A highly hydrophilic benzenesulfonic-grafted graphene oxide-based hybrid membrane for ethanol dehydration

Pervaporation Membranes Based on Polyelectrolyte Complex of Sodium Alginate/Polyethyleneimine Modified with Graphene Oxide for Ethanol Dehydration

Pervaporation is considered the most promising technology for dehydration of bioalcohols, attracting increasing attention as a renewable energy source. In this regard, the development of stable and effective membranes is required. In this study, highly efficient membranes for the enhanced pervaporation dehydration of ethanol were developed by modification of sodium alginate (SA) with a polyethylenimine (PEI) forming polyelectrolyte complex (PEC) and graphene oxide (GO). The effect of modifications with GO or/and PEI on the structure, physicochemical, and transport characteristics of dense membranes was studied. The formation of a PEC by ionic cross-linking and its interaction with GO led to changes in membrane structure, confirmed by spectroscopic and microscopic methods. The physicochemical properties of membranes were investigated by a thermogravimetric analysis, a differential scanning calorimetry, and measurements of contact angles. The theoretical consideration using computational methods showed favorable hydrogen bonding interactions between GO, PEI, and water, which caused improved membrane performance. To increase permeability, supported membranes without treatment and cross-linked were developed by the deposition of a thin dense layer from the optimal PEC/GO (2.5%) composite onto a developed porous substrate from polyacrylonitrile. The cross-linked supported membrane demonstrated more than two times increased permeation flux, higher selectivity (above 99.7 wt.% water in the permeate) and stability for separating diluted mixtures compared to the dense pristine SA membrane.

Sulfonated GO coated carbon electrodes with cation-selective functions for enhanced capacitive deionization of saltwater

Deionization of salt, contaminated underground and inorganic waste waters for water recycling and reuse is of increasing importance mainly due to the shortage of freshwater worldwide. Membrane capacitive deionization (MCDI) possessing a high electrosorption capacity and energy efficiency has been considered a promising method for desalination. However, the MCDI reaction system has limited applications because of the high interfacial resistance during operation. In the present work, the novel sulfonated graphene oxide (SGO) serving as a hydrophilic cation exchange membrane that was coated directly on the activated carbon (AC) electrode was prepared to enhance capacitive deionization of saltwater. Experimentally, the electrosorption capacity and charge efficiency of the AC/SGO (negative)||AC (positive) electrode pair using the coated SGO thin film increased from 12.8 to 19.8 mg/g and 56.7 to 89.3%, respectively. The enhancements were associated with the reduction of the co-ion effect during electrosorption. The strong negative PhSO3- group grafted on the SGO thin film could selectively accelerate the transport rate of cations during CDI. The increase of the charge efficiency also led to lower implemented current. This work demonstrates a simple, low-cost and effective desalination method that will likely have many new applications especially in water recycling and reuse.

Removal Efficiency of Sulfapyridine from Contaminated Surface Water by Carboxylated Graphene Oxide Blended PVDF Composite Ultrafiltration Membrane with Activated Carbon

In this study, sulfapyridine (SPY), an antibiotic that is less commonly treated by membrane filtration techniques but is frequently detected in the aqueous environment and at higher concentrations than other detected antibiotics, was selected for investigation. A composite ultrafiltration membrane for the removal of sulfapyridine (SPY) antibiotics from water was fabricated using polyvinylidene fluoride (PVDF), polyvinylpyrrolidone (PVP), and carboxyl-functionalized graphene oxide (CFGO) as additives. The changes in retention rate and pure water flux of sulfapyridine by the composite ultrafiltration membrane were investigated by changing the ratios of the prepared ultrafiltration membrane materials under the conditions of low-pressure operation to explore the optimal experimental conditions. The results showed that the addition of PVP and CFGO significantly increased the number of membrane pores and their pore size. The addition of CFGO in the membrane significantly improved the hydrophilicity of the membrane. The contact angle decreased from 83.7 to 31.6°. Compared to ordinary PVDF ultrafiltration membranes, the membrane’s pure water flux increased nearly three times to 2612.95 L/(m2·h). The removal rate of SPY was 56.26% under the optimal conditions. When the composite ultrafiltration membrane was combined with activated carbon, the removal rate of SPY was 92.67%, which was nine times higher than that of activated carbon alone. At this time, the flux of the composite membrane was 2610.23 L/(m2·h). This study proposes a simple, efficient, and low production cost solution for the removal of sulfapyridine from water.

