Thioflavin dye degradation by using magnetic nanoparticles augmented PolyvinylideneFlouride (PVDF) microcapsules / Mohamed Syazwan Osman ... [et al.]

Microcapsule has remarkable advantages in engineering application for pollutants removal and biomedical field for transportation. It has obviously drawn attention from the research community. Undeniably, it does have shortages but the key is to balance both the advantages and limitations to enhance microcapsule benefits. In environmental engineering applications, microcapsules could serve as encapsulation agents of nanoparticles (NPs) to drastically reduce the risk associated to nano-toxicity when it is indirect contact with surroundings. In addition, this technique could improve the physical contact and promote catalytic degradations of pollutants while exhibit better recyclability without loss of activity after multiple catalytic degradation cycles. Even though magnetic responsiveness of capsules can be used for ease of separation, one of the constraints is that the encapsulated particles will restrict the performance of capsules materials in pollutants removal. However, encapsulated magnetite particles interact with polymeric matrix chains and thus tying up the chains as knot which can restrict the expansions of whole capsules. Some-times, capsules shell is designated to remove certain target contaminants and so does for encapsulated particles. This may possibly reduce or increase the removal performance of integrated capsules which depends on the target contaminants and the underlying mechanism involved in pollutant removal. Hence, this work primarily focuses on the synthesis of magnetic nanoparticles augmented microcapsule with dual functionalities namely adsorptive and catalytic activities using membrane material, PolyvinylideneFlouride (PVDF). Feasibility study using Thioflavin dye as the representable model system for degradation will be explored

Nutrient Cycling in Tropical and Temperate Coastal Waters: Is Latitude Making a Difference?

Tropical coastal waters are highly dynamic and amongst the most biogeochemically active zones in the ocean. This review compares nitrogen (N) and phosphorus (P) cycles in temperate and tropical coastal waters. We review the literature to identify major similarities and differences between these two regions, specifically with regards to the impact of environmental factors (temperature, sunlight), riverine inputs, groundwater, lateral fluxes, atmospheric deposition, nitrogen fixation, organic nutrient cycling, primary production, respiration, sedimentary burial, denitrification and anammox. Overall, there are some similarities but also key differences in nutrient cycling, with differences relating mainly to temperature, sunlight, and precipitation amounts and patterns. We conclude that due to the differences in biogeochemical processes, we cannot directly apply cause and effect relationships and models from temperate systems in tropical coastal waters. Our review also highlights the considerable gaps in knowledge of the biogeochemical processes of tropical coastal waters compared with temperate systems. Given the ecological and societal importance of tropical coastal waters, we hope that highlighting the differences and similarities to temperate systems as well as the existing gaps, will inspire further studies on their biogeochemical processes. Such knowledge will be essential to better understand and forecast impacts on tropical coastal nutrient cycling at local, regional, and global scales

Electromechanical spring stiffness from the small perturbation linearized equations of generalized machine theory

10.1109/60.107235IEEE Transactions on Energy Conversion52374-379ITCN

A study of computational fluid dynamics on membrane module in membrane distillation

Membrane distillation is one of the recently interest rising membrane separation processes used for the separation of seawater and saline wastewater, and etc. Membrane distillation has the advantage of adopting the low grade waste energy and/or renewable energy such as solar and geothermal energy due to the nature of thermal driven process and low temperature range. Computational Fluid Dynamics (CFD) is a numerical simulation tool that is able to perform the calculation in order to investigate and simulate the performance of the processes that involve fluid, heat and mass transfer. In this study, a direct contact membrane distillation (DCMD) experiment will be studied using hollow fiber membrane module. A three dimensional (3D) CFD simulation will be examined for its viability in the investigation of the DCMD. Furthermore, various CFD multiphase models will be studied for its suitability in predicting heat and mass behavior within the membrane

Carnauba Wax/Halloysite Nanotube with Improved Anti-Wetting and Permeability of Hydrophobic PVDF Membrane via DCMD

The hydrophobic membranes have been widely explored to meet the membrane characteristics for the membrane distillation (MD) process. Inorganic metal oxide nanoparticles have been used to improve the membrane hydrophobicity, but limited studies have used nano clay particles. This study introduces halloysite nanotube (HNT) as an alternative material to synthesis a hydrophobic poly(vinylidene fluoride) (PVDF)-HNT membrane. The PVDF membranes were fabricated using functionalized HNTs (e.g., carnauba wax and 1H,1H,2H,2H-perfluorooctyl-trichlorosilane (FOTS)). The results were determined by Fourier transform infrared-attenuated total reflection, scanning electron microscope, goniometer and porometer to determine the desired hydrophobic membrane for direct contact membrane distillation (DCMD). The addition of FOTS-HNT (fs-HNT) and carnauba wax-HNT (fw-HNT) in the PVDF membrane enhanced the water contact angle (CA) to 127° and 137°, respectively. The presence of fw-HNT in the PVDF membrane exhibited higher liquid entry pressure (LEP) (2.64 bar) compared to fs-HNT in the membrane matrix (1.44 bar). The PVDF/fw-HNT membrane (Pfw-HNT) obtained the highest flux of 7.24 L/m2h with 99.9% salt removal. A stable permeability in the Pfw-HNT membrane was obtained throughout 16 h of DCMD. The incorporation of fw-HNT in the PVDF membrane had improved the anti-wetting properties and the membrane performance with the anti-fouling effect

Simultaneous water reclamation and nutrient recovery of aquaculture wastewater using membrane distillation

A large amount of aquaculture wastewater with high load of nutrients, organic matter, and microalgae will pollute receiving water body and needs to treat before discharge. In this work, membrane distillation (MD) with the ability to avoid non-volatile substances was used to purify water and simultaneously recover nutrients from aquaculture wastewater. Results showed that micro-structures have evenly distributed on the surface of polyvinylidene fluoride (PVDF) membrane using nylon taffeta substrate. Resultant membrane has surpassed superhydrophobicity benchmark. It achieved high water contact angle of 153.3° and low contact angle hysteresis of 8.4°. The continuous separation and treatment of fish farm wastewater showed a small and steady flux reduction of 1.4 kg/m2·h, indicating less fouling by the surface-printed membrane. In the batch process of feed concentration, the water recovery reached 86.3%. The retentate concentration of fish farm water is at least five times higher than initial concentration of ammonia (16.4 to 82.2 mg/L), phosphate (18.0 to 99.8 mg/L), and potassium (68.0 to 384.8 mg/L). This concentrated feed can use as primary nutrient of liquid fertilizer. In feed concentration process, except for ammonia (>86%), rejection of all selected inorganic substances is higher than 99%.This work was supported by the Ministry of Education, Malaysia, the Long Term Research Grant Scheme 1/2018 ( LRGS/203/PJKIMIA/67215002 ).Scopu