Fluoride sorption using Al and Mg modified Dicerocaryum eriocarpum leaves mucilage
Mukhethwa P. Mannzhi, Joshua N. Edokpayi
Abstract
The occurrence of fluoride at elevated levels remains a potential risk to public health globally. This study was performed to the test the potency of modified precipitate derived from the mucilage extracted from Dicerocaryum eriocarpum (DE) leaves. The mucilage was precipitated and modified using 0.1 M of aluminium and magnesium, respectively. The sorbents (AlDE and MgDE) were characterized with Fourier transform infrared spectrometer, scanning electron microscopy and energy-dispersive X-ray, Brunauer–Emmett–Teller, X-ray fluorescence and Thermo-gravimetric analyzer. Batch sorption studies including the effects of dosage, pH, time, temperature and change in water chemistry were investigated. The sorption studies recorded 84.23% removal by applying 0.25 g of AlDE for 2 h in a 100 mL aqueous solution containing 10 mgF −/L. The AlDE and MgDE recorded a significant difference in removal efficiencies when using natural water over deionized water. The highest fluoride sorption capacity recorded with the use of AlDE (69.65 mg/g) over MgDE (41.84 mg/g). The pseudo-second-order kinetic model best described the sorption kinetics using both sorbents. The sorption process was feasible and exothermic. Electrostatic interaction and ion exchange were responsible for the update of fluoride by the sorbents. De-ionize water was recorded as a good desorbing agent for the sorbents.