Chong Fai Kait

Effect of imidazolium-based ionic liquids on bacterial growth inhibition investigated via experimental and QSAR modelling studies

Tuning the characteristics of solvents to fit industrial requirements has currently become a major interest in both academic and industrial communities, notably in the field of room temperature ionic liquids (RTILs), which are considered one of the most promising green alternatives to molecular organic solvents. In this work, several sets of imidazolium-based ionic liquids were synthesized, and their toxicities were assessed towards four human pathogens bacteria to investigate how tunability can affect this characteristic. Additionally, the toxicity of particular RTILs bearing an amino acid anion was introduced in this work. EC50 values (50% effective concentration) were established, and significant variations were observed; although all studied ILs displayed an imidazolium moiety, the toxicity values were found to vary between 0.05 mM for the most toxic to 85.57 mM for the least toxic. Linear quantitative structure activity relationship models were then developed using the charge density distribution (σ-profiles) as molecular descriptors, which can yield accuracies as high as 95%.

Application of Experimental Statistical Method in Optimizing Preparation Variables for Cu-Ni/TiO2 Photocatalyst

Cu-Ni/TiO2 was prepared using sol–hydrothermal method. Response surface Method (RSM) including central composite design (CCD) was applied to study the single and combined effects of three primary preparation parameters like water to alkoxide molar ratio (A), acid to alkoxide molar ratio (B), and Cu content (C) on the growth of Cu-Ni doped TiO2 particle size. The particle size range of the photocatalysts was 13−25 nm. Analysis of variance (ANOVA) revealed a second–order polynomial regression model to fit the experimental data in CCD. A comparison between predicted and experimental values has depicted a good agreement amongst them with high coefficient of determination value (R2= 0.98). The 3-D response surface and the contour plots imply a synergistic effect of parameter A, an antagonistic effect of parameter B, and significant interaction between them on the growth of particle sizes more than parameter C and its interactions with other variables. The smaller average sizes of Cu-Ni doped TiO2 particles with higher surface area are helpful to increase the light adsorptive property in hydrogen production studies.

Study on Synthesis and Characterization of Cu-Ni Doped TiO2 by Sol-Gel Hydrothermal

Titania (TiO2) as a semiconductor has been intensively studied during the last decades. Regardless of its superior photocatalytic performance and extensive environmental applications, it has a wide bandgap which lead to a photocatalytic activity only in ultraviolet (UV) irradiation. To shift the activity of TiO2 to visible region, a series of monometallic and bimetallic doped TiO2 was prepared with 10wt% total metals loading. The photocatalysts were synthesized by sol-gel associated via hydrothermal method. The properties of the photocatalysts such as crystal size, surface morphology, total surface area, chemical state of the elements, and bandgap were investigated by using thermogravimetric analysis (TGA), X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and BrunauerEmmettTeller (BET) measurement. XRD analysis showed that all samples displayed anatase (101) as a main phase of TiO2 with average crystal size between 10-16 nm in a good agreement with the TEM results. The FESEM images show spherical particles less than 20 nm in size. The BET results indicated that all samples are mesoporous. The band gap of Ni-Cu/TiO2 is reduced to 2.65 eV with more absorbance in the visible region compared to those of cu/TiO2 and Ni/TiO2.

Integrated photooxidative-extractive desulfurization system for fuel oil using Cu, Fe and Cu-Fe/TiO2 and eutectic based ionic liquids: Effect of calcination temperature and duration

Photocatalyts TiO2 doped with Cu, Fe and Cu-Fe metal at different calcination temperature and duration were successfully prepared and characterized. Photocatalytic oxidative desulfurization of model oil containing dibenzothiophene as the sulfur compound (100 ppm) using the prepared photocatalyst was investigated. The photocatalyst calcined at 500°C and duration of 1 h showed the best performance.

Visible Light Photodegradation of Azo Dye by Cu/TiO2

Cu/TiO2 photocatalysts with different metal loading were prepared via modified depositionprecipitation method with the intention to reduce the band gap for Orange II degradation and mineralization under visible light radiation. The photocatalysts were characterized using thermal gravimetric analysis, powder X-ray diffraction, diffuse reflectance UV-Visible spectroscopy and field-emission scanning electron microscopy. 10 wt% photocatalysts showed the best performance compared to the bare TiO2.

