Kinetics And Isotherm Modeling Of Liquid Phase Adsorption Of Fluoride Onto Activated Lupinus Albus

Abstract

High concentration of fluoride (> 1.5 mg/L) in drinking water causes different health problems. Therefore, the aim of the study was fluoride removal capacity of activated L. albus under laboratory batch adsorption set up. The Physicochemical properties of the activated L. albus Moisture Content (%), Ash Content (%), pH and FTIR spectra of the adsorbent before and after adsorption were studied. The influence of parameters such as: pH of the solution, contact time, adsorbent doses, initial fluoride concentration, and the presence of co-existing anions was investigated. High fluoride removal efficiency (97.69%) was observed at PH 7 and equilibrium was achieved within 30 min of agitation time. The amount of fluoride adsorbed increase with increasing the dose of the adsorbent from 1 to 5 g/L. The equilibrium data tested with Langmuir, Freundlich, Sips and Redlich-Peterson Isotherm at room temperature and it was found that the Freundlich Isotherm (R2=0.9901) best fitted the adsorption of fluoride. The equilibrium removal capacity was observed using 5 g/L of the adsorbent. The experimental Kinetics of the data was analyzed using pseudo-first-order, pseudo-second-order and Weber Morris Intra-particle kinetics model. Kinetics data followed the non-linear pseudo-first-order model (R2 = 0.96) for L. albus adsorbent. The adsorption capacity decrease from 68 to 56% with the increase of bicarbonate concentration from 10 to 200 mg/L. The results obtained from this study could provide important information for evaluating the application of L. albus for removal of fluoride from drinking water. Therefore, the result obtained uses for further investigation.