Cu(II) transport through soybean oil-based bulk liquid membrane: Kinetic study

Kinetic study of Cu(II) transport through a soybean oil-based bulk liquid membrane (BLM) containing di-2-ethylhexylphosphoric acid (carrier) and tributylphosphate (phase modifier) diluted in soybean oil (diluent) was conducted. Effects of initial Cu(II) concentration in the feed phase and temperature were investigated and their kinetic parameters were determined from the kinetic models of two consecutive irreversible first-order reactions. Various initial Cu(II) concentrations in the feed phase (50–500 mg/L (0.788–7.88 mM)) and temperatures (27–43 °C) were found not to affect the rate of extraction process significantly, but enhanced the rate of stripping process with decreasing initial Cu(II) concentration in the feed phase and increasing temperature. The rate-controlling steps of both extraction (diffusion-controlled) and stripping (chemical reaction-controlled) processes were determined and a plausible transport mechanism was proposed. The kinetics of Cu(II) transport through soybean oil-based BLM was then compared with that of a similar kerosene-based BLM and their extraction (k1) and stripping (k2) rate constants (soybean oil-based BLM: k1 = 1.94 h−1, k2 = 0.11 h−1; kerosene-based BLM: k1 = 1.73 h−1, k2 = 0.13 h−1) were determined. Application of soybean oil-based BLM in real industrial wastewater was also studied.

► Cu(II) transport in soybean oil-based BLM was governed by the stripping process.
► Cu(II) extraction process in soybean oil-based BLM was diffusion-controlled.
► Cu(II) stripping process in soybean oil-based BLM was chemical reaction-controlled.
► Cu(II) transport rates were similar for both soybean oil- and kerosene-based BLMs.
► Cu(II) transport in soybean oil-based BLM was unaffected by use of real wastewater.