Fabrication and characterization of polyvinylidene fluoride composite nanofiber membrane for water flux property

This research is about the investigation of the pure water flux property of composite polyvinylidene fluoride (PVDF) nanofibers. Electrospinning technique was used to prepare the composite electrospun nanofibers. PVDF was dissolved in N,N-dimethylformamide (DMF) solvent and blended together with activated carbon (AC) and polyvinylpyrrolidone (PVP). The nanofibers were characterized to determine the morphologies, wettability property, and its tensile strength. The fabricated nanofibers diameter was found in the range between 20 to 180 nm. The presence of AC deteriorates the mechanical properties of the nanofibers as the size of AC is larger than the external diameter of the nanofibers. The results of contact angle confirmed that the fabricated nanofiber exhibit less hydrophobic in the presence of PVP and AC. The less hydrophobi

Catalytic oxidative desulfurization of diesel fuel utilizing alumina supported cobalt manganese oxides

The available technique of hydrodesulfurization (HDS) is no longer suitable in the purpose of achieving Euro-IV standard diesel due to high operational cost, low efficiency and operating at high temperature in the presence of hydrogen gas. In this study, the catalytic oxidative desulfurization was carried out in the presence of Co/Mn/Al2O3 catalyst and tert-butyl hydroperoxide (TBHP) as oxidant to achieve ultra low sulfur concentration in the model diesel fuel, Petronas commercial and crude diesel. The experimental variables involved were the effect of calcination temperatures of catalysts, dopant ratios, catalyst dopants, reaction times, reaction temperatures, extraction solvents, type of oxidants, reproducibility test and molar ratio of tert-butyl hydroperoxide/sulfur (TBHP/S) were studied to achieve optimum conditions for sulfur removal in the diesel fuel. From XRD analysis, the Co/Mn(10:90)/Al2O3 catalyst formed amorphous structure at 400°C while at 700°C and 900°C calcination temperature produced intermediate and highly crystalline structure, respectively. Further investigation by FESEM showed the particle size of as-synthesized Co/Mn (10:90)/Al2O3 catalyst reduced from the range of 70.3 - 90.2 nm to 50.6 - 52.6 nm after calcination at 400°C. For the EDX analysis, the chloride ions in as-synthesized Co/Mn (10:90)/Al2O3 catalyst reduced from 7.77% to 2.88% and 0.73% after calcination at 400°C and 900°C, respectively. Analysis using nitrogen adsorption showed that the surface area of Co/Mn (10:90)/Al2O3 as-synthesized catalyst was 103.8 m2g-1 which was lower than Co/Mn(10:90)/Al2O3 after calcination at 400°C which was 128.2 m2g-1. The optimum conditions for catalytic oxidative desulfurization of model diesel fuel was identified to perform at 60°C, with oxidant TBHP, molar ratio of TBHP/S = 3, in the presence of catalyst Co/Mn(10:90)/Al2O3 and using extraction solvent, dimethylformamide, where the sulfur contents was reduced from 600 ppm to 164 ppm. This optimum condition for oxidative desulfurization reaction was applied to the Petronas commercial diesel and Petronas crude diesel resulted in the reduction from 500 ppm to 127 ppm and 8269 ppm to 413 ppm of sulfur content respectively analyzed by Gas-Chromatography-Flame Photometric Detector

Fabrication and characterization of nylon 6, 6, polysulfone and polystyrene electrospun fibre membranes for adsorption of bisphenol a in water

The presence of new emerging pollutants (NEPs) residue in wastewater effluents, surface water and drinking water even after being subjected to the conventional treatment methods is an emerging concern. Hence, a few advanced technologies were introduced, such as pressure-driven membranes, for example, nanofiltration (NF) and reverse osmosis (RO). However, their performance has been limited due to high-pressure requirement and low permeate flux, leading to high operational costs. In this study, the utilization of the electrospun fibre membranes (EFMs) was explored as they possesses several advantages, such as the lower operating pressure requirement and ability to produce higher permeate flux that is favourable for adsorption technology. The nylon 6, 6 (Ny), polysulfone (PSf) and polystyrene (PSty) EFMs were fabricated by using the electrospinning technique and used for the adsorption of bisphenol A (BPA), acetaminophene (ACTP), sulfamethoxazole (SMX) and ibuprofen (IBP). The optimum conditions, such as applied voltage, flow rate and inner diameter of needle of the electrospinning process for: i) Ny (26 kV, 0.4 mL/h, 0.50 mm), ii) PSf (15 kV, 2.5 mL/h, 0.50 mm) and iii) PSty (16 kV, 1.6 mL/h, 0.60 mm) are considered achieved when continuous and stable streaming jet without any dripping and clogging with minimal beaded fibres is observed. The field emission scanning electron microscopy (FESEM) result showed that the average fibre diameter of Ny, PSf and PSty EFMs was measured at 98, 1291 and 1575 nm, respectively. The contact angle analysis of Ny EFM revealed a hydrophilic character, while PSf and PSty EFMs exhibited hydrophobic character. Fourier transform infrared spectroscopy (FTIR) analysis revealed the presence of hydroxyl groups in the BPA molecule, carbonyl and amine groups in Ny EFM and sulfonyl groups in PSf. These results demonstrated that the hydrogen bonding probably could be formed between Ny and PSf EFM with the BPA molecules, thus facilitating the BPA adsorption. When compared to ACTP, SMX, and IBP, the adsorption of BPA by Ny EFM was more effective. The adsorption of BPA in ultrapure water (UPW) by using five layers of Ny EFM was 96%, and the permeate volume of BPA solution was recorded at 193 mL after 30 mins of operation. The result also showed that both composites of Ny+PSf and Ny+PSty EFMs enhanced the permeate volume of BPA solution, which was recorded at 454 and 290 mL, respectively, after 30 mins of operation. The experiment for membrane regeneration and reusability for composites of Ny+PSf and Ny+PSty EFMs through three cycles of BPA adsorption in UPW was successful. This good performance was due to the BPA adsorption showing a consistent performance throughout the three cycles of operation. However, the volume of permeate BPA solution for both composites of Ny+PSf and Ny+PSty EFMs decreased from the first to the third operation cycle, from 454 to 150 mL and 290 to 119 mL, respectively. Additionally, the membrane regeneration and reusability for composite of Ny+PSf EFM through three cycles of BPA adsorption in tap water was also successful with the adsorption of 98 - 99% throughout the three cycles of operation. Meanwhile, the volume of permeate BPA solution was consistent, recorded at 348, 352 and 365 mL during the first, second and third cycles of operation, respectively. The successful BPA adsorption makes the Ny+PSf EFM composite a promising and suitable candidate for use in advanced water filtration systems