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AbstractThis study introduces a novel approach to CO2 capture using the ultrasonic-assisted wet impregnation technique with various MgO loadings on Fe2O3. This method allows for enhanced dispersion of MgO particles, leading to improved adsorption and desorption characteristics. The characterization was conducted using XRD, N2 adsorption-desorption isotherms and FESEM. CO2 adsorption isotherm at 25 °C and TPD-CO2 were applied to obtain the CO2 capture activities. The linearized form of adsorption isotherm model was fitted to the experimental data from the CO2 adsorption isotherm at 25 °C. The most effective adsorbent is 20MgO/Fe2O3 with 20 wt% dopant loading which has an adsorption capacity of 3.83 and 56.99 mg/g for physisorption and chemisorption, respectively. It has the highest pore size distribution at 80–150 nm among MgO/Fe2O3 series adsorbents. This discrepancy is ascribed to a good distribution of the MgO particle on the Fe2O3 surfaces and the pores generated on the MgO surfaces. XRD revealed a greater peak shift to a higher angle of 2θ for the (104) plane starting from 20MgO/Fe2O3. This shows that the Fe3+ ion in the Fe2O3 structure has been successfully replaced by a smaller ion radius of Mg2+ and the ion was successfully incorporated into the Fe2O3 as a substitutional atom. The Freundlich isotherm model fit the best with the experimental data suggesting that the heterogeneity surface facilitated a successful multilayer adsorption process. The novelty of this work lies in the ability to enhance CO2 adsorption efficiency while lowering the desorption temperature, offering a practical CO2 capture applications. [ABSTRACT FROM AUTHOR]

Owing to their eccentric thermostable ability, thermophiles are among the most utilized extremophiles in various industries, such as manufacturing, and clinical research. Researchers believe that many unknown thermophiles are yet to be discovered. This study aimed to genotypically characterize the diversity of thermophiles and screen them for the potential production of enzymes in the recreational hot springs located at Northwest Coast of Borneo. Water samples were collected at 45 °C-50 °C from Annah Rais and Panchor hot springs during the sampling period from January 2018 to January 2019. Three samples (water and sediment) were collected twice in a 3-week interval from each pool of the sampling sites. Each water sample was diluted up to 10-3 and plated on thick nutrient agar at 55 °C for 24 h. Customized nutrient agar plus Bacto-agar plates were used for the optimum growth analysis of the isolates at 40 °C-90 °C for 24 h. The thermophiles were isolated, characterized biochemically, and amplified molecularly using DNA fingerprinting and 16S rRNA gene sequencing. Lipase, protease, gelatinase, amylase, catalase, and nitrate reductase enzymatic production was examined. Twenty-one thermophilic isolates were successfully characterized into seven clusters of Amnoxybacillus spp. and Geobacillus spp. by studying their phylogenetic dendrograms. Isolates AR10 and AR15 could produce most of the tested enzymes. All the isolates showed negative results in gelatinase and lipase production. PC14 was the only isolate that did not produce any of the enzymatic reactions in this experiment. The results showed that most of the thermophiles isolated from the two Borneo hot springs can synthesize enzymes and have potential to be thermostable. In conclusion, the search for the thermophilic producers of novel enzymes in Borneo is successful; further research must focus on their applications. [ABSTRACT FROM AUTHOR]

The chemical reduction progression behaviour of transition metals (Mo, Zr, W, Ce, and Co) doped on NiO was studied using temperature programmed reduction (TPR) analysis. A wet impregnation method was applied to synthesise the doped NiO series catalysts. The reduction progress of the catalysts was attained by using a reductant gas at the concentration of 40% v/v CO/N2. X-ray diffraction (XRD) was employed to determine the composition of the reduced phases. Undoped NiO was reduced at 384? to obtain a cubic phase of NiO. It was observed that Ce/NiO exhibited the lowest reduction temperature of 370? among all catalysts. This phenomenon might be due to a higher surface area of Ce/NiO compared to undoped NiO, which facilitated a faster reduction reaction. The rest of the doped NiO series catalysts (Co/NiO, Mo/NiO, W/NiO and Zr/NiO) demonstrated a higher reduction temperature compared to undoped NiO. New peaks in the XRD pattern were observed only for the reduced catalysts of Mo/NiO and W/NiO, which were associated with monoclinic MoO2 and WO2.72 phases, respectively. The formation of new compounds or more stable nickel alloys led to a slower reduction reaction than undoped NiO. Therefore, Ce/NiO was the most efficient catalyst in promoting the formation of Ni under the CO atmosphere. [ABSTRACT FROM AUTHOR]

