Ternary Photodegradable Nanocomposite (BiOBr/ZnO/WO3) for the Degradation of Phenol Pollutants: Optimization and Experimental Design.

The degradation of environmental contaminants with photocatalysts has bright prospects for application in the control of pollution. In this study, BiOBr/ZnO/WO3 heterojunctions have been documented to be reliable visible-light photocatalysts for phenol deterioration. X-ray diffraction, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, photoluminescence spectral analysis, electrochemical impedance spectroscopy (EIS), EIS Bode plots, linear sweep voltammetry, and UV-visible diffuse reflectance spectroscopy were employed to describe the heterojunction's structure in addition to its optical features. The results revealed that the BiOBr/ZnO/WO3 ternary photocatalyst displayed more degradation activity in comparison to single-phase ZnO, WO3, or BiOBr, which is also higher than that of binary mixture photocatalysts with a phenol degradation efficiency of 90%. The influence of degradation variables, for instance, the potential of hydrogen (pH) and the initial organic contaminant content besides the heterojunction dose, on the deterioration efficiency was optimized using the response surface methodology. The degradation efficiency reached 95% under the optimal conditions of 0.08 g/0.03 L catalyst dose, a pH of 9, and an initial organic contaminant content of 10 mg L-1. However, the optimal phenol degradation efficiency of 39.37 mg g-1 was achieved under the conditions of 0.08 g/0.03 L catalyst dose, pH of 9, and 200 mg L-1 initial phenol concentration.

A strategy for the efficient removal of chlorophenols in petrochemical wastewater by organophilic and aminated silica@alginate microbeads: Taguchi optimization and isotherm modeling based on partition coefficient.

Through in situ encapsulation of cetyltrimethylammonium bromide (CTAB) and urea-functionalized SiO2 nanoparticles in alginate hydrogel, two types of new functionalized microbeads, CTAB-SiO2@alginate (organophilic) and urea-SiO2@alginate (aminated), were produced. Their adsorption behavior toward multiple chlorophenols (CPs: e.g., 4-chlorophenol (MCP), 2,4-dichlorophenol (DCP), and 2,4,6-trichlorophenol (TCP)) in petrochemical wastewater was assessed with the aid of Taguchi's L9 orthogonal array at three levels. In terms of the partition coefficient (PC: µmol/g·µM (or L/g)), the use of three-parameter models (hybrid Langmuir-Freundlich and Redlich-Peterson) yielded the best fit (R2 ≈ 1). Furthermore, the performance evaluation in terms of PC metric indicated that CTAB-SiO2@alginate (7.85 L/g) was better to treat total CPs than urea-modified SiO2@alginate microbeads (3.83 L/g). The enhanced performance of the former reflects the significant contribution of CTAB functionality (sp2 carbon tail and quaternary amine (N+) cationic head sites) for accelerating uptake of molecular (or suspended) and ionizable CPs molecules (e.g., with the aid of salting-out effect at a high initial CPs concentration and salinity) via hydrophobic/electrostatic interactions. The high performance of the CTAB-SiO2@alginate was demonstrated against petroleum hydrocarbons, CPs, and phenol contaminants using real petrochemical wastewater (up to three reusable cycles).