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Acetaminophen (Ace) is a trace pollutant widely found in sewage treatment plant (STP) wastewater. We test the feasibility of coconut shell waste, a low cost adsorbent from coconut industry, for removing Ace from synthetic solution in a fixed-bed column adsorption. To enhance its performance, the surface of granular activated carbon (GAC) was pre-treated with NaOH, HNO3, ozone, and/or chitosan respectively. The results show that the chemical modification of the GAC's surface with various chemicals has enhanced its Ace removal during the column operations. Among the modified adsorbents, the ozone-treated GAC stands out for the highest Ace adsorption capacity (38.2 mg/g) under the following conditions: 40 mg/L of Ace concentration, 2 mL/min of flow rate, 45 cm of bed depth. Both the Thomas and the Yoon-Nelson models are applicable to simulate the experimental results of the column operations with their adsorption capacities: ozone-treated GAC (20.88 mg/g) > chitosan-coated GAC (16.67 mg/g) > HNO3-treated GAC (11.09 mg/g) > NaOH-treated GAC (7.57 mg/g) > as-received GAC (2.84 mg/g). This suggests that the ozone-treated GAC is promising and suitable for Ace removal in a fixed-bed reactor.
Asymmetric alumina hollow fiber membranes were prepared using the phase inversion technique followed by the sintering process at high temperatures. The ceramic suspensions were formulated by mixing alumina powder with polyethersulfone (PESf), polyethylene glycol-30-dipolyhydroxystearate and N-methyl-2-pyrrolidone (NMP) as the polymer binder, dispersant and solvent, respectively. The objectives of this study were (i) to investigate the effects of spinning parameters, namely, ceramic loading, ceramic to polymer binder ratio, different internal coagulant temperatures and air gap variation on asymmetric structure formation and (ii) to study the self-cleaning properties of alumina hollow fiber membranes. The ceramic hollow fiber membrane was characterized in terms of its viscosity, structural morphology and mechanical strength using a scanning electron microscope (SEM). The results showed that the finger-like structures in alumina hollow fiber membranes could be formed but their patterns were influenced by the ceramic suspension and spinning parameters. Variations in their morphology resulted in significant effects on the mechanical properties and permeability of ceramic hollow fiber membranes. A CuO/CeO2 catalyst was deposited onto the alumina membrane support with the catalyst distribution determined by SEM/EDX. Self-cleaning properties were examined by comparing normal cleaning and self-cleaning properties with irradiation of UV for protein rejection. The result of self-cleaning by UV showed higher bovine serum albumin (BSA) permeation due to super-hydrophilicity of the CuO/CeO2 catalyst.
The biodegradation of nonylphenol ethoxylates (NPEOs) surfactant often produces more refractory, toxic and estrogenic intermediates.In this study, simple analytical method for NPEOs determination based on High Performance Liquid Chromatography (HPLC) was developed and complete biodegradation of NPEOs was evaluated by "serum bottle method" that uses direct measure of biogas production in anaerobic condition.The reversed phase C18 column was successfully used for detection of long chain NPEO ave9 (having an average of 9 EO units) and short chain NPEO ave1.5 (having an average of 1.5 EO units) and nonylphenol (NP) at short retention time.However, the coelution of oligomers in reversed phase chromatography is unavoidable, thus the distinction between NPEO oligomers is not possible.In biodegradation study study, the long chain NPEO ave9 was partially mineralized at approximately 37% of the theoretical CH 4 production in anaerobic condition.Nevertheless, the refractory intermediates of NPEO ave1.5 and nonylphenol adversely affects the glucoseutilizing methanogens under anaerobic condition, thereby hampering CH 4 formation.It can be concluded that the anaerobic biodegradation of nonylphenolic compounds proceeded at a very slow rate due to their complex physicochemical properties.
The synthesis of PANI incorporated with Ag-Fe in nanocomposite thin films-based electrochemical sensor was developed by irradiating with 10 kGy dose of gamma ray. PANI-Ag-Fe nanocomposite was synthesised by oxidative polymerisation process from aniline. The films was deposited using spin coater with sol-gel method before being irradiated with 10 kGy of gamma ray. The characterisation of PANI-Ag-Fe films with various concentrations of Ag-Fe was investigated using XRD, FESEM and UV-Vis spectroscopy. The sensor performance was measured using I-V measurement. The sensitivity of sensor was tested upon pure water andE. coli solution. XRD analysis shows that the crystallite size decreases with the rise of Fe concentration. FESEM images show the nanostructure of Ag-Fe particles in dendrite and spherical shape. UV-Vis absorption peaks appeared in between 420 and 450 nm wavelengths. For sensor performance, I-V characteristic and impedance analysis show PANI-Ag-Fe with highest concentration of Fe performed higher sensitivity towards E.coli presence.
As an effective effort in improving the performance of electrolyte/anode dual-layer hollow fibres (HFs) for micro-tubular solid oxide fuel cell (SOFC), high quality dual-layer HFs with controllable electrolyte layer thickness have been developed in this study by adjusting fabrication parameters of a single-step co-extrusion and co-sintering process. Uniform and defect-free outer electrolyte layer from 70 to 10μm can be achieved when the extrusion rate is reduced from 5 to 0.5mlmin−1. Although the bending strength and the gas-tightness properties are reduced slightly with the decrease in electrolyte layer thickness, significant improvement in power output of the cell is achieved. Power density as high as 1.11Wcm−2 is obtained on the cell with the electrolyte layer of 10μm in thickness, which is 114% higher than the one with an electrolyte layer of 65μm.