Visible-Light Photodegradation of Diisopropanolamine Using Bimetallic Cu-Fe/TiO2 Photocatalyst

Titania nanoparticles, TiO2 were synthesized via microemulsion method prior to monometallic (Fe, Cu) or bimetallic (CuFe) incorporation using wet impregnation method. The prepared photocatalysts were characterized using X-ray diffraction, field emission scanning electron microscopy, diffuse reflectance UV-Vis spectroscopy and point of zero charge. The addition of metals, especially Cu enhanced the absorbance in the visible region. The lowest band gap was observed for the bimetallic Cu-Fe/TiO2 (2.77 eV) compared to bare TiO2 (3.05 eV). The performance of the photocatalysts for photodegradation of diisopropanolamine (DIPA) at pH 8 was determined using a batch glass reactor under simulated sunlight (980 W/m2). The best performance was displayed by Cu-Fe/TiO2 with the highest DIPA removal of 92%.

Effect of heat treatment on the physical properties of bimetallic doped catalyst, Cu-Ni/TiO2

Post heat treatment is critical for the doped semiconductor oxide in order to improve its photocatalytic performance. Thus work had been carried out to understand the effect of different calcination temperature (400, 450 and 500°C) on the physical properties of nanosized Cu-Ni/TiO2Cu-Ni doped TiO2 nanoparticles prepared using a combined method of sol-gel and hydrothermal. The treated samples were characterized using Raman spectroscopy, Brunauer–Emmett–teller (BET) measurement, high resolution transmission electron microscopy (HRTEM), field-emission scanning electron microscopy (FESEM), and diffuse reflectance UV-Vis spectroscopy (DR-UV-Vis). Raman analysis showed that all samples displayed anatase (101) phase of TiO2, which is in good agreement with the TEM results. BET data showed that all prepared Cu-Ni/TiO2 with different calcination temperature are mesoporous. SEM images displayed spherical particles with typical size of about 15 to 20 nm. UV-Vis spectra illustrated that the absorbance edge of all pre...

Enhanced Catalytic Activity of α-Fe2O3 with the Adsorption of Gases for Ammonia Synthesis

Ab initio density functional theory employed to study the adsorption of hydrogen and nitrogen gas molecule on the α-Fe2O3 (111) surface for ammonia synthesis. The calculated adsorption energy is-4.70kcal/mol, -4.60kcal/mol,-4.38kcal/mol and-3.77kcal/mol for different orientations of adsorbed gas molecules and shows that system is stable and gas molecules have adsorbed. It can also be seen with adsorption of gas molecules the net spin of hematite enhanced from 0 to 2 hence confirms the activity of hematite surface. Hematite nanowires synthesized by oxidation method. Raman spectrum analyses demonstrates that the nanowires are single-crystalline. Field Emission Scanning Electron Microscopy (FESEM) reveals that the nanowires have lengths of 10-25 μm. The magnetic saturation of the nanowires is 15.6 emu/g investigated by vibrating sample magnetometer (VSM). Ammonia was synthesized by magnetic induction method using the hematite nanowires as catlyst and quantified by Kjeldahl method. It is found that the role of gases adsorption was able to enhance catalytic activity of hematite nanowires for the ammonia synthesis. This green synthesis method could be a contender to the Haber-Bosch process currently used by the industry.

Photodegradation of Aqueous Diisopropanolamine Using Cu/TiO2: Effect of Calcination Temperature and Duration

The effects of calcination temperature and duration during preparation of Cu/TiO2 photocatalyst were investigated. The photocatalysts were characterized using X-ray and BET specific surface area analyzer. It was observed that the temperature and duration during calcination process have a significant effect on the photocatalyst properties and photocatalytic activity. Optimum temperature and duration for the calcination of the synthesized photocatalyst were found to be at 450 °C and 1.5 h, respectively. Photodegradation study of aqueous diisopropanolamine solution (1000 ppm) using the prepared photocatalyst showed a significant COD removal under visible light irradiation. The photocatalyst calcined at optimum parameters gave the highest COD removal of 63%.

Cu-Fe/TiO2 Photocatalyst for Deep Desulfurization Process

A series of Cu-Fe/TiO2 photocatalysts were prepared and calcined at 400°C and 500°C for 1 h. The photocatalysts were characterized using diffuse reflectance spectroscopy (DR-UV-Vis), X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM). The performance for sulfur removal was carried out using model oil containing 100 ppm S (from dibenzothiophene). The highly dispersed Cu-Fe/TiO2 photocatalyst displayed mainly spherical shaped particles. The best performing photocatalyst was 0.8wt% Cu-Fe loading and calcined at 400°C (0.8wt400) giving 18% sulfur removal. The band gap for 0.8wt400 was lowered to 2.96 eV compared to 3.21 eV for TiO2.