A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Effects of fluoride on the removal of cadmium and phosphate by aluminum coagulation
This study focuses on the effects of p H and fluoride at different molar ratios of fluoride to Al（R F：Al） on the removal of cadmium（Cd~（2＋）） and phosphate by Al coagulation. Fluoride at R F：Al≥ 3：1 inhibits the removal of Cd over wide Al dose ranges from 5 to 10 mg/L as Al. The removal of phosphate decreases significantly at high R F：Al of 10：1 whereas at lowered R F：Al（i.e., ≤ 6：1）, an adverse effect is observed only at insufficient Al doses below 2 mg/L. Fluoride shows inhibitive effects towards the removal of Cd at p H 7 and 8 and that of phosphate at p H 6. Fluoride decreases the ζ-potential in both systems, and the decreasing extent is positively correlated to the elevated R F：Al. The Al fluoride interactions include the formation of Al-F complexes and the adsorption of fluoride onto Al（OH）3 precipitates, i.e., the formation of Al（OH）n F m. Al-F complex formation inhibits Al hydrolysis and increases residual Al levels, and a more significant increase was observed at lower p H. Al-F complexes at high R F：Al complicate the coagulation behavior of Al towards both negative and positive ionic species. Moreover, fluoride at low R F：Al shows little effect on Al coagulation behavior towards Cd^2＋and phosphate, and the spent defluoridation adsorbent,i.e., aluminum（Al） hydro（oxide） with adsorbed fluoride at R F：Al of below 0.1：1, may be reclaimed as a coagulant after being dissolved.
Effects of fluoride on the removal of cadmium and phosphate by aluminum coagulation
This study focuses on the effects of p H and fluoride at different molar ratios of fluoride to Al（R F：Al） on the removal of cadmium（Cd~（2＋）） and phosphate by Al coagulation. Fluoride at R F：Al≥ 3：1 inhibits the removal of Cd over wide Al dose ranges from 5 to 10 mg/L as Al. The removal of phosphate decreases significantly at high R F：Al of 10：1 whereas at lowered R F：Al（i.e., ≤ 6：1）, an adverse effect is observed only at insufficient Al doses below 2 mg/L. Fluoride shows inhibitive effects towards the removal of Cd at p H 7 and 8 and that of phosphate at p H 6. Fluoride decreases the ζ-potential in both systems, and the decreasing extent is positively correlated to the elevated R F：Al. The Al fluoride interactions include the formation of Al-F complexes and the adsorption of fluoride onto Al（OH）3 precipitates, i.e., the formation of Al（OH）n F m. Al-F complex formation inhibits Al hydrolysis and increases residual Al levels, and a more significant increase was observed at lower p H. Al-F complexes at high R F：Al complicate the coagulation behavior of Al towards both negative and positive ionic species. Moreover, fluoride at low R F：Al shows little effect on Al coagulation behavior towards Cd^2＋and phosphate, and the spent defluoridation adsorbent,i.e., aluminum（Al） hydro（oxide） with adsorbed fluoride at R F：Al of below 0.1：1, may be reclaimed as a coagulant after being dissolved.
Effects of fluoride on the removal of cadmium and phosphate by aluminum coagulation
2015
Article (Journal)
English
Impact of Phosphate on Fluoride Removal by Calcite
| British Library Online Contents | 2010