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

Abstract

<jats:p>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.</jats:p>

Investigation of electric field‐aligned edge‐oxidized graphene oxide nanoplatelets in polyethersulfone matrix in terms of pure water permeation and dye rejection

“…It can be observed that the contact angle slightly decreases as the pure polymer hosts more EOGO nanoplatelets up to 0.5 wt% while it rises again at 1 wt% loading. It can be supposed that at lower EOGO contents, the presence of hydrophilic oxygen functional groups contributed to modification of the surface nature leading to moderately lower hydrophobicity of the polymer as revealing lower contact angles, 92 although this effect subsequently became poor as higher amounts of EOGO were introduced in the matrix; in a way that, this higher EOGO content affects the homogeneous distribution of the nanoplatelets in the matrix (Figure S3) leaving them to intertwining as well as overlapping or confinement, so that finally fewer hydrophilic groups are available at the surface 93,94 . Besides, another reason for such a multistage behavior may be the changes in surface roughness obtained by AFM as mentioned earlier in section 3.1.…”

A Brief History of Colour, the Environmental Impact of Synthetic Dyes and Removal by Using Laccases

“…The use of hybrid systems integrating physical and chemical treatments is frequent for colour removal as a strategy to reduce contamination. Photocatalysts combined with membrane systems allowed Methylene Blue (MB) degradation, with 83.3% removal in 370 min; achieved by controlling pH and salt concentration [149]. Photocatalytic degradation systems under visible light have employed to evaluate the degradation of Reactive Violet 5 (RV5), and 50Fe-TiO 2 level achieved higher degradation efficiency (47.6%) in 9 h [155].…”

Application of Hybrid Membrane Processes Coupling Separation and Biological or Chemical Reaction in Advanced Wastewater Treatment

“…In addition, their abatement represents a relevant problem in the wastewater treatment processes because generally they are very stable toxic compounds. For this purpose, photocatalytic membrane reactors can be interesting technologies employed for chemical conversion of organic dyes into safe (nontoxic) or harmless compounds with minimum consumption of energy and reagents [ 24 , 27 , 36 , 37 ].…”

“…Various types of membranes have been studied to be applied in photocatalysis, such as inorganic and polymeric, under UV and visible light irradiations [ 24 , 27 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 ]. Moreover, the use of visible light in photocatalysis permits the use of renewable solar energy in view to obtain a sustainable process [ 24 , 27 ].…”

“…Alyarnezhad et al [ 37 ] investigated the degradation of MB under visible light irradiation (λ > 420 nm) by using four types of membranes prepared by using a nontoxic solvent and GO nanosheets as a metal-free catalyst to photoactivate the membrane. The incorporation of GO enhanced the mechanical strength of the prepared membranes and their wettability.…”