International Journal of Nanoparticles (5 papers in press)
Biosynthesis of Silver Nanoparticles Using Unriped Carica Papaya Fruit Extract with Different PH Conditions
by Hooi Chien Ng, Cheng Seong Khe, Azizan Aziz, Zulkifli Merican Aljunid Merican, Rajalingam Sokkalingam, Thiam Leng Chew, Chin Wei Lai
Abstract: Silver nanoparticles were successfully synthesized at room temperature from silver nitrate using unripe Carica papaya fruit extract as a reducing and capping agent. pH of the reaction solution was adjusted with the addition of sodium hydroxide from pH 5.6 (original pH of the broth) to pH 6.5, pH 7.5 and pH 8.5. Quasi spherical silver nanoparticles were obtained across the studied pH range. The average particle size obtained decreased from 34 nm to 15 nm as the pH of the solution increased from 5.6 to 8.5. From the observations and ultra violetvisible spectrophotometer analysis, the rate of reduction and formation of silver nanoparticles increased as the pH increased. The crystalline nature of the as-synthesized silver nanoparticles in a cubic structure was confirmed by the peaks in X-ray diffraction and selected area electron diffraction. From Fourier transform infrared spectra, it was found that proteins in unripe papaya fruit extract were strongly bounded to the surface of silver nanoparticles as a capping agent. The thin layer of protein coating also further confirmed under high resolution transmission electron microscope. A plausible formation mechanism has been briefly proposed.
Keywords: Biosynthesis; silver nanoparticles; Carica papaya fruit extract; pH; twinning
Comparison of Nanoparticles Zero Valent Iron and Iron Powder for Phenol Removal- Analysis and Design of Experiments Using Response Surface Methodology
by hasti daraei
Abstract: The purpose of this study was the investigation of the removal of phenol with nanoparticles zero valent iron and iron powder. The effect of various parameters such as initial concentration, pH, contact time, and dosage of NZVI and Fe powder were examined, and a central composite design (CCD) was then applied to appraisal the effect of these variables. The chemical and physical characteristics of NZVI were studied with SEM and XRD analysis. The results displayed that the adequate initial concentration for phenol sorption, pH, contact time, and sorbent dosage were 5 mg/L, pH 2, 54.75 min and 1.40 g in the case of NZVI and 5 mg/L, pH 2, 55.84 min and2.5 gin the case of Fe powder.The CCD showed that the fundamental parameters were pH and initial phenol concentration had the main effect on phenol removal.
Keywords: zero valent iron, phenol, central composite design, sorption, nanoparticles, dosage
Microalgae harvesting of nannochloropsis sp.using polyethersulfone/ lithium chloride/ functionalized multiwall carbon nanotube membranes fabricated via temperature induced phase inversion and non-solvent induced phase inversion
by Nur Farahah Mohd Khairuddin, Ani Idris, Muhammad Irfan, Teo Chee Loong
Abstract: Microalgae are a promising renewable source especially for producing biofuels and other high value products. Biofuel and biomass production involves several steps from cultivation, harvesting and extraction. Recent technology has used ultrafiltration membrane for microalgae harvesting but are faced with adverse effect of microalgae fouling. In the present study, nannochloropsis sp. harvesting was performed using an ultrafiltration hybrid membrane made of polyethersulfone (PES) blended with the two additives namely lithium chloride (LiCl) and functionalized multiwall carbon nanotube (F-MWCNT). The membranes were prepared via two methods; non-solvent induced phase separation (NIPS) and temperature induced phase separation (TIPS). The membrane performances were evaluated in terms of membrane flux and fouling for the use of microalgae harvesting. The FESEM analysis showed that the morphology of the hybrid PES-MWCNT-LiCl membranes was very much influenced by the phase separation method. Flux rates of the membranes improved dramatically with increasing amount of additives when prepared using TIPS. A 100% microalgae separation from cultivated solution without major fouling (more than 80% flux recovery) was successfully achieved.
Keywords: membrane, multiwall carbon nanotube; lithium salt; nannochloropsis algae
Structural Transformation of Polymeric and Cationic Capped Zirconia Nanoparticles with Temperature
by Sreedevi R Mohan, Uma Maheswari A, Sivakumar Manickam
Abstract: The phase transformation mechanisms of zirconia nanocrystals obtained on thermal treatment of polyvinylpyrrolidone (PVP) and cetyltrimethylammoniumbromide (CTAB) capped hydrous amorphous zirconia (HAZ) on thermal treatment are investigated. In PVP assisted synthesis, tetragonal zirconia nanoparticles formation is the predominant one as compared to CTAB assisted synthesis. The decomposition of surfactants capped on HAZ with temperature (526 oC for PVP and 466 oC for CTAB) and subsequent interaction of the by-products with zirconia nanoparticles are responsible for tetragonal to monoclinic phase transformation. The decomposition temperature of capped surfactants is observed from thermogravimetric analysis (TGA) and subsequent interaction of byproducts with zirconia nanoparticles at different temperatures is investigated from FTIR spectra. Further the structure of nanoparticles annealed at different temperatures is investigated using XRD, micro Raman and photoluminescence (PL) analysis.
Keywords: Zirconia nanoparticles; Phase transformation; Annealing; Surfactant; Mineralizer
Special Issue on: CIMDD 2013 Behaviour of Materials
Electrical properties of Nanoscale Field Effect Transistor
by Sana Kausar, Shirish Joshi
Abstract: In this paper structure of a H-passivated silicon nanowire along direction with hexagonal cross section is defined by using Virtual nanolab(VNL), and set up a nanoscale field effect transistor (FET) structure with a wrap-around gate. Then the transmission spectrum and conductance is computed as the gate bias is varied. The device characteristic curve and conductance with respect to gate voltage is studied. Also effect of doping of Al atom on characteristic curve and conductance of nanoscale field effect transistor is analyzed.
Keywords: DFT; GGA; nanowire.