Noor Fitrah Abu Bakar

Electrostatic Deposition of Aerosol Particles Generated from an Aqueous Nanopowder Suspension on a Chemically Treated Substrate

The state of electrostatically deposited aerosol particles from a suspension that contains TiO2 particles on the surface of a solid substrate using electrospray was demonstrated. The particles were initially electrosterically stable in 7.5 wt % aqueous solution with a mean particle size of 50 nm. During deposition, the particles were pumped with different flow rates between 0.6 and 1.2 mL/h through a stainless steel capillary tube of 0.1 mm inner diameter. The particles were emitted at the tip of the capillary tube as an electrified liquid cone before forming into a highly charged droplet. For comparison, two types of substrate surfaces with and without chemical treatment were prepared. Atomic force microscopy (AFM) scanning and contact angle measurements showed that surface treatment increased the substrate roughness and created a hydrophilic surface. Raman analysis also showed the existence of an oxide layer and a P–O network on the treated substrate. Field emission scanning electron microscopy FE-SEM image analysis showed that more TiO2 particles were deposited on the treated substrate than on the untreated substrate.

Immobilisation of cyclodextrin glucanotransferase into polyvinyl alcohol (PVA) nanofibres via electrospinning

Highlights • Fabrication of enzyme-carrying polymeric nanofibers by electrospinning.• PVA nanofibers structure and size were not affected by the addition of enzyme.• The electrospun CGTase/PVA nanofibers show excellent immobilisation efficiency.

Transformation of cyclodextrin glucanotransferase (CGTase) from aqueous suspension to fine solid particles via electrospraying

In this study, the potential of electrohydrodynamic atomization or electrospraying to produce nanometer-order 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.

Electrospray deposition of titanium dioxide (TiO2) nanoparticles

Deposition of titanium dioxide (TiO2) nanoparticles was conducted by using eletrospray method. 0.05wt% of titanium dioxide suspension was prepared and characterized by using Malvern Zetasizer prior to the experiment. From Zetasizer results, stable suspension condition was obtained which is at pH 2 with zeta potential value of ±29.0 mV. In this electrospraying, the suspension was pumped at flowrate of 5 ml/hr by using syringe pump. The input voltage of 2.1 kV was applied at the nozzle tip and counter electrode. Electrosprayed particles were collected on the grounded aluminium plate substrate which was placed at 10–20 cm from counter electrode. Particles were then characterized using FESEM and average size of electrosprayed particles obtained. Initial droplet size was calculated by scaling law and compared with FE-SEM results in order to prove droplet fission occur during electrospray. Due to the results obtained, as the working distance increase from 10–20 cm the deposited TiO2 droplet size decrease from 247–116 nm to show droplet fission occur during the experiment.

Formation of fine and encapsulated mefenamic acid form I particles for dissolution improvement via electrospray method

ABSTRACT The potential of using electrostatic atomizer or electrospray in producing fine and encapsulated particle of mefenamic acid (MA) form I with β-cyclodextrin (βCD) was demonstrated in this study. Encapsulated MA-βCD with a molar ratio of 1:2 was prepared in water-ethanol suspension, followed by the electrospray process to atomize the droplet into fine dried particles. The working distance (WD) between the electrospray needle tip and the substrate were varied from 15 to 25 cm. The sizes of encapsulated MA-βCD particles were found to decrease from 91 ± 26 to 42 ± 35 nm as the WD increased. The dissolution rate of encapsulated particles of MA-βCD was found to be higher compared to the particles of as-received MA and the unencapsulated MA. The presence of the encapsulated MA-βCD was proven by a thermal analysis with the disappearance of MA peak after the atomization process. The x-ray diffraction and FTIR analysis showed that the encapsulation occurred with the existence of new solid phase that was expected from interaction between MA and βCD and the appearance of C = C. Further analysis by transmission electron microscopy showed the size and morphology of MA-βCD particles when immersed in water and acetone. Encapsulated MA-βCD particles were solubilized in water but suspended as spherical shape in acetone.

