Modelling and Measurement of Bubble Formation and Growth in Electroflotation Processes
Electroflotation is used in the water treatment industry for the recovery of suspended particles. In this study the bubble formation and release of hydrogen bubbles generated electrolytically from a platinum cathode was investigated. Previously, it was found that both the growth rate and detachment diameter increased with increasing wire diameter. Conversely, current density had little effect on the released bubble size. It was also found that the detached bubbles rapidly increased in volume as they rose through the liquid as a result of decreasing hydrostatic pressure and high levels of dissolved hydrogen gas in the surrounding liquid. The experimental system was computationally modelled using a Lagrangian-Eulerian Discrete Particle approach. It was revealed that desorption of gaseous solutes from the electrolyte solution, other than hydrogen, may have a significant impact on the diameter variation of the formed bubbles. The simulation confirmed that liquid circulation, either forced or induced by the rising bubble plume, influences both the hydrogen supersaturation (concentration) in the neighbourhood of the electrode and the size of the resulting bubbles.
- School of Engineering, The University of Newcastle, Callaghan, NSW, 2308 Australia
- Warsaw University of Technology, Faculty of Chemical and Process Engineering, ul. Waryńskiego 1, 00-645 Warsaw, Poland
- School of Engineering, The University of Newcastle, Callaghan, NSW, 2308 Australia , Geoffrey.Evans@newcastle.edu.au
- Bird R.B., Steward W.E., Lightfoot E.N., 2002. Transport Phenomena. 2nd ed., John Wiley & Sons, New York.
- Delnoij E., Lammers F.A., Kuipers J.A.M., van Swaaij W.P.M., 1997. Dynamic simulation of dispersed gasliquid two-phase flow using discrete bubble model. Chem. Eng. Sci., 52, 1429-1458. DOI: 10.1016/S0009-2509(96)00515-5.[Crossref]
- Levich V., 1962. Physicochemical Hydrodynamics. Prentice-Hall, Englewood Cliffs, NY.
- Müller L., Krenz M., Rübner K., 1989. On the relation between the transport of electrochemically evolved Cl2 and H2 into the electrolyte bulk by convective diffusion and by gas bubbles. Electrochimica Acta, 34, 305-308. DOI: 10.1016/0013-4686(89)87002-1.[Crossref]
- Sarkar M.S.K.A., Donne S.W., Evans G.M., 2010. Hydrogen bubble flotation of silica. Adv. Powder Technol., 21, 412-418. DOI: 10.1016/j.apt.2010.04.005.[WoS][Crossref]
- Sarkar M.S.K.A., Evans G.M., Donne S.W., 2010. Bubble size measurement in electroflotation. Minerals Engng., 23, 1058-1065. DOI: 10.1016/j.mineng.2010.08.015.[Crossref][WoS]
- Sarkar M.S.K.A., Donne S.W., Evans G. M., 2011. Utilization of hydrogen in electroflotation of silica. Adv.Powder Technol., 22, 482-492. DOI: 10.1016/j.apt.2011.05.007.[Crossref][WoS]
- Sarkar M.S.K.A., 2011. Electroflotation: Its application to water treatment and mineral processing. PhD Thesis, The University of Newcastle, Australia.
- Vogt H., 1984a. The rate of gas evolution of electrodes-i. An estimate of the efficiency of gas evolution from the supersaturation of electrolyte adjacent to a gas-evolving electrode. Electrochimica Acta, 29, 167-173. DOI: 10.1016/0013-4686(84)87043-7.[Crossref]
- Vogt H., 1984b. The rate of gas evolution at electrodes-ii. An estimate of the efficiency of gas evolution on the basis of bubble growth data. Electrochimica Acta, 29, 175-180. DOI: 10.1016/0013-4686(84)87044-9.[WoS][Crossref]