Analysis of herbicide and its applications through a sensitive electrochemical technique based on MWCNTs/ZnO/CPE fabricated sensor

The electrochemical performance of linuron (LNR) was studied by fabricating the carbon paste electrode (CPE) using multiwalled carbon nanotubes (MWCNTs) along with zinc oxide (ZnO) nanoparticles (MWCNTs/ZnO/CPE). The influence of electro-kinetic specifications involving steady heterogeneous rate, pH, sweep rate, temperature effect, transfer coefficient, accumulation time, activation energy, as well as the total number of protons and electrons participating in electro-oxidation of LNR has been established using voltammetric techniques like cyclic voltammetry (CV) and square wave voltammetry (SWV). These techniques were applied to investigate LNR in real samples such as soil including water samples. Over the 0.02 μM-0.34 μM ranges, a linear relationship was confirmed along with the limit of detection and quantification (LOD and LOQ) of the LNR. The synthesized ZnO nanoparticles were characterized by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and X-ray diffraction (XRD) analysis. The MWCNTs/ZnO/CPE sensor was considered sensitive for LNR detection because the sensor exhibited enhanced catalytic qualities with peak current in the involvement of 0.2 M phosphate buffer solution (PBS) of pH 6.0, attributed to the ultimate sensing performance of the sensor.

Laser-Induced Graphene Heater Pad for De-Icing

The replacement of electro-thermal material in heaters with lighter and easy-to-process materials has been extensively studied. In this study, we demonstrate that laser-induced graphene (LIG) patterns could be a good candidate for the electro-thermal pad. We fabricated LIG heaters with various thermal patterns on the commercial polyimide films according to laser scanning speed using an ultraviolet pulsed laser. We adopted laser direct writing (LDW) to irradiate on the substrates with computer-aided 2D CAD circuit data under ambient conditions. Our highly conductive and flexible heater was investigated by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy, X-ray diffraction, and Brunauer-Emmett-Teller. The influence of laser scanning speed was evaluated for electrical properties, thermal performance, and durability. Our LIG heater showed promising characteristics such as high porosity, light weight, and small thickness. Furthermore, they demonstrated a rapid response time, reaching equilibrium in less than 3 s, and achieved temperatures up to 190 °C using relatively low DC voltages of approximately 10 V. Our LIG heater can be utilized for human wearable thermal pads and ice protection for industrial applications.

Dimensional Nanofillers in Mixed Matrix Membranes for Pervaporation Separations: A Review

Pervaporation (PV) has been an intriguing membrane technology for separating liquid mixtures since its commercialization in the 1980s. The design of highly permselective materials used in this respect has made significant improvements in separation properties, such as selectivity, permeability, and long-term stability. Mixed-matrix membranes (MMMs), featuring inorganic fillers dispersed in a polymer matrix to form an organic-inorganic hybrid, have opened up a new avenue to facilely obtain high-performance PV membranes. The combination of inorganic fillers in a polymer matrix endows high flexibility in designing the required separation properties of the membranes, in which various fillers provide specific functions correlated to the separation process. This review discusses recent advances in the use of nanofillers in PV MMMs categorized by dimensions including zero-, one-, two- and three-dimensional nanomaterials. Furthermore, the impact of the nanofillers on the polymer matrix is described to provide in-depth understanding of the structure-performance relationship. Finally, the applications of nanofillers in MMMs for PV separation are summarized.

Electrocatalytic behavior of a heterostructured nanocomposite sensor for aminotriazole

Heterostructured nano-composite sensor for aminotriazole.