Removal of phthalate esters (PAEs) by zeolite/Fe3O4: Investigation on the magnetic adsorption separation, catalytic degradation and toxicity bioassay

Zeolite/Fe3O4 magnetic nanocomposite (MZNC), was successfully prepared using in situ co-precipitation method and applied for the adsorption and degradation of phthalate esters in the presence of H2O2. The surface morphology of MZNC was characterized by XRD, SEM, TEM, FTIR, BET and VSM techniques. The effects of Fe3O4 loading, pH, contact time, initial MZNC and PAE concentration, temperature and co-esters on the removal of PAE were examined. The maximum removal by adsorption were 95.4% and 41.14% after 30 min (equilibrium time), at pH 3 and 0.2 g/L adsorbent dosage in initial concentration of 10 and 50 mg/L, whereas the MZNC-H2O2 process led to higher removal of DEP (99.7%) in initial concentration of 50 mg/L after 9 min. Furthermore, the MZNC showed stable activity and convenient recycling. The mechanism of the DMP, MMP and MBP adsorption as the main competitors for DEP adsorption on MZNC was investigated. The MZNC proved the significant ability of adsorption and degradation efficiency in term of DEP rather than the bare Fe3O4 in the batch experiments (99.7% vs. 51.23%). The enhanced degradation efficiency of MZNC could be due to the DEP enrichment by Fe3O4 molecules in the vicinities of active sites. Daphnia magna and Ceriodaphnia dubia were used as a test organism for assess the left over toxicity in effluents containing DEP, before and after treatment process.