Pharmaceutical and Personal Care Products (PPCPs) are regarded endocrine-disrupting chemicals. They have been found with trace concentrations in aquatic environment, which will impact water quality and subsequently increase water treatment cost. Thus, the efficient removal of PPCPs from aquatic environment is of great challenge. Bioretention system is one of the most promising Best Management Practices (BMPs) and sustainable technologies to control urban storm water pollutants if tailored properly, because of its excellent performance in reducing runoff quantity and improving quality in a natural way. The removal of PPCPs from water by pure metal oxides was investigated by some previous studies. However, metal oxides are commonly present as the coatings of natural sands instead of a pure form. This study presents the use of iron oxides-coated sand (IOCS) and manganese oxides-coated sands (MOCS) to remove caffeine (CF) and ketoprofen (KEP) from artificial urban storm water as the model compounds. The coating efficiencies for IOCS and MOCS are 99% and 11%, respectively. IOCS showed better alkali/acid resistance, while MOCS was more sensitive to alkaline or acidic conditions. The PPCP removal efficiency could be improved by metal oxides coatings. The concentrations of both CF and KEP steadily declined with the presence of IOCS and MOCS in reaction solution. Compared with raw sands, IOCS exhibited the best performance in removing CF and KEP, followed by MOCS. CF and KEP removal kinetic and isotherm studies were carried out at pH 6 on raw and coated sands. The isotherm data were fitted well using Freundlich isotherm model, with the Nf values closed to 1, indicating that the majority of the media surface were homogeneous. The reaction of CF and KEP removed by raw and modified media followed an exponential decay model, fitting well to the pseudo-second order kinetics model. Approximately 50% of CF and KEP were removed in 15 min and 80% removed in 1h. The comparison study was carried out in order to evaluate the contribution of the oxidation and adsorption of CF and KEP on modified sands, respectively. The oxidation of CF and KEP was found to be the dominant process during the overall reaction. Only a very limited removal of CF and KEP was attributed to the adsorption process.

Removal of caffeine and ketoprofen by metal oxides-coated sands

248th National Meeting (2014)

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