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    A multifaceted aggregation and toxicity assessment study of sol-gel-based TiO2 nanoparticles during textile wastewater treatment
    (DESALINATION PUBL, 2016) Yuzer, Burak; Guida, Marco; Ciner, Fehiman; Aktan, Burcu; Aydin, M. Iberia; Meric, Sureyya; Selcuk, Huseyin
    Innovative textiles have been concern of emerging risk of nanoparticles (NPs) to human and environment. This study aimed to investigate the aggregation, removal and biological, and ecotoxicological effects of sol-gel-based TiO2 NPs while the treatment of textile wastewater. Fe(II) and alum coagulants were applied for the removal of spiked TiO2 NPs from textile wastewater. Particle size distribution, absorbance values (UV-vis range), and residual TiO2 NPs were followed to define aggregation mechanism, including pH variation during treatment of wastewater. The effect of TiO2 on activated sludge treatment was followed by monitoring of oxygen uptake rate (OUR). Ecotoxicity of sol-gel and coagulated samples was observed by Ceriodaphnia magna immobilization test. Adjustment of pH to 8 enlarged mean particle size distribution of sol-gel-based TiO2 NPs from 30 to 450nm. After alum and Fe(II) coagulations, average particle size distributions were observed to be 650 and 960nm, respectively. Coagulation with alum and Fe(II) resulted over >95% removal of TiO2 from biologically treated textile wastewater (BTTWW). The value for residual TiO2 concentration in BTTWW was reduced from 120g/L to around 8g/L TiO2 NPs exhibited slight/no toxicity on the OUR while toxicity to Ceriodaphnia dubia increased in some coagulated samples, most probably due to higher residual coagulant concentrations.
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    Investigation of inhibition effects of different sol-gel based TiO2 nanoparticles on activated sludge and toxicity to Daphnia magna
    (Desalination Publ, 2019) Yuzer, Burak; Ciner, Fehiman; Calhan, Rahman; Selcuk, Huseyin; Meric, Sureyya
    The application of nanotechnology in textile products is progressively increasing as it is proving to be a useful tool in improving the performance of textiles. Titanium dioxide (TiO2) nanoparticles (NPs) have been the most studied ones to develop self-cleaning and anti-bacterial nano textiles. However, the adverse effects of NPs and the risk of the possible release of NPs into the wastewater process and then in receiving waters, thus ecotoxicity studies need to be performed for the safeguard of the environment. Monitoring oxygen uptake rate (OUR) has been demonstrated to be are a liable method to show any inhibition response of the activated sludge. Hence this study was performed to investigate the ecotoxicity and inhibition effects of NPs to Daphnia magna and activated sludge comparatively. Activated sludge inhibition tests were conducted to define the EC50 levels after 30 and 180 min of reaction time for TiO2 NPs, Ag-doped TiO2 NPs, and Cu-doped TiO2 NPs while Daphnia magna immobilization test was carried out for TiO2 NPs prepared by Degussa P25 and sol-gel method. The Ag-doped TiO2 NPs exhibited a toxic effect on the activated sludge 10 times higher than the TiO2 NPs.TiO2 NPs prepared by the sol-gel method caused 100% immobilization to Daphnia magna when exposed to 1 h settled sample after 48 h, and this severe toxicity repeated in the 2 h settled sample too. As a whole, the results obtained indicate that the technology should be accurately evaluated for the safety of the environment and human beings.