8 research outputs found
Morphology and Properties of Hollow Fiber Membrane Prepared Under Different Air Gap Lengths
No full textThe fabrication of hollow fibre membrane modules is affected by many spinning variables, including polymer composition, bath temperature, bore fluid ratio, fibre take-up velocity, and air gap length, resulting in varying properties. This study uses a dry-jet wet-spinning process to investigate the morphology and characteristics of PVDF hollow fibre membranes prepared at 10 cm (P10) and 20 cm (P20) air gap lengths. Polypropylene glycol was used as an additive. The dope extrusion rate, coagulation bath temperature, bore fluid ratio, and take-up velocity were set at 4 rpm, 30°C, 1.5 ml/hr, and 2 m/min, respectively. Atomic force microscopy determined the pore size distribution, roughness, and membrane thickness. Field emission scanning electron microscope (FESEM) analyzed membrane morphology. Membrane performance was tested using 10 mg/L of synthetic protein solution. The results showed that the diameters of the fibers as well as the inner and outer lumens were significantly influenced by the air gap. Membrane dimensions decreased with the increased air gap distance with the outer and inner diameter by 5% at a 10 cm air gap. FESEM images verified that the thickness of the skin layer increases with the increase in air gap distance. The resulting roughness of the membrane layer was found to be dependent on the pore size of the support layer. The protein separation test achieved the best rejection of 98% using the P20 membrane. Thus, selecting an optimum air gap distance for hollow fibre membrane fabrication was discovered to be a viable strategy for improving separation performance in membrane filtration and improving solute separation in wastewater
Design optimisation of solar shading systems for tropical office buildings: Challenges and future trends
No full text© 2018 Elsevier Ltd Most high-rise office buildings in the tropics, particularly in Malaysia and Singapore, exceed the required level of the energy efficiency index. The implementation of conventional shading systems in the tropics has been proven to have limitations in terms of controlling the quantity and quality of received solar light throughout the year, especially at different solar angles with varying sky conditions. Therefore, the main objective of this work is to investigate the challenges and future trends of solar shading systems by examining their mechanisms, functions and materials for application in tropical regions. This study used evidence review to evaluate various types and models of shading systems based on a systematic method to identify patterns and trends through classification and comparison. Three main categories of shading systems were identified based on the energy involvement and the design approach: (i) passive systems with zero energy use, (ii) active systems that use mechanical devices and (iii) hybrid systems integrated with a biomimetic approach. Specific conclusions were drawn to emphasise the efficiency of developed shading systems in the tropics
Characterization of empty fruit bunch for microwave-assisted pyrolysis
No full textAgricultural waste such as oil palm empty fruit bunch (EFB) is of environmental concern to Malaysia as one of the world’s largest oil palm producers. Pyrolysis can be used to treat biomass waste due to its flexibility in producing solid, liquid and gas products. This study attempts to characterize EFB for pyrolysis using microwaves as an alternative heating source. EFB taken from a local oil palm mill was subjected to fuel, chemical and dielectric property analysis. The findings revealed that high moisture and 47% oxygen gave low calorific value of 16 MJ/kg. Notably, high water content is an advantage in microwave heating as water is a good microwave absorber, which results in fast drying. Further, a high volatile content at 70% gave the EFB an advantage of high reactivity. A moderate potassium content of 12.8% could also positively affect microwave absorption. The dielectric properties of EFB were observed to be proportional to the moisture content. Furthermore, the microwave penetration depth was found highest at 20% moisture, i.e. 3.5 cm. However, low values of both dielectric constant and loss of dried EFBs would require the addition of microwave absorbers for pyrolysis reaction. The fuel and chemical characteristics of EFB were found comparable to other biomasses, which indicated a good candidate for microwave pyrolysis treatment
Permeability and antifouling augmentation of a hybrid PVDF-PEG membrane using nano-magnesium oxide as a powerful mediator for POME decolorization
