Removal of cadmium from aqueous solution using adsorptive bubble separation techniques
Cadmium ion was removed from aqueous solutions using adsorptive bubble separation techniques. The effect of pH, coagulant and activator concentrations and ionic strength on separation efficiency was studied. Adsorbing colloid flotation using ferric hydroxide and aluminum hydroxide as the coprecipitant and sodium lauryl sulfate as the collector and frother was found to be very effective provided that the ionic strength of the solution was no greater than 0.01 M. The residual cadmium concentration was less than 0.02 ppm after foaming for 10 min from a solution containing 20 ppm cadmium initially. Effective separation can be achieved from solutions containing 0.1 M NaNO/sub 3/ or 0.05 M Na/sub 2/SO/sub 4/ when zinc ion is used as the activator. The results of foam flotation were compared with the zeta potential of the floc. It was found that the zeta potential of the floc decreases with increasing ionic strength of the solution. The zeta potential of the floc is more positive when activators (aluminum and zinc ions) were added, which presumably gives the floc a stronger affinity for anionic surfactant adsorption, resulting in better separation efficiency. Adsorbing colloid flotation becomes less effective with increasing inert salt concentration of the solution; this effect can be compensated for to quite a large extent with the aid of activators, and the applicability of foam separation techniques for heavy metal removal from wastewater is thus greatly extended.
- Research Organization:
- National Tsing Hua Univ., Hsinchu (Taiwan)
- OSTI ID:
- 5995456
- Journal Information:
- Sep. Sci. Technol.; (United States), Journal Name: Sep. Sci. Technol.; (United States) Vol. 23:10-11; ISSN SSTED
- Country of Publication:
- United States
- Language:
- English
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400105* -- Separation Procedures
520200 -- Environment
Aquatic-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
ADSORPTION
AQUEOUS SOLUTIONS
BUBBLES
CADMIUM
COLLOIDS
DATA
DISPERSIONS
EFFICIENCY
ELEMENTS
EXPERIMENTAL DATA
INFORMATION
METALS
MIXTURES
NUMERICAL DATA
PH VALUE
QUANTITY RATIO
SOLUTIONS
SORPTION