Removal of fluoride using fly ash adsorbent

Abstract

Flouride (F) content in groundwater above 1.5 mg/L is a serious concern all over the world due to adverse health effects beyond that concentration. Hence, apart from its monitoring, an effective and low-cost removal technique is necessary. In this work, the removal of fluoride using fly ash has been studied. Batch adsorption studies, using laboratory shaker, were performed to examine the effect of pH in the range 2-10, adsorbent size (0.225 mm, 0.45 mm, and 0.90 mm), and adsorbent dose, varied from 2-6 g/L, for a contact time of 4 hours in all the experiments. The optimum condition for the F” removal was observed as pH:5, adsorbent size:0.225 mm and adsorbent dose: 5 mg/L, providing 67.20 % F“removal from the solution. Different kinetic models were tested and it was found that adsorption kinetics is of Pseudo second order and Elovich type. The study showed that fly ash can be effectively used for fluoride removal from water.

Adsorption of Fluoride from Aqueous Solution using Eggshell Pretreated with Plasma Technology

“…At the optimum dosage of 30 g/L of untreated eggshell, the average fluoride removal efficiencies were 34.50, 46.61 and 59.88 % for the size Sieve no.12 (≤1.70 mm diameter), Sieve no.16 (≤1.18 mm diameter) and Sieve no.20 (≤0.85 mm diameter), respectively. This is because the smaller adsorbent size offered comparatively higher available adsorption sites [23], which is consistent with the previous studies of Bhaumik et al [24] and Chandraker et al [25]. However, at the optimum dosage of 25 g/L of pretreated eggshell, the maximum average removal efficiency was obtained with size Sieve no.16 (90.34 %), followed by Sieve no.20 (72.25 %) and Sieve no.12 (57.25 %) (Figure 4(a)).…”

Application of fly ash for flouride adsorption

“…Chandraker et al achieved optimal conditions for fluoride removal in a slightly acidic environment and with a high initial fluoride concentration (50 mg/L). The adsorption corresponded to Freundlich's isotherm model and pseudo-second-order kinetics [56].…”

“…Recent research has confirmed the fact that in batch conditions, the adsorption of fluoride from aqueous solutions using fly ash is highly affected by the acidic environment [54,56]. Chakraborty et al achieved maximum adsorption capacity under strongly acidic conditions, lower initial fluoride concentrations (5 mg/L), and higher temperatures.…”