Optimization of ion exchange process on the removal of heavy metals from cooling tower water and regeneration of ion exchange resins.

dc.contributor.authorMbedzi, Robert Mbavhalelo
dc.contributor.supervisorRutto, H. L., Prof.
dc.descriptionM.Tech. (Department of Chemical Engineering, Faculty of Engineering and Technology), Vaal University of Technology.en_US
dc.description.abstractIn the present study, the removal of Ca2+ and Mg2+ from cooling tower water using Amberlite IR120 and Amberjet 1200 was studied by the application of one factor at a time method (OFAT) and response surface modelling (RSM). The effect of operational parameters such as contact time (min), pH, dosage (mL), concentration (mg/L) and temperature (K) were investigated using central composite design. The regeneration of the Amberlite IR120 and Amberjet were also studied. The purpose of the study was to apply OFAT and RSM to investigate and optimize the ion exchange operating parameters. Furthermore, the second-order empirical model that was developed, using the analysis of variance (ANOVA), presented a sufficient correlation to the ion exchange experimental data. The optimal ion exchange operating conditions for Amberlite IR120 and Amberjet 1200 were found to be: contact time was 120 min, dosage of 150mL, initial pH level of 2, concentration of 400mg/L and temperature of 343K. Regeneration of Amberlite IR120 and Amberjet 1200 using 0.5 M NaCl stripping solution initially showed an increase in % Ca2+ and Mg2+ removal, then a decrease in subsequent cycles. The correlation coefficients (R2) of Langmuir, Freudlich and Tempkin isotherms were found to range from 0.92 to 1 and this suggest that experimental data best described the models. However correlation coefficients (R2) for Dubinin–Radushkevich (D-R) model were found to range between 0.5 to 0.8 and this means that experimental data does not fit the model. Thermodynamic functions such as entropy (Δ𝑆𝑜), enthalpy (Δ𝐻𝑜) and change of free energy (Δ𝐺𝑜) were obtained from the gradient and intercepts of straight line graphs. The positive values of ΔG° were found meaning that the adsorption is not spontaneous and positive values of ΔH° were found meaning the endothermic type of adsorption which indicate the chances of physical adsorption.The correlation coefficient (R2) values of pseudo-first-order, pseudo-second-order and intraparticle models were found to range from 0.89 to 1 on both metals as shown in table 4.4. This observation clearly indicates that pseudo-first-order, pseudo-second-order and intraparticle diffusion models best describe the experimental data in the removal Ca2+ and Mg2+ from cooling tower water.en_US
dc.publisherVaal University of Technologyen_US
dc.subjectAmberlite IR120en_US
dc.subjectAmberjet 1200en_US
dc.subjectCooling tower wateren_US
dc.subjectResponse surface modellingen_US
dc.subjectIon exchangeen_US
dc.subjectKinetics, isothermsen_US
dc.subjectCa2+, Mg2+ and regenerationen_US
dc.subjectHeavy metals removalen_US
dc.subject.lcshDissertations, Academic -- South Africaen_US
dc.subject.lcshCooling towersen_US
dc.subject.lcshWater -- Purification -- Ion exchange processen_US
dc.subject.lcshHeavy metals -- Environmental aspectsen_US
dc.titleOptimization of ion exchange process on the removal of heavy metals from cooling tower water and regeneration of ion exchange resins.en_US
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