseudo-second-order odel. The adsorption isotherm study indicated that the adsorption process was best fitted with the Langmuir model with the maximum adsorption capacity of 128.205 mg/g (CaAl- LDH/GP), 101.010 mg/g (CuAl-LDH/GP), and 100.000 mg/g (NiAl-LDH/GP). The adsorption thermodynamic analysis indicated that the adsorption process was spontaneous and favorable in the higher temperature. Furthermore, all the tested adsorbent exhibited high reusability and stability even after the fifth adsorption-desorption cycle.