Inspired by the lotus leaf surface structure, which possesses a hydrophobicity behaviour, a low cost, high performance superhydrophobic and superoleophilic kaolin hollow fibre membrane (KHFM) was obtained by a simple sol-gel grafted method using tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES) for oil removal from water. The KHFM was grafted at various grafting times ranging from 1 to 5 coating cycles. Prior to the calcination process at 400 °C, the grafted KHFM was dried in an oven at 100 °C for 1 hour for each grafting coating cycle. The grafting process efficiency was measured by the contact angle of water and hexane. Scanning electron microscopy (SEM) and Atomic Force Microscopy (AFM) were used to study the morphology and surface roughness, respectively, of the grafted KHFM. The oil removal was conducted by using the homogeneous mixture of hexane and water. The highest hydrophobicity and oleophilicity was obtained for the KHFM grafted at 2 coating cycles with a contact angle value equal to 157° and 0°, respectively. In fact, the mechanical strength of KHFM was also improved from 16.21 MPa to 72.33 MPa after grafting. In terms of performance, KHFM grafted for 2 coating cycles obtained an almost 99.9% absorption of oil. Thereby, KHFMs were assembled into a module for a filtration study. A high oil flux of 102 L m-2 h-1 was obtained for superhydrophobic and superoleophilic KHFM with 2 grafting coating cycles of 2, and this result is in agreement with the trend of the adsorption result.
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This work initiates the development of clean technology in carbon dioxide (CO2) capture using ceramic membrane inspired by gas–liquid contacting system. A low cost, high performance superhydrophobic kaolin-alumina hollow fibre membrane was prepared via phase inversion-based extrusion and sintering techniques, followed by a grafting with fluoroalkylsilane (FAS). The membrane was characterized by scanning electron microscopy (SEM), gas permeation test, contact angle, wetting resistance, X-ray photoemission spectroscopy (XPS), X-ray diffraction (XRD) and thermal gravimetric analysis (TGA). The fabricated membrane was highly porous, thus increasing the gas permeation rate. By surface modification, the membrane contact angle was increased from 0° to 142°. In fact, wettability resistance of the membrane was also improved. The membrane was subsequently applied in membrane contactor for carbon dioxide (CO2) absorption. The CO2 absorption flux as high as 0.18 mol m−2 s−1 was achieved at the liquid flow rate of 100 mL min−1 which was far above the fluxes of some commercial and in-house made polymeric and ceramic membranes. In conclusion, the modified kaolin-alumina hollow fibre membrane with the superhydrophobic surface, high permeance, and absorption flux is suitable for CO2 post-combustion capture, due to its outstanding chemical and thermal stabilities.
Endocrine disrupting compound (EDC) namely bisphenol A (BPA) is toxic and has capability to give adverse effect towards health. The outflow of BPA into water bodies raised concern and suitable water treatment is needed. Photocatalysis is promising method nowadays to move towards green technology. The combination of copper (II) oxide-vanadium tetrasulfide (CuO-VS4) incorporated with polyvinylidene fluoride (PVDF) membrane as photocatalytic dual layer hollow fibre membrane (DLHF) was chosen in this study as novel energy storage photocatalytic membrane towards efficient degradation of BPA under visible light illumination. CuO and CuO-VS4 was synthesized via sol-gel and hydrothermal method respectively at different drying temperature and hydrothermal time. PVDF/CuO-VS4 DLHF photocatalytic membrane was fabricated using co-extrusion method by varying the ratio of CuO-VS4 and characterized for the morphology and properties as well photocatalytic test by collecting the sample from photoreactor. CuO synthesized at room temperature while CuO-VS4 synthesized at 12 hours hydrothermal time was chosen to be depositing into PVDF membrane matrix. The 0.25 PVDF/CuO-VS4 DLHF exhibit the largest pore size and uniform distribution of CuO-VS4 while photocatalytic activity achieved 70.19% and 73.24% of photodegradation and removal of BPA respectively. Around 53.09% of BPA successfully degraded after 120 min of analysis in dark condition for efficient energy storage capability. A novel PVDF/CuO-VS4 DLHF can act as preferential photocatalytic membrane for BPA removal and as potential energy storage material for wastewater treatment.
Solid oxide fuel cell (SOFC) performance depends greatly on the anode conductivity, which in traditional nickel-yttria stabilized zirconia (Ni-YSZ) anode is determined by the Ni content that is infamous for its coking problem under hydrocarbon fuel. Without the use of high content of Ni, anode conductivity can be elevated by adding an external metal layer on top of the anode. In this study, we present the incorporation of copper (Cu) metal layer on top of the anode of micro-tubular SOFC by applying a modified sol-gel method using syringe deposition technique at various chemical compositions and deposition cycles. Cu sol was found best to be made up of 2:1:8 ratio of Cu: citric acid: ethylene glycol, with 1.36 μm metal layer formed at 5 deposition cycle, and no obvious increase in thickness after the fifth cycle. The Cu layer elevated the conductivity by 1010 times compared to the uncoated anode. However, the coated layer also reduced the gas permeability by 10 times in the anode, which resulted from the blocking of a nano-sized pore in the anode, rather than the micron size pore. This blocking can be resolved by increasing the amount of micron-sized pore by using pore former during anode fabrication. From electrochemical impedance spectroscopy (EIS), Cu coating reduced the ohmic resistance (Rohm) and charge transfer resistance (Rct). From the current-voltage curve, the maximum power density (MPD) was found to increase linearly with the increase of the Cu coating cycle, but the value is almost stagnant at 2.3 to 2.5 mW cm−2 when the coating cycle of more than 4 was employed. This suggests that anode gas permeation plays an important role in anode conductivity. The findings from this study suggested that 5 deposition cycle shows to be the optimal coating layer required to achieve the percolation threshold without unnecessary loss in permeability.
