Improving the Performance of Composite Hollow Fiber Membranes with Magnetic Field Generated Convection Application on pH Correction

Abstract

The membranes and membrane processes have succeeded in the transition from major technological and biomedical applications to domestic applications: water recycling in washing machines, recycling of used cooking oil, recovery of gasoline vapors in the pumping stations or enrichment of air with oxygen. In this paper, the neutralization of condensation water and the retention of aluminum from thermal power plants is studied using ethylene propylene diene monomer sulfonated (EPDM-S) membranes containing magnetic particles impregnated in a microporous propylene hollow fiber (I-PPM) matrix. The obtained membranes were characterized from the morphological and structural points of view, using scanning electron microscopy (SEM), high resolution SEM (HR-SEM), energy dispersive spectroscopy analysis (EDAX) and thermal gravimetric analyzer. The process performances (flow, selectivity) were studied using a variable magnetic field generated by electric coils. The results show the possibility of correcting the pH and removing aluminum ions from the condensation water of heating plants, during a winter period, without the intervention of any operator for the maintenance of the process. The pH was raised from an acidic one (2–4), to a slightly basic one (8–8.5), and the concentration of aluminum ions was lowered to the level allowed for discharge. Magnetic convection of the permeation module improves the pH correction process, but especially prevents the deposition of aluminum hydroxide on hollow fibers membranes.

Osmium Nanoparticles-Polypropylene Hollow Fiber Membranes Applied in Redox Processes

“…The fibers have a porosity of 40% [54,55] and a pore diameter of less than 0.2 µm [56] (Figure 2). This type of module with polypropylene hollow fiber membranes allows operation over the entire pH range, in oxidizing or reducing solutions at temperatures up to 100 • C without dimensional changes and can be sterilized by known physical-chemical methods [57][58][59]. Polypropylene hollow fiber membranes at a length of 700 mm and a diameter of 0.3 mm are assembled so as to achieve a filtering surface of 1 m 2 [52,54].…”

“…After the oxidation process, the reaction compartment underwent three stages of tartar: with nitrogen gas to remove residual oxygen, with hydrogen (at least two hours to reduce any traces of osmium tetroxides), and then with nitrogen to remove residual hydrogen. The filtration characteristics of polypropylene hollow fiber membranes [56][57][58][59][60][61][62][63][64] ensured the complete retention of osmium nanoparticles in the reaction compartment which could be followed by established analytical techniques [74][75][76][77][78].…”

Transport and Separation of the Silver Ion with n–decanol Liquid Membranes Based on 10–undecylenic Acid, 10–undecen–1–ol and Magnetic Nanoparticles

“…The method of obtaining iron-based magnetic nanoparticles is the electrochemical one, previously presented in detail [42,43]. In this case, the electrolysis is performed in pure water (to obtain magnetic nanoparticles of iron oxides) and in silver nitrogen electrolyte 10 −1 mol/L (to obtain magnetic nanoparticles based on silver and iron oxides).…”

“…Continuous dialysis was performed until a pH sample was obtained. The pH was followed up with a combined selective glass electrode (HI 4107, Hanna Instruments Ltd., Leighton Buzzard, UK) and a multi-parameter system (HI 5522, Hanna Instruments Ltd., Leighton Buzzard, UK) [43].…”

“…Oxide nanoparticles have a similar morphology for both types of nanoparticles (Figure 4a-d). The nanoparticle sizes range between 20 and 50 nm, detailed for a wider range of electrolytes [42,43,[55][56][57].…”