Nazli Naim - Academia.edu (original) (raw)
Uploads
Papers by Nazli Naim
Japanese Journal of …, 2010
Potable water from several residential areas on the east coast of Malaysia was filtered using a p... more Potable water from several residential areas on the east coast of Malaysia was filtered using a polyether-sulphone (PES) membrane to separate the coarse and fine iron-oxide particles inside the pipelines. The as-received samples consisted of a wide distribution of particle sizes, ranging from 5 m to 400 nm. The concentration of fine iron-oxide particles inside a distribution system was extremely low. Hence, a specific method is necessary to concentrate and separate the fine particles from the coarse ones. To study the fine particles from the bulk, excess pressure was applied to the membrane filter so that the clogged particles were released into the permeate. A 100 kDa PES membrane was used to separate the particles , because the samples consisted of a wide molecular-weight cutoff range from 89 g/mol goethite (-FeOOH) to 231 g/mol hematite (Fe 2 O 3). After the filtration process, the size distribution of permeated particles reduced to 550–400 nm. Through X-ray diffraction analysis, numerous polymorphs such as-FeOOH, Fe 3 O 4 , Fe 2 O 3 and maghemite were detected from the samples. The zeta potential value of the permeated particles changed from −18.5 to −13 mV, suggesting that the dispersity of permeated iron-oxide particles became unstable, but remained adequate for electrophoretic deposition (EPD). The fibrous carbon electrode used in the EPD process, could remove up to 87% of the permeated iron-oxide particles compared to solid carbon electrodes (<56%). A high-surface-area, porous electrode and a moderate applied voltage were preferred in order to minimise gas formation, reduce the electro-osmosis effect and increase the deposition efficiency.
A nanostructure derived from TiO 2 particle deposition onto a biocomposite surface derived from c... more A nanostructure derived from TiO 2 particle deposition onto a biocomposite surface derived from coir dust (CD) was developed to control degradation using a spray dry technique. To stabilise and reduce the size of dispersed particles, the TiO 2 powder was prepared in deionised water at pH 10 and sonicated at 20 kHz and 400 W. The coir dust was obtained from coconut kernel waste and underwent drying treatment before it was mixed with polypropylene (PP) as the substrate. The suspension consisted of particles with an average size and zeta value of 285 nm and À19.2 mV, respectively. The suspension was spray dried onto a hot-pressed substrate (biocomposite) with a surface roughness between 0.23 and 1.57 lm at ambient temperature. Scanning electron microscopy image analysis and Fourier transform infrared spec-troscopy analysis indicated that the TiO 2 particles were successfully deposited onto the substrate, shown by the existence of a carboxylic acid group (ACOOH) in the CD matrix. Moreover, the weight of the deposited substrate increased exponentially with deposition time compared to pure PP substrate. However, the deposition rate of TiO 2 nanoparticles was limited by the ratio of the substrate surface roughness to particle diameter, as predicted by a previous study.
Enzyme and Microbial Technology, 2014
In this study, the potential of electrohydrodynamic atomization or electrospraying to produce nan... more In this study, the potential of electrohydrodynamic atomization or electrospraying to produce nanometerorder CGTase particles from aqueous suspension was demonstrated. CGTase enzyme was prepared in acetate buffer solution (1% v/v), followed by electrospraying in stable Taylor cone-jet mode. The deposits were collected on aluminium foil (collector) at variable distances from the tip of spraying needle, ranging from 10 to 25 cm. The Coulomb fission that occurs during electrospraying process successfully transformed the enzyme to the solid state without any functional group deterioration. The functional group verification was conducted by FTIR analysis. Comparison between the deposit and the as-received enzyme in dry state indicates almost identical spectra. By increasing the distance of the collector from the needle tip, the average particle size of the solidified enzyme was reduced from 200 ± 117 nm to 75 ± 34 nm. The average particle sizes produced from the droplet fission were in agreement with the scaling law models. Enzyme activity analysis showed that the enzyme retained its initial activity after the electrospraying process. The enzyme particles collected at the longest distance (25 cm) demonstrated the highest enzyme activity, which indicates that the activity was controlled by the enzyme particle size.
