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Fig. 15. UV-vis absorbance of aqueous PVAm-Cu (II) complex solutions, prepared by adding different volumes of CuSO, solutions (Cu (II) concentration 1000 ppm) tc 100 mL of an aqueous PVAm solution at given PVAm concentrations.

Figure 15 UV-vis absorbance of aqueous PVAm-Cu (II) complex solutions, prepared by adding different volumes of CuSO, solutions (Cu (II) concentration 1000 ppm) tc 100 mL of an aqueous PVAm solution at given PVAm concentrations.

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Fig. 1. Schematic diagram of ultrafiltration set-up. The concentrations of the heavy metal ions in the feed and per- meate solutions were determined using a Prodigy radial induc- tively coupled plasma optical emission spectrometry (ICP-OES) (Teledyne-Leeman). The system was standardized for each metal analyte through a series of standard solutions over a concentration range of 0-160 ppm, prepared from certified commercial stock solutions. Yttrium was used as an internal standard at a fixed con- centration of approximately 10 mg/L. Each sample was analyzed 3
Fig. 1. Schematic diagram of ultrafiltration set-up. The concentrations of the heavy metal ions in the feed and per- meate solutions were determined using a Prodigy radial induc- tively coupled plasma optical emission spectrometry (ICP-OES) (Teledyne-Leeman). The system was standardized for each metal analyte through a series of standard solutions over a concentration range of 0-160 ppm, prepared from certified commercial stock solutions. Yttrium was used as an internal standard at a fixed con- centration of approximately 10 mg/L. Each sample was analyzed 3
Fig. 2. Heavy metal rejections using PVAm enhanced ultrafiltration. The rejectior data was measured based on the filtrate concentration after the first 40 g of filtrate: was discarded.
Fig. 2. Heavy metal rejections using PVAm enhanced ultrafiltration. The rejectior data was measured based on the filtrate concentration after the first 40 g of filtrate: was discarded.
Fig. 3. Metal rejections as a function of accumulative amount of filtrate at different feed metal and PVAm concentrations. a) Co (II), b) Cu (II), c) Ni (II) and d) Pb (II) Transmembrane pressure: 200 kPa.
Fig. 3. Metal rejections as a function of accumulative amount of filtrate at different feed metal and PVAm concentrations. a) Co (II), b) Cu (II), c) Ni (II) and d) Pb (II) Transmembrane pressure: 200 kPa.
Fig. 4. Permeation flux in PEUF versus accumulative amount of filtrate at differen PVAm dosages. Open keys: [PVAm] = 1 wt%, solid keys: [PVAm] = 0.1 wt%; concen- trations of metals: 25 ppm; transmembrane pressure: 200 kPa. Although an increase in the PVAm dosage can improve the metal rejection in PEUF, there will be a decrease in water flux. This is shown in Fig. 4, where a significant reduction in the permeation flux was noticed when the initial PVAm dosage increased from 0.1 to 1 wt%. This is not unexpected because of the intensified concen- tration polarization and membrane fouling. Interestingly, the per- meation flux was shown to be independent of the types of heavy metals involved. This suggests that the PVAm dosage is a primary
Fig. 4. Permeation flux in PEUF versus accumulative amount of filtrate at differen PVAm dosages. Open keys: [PVAm] = 1 wt%, solid keys: [PVAm] = 0.1 wt%; concen- trations of metals: 25 ppm; transmembrane pressure: 200 kPa. Although an increase in the PVAm dosage can improve the metal rejection in PEUF, there will be a decrease in water flux. This is shown in Fig. 4, where a significant reduction in the permeation flux was noticed when the initial PVAm dosage increased from 0.1 to 1 wt%. This is not unexpected because of the intensified concen- tration polarization and membrane fouling. Interestingly, the per- meation flux was shown to be independent of the types of heavy metals involved. This suggests that the PVAm dosage is a primary
Fig. 5. Effect of transmembrane pressure on water flux and metal rejection in PEUF. PVAm concentration: 0.1 wt%, metal concentration: 25 ppm. Temperature: ambient. The effects of operating pressure and temperature on the PEUF performance for metal rejection were studied. Fig. 5 shows the metal rejection and water f PVAm dosage, there was lit metals over a wide range of This is easy to understand be ux at different pressures. At a given tle change in the rejection of heavy pressures (from 40 to 800 kPa gauge). cause the pressure did not have a sig- nificant influence on the interaction between the chelating poly- mer and the metal ions and it only provided a driving force for mass transport across the membrane. As observed in typical ultra- filtration processes [30], the permeation flux increases with an plied, but the increase in the flux is increase in the pressure ap less than proportional. When the pressure is relatively low, the
