Effect of aqueous matrix species on synergistic removal of bisphenol-A under solar irradiation using nitrogen-doped TiO2/AC composite

A bi-functional composite, namely nitrogen-doped titanium dioxide anchored on activated carbon (N-TiO2/AC) was synthesized using the sol-gel method with two-stage calcination procedure. Bisphenol-A (BPA) was used as a model contaminant. The effects of co-existing aqueous species viz, prevalent inorganic anions (CI-, NO3-, SO42-, HCO3-. H2PO4- and silica), organic anion (C2O42-), photocatalysis inhibitor (CH3OH) and oxidant (H2O2) were comprehensively studied using the best performing composite, i.e. N-TiO2/AC (400M-700T). Introduction of H2PO4- (0.01-0.1 mM) led to a slight enhancement in the photocatalytic degradation (PCD) efficiency for BPA removal. Provision of AC support for N-TiO2 abated the inhibitory effect induced by SO42- at high concentration (up to 100mM). Decreased BPA photodegradation was observed with increasing concentrations of C2O42-, thus suggesting that direct hole (h(+)) oxidation occurred. Variation of pH (from 4 to 10) in the presence of 0.1 mM of silica induced little effect on BPA photodegradation. Addition of H2O2 into N-TiO2/AC system apparently resulted in decreased BPA removal because some adsorbed BPA was released from surface-degraded AC. (C) 2010 Elsevier B.V. All rights reserved.