Exposure of synthetic dye, such as methylene blue (MB), in water bodies led to a serious threat to living things because they are toxic and non-degradable. Amongst the introduced dye removal methods, membrane separation process can be considered a powerful technique for treating dye contamination. However, this method commonly suffered from drawbacks, such as short membrane lifetime, low permeability and selectivity. To overcome these issues, graphene oxide (GO) and titanium dioxide (TiO2) were used as additives to fabricate polyethersulfone (PES)- and polyvinylidene fluoride (PVDF)-based hybrid membranes via non-solvent-induced phase separation method. Prior to membrane fabrication, GO was synthesised via electrochemical exfoliation method assisted by customised triple-tail surfactant. The potential of PES- and PVDF-based hybrid membranes for wastewater treatment has been discussed widely. However, direct comparison between these two polymeric membranes is not critically discussed for MB dye separation application yet. Therefore, this study is aimed at evaluating the performance of different types of polymers (e.g. PES and PVDF) in terms of membrane morphology, properties, dye rejection and antifouling ability. Results showed that the incorporation of GO and TiO2 alters the morphology of the fabricated membranes and affects dye rejection further, as well as their antifouling performance. In contrast with pristine membrane, PES-GO/TiO2 and PVDF-GO/TiO2 possessed high hydrophilicity, as indicated by their low contact angle (67.38° and 62.12°, respectively). Based on this study, PVDF-GO/TiO2 showed higher porosity value (94.88%), permeability (87.32 L/m2hMPa) and MB rejection rate (92.63%), as well as flux recovery ratio value of > 100% as compared with others. Overall, the incorporation of GO and TiO2 with PVDF polymer are proven to be effective hybrid materials of membrane fabrication for dye rejection application in the near future. The polymer material's intrinsic properties can affect the attributes of the fabricated membrane.
The fabrication of a zinc hydroxide nitrate-sodium dodecylsulfate bispyribac modified with multi-walled carbon nanotube (ZHN-SDS-BP/MWCNT) paste electrode for uric acid and bisphenol A detection was presented in this study. Electrochemical impedance spectroscopy, chronocoulometry, square-wave voltammetry, and cyclic voltammetry were all used to examine the electrocatalytic activities of modified paste electrodes. The modified electrode's sensitivity and selectivity have been considered in terms of the composition of the modifier in percentages, the types of supporting electrolytes used, the pH of the electrolyte, and square-wave voltammetry parameters like frequency, pulse size, and step increment. Square-wave voltammetry is performed by applying a small amplitude square-wave voltage to a scanning potential from -0.3 V to +1.0 V, demonstrating a quick response time and high sensitivity. The ZHN-SDS-BP/MWCNT sensor demonstrated a linear range for uric acid and bisphenol A from 5.0 µM to 0.7 mM, with a limit of detection of 0.4 µM and 0.8 µM, respectively, with good reproducibility, repeatability, and stability as well. The modified paste electrode was successfully used in the determination of uric acid and bisphenol A in samples of human urine and lake water.