Integrated ozone-sono-Fenton for the enhanced degradation of acid orange 7: process optimization and kinetic evaluation.

The performance of novel hybrid advanced oxidation, ozone-sono-Fenton process in degradation of acid orange 7 (AO7), as a model of azo dyes was modelled and optimized using response surface methodology (RSM) based on central composite design (CCD). Utilizing a bubbling reactor equipped with an ultrasound probe and in the presence of Fenton reagents, a promising hybrid homogeneous AOP, ozone-sono-Fenton, was investigated. According to the experimental results, the variation trend of degradation efficiency (DE%) with pH, reaction time and Fe2+/H2O2 molar ratio was modelled with the reduced quadratic model. Additionally, the suitability of the model was indicated with close to unity regression coefficient [Formula: see text]. Furthermore, the comparative study of degradation efficiency and COD removal for the individual methods including ozonation, sonication and Fenton reagents as well as their hybrid processes reveals that the novel proposed technique, ozone-sono-Fenton process, is able to rapid and complete degradation of acid orange 7 with initial concentration of 300 mg L-1, 100% in only 12 min. The complete degradation was obtained under optimum conditions such as pH = 6, reaction time = 12 min and Fe2+/H2O2 molar ratio = 0.0040. The kinetics evaluation of the acid orange 7 concentration during the processing implied the first-order reaction. Considering the synergetic effect and cost-effectiveness of the hybrid method, the promising ozone-sono-Fenton method could effectively degrade using a wide range of organic contaminants.

Polyvinylidene Fluoride-Graphene Oxide Membranes for Dye Removal under Visible Light Irradiation.

In this study, polyvinylidene fluoride (PVDF)-graphene oxide (GO) membranes were obtained by employing triethyl phosphate (TEP) as a solvent. GO nanosheets were prepared and characterized in terms of scanning and transmission electron microscopy (SEM and TEM, respectively), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), chemical analysis and inductively coupled plasma mass spectroscopy (ICP). Two different phase inversion techniques, Non-Solvent Induced Phase Separation (NIPS) and Vapour-Induced Phase Separation (VIPS)/NIPS, were applied to study the effect of fabrication procedure on the membrane structure and properties. Membranes were characterized by SEM, AFM, pore size, porosity, contact angle and mechanical tests, and finally tested for photocatalytic methylene blue (MB+) degradation under visible light irradiation. The effect of different pH values of dye aqueous solutions on the photocatalytic efficiency was investigated. Finally, the influence of NaCl salt on the MB+ photodegradation process was also evaluated.

Preparation of thermo-responsive PNIPAAm-MWCNT membranes and evaluation of its antifouling properties in dairy wastewater.

A novel MWCNT-PNIPAAm nanocomposite membrane was developed with an excellent cleaning efficiency of thermo-responsive surface. The thermo-responsive N-isopropyle acryleamide (NIPAAm) monomer was polymerized on the surface of MWCNT via free radical polymerization. The prepared MWCNT-PNIPAAm nanocomposite was characterized by FTIR, SEM and TGA analyses. Various amounts of the prepared nanocomposite were incorporated into the membrane matrix by the physical blending method. The resultant membranes showed better surface wettability and pure water flux compared to pristine Polyethersulfone (PES) membrane. Furthermore, after filtration, the COD value of dairy wastewater was reduced to around 90% for all membranes. The thermo-responsive cleaning method was employed to investigate the cleaning efficiency of MWCNT-PNIPAAm membrane for dairy wastewater. The 99.9% flux recovery ratio was obtained for MWCNT-PNIPAAm-0.05% membranes. All these results confirmed that the presence of MWCNT-PNIPAAm nanocomposite in the membrane matrix improves the membrane hydrophilicity and antifouling properties.