TY - JOUR
T1 - Removal of fluoride ions from aqueous solution at low pH using schwertmannite
AU - Eskandarpour, Akbar
AU - Onyango, Maurice S.
AU - Ochieng, Aoyi
AU - Asai, Shigeo
PY - 2008
Y1 - 2008
N2 - Wastewater containing fluoride requires polishing after precipitation/coagulation treatment in order to meet stringent environmental legislation. Accordingly, adsorption characteristics of fluoride onto schwertmannite adsorbent were studied in a batch system with respect to changes in initial concentration of fluoride, equilibrium pH of sample solution, adsorbent dosage and co-existing ions. Equilibrium adsorption data were obtained at 295.6, 303 and 313K, and are interpreted in terms of two-site Langmuir, Freundlich, Langmuir–Freundlich, Redlich–Peterson, Tóth and Dubinin–Radushkevitch isotherm models. The experimental and equilibrium modeling results revealed that the capacity of schwertmannite for fluoride is high but insensitive to changes in solution temperature. An increase in equilibrium pH of sample solution reduced significantly the fluoride removal efficiency. In binary component systems, inner-sphere complex forming species had negative effects on fluoride adsorption while outer-sphere complex forming species improved slightly the fluoride removal efficiency. The schwertmannite adsorbent was regenerable and had the ability to lower the fluoride concentration to acceptable levels.
AB - Wastewater containing fluoride requires polishing after precipitation/coagulation treatment in order to meet stringent environmental legislation. Accordingly, adsorption characteristics of fluoride onto schwertmannite adsorbent were studied in a batch system with respect to changes in initial concentration of fluoride, equilibrium pH of sample solution, adsorbent dosage and co-existing ions. Equilibrium adsorption data were obtained at 295.6, 303 and 313K, and are interpreted in terms of two-site Langmuir, Freundlich, Langmuir–Freundlich, Redlich–Peterson, Tóth and Dubinin–Radushkevitch isotherm models. The experimental and equilibrium modeling results revealed that the capacity of schwertmannite for fluoride is high but insensitive to changes in solution temperature. An increase in equilibrium pH of sample solution reduced significantly the fluoride removal efficiency. In binary component systems, inner-sphere complex forming species had negative effects on fluoride adsorption while outer-sphere complex forming species improved slightly the fluoride removal efficiency. The schwertmannite adsorbent was regenerable and had the ability to lower the fluoride concentration to acceptable levels.
U2 - 10.1016/j.jhazmat.2007.07.020
DO - 10.1016/j.jhazmat.2007.07.020
M3 - Article
SN - 0304-3894
VL - 152
SP - 571
EP - 579
JO - Journal of Hazardous Materials
JF - Journal of Hazardous Materials
IS - 2
ER -