In recent years, previously reported studies revealed a high efficiency of pollutant degradation by coupling photocatalysis and electrochemical processes (PECs) using titanium dioxide (TiO2) photoelectrode rather than using photocatalysis or electrocatalysis alone. However, some of the TiO2 photoelectrodes that have been reported were not cost-effective. This is due to the use of expensive chemicals and certain expensive equipment in the fabrication process, other than involving complicated preparation steps. Therefore, this study is aimed at investigating the PEC performance and stability of low-cost TiO2-polyvinyl chloride (TiO2-PVC) composite photoelectrode for Reactive Orange 16 (RO16) degradation. The materials characterisation using the ATR-FTIR, XRD and UV-Vis DRS proved that TiO2 and TiO2-PVC were successfully synthesised. The micrograph obtained for the surface characterisation using the FESEM showed that the smooth surface of freshly prepared photoelectrodes turned slightly rough with tiny pits formation after five continuous PEC processes. Nevertheless, the photoelectrode retained its original shape in good condition for further PEC processes. By PEC process, the fabricated photoelectrode showed 99.4% and 51.1% of colour and total organic carbon (TOC) removal, respectively, at optimised PEC parameters (1.0 mol L−1 NaCl concentration, 10 V applied voltage, 120 min degradation time and initial pH 2). Moreover, the fabricated photoelectrode demonstrated sufficient reusability potential (~ 96.3%) after five cycles of PEC processes. In summary, a low-cost and stable composite photoelectrode with high efficiency in RO16 degradation was successfully fabricated and could be potentially applied for other emerging pollutants degradation via the PEC degradation technique. [ABSTRACT FROM AUTHOR]

Various metal oxides of CeO2, ZnO, and Co3O4 impregnated on activated carbon (AC) were synthesized to determine the CO2 capture efficiency and analyse with adsorption kinetics model. Batch kinetic studies showed that CeO2/AC is the most efficient adsorbent with an equilibrium time of 10 minutes that was needed to obtain adsorption capacity of 52.68 mg/g. CO2 adsorption at 30 °C exhibits the optimum temperature with only 6.53% loss in adsorption capacity after 5 cycles of CO2 adsorption-desorption. The CeO2 on AC was detected through X-ray diffraction and the scanning electron microscope image shows well-distributed CeO2 particles on AC surfaces. CO2 adsorption at 30 °C is best fitted with the pseudo-second-order kinetics with R2 = 0.9994 and the relative error between calculated and experimental adsorption capacity only 1.32%. The adsorption considering chemisorption is responsible for improving adsorption capacity. The addition of CeO2 on AC enhanced the adsorption capacity by providing active sites to attract CO2. [ABSTRACT FROM AUTHOR]

Various metal oxides of CeO2, ZnO, and Co3O4 impregnated on activated carbon (AC) were synthesized to determine the CO2 capture efficiency and analyse with adsorption kinetics model. Batch kinetic studies showed that CeO2/AC is the most efficient adsorbent with an equilibrium time of 10 minutes that was needed to obtain adsorption capacity of 52.68 mg/g. CO2 adsorption at 30 °C exhibits the optimum temperature with only 6.53% loss in adsorption capacity after 5 cycles of CO2 adsorption-desorption. The CeO2 on AC was detected through X-ray diffraction and the scanning electron microscope image shows well-distributed CeO2 particles on AC surfaces. CO2 adsorption at 30 °C is best fitted with the pseudo-second-order kinetics with R2 = 0.9994 and the relative error between calculated and experimental adsorption capacity only 1.32%. The adsorption considering chemisorption is responsible for improving adsorption capacity. The addition of CeO2 on AC enhanced the adsorption capacity by providing active sites to attract CO2.