Abstract

ABSTRACT

Electrochemical filtration technology for the removal and degradation of ibuprofen and bisphenol A from aqueous solutions

Ahmed R. Bakr, PhD
Concordia University, 2017

Electrochemical filtration is a promising technology that aims for the efficient removal of persistent contaminants that cannot be effectively eliminated through conventional treatment methods. Multiwalled carbon nanotubes (MWNTs) and carbon substrates can be employed as filtration media to which a DC potential can be applied for further electrochemical treatment.
Ibuprofen and Bisphenol A, two emerging contaminants of concern, have been reported to exist in natural waters, influent, secondary treated effluent of wastewater, and in primary and secondary wastewater sludge. In this study, dead-end electrochemical filtration was investigated as a removal method for these contaminants. This technique has shown promise in the elimination of both of these compounds and the reduction of their overall toxicity.
Carboxylated multiwalled carbon nanotubes (MWNTs-COOH) were used with the aim of increasing the filtration efficiency for the removal of carboxylated ibuprofen under different pH and electrolytic conditions. It was found that the presence of oxy-functional groups can increase the functional surface area of MWNTs and increase the filtration capacity in low voltage applications. In high voltage applications, it was found that electrochemical filtration is controlled by bulk electroactive species. Boron doped multiwalled carbon nanotubes (BMWNTs) were also studied, with the goal of improving electrical conductivity during bisphenol A electrochemical filtration experiments. It was found that despite previous reports describing the higher oxidative power of doped carbon nanotubes, with the highest reported for BMWNTs, pristine MWNTs and BMWNTs showed similar outcomes in eliminating bisphenol A.
The removal of ibuprofen and bisphenol A was also investigated by using crossflow electrochemical filtration. The crossflow configuration shows great potential in eliminating these two contaminants in both individual component and mixed solutions from pure and fouling electrolytes. This outcome can mainly be attributed to the crossflow mechanism and can be assigned to the horizontal shear flow, which likely leads to a consistent surface coverage. The long residence time within the membrane likely leads to a significant reduction in toxicity under applied voltage. Our results suggest that the electrochemical filtration technology has a potential for use as a polishing step for removal of emerging contaminants from different water sources.