Extracted Lignin from Rhizophora’s Black Liquor as Fluid Loss Control Additive in Water Based Drilling Mud

The ability of lignin from Rhizophora Apiculata’s black liquor to act as a fluid loss additive in water-based drilling at HTHP condition was investigated. The lignin biopolymer was extracted from the black liquor using acid precipitation technique using 20% by volume of sulphuric acid at temperature of 45°C and 60°C for pH 4, 6 and 8 respectively. The produced lignin was tested in water based drilling mud at temperature of 250°F, 300°F,350°F and 400°F . The optimum extraction parameters showed that the highest yield of lignin extraction of approximately 51.2% was obtained at pH 4 and extraction temperature of 45°C. It was also observed that the Rhizophora Apiculata’s lignin has remarkable rheological and filtration controlling properties at HTHP condition as compared to the commercial lignin additive.

Electrophoretic deposition of adsorbed arsenic on fine iron oxide particles in tap water

Electrophoretic deposition (EPD) technique has been demonstrated to remove arsenic with natural adsorbent (fine iron oxide particles) in tap water samples. Characterizations of metal element particularly arsenic and fine iron oxide particles in tap water from two different locations, i.e. commercial and residential areas, were conducted. Results showed that the concentration of arsenic in tap water from residential area was higher than commercial area samples i.e. 0.022 ± 0.004 and 0.016 ± 0.008 ppm, respectively. The same finding was observed in zeta potential value where it was higher in the residential area than commercial area, i.e. −42.27 ± 0.12 and −34.83 ± 0.23 mV, respectively. During the removal of arsenic using the EPD technique, direct current (DC) voltage was varied from 5 to 25V at a constant electrode distance of 30 mm. Effect of zeta potential, voltage and electrode type were intensively investigated. High percentage removal of arsenic was obtained from carbon plate than carbon fibre electr...

Induction Time of L-Isoleucine Crystallization with the Presence of Electric Field

Nucleation signifies the start of phase transition where nuclei of crystalline forms in the solution prior to crystal growth. There is an increasing demand in investigating reliable method to measure the nucleation rate in order to control the process an it has been reported that electric field has been successfully used to control the nucleation consequently the crystallization process. Hence, it becomes the objective of this paper to examine the effect of electric field on the induction time crystallization of L-isoleucine. The experiment was conducted in a 200 mL jacketed reactor where constant stirring was provided by retreat curve impeller and the temperature was regulated using two refrigerated baths. The induction time in this work was found to be lower than system without the application of electric field due to the hydrophobicity of L-isoleucine molecule and competition to form hydrogen bond with water when electrolysis occurs. The interfacial tension calculated shows no significant change with concentration while nucleation rate increases as the supersaturation increases. The critical radius calculated also proves to be smaller and decreases when supersaturation increases. The result also suggests the presence of new crystalline phase for the crystals produced at 48 g/L and supersaturation ratio of 1.08 and 1.14.

Effect of Microwave Absorber towards Pyrolysis Yield of Automotive Paint Sludge

Application of microwave absorber (MWA) does affect the yield of microwave pyrolysis process. In this study, activated carbon and graphite have been used as microwave absorbers and the results were then compared with the microwave pyrolysis process without microwave absorber. The yield of solid and liquid increased while the yield of gas decreased with the application of MWA. Chemical functional group inside MWA also affected by the microwave pyrolysis process and energy content of MWA slightly increased from 24.54 MJ/kg to 29.57 MJ/kg and 32.17 MJ/kg to 32.24 MJ/kg for activated carbon and graphite, respectively.

Nanoparticle preparation of Mefenamic acid by electrospray drying

Nanoparticles preparation of Mefenamic acid (MA) by using an electrospray drying method was conducted in this study. Electrospray drying is a process that uses electrostatic force to disperse a conductive liquid stream into fine charged droplets through the coulomb fission of charges in the liquid and finally dry into fine particles. Electrospray drying modes operation usually in Taylor cone jet, and it was formed by controlling applied voltage and liquid flow rate. A conductive liquid (2.77–8.55μScm−1) which is MA solution was prepared by using acetone with concentration 0.041 and 0.055 M before pumping at a flow rate of 3–6ml/h. By applying the applied voltage at 1.3–1.5 kV, Taylor cone jet mode was formed prior to the electrospray. During electrospray drying process, solvent evaporation from the droplet was occurring that leads to coulomb disruption and may generate to nanoparticles. The dried nanoparticles were collected on a grounded substrate that was placed at varying distance from the electrospray. MA particle with size range of 100–400 nm were produced by electrospray drying process. Characterization of particles by using X-ray diffractometry (XRD) and differential scanning calorimetry (DSC) show that particles formed into polymorph I.