Heavy metals are well known toxic priority pollutants. Hence, wastewaters containing these species must be treated prior to discharge into receiving bodies. In this study, the potential of Bigadiç / clinoptilolite for Cu2+ and Ni2+ removal from wastewaters was investigated in batch and continuous reactors.
Results of the preliminary experiments revealed the optimum operating conditions, namely, initial solution pH of 5 and 4 for Cu2+ and Ni2+, respectively and contact time of 48 hours. Additionally, conditioning of clinoptilolite with 2M NaCl solution for 24 hours was found to considerably improve the capacity utilized at breakthrough.
Maximum removal capacities and prevailing mechanisms in the system were investigated via equilibrium studies under preliminary determined optimum operating conditions. Langmuir and Freundlich models were fitted to the experimental data and Langmuir model was found to be better in describing the system behavior. Maximum removal capacities obtained from non-linear regression of Langmuir model are almost the same for Cu2+ and Ni2+ removal using as received
clinoptilolite samples (0.31 and 0.32 meq/g respectively). However, conditioned clinoptilolite samples exhibit higher capacity for Cu2+ over Ni2+ (0.5 and 0.43 meq/g, respectively). Analyses of exchangeable cations in the aqueous phase were carried out to examine the prevailing mechanisms in the system. As a result, adsorption, dissolution of clinoptilolite and surface precipitation (particularly in the case of Cu2+ removal) are considered to accompany ion exchange.
Finally, fixed-bed column studies were conducted with conditioned clinoptilolite samples for Cu2+ removal. An improvement in Cu2+ uptake was observed with decreasing volumetric flow rate (from 8 BV/h to 2-4 BV/h) and decreasing particle size (from 1.180-1.400 mm to 0.833-1.180 mm). Analyses of exchangeable cations as well as Si4+, Fe(total) and Al3+ were also carried out to examine the prevailing mechanisms. Ion exchange was discussed as the predominant mechanism in the system with minor contributions from adsorption and dissolution of clinoptilolite to the total amount of Cu2+ uptake and to the total amount of exchangeable cations release, respectively.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12606984/index.pdf |
| Date | 01 January 2006 |
| Creators | Volkan, Cagin |
| Contributors | Imamoglu, Ipek |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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