Japanese Journal of …, 2010
Potable water from several residential areas on the east coast of Malaysia was filtered using a p... more Potable water from several residential areas on the east coast of Malaysia was filtered using a polyether-sulphone (PES) membrane to separate the coarse and fine iron-oxide particles inside the pipelines. The as-received samples consisted of a wide distribution of particle sizes, ranging from 5 m to 400 nm. The concentration of fine iron-oxide particles inside a distribution system was extremely low. Hence, a specific method is necessary to concentrate and separate the fine particles from the coarse ones. To study the fine particles from the bulk, excess pressure was applied to the membrane filter so that the clogged particles were released into the permeate. A 100 kDa PES membrane was used to separate the particles , because the samples consisted of a wide molecular-weight cutoff range from 89 g/mol goethite (-FeOOH) to 231 g/mol hematite (Fe 2 O 3). After the filtration process, the size distribution of permeated particles reduced to 550–400 nm. Through X-ray diffraction analysis, numerous polymorphs such as-FeOOH, Fe 3 O 4 , Fe 2 O 3 and maghemite were detected from the samples. The zeta potential value of the permeated particles changed from −18.5 to −13 mV, suggesting that the dispersity of permeated iron-oxide particles became unstable, but remained adequate for electrophoretic deposition (EPD). The fibrous carbon electrode used in the EPD process, could remove up to 87% of the permeated iron-oxide particles compared to solid carbon electrodes (<56%). A high-surface-area, porous electrode and a moderate applied voltage were preferred in order to minimise gas formation, reduce the electro-osmosis effect and increase the deposition efficiency.
A nanostructure derived from TiO 2 particle deposition onto a biocomposite surface derived from c... more A nanostructure derived from TiO 2 particle deposition onto a biocomposite surface derived from coir dust (CD) was developed to control degradation using a spray dry technique. To stabilise and reduce the size of dispersed particles, the TiO 2 powder was prepared in deionised water at pH 10 and sonicated at 20 kHz and 400 W. The coir dust was obtained from coconut kernel waste and underwent drying treatment before it was mixed with polypropylene (PP) as the substrate. The suspension consisted of particles with an average size and zeta value of 285 nm and À19.2 mV, respectively. The suspension was spray dried onto a hot-pressed substrate (biocomposite) with a surface roughness between 0.23 and 1.57 lm at ambient temperature. Scanning electron microscopy image analysis and Fourier transform infrared spec-troscopy analysis indicated that the TiO 2 particles were successfully deposited onto the substrate, shown by the existence of a carboxylic acid group (ACOOH) in the CD matrix. Moreover, the weight of the deposited substrate increased exponentially with deposition time compared to pure PP substrate. However, the deposition rate of TiO 2 nanoparticles was limited by the ratio of the substrate surface roughness to particle diameter, as predicted by a previous study.
Enzyme and Microbial Technology, 2014
In this study, the potential of electrohydrodynamic atomization or electrospraying to produce nan... more In this study, the potential of electrohydrodynamic atomization or electrospraying to produce nanometerorder CGTase particles from aqueous suspension was demonstrated. CGTase enzyme was prepared in acetate buffer solution (1% v/v), followed by electrospraying in stable Taylor cone-jet mode. The deposits were collected on aluminium foil (collector) at variable distances from the tip of spraying needle, ranging from 10 to 25 cm. The Coulomb fission that occurs during electrospraying process successfully transformed the enzyme to the solid state without any functional group deterioration. The functional group verification was conducted by FTIR analysis. Comparison between the deposit and the as-received enzyme in dry state indicates almost identical spectra. By increasing the distance of the collector from the needle tip, the average particle size of the solidified enzyme was reduced from 200 ± 117 nm to 75 ± 34 nm. The average particle sizes produced from the droplet fission were in agreement with the scaling law models. Enzyme activity analysis showed that the enzyme retained its initial activity after the electrospraying process. The enzyme particles collected at the longest distance (25 cm) demonstrated the highest enzyme activity, which indicates that the activity was controlled by the enzyme particle size.