A stock solution of fluoride (1000 ppm) was prepared by dissolving the required amount of NaF in deionized water. It was then diluted to the desired concentration. Tests were conducted to investigate the pH dependence of fluoride adsorption by varying the initial pH from 2 to 9. Test solutions containing 350 ppm fluoride (20.0 ml) with 0.04 g were used and the pH of the solutions was adjusted using aqueous 0.1 M HCl and 0.1 M NaOH. The effect of time on the adsorption capacity for fluoride was also investigated, using 20.0 ml of a 350 ppm fluoride solution at the optimum pH of 5.2 ± 0.1.
Batch adsorption studies were conducted at pH 5.2 in the concentration range from 40 ppm to 350 ppm using a fixed volume of 20.0 ml and an adsorbent dosage of 0.020 g. Residual fluoride concentrations were measured using a fluoride ion selective electrode (Hanna Instruments).
Batch adsorption studies were conducted at pH 5.2 in the concentration range from 40 ppm to 350 ppm using a fixed volume of 20.0 ml and an adsorbent dosage of 0.020 g. Residual fluoride concentrations were measured using a fluoride ion selective electrode (Hanna Instruments).
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