Enhanced removal of lead(II) and cadmium(II) from water in alum coagulation by ferrate(VI) pretreatment.
A laboratory study demonstrated that ferrate pretreatment significantly enhanced lead and cadmium removal in alum coagulation, under the conditions of natural surface water. The enhancement of lead removal was approximately 21 to 37% by ferrate pretreatment at a dosage of 1 to 5 mg/L. The enhanced removal of cadmium by ferrate pretreatment at a dosage of 1 to 5 mg/L exceeded the removal by alum coagulation alone 2-to 12-fold. Cadmium is much more difficult to remove than lead in alum coagulation. The performance of ferrate in enhancing the removal of lead and cadmium in alum coagulation was better than that of ferric chloride. The removal of lead and cadmium was highly pH-dependent, following the general trend of higher pH being related to higher removal. Satisfactory removal of cadmium could be expected by ferrate pretreatment combined with adjusting the pH of the water.
School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin, P.R. China.
Yong-mei
YM
Liang
Ma
M
Jun
Wei
W
Liu
D000534:Alum Compounds / Q000737:chemistry*; D002104:Cadmium / Q000737:chemistry* / Q000302:isolation & purification; D007501:Iron / Q000737:chemistry*; D007854:Lead / Q000737:chemistry* / Q000302:isolation & purification; D011522:Protons; D015203:Reproducibility of Results; D018508:Water Purification / Q000379:methods*
D000534:Alum Compounds; D011522:Protons; D002104:Cadmium; C017311:ferrate ion; D007854:Lead; C041524:aluminum sulfate; D007501:Iron