The removal of heavy metals from wastewater using South African clinoptilolite
Date
2010-04-09T06:47:52Z
Authors
Kapanji, Kutemba Kaina
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Abstract
This research concerns the further characterisation and establishment of adsorption
behaviour of the South African clinoptilolite. Synthetic single- and multi-component
wastewaters were used, and experiments conducted in both batch and column systems
at 25oC ± 2. Wastewaters containing heavy metals ions Cu2+, Co2+, Ni2+ and Cr3+,
were used at different feed concentrations (50 - 500 mg/L), and adsorbed onto natural
and homoionic (Na+, K+, Ca2+, NH+
4) forms of the zeolite. The Na+-form
clinoptilolite had an improved cation exchange capacity over the natural one, and the
selectivity series of metal ions by these two forms varied. Brunauer Emmett Teller
surface area analysis carried out also confirms that preconditioning clinoptilolite with
Na+ ions results in an increase in pore diameter, allowing for easier diffusion of ions
and more adsorption. An atomic adsorption spectrophotometer (AAS) was used to
analyse metal ions in solution. Adsorption efficiencies with over 75% of metal ions
adsorbed in the first hour of contact were recorded, and complete adsorption
equilibrium being reached in 4 hrs. Regeneration of Na+-form and natural
clinoptilolite (using 0.5M NaCl stripping solution) initially showed an increase in
loading capacities, then a decrease with the subsequent cycles. A comparison between
two particle sizes revealed that smaller particle sized clinoptilolite have slightly
higher adsorption capacities. The equilibrium data also fitted well with the linear
form of the Langmuir and Freundlich isotherms at lower concentrations of 50 mg/L.
Description
Thesis MSc Faculty of Engineering and the Built Environment,School of Chemical and Metallurgical Engineering, University of the Witwatersrand
Keywords
clinoptilolite, zeolites, water