Afizah Ayob, Prof. Madya Dr.
http://dspace.unimap.edu.my:80/xmlui/handle/123456789/40888
This page provides access to scholarly publication by UniMAP Faculty members and researchers.
2024-03-28T15:56:34Z
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Effect of frying on the rheological and chemical properties of palm oil and its blends
http://dspace.unimap.edu.my:80/xmlui/handle/123456789/41259
Effect of frying on the rheological and chemical properties of palm oil and its blends
Bazlul Mobin, Siddique; Ida Idayu, Muhamad; Anees, Ahmad; Afizah, Ayob; Mahamad Hakimi, Ibrahim; Mohd Omar, Ab Kadir
The aim of this research was to determine the changes in the physicochemical properties of palm oil and its blends by FTIR and rheological measurements. Application of heat produces some chemical compounds as impurities and even toxic compounds in oils and fats that give absorbance at different region. FTIR spectra of pure palm olein shows an absorbance at 3002 cm−1 whereas other pure oils show maximum absorption at around 3007 cm−1 due to C-H stretching vibration of cis-double bond (=C-H). By blending of high unsaturated oils with palm olein, a clear shift of 3007 cm−1 band to 3005 cm−1 occurs. Viscosity of palm olein was found higher among all oils while it subsequently and substantially reduced by blending with other oils. Since it is a function of temperature, viscosity of pure oils and their blends decreases with the increase of temperature. The loss modulus (G′′), for all oil blends before and after frying, in rheological experiment was found higher for all oils than the storage modulus (G′), therefore, the viscous property was found higher than elastic property of oils and blends. However, the critical stress for all oil blends was found higher than that of pure oils.
Link to publisher's homepage at http://link.springer.com/
2015-03-01T00:00:00Z
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Characterization of polymer-stabilized nano zero-valent iron particle by ultrasonic irradiation-assisted method
http://dspace.unimap.edu.my:80/xmlui/handle/123456789/41160
Characterization of polymer-stabilized nano zero-valent iron particle by ultrasonic irradiation-assisted method
Afizah, Ayob; Norli, Ismail; Tjoon, Tow Teng; Ahmad Zuhairi, Abdullah; Bazlul Mobin, Siddique
We present a study of the influence of pH and ultrasonic irradiation-assisted method on the dispersion of stabilized commercial nanoparticles in post-synthesis using two types of polymers. The great pH responsive and weak polyelectrolyte in aqueous medium solution, poly(acrylic acid) (PAA) and carboxymethyl cellulose (CMC) were employed in the study. We obtained TEM images, quantitative ATR FTIR and UV-Vis measurements to characterize the morphology, dispersion and size distribution of PAA and CMC absorb onto the commercial nanoparticle at both pH 2.2 and 8.6. PAA and CMC not only stabilized the colloid by promoting nucleation but also played a role as dispersing agent and FTIR exhibited that these surfactants chemically . absorb on the surface of commercial nZVI through carboxylic group and monodentate interaction. Dispersion of stabilized-commercial nanoparticles could be controlled by adjusting the pH value of suspension and it revealed at higher alkaline medium numerous of small particles observed through TEM images. In addition, absorbance spectra provide more information and quantitatively confirmed significant differences for two colloidal suspensions with better dispersion for CnZVI at higher pH 8.6. © MD Publications Pvt. Ltd.
Link to publisher's homepage at http://www.printspublications.com
2012-01-01T00:00:00Z
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Immobilization of Cu 2+ using stabilized nano zero valent iron particles in contaminated aqueous solutions
http://dspace.unimap.edu.my:80/xmlui/handle/123456789/41159
Immobilization of Cu 2+ using stabilized nano zero valent iron particles in contaminated aqueous solutions
Afizah, Ayob; Norli, Ismail; Tjoon, Tow Teng; Aahmad Zuhairi, Abdullah
Batch kinetic experiments were conducted to investigate the feasibility of using carboxylmethyl cellulose (CMC)-stabilized nano zero valent iron (nZVI) particles for immobilization of Cu 2+ in water. The effects of nZVI concentration, pH, and initial concentration of Cu 2+ have been studied. Cu 2+immobilization increased from 59.10% to 98.10% as the nZVI concentration increased from 0.2 to 2.0 g/1. The adsorption kinetics of Cu 2+ ions was fitted to a pseudo-second order model and both Langmuir and Freundlich isotherms fit experimental data. SEM-EDX indicates that slightly porous and fragile particles were formed due to the corrosion on the nZVI surface.
Link to publisher's homepage at http://epe.pwr.wroc.pl/index.html
2012-01-01T00:00:00Z
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Kinetic removal of Cr⁶⁺ in aqueous solution by carboxymethyl cellulose-stabilized nano zero-valent iron particles
http://dspace.unimap.edu.my:80/xmlui/handle/123456789/40889
Kinetic removal of Cr⁶⁺ in aqueous solution by carboxymethyl cellulose-stabilized nano zero-valent iron particles
Afizah, Ayob; Salina, Alias; Farrah Aini, Dahalan; Ragunathan, Santiagoo; Ahmad Zuhairi, Abdullah; Tjoon, Tow Teng
Carboxymethyl cellulose (CMC) was used in the chemical reduction method for producing dispersible nano zero-valent iron (nZVI) particles served as reactive, mobile and convenient adsorbent. CMC-stabilized nZVI particles at CMC:Fe2+ = 0.0034 molar ratio were characterized using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) assisted with probe ultrasonication dispersing tool. FTIR depicted that the CMC monomers were adsorbed onto nZVI particles primarily through carbonyl head groups via monodentate bonding. The botryoidally clusters were the predominant morphology of CMC-stabilized nZVI particles under SEM observation. Those spherical particles were evenly dispersed at sizes less than 100 nm under TEM analysis. nZVI particles stabilization with CMC (at CMC:Fe2⁺ molar ratio of 0.005) prevented the aggregation and resulted in high catalytic reactivity observed at pseudo-first order constant value, K1 of 0.0196 min1 for Cr⁶⁺ removal in aqueous solution. This study demonstrates that CMC-stabilized nZVI particle has the potential to become an effective agent for in situ subsurface environment remediation.
Link to publisher's homepage at http://www.mjcce.org.mk
2015-01-01T00:00:00Z