Electrochemically assisted coagulation for the adsorptive removal of dimethyl phthalate from aqueous solutions using iron hydroxides

Highlight
• High removal efficiency of DMP was achieved by electrochemically assisted coagulation.
• Iron hydroxides generated during EC were used to remove DMP.
• The adsorption process was favorable, spontaneous, and endothermic in nature.
• Adsorption of DMP fits with Langmuir adsorption isotherm.

In this study, the adsorptive removal of dimethyl phthalate (DMP) from aqueous solutions by electrochemically generated iron hydroxides was investigated in batch mode. Four electrode pairs were used to characterize the performance of electro-coagulation (EC) for the DMP removal efficiency. Experimental results indicated that a Fe/Al electrode pair was the optimum choice out of four different electrode pair combinations. In addition, the effects of varying current density and solution temperature on DMP adsorption characteristics were evaluated. The findings indicated that complete DMP removal could be achieved within reasonable removal efficiency and with relatively low electrical energy consumption. The optimum current density and temperature were found to be 20 mA/cm2 and 298 K, respectively. Thermodynamic parameters, including the Gibbs free energy, enthalpy, and entropy, indicated that the DMP adsorption of aqueous solutions on metal hydroxides was feasible, spontaneous and endothermic in the temperature range of 288–318 K. The experimental data were fitted with several adsorption isotherm models to describe the EC process. The adsorption of DMP preferably fitting the Langmuir adsorption isotherm suggests monolayer coverage of adsorbed molecules.