Novel hydroxyapatite-biomass nanocomposites for fluoride adsorption

SCHEVERIN, V.N.; HORST, M.F.; LASSALLE, V.L.

Results in Engineering

Elsevier

Año: 2022

2590-1230

Hydroxyapatite-biomass nanocomposite (HAp-C) was successfully synthesized througha combined ultrasonic/hydrothermal one-pot method and used as a novel adsorbent toremove fluoride ions from groundwater. The obtained HAp-C composite was entirelycharacterized by TG, FTIR, XRD, SEM, and TEM. The point of zero charge wasdetermined by the drift method. It was found that the HAp partially coats thelignocellulosic matrix. XRD data suggested that biomass incorporation did not affect thecrystalline structure of the HAp. FTIR analysis suggests that the bond betweenhydroxyapatite and biomass is given by coordinating links. The fluoride adsorption onHAp-C was tested through batch assays using model solutions. The effect of contacttime, initial fluoride concentration, sorbent dose, pH, and co-existing species on theadsorption capacity was investigated. The results showed that fluoride adsorptioncapacity increased with contact time and initial fluoride concentration, decreasing withJournal Pre-proof2increasing sorbent dose. The maximum experimental adsorption capacity was 10.9 mgF- g-1 at the maximum concentration tested in this work (80 mg L-1). The pH variation(4.5-8.5) did not significantly affect the adsorption efficiency of the nanocomposite(~90%), while the presence of co-existing species significantly decreased its removalefficiency (~80%). The fluoride adsorption could be fitted by the Freundlich isotherm, andthe adsorption kinetic data followed the pseudo-second-order model. Besides,adsorption assays were replicated using natural groundwater samples from a rural regionof the southern Chaco-Pampean plain (Villarino, Buenos Aires, Argentina), registeringup to 77.4 % removal, reaching a fluoride concentration value (1.16 mg L-1) within thepermitted limits