Photocatalysis-enhanced electrosorption process for degradation of high-concentration dye wastewater on TiO2/carbon aerogel

TiO2/carbon aerogel (TiO2/CA) electrode was prepared by ambient drying and sol–gel method. Its morphology and surface chemical composition were characterized with SEM, X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and Raman spectra. The electrosorption characteristics were investigated with N2 adsorption, electrochemical impedance spectrum (EIS) and physical resistance. The photocatalytic activity of TiO2/CA was evaluated by measuring the photocurrent response. The electrode was used in photocatalysis-enhanced electrosorption (PES) treatment of high-concentration (400 mg L−1) alizarin red (AR) wastewater. Results revealed that the efficiency in the PES process with TiO2/CA electrode was much better than that in traditional electrosorption with CA. In 240 min, AR removal by PES is 97.3%, 3.1 times that of electrosorption. It was found that the in situ photocatalytic regeneration of the adsorbent enhanced the removal capability and stability in treatment of high-concentration wastewater. The degradation intermediates and reaction pathway were also investigated. The AR molecules and intermediates were degraded effectively and mineralized in the PES process. The TOC removal in 240 min was 90.2%.