Removal of heavy metals by sulfide precipitation in the presence of complexing agents
Heavy metal removals and particle size distributions were presented for both hydroxide precipitation and sulfide precipitation of zinc, cadmium, copper, and nickel in the presence of various complexing agents. Both batch and continuous experiments were performed for synthetic and actual metal-containing wastewaters. Metal concentrations complexing agent concentrations, sulfide dosages, pH levels of the solutions, and reaction or residence times were varied to determine the reaction kinetics. Sulfide precipitation always achieved lower residual metal concentrations than the corresponding hydroxide precipitation. The presence of strong complexing agents severely inhibited the removal of heavy metal by the precipitation process. Weak complexing agents exhibited little effect on the chemical equilibria for both hydroxide and sulfide precipitation systems. Weak complexing agents did affect the particle size distribution through a nucleation/growth inhibition, general forming smaller particles.
- Research Organization:
- Purdue Univ., Lafayette, IN (USA)
- OSTI ID:
- 6527446
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
Aquatic-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
CADMIUM
CHALCOGENIDES
CHEMICAL COMPOSITION
CHEMICAL REACTION KINETICS
COPPER
ELEMENTS
HYDROGEN COMPOUNDS
HYDROXIDES
KINETICS
LIQUID WASTES
METALS
NICKEL
OXYGEN COMPOUNDS
PARTICLE SIZE
PH VALUE
PRECIPITATION
REACTION KINETICS
REMOVAL
SEPARATION PROCESSES
SIZE
SULFIDES
SULFUR COMPOUNDS
TRANSITION ELEMENTS
WASTE WATER
WASTES
WATER
ZINC