Effect of Process Parameters on Removal of Salicylic Acid from Aqueous Solutions via Electrocoagulation

Feasibility of salicylic acid removal from an aqueous solution was investigated in an electrochemical cell equipped with either aluminum or iron plates by using electrocoagulation (EC). Several parameters, including electrode materials, solution pH variation, applied voltage, and solution temperature, were investigated. In addition, effects of applied voltage and solution temperature on electric energy consumption and time needed to reach 90% removal were investigated. Experimental results indicated that the Al/Al electrode pair was the most efficient choice of the two electrode pairs tested in terms of salicylic acid removal efficiency. In terms of pH variation during EC, generation of coagulant metal hydroxides for the Al/Al electrode pair was greater than that for the Fe/Fe electrode pair, which also enhanced the removal efficiency. The optimum applied voltage and solution temperature were found to be 20 V and 308 K, respectively. A pseudo-second-order kinetic model provided a good fit to the experimental results at various applied voltages and solution temperatures. In addition, the activation energy was calculated as 20.21 J mole(-1) based on pseudo-second-order rate constants from the Arrhenius equation, indicating that salicylic acid precipitation in an aqueous solution was attributable to the EC process.