Proton exchange membrane based on graphene oxide/polysulfone hybrid nano-composite for simultaneous generation of electricity and wastewater treatment.

Microbial fuel cell (MFC) is a combined technology for simultaneous generation of electricity and wastewater treatment. In MFC, the proton exchange membrane (PEM) is an essential component affecting electricity generation. In the current study, two proton exchange membranes, namely sulfonated polyethersulfone (SPES) and graphene oxide/sulfonated -polyethersulfone hybrid nanocomposite (GO-SPES), were prepared and characterized using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The collected information confirmed the successful preparation of the membranes. Moreover, contact angle measurements, ion exchange capacity and degree of sulfonation of the prepared membranes were determined. The results showed that the introduction of GO nanoparticles into SPES membrane improved its proton exchange capability and resulted in better performance. The power density and the current generated from SPES membrane were 60 mW/m2 and 425 mA/m2, respectively. For GO-SPES, the obtained power density was 101.2 mW/m2 and the current was 613 mA/m2. Both membranes showed comparable chemical oxygen demand (COD) removal efficiency of about 80%; suggesting that the prepared membranes are working efficiently in wastewater treatment as PEMs in MFCs. As a final point, the performance of GO-SPES membrane was compared to the performance of the well-known Nafion® 117 membrane and the results were promising. To conclude, the GO-SPES membrane is an outstanding membrane for use as PEM in MFCs for simultaneous generation of electricity and wastewater treatment.

A separation strategy combining three HPLC modes and polysaccharide-based chiral stationary phases.

Nine polysaccharide-based chiral stationary phases (CSPs) were used to define a separation strategy that combines normal-phase (NP), reversed-phase (RP) and polar organic solvent chromatography (POSC) modes. After limiting ourselves to two CSPs per mode, in total, five CSPs, Chiralpak AD (NP), Chiralcel OD (RP and POSC), Lux Cellulose-1 (NP), Lux Cellulose-2 (POSC) and Lux Cellulose-3 (RP), showed the broadest enantioselectivity and most complementarity. Six sequences of the three modes were considered to decide which sequence is the most successful for screening a set of 56 pharmaceutical compounds. Starting the strategy with the NP mode, followed by RP and finally POSC was found preferable from both the number of cumulative separations and of baseline separations. Two approaches were considered for strategy fine tuning using an additional set of eight racemic mixtures. In both approaches, seven of the eight compounds were baseline resolved, on one of the examined columns at either screening or optimization conditions of a mode. One approach was finally preferred because of its lower workload.

Chiral separations in normal-phase liquid chromatography: Enantioselectivity of recently commercialized polysaccharide-based selectors. Part II. Optimization of enantioselectivity.

Earlier, a set of pharmaceuticals with different chemical structures has been used to evaluate the enantioselectivity of four recently commercialized polysaccharide-based chiral stationary phases, Lux Cellulose-1/Sepapak 1, Lux Cellulose-2/Sepapak 2, Lux Amylose-2/Sepapak 3 and Lux Cellulose-4/Sepapak 4 and of three Daicel columns, Chiralpak AD-H, Chiralcel OD-H and Chiralcel OJ-H, using the screening conditions of an existing generic separation strategy in normal-phase liquid chromatography (NPLC). In this study, the applicability of the optimization steps of the existing separation strategy was examined using 44 drugs (70 optimization cases) representing the three possible resolution situations that occur after screening. Optimizations are demonstrated by modifying parameters such as polar modifier percentages, temperatures, flow rates and additives concentration. Changing the percentage of polar modifier was found to have the largest influence on the resolution. The resolution, peak shape and the analysis time were nicely improved for 49/70 cases (70%) after the application of the original optimization steps. The introduction of some modifications to the original optimization increased this number from 49 to 62 cases, i.e. from 70% to 88.6%. Finally, an updated generic separation strategy in NPLC was proposed.