Ranitidine abatement in chemically activated persulfate systems: Assessment of industrial iron waste for sustainable applications

This work assessed the use of industrial iron waste in the activation of persulfate (PS) (100 mu M) into sulfate radicals (SRs) for the removal of ranitidine (RAN) (28.5 mu M) from aqueous systems. The released iron corrosion products (ICPs) e.g. mainly Fe2+ species are responsible of PS activation. The optimal molar ratio of Fe2+:PS was found to be 1:1. A comparative study between industrial iron (iFe) and commercial iron (cFe) at 2 successive experimental runs showed that iFe has some advantages over cFe in terms of sustainability and less sludge formation. At low load of iFe (1 mg/20 mL), RAN removal was 95% over one hour of reaction time with a ratio of released Fe2+:PS of only 0.16:1.00. This system was evaluated at different ionic strength [1] conditions with NaClO4 neutral electrolyte, as well as in the presence of Cl- and Br-, the main seawater components. Results showed that at elevated [I] conditions, the rate of RAN degradation has decreased. However, in the presence of Cl- and Br-, with optimum levels of 1.0 mM at [I] = 100 mM, RAN removal was enhanced rather than quenched. The total organic carbon (TOC) was analyzed at different PS:iFe molar ratios. Although degradation was successful at a very low iFe load, mineralization was negligible. However, RAN co-precipitation with in-situ formed ICPs improved TOC removal at higher iFe levels. The HPLC/MS chromatograms showed the presence of an oxidized RAN intermediate detected at 331 m/z that dissipated gradually throughout the treatment. (C) 2015 Elsevier B.V. All rights reserved.