The Aqueous Process Engineering and Chemistry Group (APEC) was established at the University of Toronto’s Department of Chemical Engineering and Applied Chemistry in 1992, under the leadership of Professor Vladimiros G. Papangelakis

Mission Statement

Our group focuses on developing novel sustainable processes and environmentally responsible solutions for the metals/minerals industry by studying the fundamentals of aqueous industrial processes.

Core Values

Our research approaches include:

  • Thorough study of the underlying chemistry of the process under investigation and precision in design and conduct of experimental work while maintaining close connection between theoretical and practical aspects;
  • Highest standards of reporting research results;
  • Respect for deadlines.

Areas of expertise

  • Aqueous process engineering
  • Chemical process metallurgy
  • Hydrometallurgy
  • Process modelling
  • Electrolyte solution chemistry
  • Mineral-water interfaces
  • Recycling of inorganic wastes
  • Environmental remediation from mining and metallurgical activities.

Main Areas of Research

  • Industrial water chemistry;
  • Hydrometallurgy and bio-hydrometallurgy;
  • Chemical modeling of electrolyte systems via OLI™ software;
  • Scale abatement in industrial reactors;
  • Focus metals: nickel, cobalt, gold, calcium, magnesium, rare earths (lanthanides);
  • Recycling and cleaning of inorganic wastes;
  • Development of industrial sensors for acid and redox monitoring at low and high temperature.

For a more in-depth look at our research interests and achievements, please consult the “Projects” page.

