Characterisation and mechanical modelling of polyacrylonitrile-based nanocomposite membranes reinforced with silica nanoparticles

In this study, neat polyacrylonitrile (PAN) and fumed silica (FS)-doped PAN membranes (0.1, 0.5 and 1 wt% doped PAN/FS) are prepared using the phase inversion method and are characterised extensively. According to the Fourier Transform Infrared (FTIR) spectroscopy analysis, the addition of FS to the neat PAN membrane and the added amount changed the stresses in the membrane structure. The Scanning Electron Microscope (SEM) results show that the addition of FS increased the porosity of the membrane. The water content of all fabricated membranes varied between 50% and 88.8%, their porosity ranged between 62.1% and 90%, and the average pore size ranged between 20.1 and 21.8 nm. While the neat PAN membrane’s pure water flux is 299.8 L/m2 h, it increased by 26% with the addition of 0.5 wt% FS. Furthermore, thermal gravimetric analysis (TGA) and differential thermal analysis (DTA) techniques are used to investigate the membranes’ thermal properties. Finally, the mechanical characterisation of manufactured membranes is performed experimentally with tensile testing under dry and wet conditions. To be able to provide further explanation to the explored mechanics of the membranes, numerical methods, namely the finite element method and Mori–Tanaka mean-field homogenisation are performed. The mechanical characterisation results show that FS reinforcement increases the membrane rigidity and wet membranes exhibit more compliant behaviour compared to dry membranes

An experimental study on manganese(II) removal with manganese dioxide recycling

Manganese dioxide (MnO2) particles have a catalytic effect on removing Mn(II) from contaminated water. On the basis of this effect, a manganese removal process was proposed in this paper. For this purpose, the oxidation of Mn(II) was studied first in batch reactor and then in continuous reactor. The experimental conditionals for batch reactor were Mn(II): 3 mg/l, Mn(IV): 0-800 mg/l, pH: 9.6, temperature: 25 degrees C and for continuous system, the conditionals were kept the same except Mn(II) concentration. A quadratic equation was obtained as a function of Mn(IV) concentration to determine the catalytic reaction rate constant. It was experimentally demonstrated that there was no significant effect of Mn(IV) on the Mn(II) oxidation at Mn(IV) concentrations beyond 800 mg/l. Furthermore, reaction kinetics was derived from the data of batch experiments. Based upon the reaction kinetics, it has been theoretically demonstrated that the volume of aeration tank can be significantly reduced by keeping a high concentration of Mn(IV) in the reactor. Lastly, manganese oxidation was studied in a continuous flow lab scale system with and without MnO2 sludge recirculation. In this system, until Mn(IV) concentration had reached 300 mg/l, Mn(II) removal rate had increased linearly, but beyond this level increase had continued decreasingly. This study shows that, instead of using stronger oxidants in the drinking water treatment systems, recycling of MnO2 flocks provides important advantages like low investment cost, minimization of treatment area and, because of the lack of using oxidants, low operation cost

Modelling of long-term permeability of compacted and consolidated clays permeated with leachate

In this study, permeability variations of clay soil and removal rates of ions presented in the leachate are determined. Penalized linear regression (Lasso) and support vector regression methods are applied in order to model the relationship between the metal ions and the permeability. For this purpose, leachate is collected from Sanitary Landfill at Sile-Komurcuoda, Istanbul. Permeability of samples is determined via consolidated clays which are compacted via standard methods. The concentrations of Fe2+, Mn2+, Zn2+, Cu2+ and Pb2+ ions in influent and effluent of reactor are anayzed and the removal rate of these ions are calculated in order to detect removal ability of clay soil. An overall evolution of Fe2+, Mn2+, Zn2+, Cu2+ and Pb2+ parameters is that removal rate of clay soil which was compressed with standard methods and consolidated was found higher than that of clay soil compressed with standard compaction method. For prediction accuracy and interpretation purposes, two methods are considered for modelling the data. Both methods show good generalization capabilities

Modelling of Long Term Permeability of Compacted and Consolidated Clays Permeated With Leachate

In this study, permeability variations of clay soil and removal rates of ions presented in the leachate are determined. Penalized linear regression (Lasso) and support vector regression methods are applied in order to model the relationship between the metal ions and the permeability. For this purpose, leachate is collected from Sanitary Landfill at Sile-Komurcuoda, Istanbul. Permeability of samples is determined via consolidated clays which are compacted via standard methods. The concentrations of Fe2+, Mn2+, Zn2+, Cu2+ and Pb2+ ions in influent and effluent of reactor are anayzed and the removal rate of these ions are calculated in order to detect removal ability of clay soil. An overall evolution of Fe2+, Mn2+, Zn2+, Cu2+ and Pb2+ parameters is that removal rate of clay soil which was compressed with standard methods and consolidated was found higher than that of clay soil compressed with standard compaction method. For prediction accuracy and interpretation purposes, two methods are considered for modelling the data. Both methods show good generalization capabilities

Characterisation and modelling the mechanics of cellulose nanofibril added polyethersulfone ultrafiltration membranes

The performance of the membranes can be improved by adding the appropriate amount of nanomaterials to the polymeric membranes that can be used for water/wastewater treatment. In this study, the effects of polyvinylpyrrolidone (PVP), the impact of different amounts (0.5% and 1% wt.) of cellulose nanofibril (CNF), and the combined effects of PVP-CNF on the properties/performance of the polyethersulfone-based (PES-based) membrane are investigated. All PES-based ultrafiltration (UF) membranes are manufactured employing the phase inversion method and characterised via Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and the relevant techniques to determine the properties, including porosity, mean pore size, contact angle, water content, and pure water flux tests. Furthermore, the thermal properties of the prepared membranes are investigated using thermal gravimetric analysis (TGA) and differential thermal analysis (DTA) techniques. Experimental and numerical methods are applied for the mechanical characterisation of prepared membranes. For the experimental process, tensile tests under dry and wet conditions are conducted. The finite element (FE) method and Mori-Tanaka mean-field homogenisation are used as numerical methods to provide more detailed knowledge of membrane mechanics