Fig. 5. Effect of transmembrane pressure on water flux and metal rejection in PEUF. PVAm concentration: 0.1 wt%, metal concentration: 25 ppm. Temperature: ambient. The effects of operating pressure and temperature on the PEUF performance for metal rejection were studied. Fig. 5 shows the metal rejection and water f PVAm dosage, there was lit metals over a wide range of This is easy to understand be ux at different pressures. At a given tle change in the rejection of heavy pressures (from 40 to 800 kPa gauge). cause the pressure did not have a sig- nificant influence on the interaction between the chelating poly- mer and the metal ions and it only provided a driving force for mass transport across the membrane. As observed in typical ultra- filtration processes [30], the permeation flux increases with an plied, but the increase in the flux is increase in the pressure ap less than proportional. When the pressure is relatively low, the
Fig. 6. Water flux versus transmembrane pressure at different dosages of PVAm. Pure water flux and water flux of an aqueous PVAm solution in the absence of heavy metals were also shown for comparison. Temperature: ambient. To investigate the effects of temperature on the performance of PEUF for metal rejection, the PVAm-CuSO, system was selected for studies at different copper concentrations, and the results are shown in Fig. 7. It can be seen that at a given copper concentration,
Fig. 6. Water flux versus transmembrane pressure at different dosages of PVAm. Pure water flux and water flux of an aqueous PVAm solution in the absence of heavy metals were also shown for comparison. Temperature: ambient. To investigate the effects of temperature on the performance of PEUF for metal rejection, the PVAm-CuSO, system was selected for studies at different copper concentrations, and the results are shown in Fig. 7. It can be seen that at a given copper concentration,
Fig. 7. Effects of temperature on copper (II) rejection and water flux at different feed copper concentrations. Copper (II) compound: CuSO,, PVAm dosage 1 wt%, transmembrane pressure 200 kPa. It may be mentioned that the solution pH was not used as an independent operating parameter in testing the separation perfor- mance. When an acid or alkali was used to adjust the solution pH, the solution composition would have changed, thereby affecting the polymer-metal complexation. As such, the solution pH cannot be considered as an independent operating parameter because the pH effect has actually been reflected by the solution composition. At the low feed metal concentrations studied, there was only a small change in the pH of the feed solution (from 7.1 to 7.5) when the PVAm concentration varied from 0.1 to 1 wt%.
Fig. 7. Effects of temperature on copper (II) rejection and water flux at different feed copper concentrations. Copper (II) compound: CuSO,, PVAm dosage 1 wt%, transmembrane pressure 200 kPa. It may be mentioned that the solution pH was not used as an independent operating parameter in testing the separation perfor- mance. When an acid or alkali was used to adjust the solution pH, the solution composition would have changed, thereby affecting the polymer-metal complexation. As such, the solution pH cannot be considered as an independent operating parameter because the pH effect has actually been reflected by the solution composition. At the low feed metal concentrations studied, there was only a small change in the pH of the feed solution (from 7.1 to 7.5) when the PVAm concentration varied from 0.1 to 1 wt%.
Fig. 8. UV-vis absorption spectra of PVAm-metal complex solutions. PVAm concentration 1000 ppm, metal concentration 25 ppm. In order to further investigate the properties of PVAm-metal complexes and to get a clearer picture about the interactions of PVAm-Ni (II), PVAm-Zn (II) and PVAm-Mn (II) complexes, conduc- tometric titration experiments were conducted. The results of the titration experiments are presented in Fig. 10, where the conduc- tivity of the resulting (titrand + titrant) solution mixture was plot- ted as a function of the metal ion concentration in the solution. Normally, the addition of an ionic compound into an aqueous solu- tion will increase the conductivity of the solution due to increased concentration of free ions. As expected, when the metal salt solu- tion was added to deionized water, the conductivity of the solution increased because of the increased ion concentrations in the
Fig. 8. UV-vis absorption spectra of PVAm-metal complex solutions. PVAm concentration 1000 ppm, metal concentration 25 ppm. In order to further investigate the properties of PVAm-metal complexes and to get a clearer picture about the interactions of PVAm-Ni (II), PVAm-Zn (II) and PVAm-Mn (II) complexes, conduc- tometric titration experiments were conducted. The results of the titration experiments are presented in Fig. 10, where the conduc- tivity of the resulting (titrand + titrant) solution mixture was plot- ted as a function of the metal ion concentration in the solution. Normally, the addition of an ionic compound into an aqueous solu- tion will increase the conductivity of the solution due to increased concentration of free ions. As expected, when the metal salt solu- tion was added to deionized water, the conductivity of the solution increased because of the increased ion concentrations in the
Fig. 10. Conductivity of (titrand+ titrant) solution mixtures. Titrand, aqueous solutions of 1000 ppm; titrate, 100 mL of PVAm aqueous solution (1 wt%) or deionized water. Fig. 9. UV-vis absorption spectra of PVAm-Cu (II) complex solutions. Copper (II) compound CuSOg, Cu (II) concentration 50 ppm. PVAm concentration varied from 40 to 250 ppm as labeled.
