Treatment of metal-containing wastewater by adsorption of metal-chelate complexes onto activated carbon

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:5606900

Shay, M A

To eliminate difficulties associated with interference of chelating or complexing agents on precipitation of heavy metals from wastewaters, the feasibility of a process which utilized chelating agents in the removal of the heavy metals was investigated. Heavy metal ions were removed from simulated metal plating wastewater by sorption of a heavy metal chelate complex onto activated carbon. In this process, a chelate which might be present in a wastewater could be used in removal of a heavy metal, rather than interfere with its removal. System development of a continuous flow process consisted of bench scale column tests to answer questions about key adsorption column operating parameters. The metals investigated were Cu(II), Ni(II) and Zn(II). Hydrogen ion concentration had the largest effect on removal of heavy metalchelate complexes, but contact time and heavy metal:chelate ratio were important. The normal contact time for activated carbon columns of 30 to 60 minutes was found adequate to achieve heavy metal-chelate removals of at least 90% for citrate or EDTA complexes. For citrate complexes better removals were achieved at heavy metal:chelate ratios greater than 1:1. For EDTA, there was no advantage to ratios greater than 1:1. Increasing pH, at least to pH 9.0, increased the heavy metal chelate removal; however, for EDTA, removals greater than 90% could be achieved at a pH as low as 3.0. The maximum amount of Cu(II)-citrate complex that could be removed was 2.8 mg per gram of carbon, the maximum amount for Zn(II)citrate complex was 1.2 mg per gram of carbon, and for Ni(II)-citrate, the maximum was 1.3 mg per gram of carbon. For the EDTA complexes, the maximum removal was 2.1 mg of Cu(II)-EDTA complex per gram of carbon, 6.9 mg of Zn(II)-EDTA complex per gram of carbon, and 3.2 mg of Ni(II)-EDTA complex per gram of carbon.

• Research Organization: Purdue Univ., Indianapolis, IN (United States)
• OSTI ID: 5606900
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540320* -- Environment
Aquatic-- Chemicals Monitoring & Transport-- (1990-)
AMINO ACIDS
CARBOXYLIC ACIDS
CHELATING AGENTS
CLEANING
COMPLEXES
COPPER
DECONTAMINATION
EDTA
ELEMENTS
HYDROGEN COMPOUNDS
LIQUID WASTES
MANAGEMENT
MATERIALS RECOVERY
METALS
NICKEL
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
POLLUTION
PRECIPITATION
PROCESSING
RECOVERY
SEPARATION PROCESSES
TRANSITION ELEMENTS
WASTE MANAGEMENT
WASTE PROCESSING
WASTE WATER
WASTES
WATER
WATER POLLUTION
ZINC