Publications

Industrial waste consisting of dyes has emerged as a major waterbody pollutant in these modern times. Therefore, an efficient method is required to remove and address these water contaminant concerns. The current study reported the fabrication of a new hybrid type carboxylatedalginic acid (CAA) coordinated with Sn-metal (Sn-CAA) green composite absorbent for the removal of toxic dyes such as Acid Red (AR.) and Brilliant Green (BG). To obtain CAA, alginic acid was chemically oxidised via KMnO4 and it was subsequently used to coordinate with Sn2+ metal ion. The characterisation such as field emission-scanning electron microscope, X-ray powder diffraction technique and Fourier-transform-infrared spectroscopy was carried out to confirm the fabrication of CAA and Sn-CAA adsorbents. Several parameters including shaking time, pH, heating and concentration-effect were employed to conduct solid-phase extraction and UV-vis spectroscopy experiments were conducted to confirm the successful removal of toxic dyes from the aqueous media. The dye removal results established the spontaneous and endothermic nature of dye removal process as assessed through obtained thermodynamic and kinetic parameters. Furthermore, for the removal of BG and AR, the fabricated Sn-CAA-based adsorbent found to be more proficient than pristine CAA.

Environmental pollution is one of the global hot issues and need an urgent demand to detect and monitor the pollutants which affect the environment. Ammonia is one of the organic pollutants which cause severe harmful effect on environment due to its toxic nature. Therefore, electrochemical sensor has been fabricated using CeO2 nanoparticles (NPs) as a redox mediator to detect aqueous ammonia for environmental safety. The electrical response of the ethanol sensor was investigated by I-V technique which exhibited high sensitivity (0.3519 μA.cm-2.mM-1) and lower limit of detection (LOD = 0.395 μM). CeO2 nanoparticles were synthesized hydrothermally at low temperature and field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), and Raman spectroscopy corroborated that the synthesized product is aggregated form of spherical nanoparticles, well crystalline possessing cubic phase with an average size of ~ 50 ± 10 nm. UV-Visible absorption spectrum confirmed that CeO2 nanoparticle is optically active with absorption band of 297 nm. Keywords: CeO2 nanoparticles, Structural properties, Optical properties, Ammonia chemi-sensor

Typhonium flagelliforme (Araceae) is a medicinal herb which is endowed with curative properties against a variety of illness including injuries, oedema, coughs, pulmonary ailments, bleeding and cancer. In order to assess its phytochemical components, an experiment was conducted on one to six month old ex vitro and in vitro extracts of T. flagelliforme. The active (ex vitro and in vitro) extracts of T. flagelliforme were screened for phytochemicals components such as alkaloids, flavonlids, terpenoids and steroids. Alkaloids and flavonoids are the main phytochemical constituents of T. flagelliforme which are found to be in the highest amount in two and four month old of ex vitro plants. High amounts of main phytochemical constituents were observed during the flowering process which started in two month old plant and finished at the end of the three month old plant.   Key words: Typhonium flagelliforme, phytochemicals, traditional medicine.

Layered double hydroxides (LDHs) are promising materials for CO2 sorption, although improvements in performance are required for practical applications. In the current study, the CO2 sorption capacity and multi-cycle stability were both increased by introducing an open supporting framework of multi-walled carbon nanotubes (MWNTs). This nanostructured inert network provides a high surface area, maximizing the gas accessibility and minimizing coarsening effects. Specifically, LDH nanoparticles were precipitated directly onto MWNTs, initially oxidised to ensure a favourable electrostatic interaction and hence a good dispersion. The dependence of the structural and physical properties of the Mg–Al LDH grown on MWNT supports has been studied, using electron microscopy, X-ray diffraction, thermogravimetric analysis (TGA), and BET surface area, and correlated with the CO2 sorption capacity, established via TGA and temperature programmed desorption measurements. The use of a MWNT support was found to improve the absolute capacity and cycle stability of the hybrid adsorbent under dry conditions.

This work develops an extended Stöber method to obtain SiO 2 @polydopamine with a one‐pot process. Such composites can be further processed to obtain hollow N‐doped carbon capsules (HNCSs). More importantly, the HNCSs can be used as templates to synthesise HNCSs@Fe 3 O 4 and HNCSs@MnO 2 composites, which greatly widened the application of HNCSs.

Insider attacks have become increasingly frequent and more difficult to detect. Modeling user activities to capture the temporal features and connections between activities can enhance the detection of insider threats. In this work, we present a novel insider activity modeling approach that uses effective representations of user activities to enhance the detection performance. The proposed activity modeling and detection system has been evaluated using log files from the CMU CERT r4.2 insider dataset that provides the activities of employees for eighteen working months. Our results have shown that the proposed system achieves high malicious activity identification performance with the proposed data modeling techniques.

Currently, industrial-scale NH3 production almost relies on energy-intensive Haber-Bosch process from atmospheric N2 with large amount of CO2 emission, while low-cost and high-efficient catalysts are demanded for the N2 reduction reaction (NRR). In this study, Mn3O4 nanoparticles@reduced graphene oxide (Mn3O4@rGO) composite is reported as an efficient NRR electrocatalyst with excellent selectivity for NH3 formation. In 0.1 M Na2SO4 solution, such catalyst obtains a NH3 yield of 17.4 μg·h−1·mg−1cat. and a Faradaic efficiency of 3.52% at −0.85 V vs. reversible hydrogen electrode. Notably, it also shows high electrochemical stability during electrolysis process. Density functional theory (DFT) calculations also demonstrate that the (112) planes of Mn3O4 possess superior NRR activity.