No full textThis study focused on developing a hydrophilic hybrid polyvinylidene fluoride (PVDF)-polyethylene glycol (PEG) hollow membrane by incorporating Nano-magnesium oxide (NMO) as a potent antifouling mediator. The Nano-hybrid hollow fibers with varied loading of NMO (0 g; 0.25 g; 0.50 g; 0.75 g and 1.25 g) were spun through phase inversion technique. The resultants Nano-hybrid fibers were characterized and compared based on SEM, EDX, contact angle, surface zeta-potential, permeability flux, fouling resistance and color rejection from palm oil mill effluent (POME). Noticeably, the permeability flux, fouling resistance and color rejection improved with the increase in NMO loading. PVDF-PEG with 0.50 g-NMO loading displayed an outstanding performance with 198.35 L/m2·h, 61.33 L/m2·h and 74.65% of water flux, POME flux and color rejection from POME, respectively. More so, a remarkable fouling resistance were obtained such that the flux recovery, reversible fouling percentage and irreversible fouling percentage remains relatively steady at 90.98%, 61.39% and 7.68%, respectively, even after 3 cycles of continuous filtrations for a total period of 9 h. However, at excess loading of 0.75 and 1.25 g-NMO, deterioration in the flux and fouling resistance was observed. This was due to the agglomeration of nanoparticles within the matrix structure at the excessive loading
-POME treatment
No full textAeration effects on membrane filtration of wastewater remain partially explored, as lesser or excessive application often aggravates the fouling. Furthermore, most polymeric membranes are hydrophobic, which facilitates the deposition of foulants and layer formation. There is a need for further investigation on the use of aeration and membrane modifications with a better antifouling property. This study focused on investigating the influence of aeration intensity on the antifouling performance of a modified co-polymerized polyvinylidene-fluoride (PVDF-PEG) fiber using a hydrophilic nano-MgO to treat anaerobically digested palm oil mill effluent (AnT-POME). The aeration intensity was varied to three levels (3,4,5Lmin-1). Both neat and modified membranes obtained their best AnT-POME permeate flux at 4Lmin-1 with a relatively stable value of 28.67 and 89.85 Lm-2 h-1 after 5 h filtration, respectively. The irreversible fouling percentage (IFP) for the neat and modified membrane at 4Lmin-1 aeration intensity, was 66.67 and 12.42, respectively. This indicates that the neat membrane is more susceptible to fouling. To investigate the changes in the membranes, the fouled membranes were characterized using SEM, FTIR and porosity, then compared with that of the pristine samples. Cake-scaly layers were noticed on the neat membrane. Additionally, both membranes successfully reduced the COD, TDS, TSS, and TN above 60%
Integrated phycoremediation and modified PES-PVP fiber with biosynthesized n-AgO from Arabidopsis thaliana extract for remediating shrimp wastewater
No full textDespite the economic benefits of phycoremediation in wastewater treatment, existing scientific reports have highlighted its limited efficacy in contaminant removal. Similarly, membrane separation faces significant challenges due to associated fouling, hindering its widespread application. Addressing these issues, this study introduces an innovative approach utilizing Arabidopsis thaliana (AT) extract as a dual-function capping and reducing agent to synthesize bio-based silver nanoparticles (n-AgO), eliminating the need for additional reducing agents. The process involved homogenizing 300 g of fresh AT leaves with 500 mL of DI water, filtering the extract, and subsequently mixing 100 mL of this extract with 50-mL AgNO3, followed by agitation and centrifugation, resulting in n-AgO with an average size of ≈10 nm and a face-centered cubic crystalline structure confirmed using X-ray dispersive spectroscopy. These nanoparticles were then applied to modify polyethersulfone-polyvinylpyrrolidone (PES-PVP) hollow fibers at varying loadings using the non-solvent-induced phase technique. The resultant membranes were characterized using scanning electron microscopy, Fourier transforms infrared spectroscopy, contact angle, and porosity analysis. Assessment using shrimp wastewater as an influent demonstrated that the 0.50-g n-AgO modified PES-PVP exhibited the highest flux recovery ratio (FRR) of 0.932 and significantly reduced irreversible fouling compared to neat PES-PVP. Integration of Chlamydomonas sp. phycoremediation achieved substantial ammonia removal (87.94%) and TSS exclusion (61.41%), but the integration with the 0.50-g n-AgO modified membrane significantly enhanced the overall remediation efficiency to over 94%. Statistical analysis confirmed the significance of this improvement (P ≤ 0.05, F value of 13.49). This study highlights the potential of hybrid phycoremediation with modified membranes in wastewater treatment, emphasizing the need for further exploration into optimizing hybrid performance and extending assessments to diverse pollutants for broader applicability. Graphical abstract: (Figure presented.) © The Author(s) under exclusive licence to Iranian Society of Environmentalists (IRSEN) and Science and Research Branch, Islamic Azad University 2024
