Biowaste-Derived Hydroxyapatite for Effective Removal of Reactive Yellow 4 Dye: Equilibrium, Kinetic, and Thermodynamic Studies

Abideen Idowu Adeogun; Edwin Andrew Ofudje; Mopelola Abidemi Idowu; Sarafadeen Olateju Kareem; Shappur Vahidhabanu; B Ramesh Babu

doi:10.1021/acsomega.7b01768

Biowaste-Derived Hydroxyapatite for Effective Removal of Reactive Yellow 4 Dye: Equilibrium, Kinetic, and Thermodynamic Studies

ACS Omega. 2018 Feb 16;3(2):1991-2000. doi: 10.1021/acsomega.7b01768. eCollection 2018 Feb 28.

Authors

Abideen Idowu Adeogun¹, Edwin Andrew Ofudje^{1

2}, Mopelola Abidemi Idowu¹, Sarafadeen Olateju Kareem¹, Shappur Vahidhabanu³, B Ramesh Babu³

Affiliations

¹ Department of Chemistry and Department of Microbiology, Federal University of Agriculture, Abeokuta, Nigeria.
² Department of Chemical Sciences, McPherson University, Abeokuta, Nigeria.
³ CSIR-Central Electrochemical Research Institute, Karaikudi, Tamil Nadu 630006, India.

Abstract

This study examines the application of poultry eggshell (PES) as a source of calcium for the synthesis of hydroxyapatite (HA) via annealation. The synthesized powder (poultry eggshell hydroxyapatite (PESHA)) was characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), EDAX, and transmission electron microscopy (TEM) analytical techniques. This powder was used for adsorptive removal of the Reactive Yellow 4 (RY4) dye in a batch process. Results from morphological analysis by SEM and TEM revealed that the microstructure of the apatite is made up of needle-rod-like particles with the length of 15-60 nm, breadth of 4-6 nm, and crystallite size of 86.32 nm. EDAX revealed that HA has Ca/P ratio of 1.63, indicating a nonstoichiometric apatite, whereas XRD analysis presented it as a pure monophasic hydroxyapatite powder. Fourier Transform Infrared (FTIR) spectroscopy indicated that the adsorption is due to the electrostatic interaction between the functional groups of the dye and those on the apatite surface. The maximum adsorption capacity (Q _max) of 127.9 mg g^-1 was obtained for the adsorption process, whereas the pseudo-first-order model with R ² > 0.99 best described the adsorption mechanism. Furthermore, the thermodynamic studies revealed that the adsorption process was exothermic and spontaneous in nature with ΔH and ΔS values of 120.79 kJ mol^-1 and 0.395 kJ mol^-1 K^-1, respectively. Thus, hydroxyapatite fabricated from the poultry waste of eggshell can be effectively utilized as an excellent nontoxic and cheap adsorbent for the removal of RY4 dye from aqueous medium.