The removal of methyl orange by nanohydroxyapatite from aqueous solution: isotherm, kinetics and thermodynamics studies

Abstract

a b s t r a c tHydroxyapatite (HAp) is a biomaterial with a large number of useful applications. In this work, a method for the preparation of HAp at nanoscale was developed (nano-HAp). The prepared nano-HAp was used in the extraction of methyl orange (MO) from water. The special chemical composition, the crystal structure of HAp and molecular structure of MO made extraction occurs at a good efficiency. Structure of the prepared HAp was confirmed by powder X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscope. Batch experiments were used to evaluate the tendency of the prepared nano-HAp for extracting the MO from water. The effect of temperature, time, pH and the amount of adsorbent on the rate of adsorption were evaluated and found to have a noticeable effect on the adsorption efficiency. The optimum conditions for extraction of MO by nano-HAp were determined. In all runs, in the first 5-15 min of contact time at room temperature the nano-HAp showed the highest rate of adsorption. Then, the rate leveled off after about 20 min. The temperature showed almost directly proportional with the rate of adsorption. The thermodynamic studies revealed a spontaneous nature of adsorption at different temperature.

Characterization and Antimicrobial Activity of Nigella sativa Extracts Encapsulated in Hydroxyapatite Sodium Silicate Glass Composite

“…The small and broad bands at 1650 cm −1 and 3480 cm −1 correspond to deformation and vibration of water molecules (H 2 O), respectively [ 30 ]. In addition, the weak band near 3560 cm −1 was assigned to stretching vibration of OH − groups in hydroxyapatite structure [ 31 ].…”

Removal and extraction efficiency of Quaternary ammonium herbicides paraquat (PQ) from aqueous solution by ketoenol–pyrazole receptor functionalized silica hybrid adsorbent (SiNPz)

“…The other type of isotherm model is Freundlich isotherm is an empirical formula which used for low concentrations and can be presented as [30]:where K F is the Freundlich constant that deal with adsorption capacity (mg/g) and n is the heterogeneity coefficient which leads to how favorable the adsorption process (g/L).…”