Synthesis of alginate beads filled with nanohydroxyapatite: An efficient approach for fluoride sorption

Abstract

Nanohydroxyapatite (n-HAp) powder is a promising adsorbent material with high defluoridation capacity (DC); however, it causes pressure drop during field applications. To overcome such problems and utilize the advantages of n-HAp, it is aimed to prepare n-HAp in a usable bead form with the support of alginate (Alg) biopolymer. n-HApAlgLa composite beads were synthesized by introducing n-HAp powder in Alg polymeric gel, and the resulting solution was dropped into La 31 ions for crosslinking. Defluoridation experiments were carried out in batch mode to optimize various influencing parameters like contact time, pH, challenger anions, initial fluoride concentrations, and temperature. The beads were characterized using Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy with energy-dispersive X-ray analyzer analysis. The sorption process was explained using diverse isotherms and kinetic models. The values of thermodynamic parameters indicate that the nature of fluoride is spontaneous and endothermic in nature. In field studies, n-HApAlgLa beads reduce the fluoride concentration below the tolerance limit. The regeneration and reusability studies were proposed to effectively use the sorbent.

Encapsulation of a powdery spinel-type Li+ ion sieve derived from biogenic manganese oxide in alginate beads

“…ALs form hydrogels by networking with cations. AL beads containing silica-AL-fungi biocomposites [19], lanthanum carbonate [20], layered double hydroxides [21], hydroxyapatite [22] and iron nanoparticles [23] have been produced and used for remediation of a diverse range of aqueous pollutants. However, Li + adsorption to AL composite beads has been scarcely reported in the literature.…”

Hydrothermal Synthesis of Melamine-Functionalized Covalent Organic Polymer-Blended Alginate Beads for Iron Removal from Water

“…In addition, −N–H deformation and the carboxylate bands were highly shifted in their wavenumber (shifted from 3417 to 3397 cm –1 ) because of the formation of electrostatic attraction with surface complexation between MCOP–Alg beads and iron during its adsorption. The carboxylate band were shifted because MCOP−Alg composite beads possess metal-chelating groups such as N–H and COO – which easily attract iron by means of electrostatic attraction with surface complexation …”

“…The carboxylate band were shifted because MCOP−Alg composite beads possess metal-chelating groups such as N−H and COO − which easily attract iron by means of electrostatic attraction with surface complexation. 38 3.2. XRD Analysis.…”

Fabrication of Multi-functionalized Graphene Oxide Doped Alginate Hybrid Spheres for Enhanced Fluoride Adsorption

“…After that, AGO@Alg biocomposite solution was gradually dropped into 2 % CaCl 2 (50 mL) solution to obtain an exploitable AGO@Alg hybrid spheres. The obtained AGO@Alg spheres were kept in the mother liquor upto 24 h for intensification purpose [35]. Lastly, AGO@Alg spheres were filtered and it was dried out in hot air oven at 80 °C upto 2 h for defluoridation studies.…”