Selected Publications

  1. Eric Shum, Vladimiros G. Papangelakis, “Water Recovery from Inorganic Solutions via Natural Freezing and Melting,” Journal of Water Process Engineering, Volume 31, October 2019, 100787, doi.org/10.1016/j.jwpe.2019.100787
  2. Georgios Kolliopoulos, Jeffrey T. Martin, Vladimiros G. Papangelakis, “Energy Requirements in the Separation-Regeneration Step in Forward Osmosis Using TMA-CO2-H2O as the Draw Solution,” Chemical Engineering Research and Design, 140 (2018), 166–174
  3. Georgios Kolliopoulos and Vladimiros G. Papangelakis, “Temperature and Pressure Effects on the Separation Efficiency and Desorption Kinetics in the TMA-CO2-H2O System,” Ind. Eng. Chem. Res. 2018, 57, 14767−14773,http://dx.doi.org/10.1021/acs.iecr.8b03926
  4. Georgios Kolliopoulos, Eric Shum, and Vladimiros G. Papangelakis, “Forward Osmosis and Freeze Crystallization as Low Energy Water Recovery Processes for a Water-Sustainable Industry,” Environ. Process. (2018).https://doi.org/10.1007/s40710-018-0316-5
  5. Georgios Kolliopoulos, Amy M. Holland, and Vladimiros G. Papangelakis, “Modeling of Density and Electrical Conductivity of Aqueous Carbonated Trimethylamine (TMA-CO2-H2O) Solutions at 20 °C,” Monatshefte für Chemie – Chemical Monthly, 2017, https://doi.org/10.1007/s00706-017-2091-9
  6. Igor Guzman, Steven J. Thorpe & Vladimiros G. Papangelakis (2017): Redox potential measurement during pressure oxidation (POX) of a refractory gold ore, Canadian Metallurgical Quarterly, DOI: 10.1080/00084433.2017.1386363
  7. Srinath Garg, Kurtis Judd, Radhakrishnan Mahadevan, Elizabeth Edwards & Vladimiros G. Papangelakis (2017) Leaching characteristics of nickeliferous pyrrhotite tailings from the Sudbury, Ontario area, Canadian Metallurgical Quarterly, 56:4, 372-381, DOI: 10.1080/00084433.2017.1361162
  8. Igor Guzman, Steven J. Thorpe, Vladimiros G. Papangelakis, “Redox potential measurements in the H2SO4-FeSO4-Fe2(SO4)3-H2O system at high temperature using an Ir electrode,” Journal of Electroanalytical Chemistry, 799 (2017), 399-405.
  9. Srinath Garg, Vladimiros Papangelakis, Elizabeth Edwards, Radhakrishnan Mahadevan, “Application of a Selective Dissolution Protocol to Quantify the Terminal Dissolution Extents of Pyrrhotite and Pentlandite From Pyrrhotite Tailings,” International Journal of Mineral Processing, 158 (2017), 27-34.
  10. Georgios Kolliopoulos, Michael Carlos, Timothy J. Clark, Amy M. Holland, Ding-Yu Peng, Vladimiros G. Papangelakis, “Chemical Modeling of the TMA-CO2-H2O System: A Draw Solution in Forward Osmosis for Process Water Recovery,” Journal of Chemical and Engineering Data, 62(4), 1214-1222, 2017, DOI: 10.1021/acs.jced.6b00780
  11. Ilya Perederiy and Vladimiros G. Papangelakis, “Why amorphous FeO-SiO2 slags do not acid-leach at high temperatures,” Journal of Hazardous Materials, 321 (2017), 737-744
  12. Georgiana Moldoveanu and Vladimiros Papangelakis, “An overview of rare earth recovery by ion exchange leaching from ion-adsorption clays of various origins,” Mineralogical Magazine, 80(1), 63-76, 2016.
  13. Nazanin Samadifard, Cheryl E. Devine, Elizabeth Edwards, Krishna Mahadevan, and Vladimiros G. Papangelakis, “Ferric sulphate leaching of pyrrhotite tailings between 30 to 55 °C,” Minerals, 5 (2015), 801–814; doi:10.3390/min5040526
  14. Georgiana A. Moldoveanu and Vladimiros G. Papangelakis, “Effects of thermal pre-treatment and ore dryness on the recovery of lanthanides from ion-adsorption clays”, Hydrometallurgy, 158 (2015), 180-185.
  15. Georgiana A. Moldoveanu and Vladimiros G. Papangelakis, “Strategies for calcium sulphate scale control in hydrometallurgical processes at 80 °C”, Hydrometallurgy, 157 (2015).  133-139.
  16. G.A. Moldoveanu, V.G. Papangelakis, “Recovery of rare earth elements adsorbed on clay minerals: II. Leaching with Ammonium Sulphate,” Hydrometallurgy, 131-132 (2013), 158-166.
  17. Georgiana A. Moldoveanu, Vladimiros G. Papangelakis, “Recovery of rare earth elements adsorbed on clay minerals: I. Desorption mechanism,” Hydrometallurgy 117118 (2012) 7178.
  18. I.V. Bylina, S.C. Mojumdar, V.G. Papangelakis, “Effect of storage time on the pressure oxidation enthalpy of pyrite,” Journal of Thermal Analysis and Calorimetry (2012): 1-7, April 06, 2012.
