Removal efficiency and mechanism of phycocyanin in water by zero-valent iron

The efficiencies and mechanism of phycocyanin removal from water by zero-valent iron (ZVI) were studied. The trend for dissolved organic nitrogen removal was similar to phycocyanin and the removal efficiency was high at similar to 81% and 95%, respectively, in 90 min. The experimental results showed that the phycocyanin removal efficiency was higher at pH < 6, with an almost complete removal. However, only 68% was removed at pH 9. Within 30 min, the removal efficiency of phycocyanin for 1-4 tested cycles was reduced from 55.8% to 15.2%. Scanning electron microscopy and energy dispersive spectroscopy, Fourier transform infrared spectroscopy analysis and X-ray photoelectron spectroscopy were used to analyze the mechanisms of phycocyanin removal, which indicated that a small amount of phycocyanin was immobilized on the ZVI surface by adsorption. In addition, the main removal pathway was coagulation by dissolved iron ions. The Fe oxide formed in situ from ZVI had a higher removal efficiency than that in FeCl3, which can play improved roles in charge neutralization. The production of disinfection byproducts also decreased because of the decrease of precursors. (C) 2018 Elsevier Ltd. All rights reserved.