Shinyei Based Sensor with Added Roof Enhanced Detection of Indoor Particulate Matter

Commercially available monitoring systems in the market are expensive and rather challenging to maintain, had prompted researchers to invent low-cost monitoring system as alternative. New cost-effective, portable and user-friendly prototypes have been proposed using Shinyei PPD42NS sensor for PM10 monitoring. The performances of the original and roofed prototype were tested by measuring indoor PM10 concentrations. The roofed prototype showed a higher reading of PM10 (822 μgm-3) detected at minutes 16 compared to the original prototype (0 μgm-3) due to the presence of a roof decreased the velocity of particulate matter and accumulate before entered the Shinyei sensor inlet. CFD analysis of the roofed prototype illustrated lower air velocity of 0.3ms-1 compared to original prototype having a velocity of 0.4 ms-1. The original prototype exhibit comparable performance to the reference instrument (GRIMM) in detecting PM10 concentration. Shinyei PPD42NS inside the original prototype showed high sensitivity by detecting higher concentration of PM10 with readings of 79 μgm-3. The prototypes were successfully developed by detecting the presence of PM10 and addition of roof showed increase efficiency in detecting particulate matter in the air

Electrospinning of PLA with DMF: Effect of polymer concentration on the bead diameter of the electrospun fibre

Electrospinning has been known for its' ability in producing nanoporous fibres which uses electrical force to form a spinning jet out of a polymer solution. The electrospinning condition and polymer solution properties can influence the electrospinning jet formation as well as jet path. Polylactic acid (PLA) was dissolved in dimethylformamide (DMF) to produce a polymer solution. Bead is considered as a defect towards an electrospun fibres, yet previous study found that PLA/DMF produced beaded fibres for all concentrations. However, there is a limited study that explain the effect of concentration on the diameter of beads. Therefore, in this study we investigated the formation of electrospinning jet as well as the effect of PLA concentration of formation of beads, particularly the diameter of the beads. Polymer solution with different concentration was prepared. The concentration investigated in this study were 7.5, 10, 12.5, 15, 17.5, and 20 % w/v. Polymer solution was then subjected to the electrospinning process to evaluate the morphology of the electrospun produced via optical microscope. Simultaneously, the formation of electrospinning jet is observed with portable digital microscope. The morphology of the electrospun fibres, especially the fibre and bead diameter are analyzed using image analysis software, ImageJ. From this research, it is found that at voltage of 10 and 12.8 kV, a stable electrospinning jet can be formed which consists of 'Taylor cone', straight jet, and plume. Concentration from 7.5-20 % w/v were able to form electrospun fibres, yet only 12.5 and 15 % w/v PLA concentrations can produce an effective electrospun fibres with beads diameter of 3393 nm and 3642 nm, respectively. Also, the number of beads for both concentrations are 34 and 19, respectively. Since the main criteria in producing electrospun fibres is no beads or small and minimal beads at best, therefore 12.5 and 15 % w/v PLA concentration are considered as efficient electrospun fibres

Design and fabrication of solar light responsive new metal organic frameworks for photocatalysis / Nur Atiqah Surib

Design and synthesis of multi-dimensional metal organic frameworks has attracted much attention not only due to their intriguing structures and unique properties, but also for their potential applications especially in catalysis. Recently, much effort has been devoted to develop new photocatalyst based on MOFs, motivated largely by a demand for solving pollution problems in view of their potential applications in the green degradation of organic pollutants. MOFs, known as coordination polymers are crystalline materials constructed from metal ions or clusters bridged by organic ligands to form one-, two-, or three-dimensional infinite networks. There are several methods have been applied for synthesis of MOFs particularly solvothermal, hydrothermal, microwave-assisted, electrochemical, mechanochemical and sonochemical synthesis. In this work, new Cadmium and Copper based Metal Organic Framework (MOF) was synthesized under hydrothermal and solvothermal conditions. Its structure was resolved by single crystal X-ray diffraction and further characterized by Powder X-ray diffraction (PXRD), Field Emission Scanning Electron Microscopy (FESEM), Infrared Spectra (IR), Thermogravimetric (TGA), UV-Vis, Photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS) analysis. The Cd-MOF and Cu-MOF were photocatalytically active for degradation of 2-chlorophenol (2-CP) under solar light irradiation where 69% and 100% of phenol removal was observed respectively. To improve photocatalytic activity of Cd-MOF, different metal ions such as Ag+, Fe3+ and Zn2+ were introduced into the framework through ion-exchange reaction. The UV-Vis results revealed that Fe-Cd-MOF showed an enhanced photoresponse in the visible region, whereas the photoresponse of Ag-Cd-MOF and Zn-Cd-MOF in the ultraviolet light region. Photocatalytic performances of synthesized materials were investigated fordegradation of 2-CP. Among them, Cd-MOF intercalated with Fe3+ exhibited excellent photocatalytic activity compared with Cd-MOF, degrading 92% of 2-CP in 5 hours. It can be attributed to the intercalation of Fe3+, which reduced energy gap of pure MOF, thus increases photocatalytic efficiency

Ag+, Fe3+ and Zn2+-intercalated cadmium(II)-metal-organic frameworks for enhanced daylight photocatalysis

Design and synthesis of multi-dimensional metal-organic frameworks are fascinating because MOFs possess intriguing structures and unique properties and exhibit potential applications in photocatalysis. In the present study, we endeavoured to synthesize a new Cd-linked MOF through a simple hydrothermal route. The daylight utilising attributes of the Cd-MOF were enhanced by intercalating Ag+, Fe3+, and Zn2+ into the framework via an ion-exchange technique. The optical property shows that Fe3+ stimulates the photo response in the visible region, whereas Ag+ and Zn2+ stimulate the photo response in the ultraviolet light region. Photocatalytic efficiency of the developed MOFs was investigated by degradation of 2-CP under daylight illumination. The Cd-MOFs intercalated with Fe3+ exhibit excellent photocatalysis as compared to the rest, degrading 93% of 2-CP in 5 h of illumination. The intercalation of Fe3+ onto the Cd-MOF significantly reduced the energy gap of the pure MOF; this led to an increased formation of reactive oxygen species driven by the electrons (e-) and holes (h+). Thus, the developed modified MOF clearly demonstrated its capability as a daylight photocatalyst as compared to the existing conventional photocatalysts