  19. Ilya Perederiy, V. G. Papangelakis, Mohamed Buarzaiga, Indje Mihaylov, “Co-treatment of converter slag and pyrrhotite tailings via high pressure oxidative leaching,” Journal of Hazardous Materials, 194 (2011), 399–406.
  20. G. Azimi, V.G. Papangelakis, “Mechanism and Kinetics of gypsum-anhydrite transformation in Aqueous Electrolyte Solutions,” Hydrometallurgy, 108 (2011), Description: http://www.sciencedirect.com/scidirimg/clear.gif122-129.
  21. R.J. Mathew, V.G. Papangelakis, E. Guerra, “Interfacial phenomena in the sulphur-polytetrafluoroethylene system under hydrothermal conditions,” Minerals Engineering, 23 (2010) 1113-1119.
  22. Z. Jankovic, V.G. Papangelakis, “Measurement of pH in high-temperature nickel laterite pressure acid leach process solutions, Hydrometallurgy 105 (2010), 155-160.
  23. G. Azimi, V.G. Papangelakis, “Solubility of gypsum and anhydrite in simulated laterite pressure acid leach solutions up to 250°C,” Hydrometallurgy, 102, 1–13, 2010.
  24. D. Georgiou, V. G. Papangelakis, “Behaviour of cobalt during sulphuric acid pressure leaching of a limonitic laterite,” Hydrometallurgy, 100, 35–40, 2009.
  25. G. Azimi, V.G. Papangelakis, “Thermodynamic modeling and experimental measurement of calcium sulfate in complex aqueous solutions,” Fluid Phase Equilibria, 290, 88–94, 2010.
  26. G. Azimi, V.G. Papangelakis, and J.E. Dutrizac, “Development of a Chemical Model for the Solubility of Calcium Sulphate in Zinc Processing Solutions,” Canadian Metallurgical Quarterly, Vol. 49 (1), 2010.
  27. D. Georgiou, V. G. Papangelakis, “Behaviour of cobalt during sulphuric acid pressure leaching of a limonitic laterite,” Hydrometallurgy, 100, 35–40, 2009.
  28. M.W. Jones, V.G. Papangelakis, and J.D.T. Steyl, “Kieserite Solubility in the Aqueous FeCl3 + MgCl2 + HCl System between (338 and 378) K,” J. Chem. Eng. Data, 54 (7), 2009, pp 1986–1990.
  29. Z. Jankovic, V.G. Papangelakis and S.N. Lvov, “Effect of nickel sulphate and magnesium sulphate on pH of sulphuric acid solutions at elevated temperatures,” J. Appl. Electrochem., 39(6), 2009, 751.
  30. M. Huang and V.G. Papangelakis, “High Temperature Conductivity Measurements of  Concentrated NaCl-H2SO4-H2O Solutions up to 250 °C”, Ind. Eng. Chem. Res., 2009, 48, 2781–2785.
  31. I. Bylina, L. Trevani, S. C. Mojumdar, P. Tremaine and V. G. Papangelakis, “Measurement of Reaction Enthalpy During Pressure Oxidation Of Sulphide Minerals,” Journal of Thermal Analysis and Calorimetry, Vol. 96 ,2009, 1, 117–124.
  32. Yunjiao Li, Ilya Perederiy, Vladimiros G. Papangelakis, “High Pressure Oxidative Acid Leaching of Nickel Smelter Slag: Characterization of Feed and Residue” Hydrometallurgy, 97 (3), 185-193, Jul 2009.
  33. M. Huang and V.G. Papangelakis, “On-Line Free Acidity Measurements of Solutions Containing Base Metals,” Canadian Metallurgical Quarterly, Special Issue, V. 47, No. 3, 2008, pp. 269-276.
  34. G. Azimi, V.G. Papangelakis and J.E. Dutrizac, “Development of an MSE-Based Chemical Model for the Solubility of Calcium Sulphate in Mixed Chloride-Sulphate Solutions,” Fluid Phase Equilibria, 266, 172-186, 2008.
  35. Yunjiao Li, Ilya Perederiy, Vladimiros G. Papangelakis, “Cleaning of waste smelter slags and recovery of valuable metals by pressure oxidative leaching” Journal of Hazardous Materials 152, 607–615, 2008.
  36. G. Azimi, V.G. Papangelakis and J.E. Dutrizac, “Modelling of Calcium Sulphate Solubility in Concentrated Multi-Component Sulphate Solutions,” Fluid Phase Equilibria, 260, 300-315, 2007.
  37. J. F. Adams, and V.G. Papangelakis, “Optimum Reactor Configuration for Prevention of Gypsum Scaling During Continuous Sulphuric Acid Neutralization,” Hydrometallurgy, 89, 269-278, 2007.
  38. H. Ming and V.G. Papangelakis, “Electrical Conductivity of Concentrated Al2(SO4)3-MgSO4-H2SO4 Aqueous Solutions up to 250 °C”, Industrial and Engineering Chemistry Research, 46, 1598 – 1604, 2007.
  39. M. Baghalha, V.G. Papangelakis, W. Curlook, “Factors Affecting the Leachability of Ni/Co/Cu Slags at High Temperature,” Hydrometallurgy, 85, 42 – 52, 2007.