The Influence of Fulvic Acid on Cu2+, Cd2+ and Zn2+ Removal from Drinking Water by Alum Coagulation and Cu2+ and Cd2+ Complexing Capacity Measurements of Fulvic Acid and Natural Freshwater Samples by Dialysis Titration

摘要

Two studies of metal ion complexation by humic material were conducted. In the first, Cu(+2), Cd(+2) and Zn(+2) removal from solution during alum coagulation treatment was measured in the presence and absence of soil-derived fulvic acid (SFA). In a statistically designed experiment, it was found that a 6-96% Cu(+2), -6 to 59% Cd(+2), and -7 to 82% Zu(+2) losses were effected. The significant variables were pH, alum dosage, and an interaction effect of SFA level with both pH and alum dosage. In the second study, a dialysis titration technique for the measurement of natural water Cu(+2) and Cd(+2) complexing capacity was critically evaluated. Complexing capacities of 6.25 M EDTA, 15.5 M SFA, and 7 freshwater samples were measured. No more than 10% of the SFA binding material permeates the dialysis membrane. Correlation of several water properties reveals that only the Cu(+2) titration results correlate with pH, alkalinity, hardners and conductance. Color and DOC do not correlate with any water property.