Fig. 10. Conductivity of (titrand+ titrant) solution mixtures. Titrand, aqueous solutions of 1000 ppm; titrate, 100 mL of PVAm aqueous solution (1 wt%) or deionized water. Fig. 9. UV-vis absorption spectra of PVAm-Cu (II) complex solutions. Copper (II) compound CuSOg, Cu (II) concentration 50 ppm. PVAm concentration varied from 40 to 250 ppm as labeled.
Fig. 12. Nickel (II) rejection in PEUF and conductivity of the PVAm-Ni (II) solutio1 at different metal-to-PVAm ratios. Fig. 11. Copper (II) rejection in PEUF and conductivity of the PVAm-Cu (II) solutions at different metal-to-PVAm ratios for different copper compounds.
Fig. 12. Nickel (II) rejection in PEUF and conductivity of the PVAm-Ni (II) solutio1 at different metal-to-PVAm ratios. Fig. 11. Copper (II) rejection in PEUF and conductivity of the PVAm-Cu (II) solutions at different metal-to-PVAm ratios for different copper compounds.
ig. 13. UV-vis spectra to illustrate formation of PVAm-metal complexes and their precipitations. (a) 100 mL of PVAm solution (0.1 wt%) + different volumes of CuSO, lution (1000 ppm Cu); (b) 100 mL of PVAm solution (0.1 wt%) + different volumes of CoSO, solution (1000 ppm Co).
ig. 13. UV-vis spectra to illustrate formation of PVAm-metal complexes and their precipitations. (a) 100 mL of PVAm solution (0.1 wt%) + different volumes of CuSO, lution (1000 ppm Cu); (b) 100 mL of PVAm solution (0.1 wt%) + different volumes of CoSO, solution (1000 ppm Co).
Fig. 14. Effects of anions of copper salts on the UV-vis absorbance of aqueous PVAm-Cu (II) complex solutions, prepared by adding different volumes of copper salt solutions (Cu (II) concentration 1000 ppm) to 100 mL of an aqueous PVAm solution (0.1 wt%).
Fig. 14. Effects of anions of copper salts on the UV-vis absorbance of aqueous PVAm-Cu (II) complex solutions, prepared by adding different volumes of copper salt solutions (Cu (II) concentration 1000 ppm) to 100 mL of an aqueous PVAm solution (0.1 wt%).
Fig. 16. Effect of PVAm concentration on the flocculation capacity of PVAm to capture CuSO,.
Fig. 16. Effect of PVAm concentration on the flocculation capacity of PVAm to capture CuSO,.
Fig. 18. Effect of PVAm-Co (II) flocculation on water flux in PEUF at a transmem- brane pressure of 200 kPa. The corresponding absorbance data of the solution at 2= 306 nm was shown for purpose of comparison. Fig. 17. Illustration of floc growth and flocculation induced by sulfate anions for the PVAm-CuSOy, system.
Fig. 18. Effect of PVAm-Co (II) flocculation on water flux in PEUF at a transmem- brane pressure of 200 kPa. The corresponding absorbance data of the solution at 2= 306 nm was shown for purpose of comparison. Fig. 17. Illustration of floc growth and flocculation induced by sulfate anions for the PVAm-CuSOy, system.
Fig. 19. Fouled membrane surfaces by (a) soluble PVAm-CoSO, complex solutions, and (b) PVAm-CoSO, flocculants.
Fig. 19. Fouled membrane surfaces by (a) soluble PVAm-CoSO, complex solutions, and (b) PVAm-CoSO, flocculants.
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