Kinetic study on removal of toxic metal Cr(VI) through a bulk liquid membrane containing p-tert-butylcalix[4]arene derivative

The transport of Cr(VI) from aqueous solutions through bulk liquid membrane was studied using p-tert-butylcalix[4]arene 3-diethylaminopropyl diamide derivative as a carrier. The aqueous solution of potassium dichromate was used as the model contaminant. The kinetic parameters (k1, k2, tmax, Rmmax, Jdmax and Jamax) for the forward and the back extraction were calculated by means of Cr(VI) concentrations of the donor and the acceptor phase. The results showed that it was possible to transport 96.65% of Cr(VI) from the acidic donor solutions to the acceptor solutions at the optimum operating conditions after 10 h contact time. The highest transport efficiency was observed at pH 2 in the donor phase and at pH 5 in the acceptor phase. It was shown that the transport of Cr(VI) stem from pH difference between the donor and the acceptor phases. The activation energy values were calculated as 5.77 and 7.99 kJmol− 1 for the forward and the back extraction, respectively. It was indicated that the process was diffusionally controlled by dichromate anions. The experimental results demonstrated that p-tert-butylcalix[4]arene derivative was an effective carrier for the transport of Cr(VI).

Research Highlights► It was demostrated that p-tert-butylcalix[4]arene 3-diethylamino propyl diamide derivative could be regarded as an effective agent for transport of Cr(VI) from acidic aqueous solution. ► The highest transport rate was found as 96.65% by using BLM. ► A pH gradient between the donor and acceptor phases is the driving force for the transport of Cr(VI) through the membrane phase.