Universiti Brunei Darussalam
  • Bandar Seri Begawan, Brunei
Recent publications
This paper proposes a plasmonic ultrawide bandstop filter using a metal-insulator-metal waveguide cooperating with five symmetrical semi-circular-like resonators, including the silver nanorods (AgNDs). We calculated transmittance spectrum and electromagnetic field distribution employing the finite element method. The advantages of the design reveal the surface, cavity, and gap plasmon resonance effects that can simultaneously exist in the proposed device. Our design can achieve a tunable wide-bandgap by adding the AgNDs in resonators and attain an extensive stop wavelength range of 2104 nm, which is the highest bandgap width to our knowledge. Simulations results show that the AgNDs and coupling distance are pivotal factors influencing the bandgap formation, changing the resonators' resonance condition and effective refractive index. Besides, the designed filter can also serve as a nanosensor with an ultrahigh sensitivity of 7980 nm/RIU. Thus, the designed plasmonic filter can be a promising alternative candidate for optical trapping and tunable devices working in visible, near-infrared, and mid-infrared spectra.
Pristine silver niobate and Zr-doped silver niobates as photocatalysts were synthesized by the sol-gel method. The synthesized samples were characterized by X-ray diffraction (XRD) and were found to contain both AgNbO3 and AgNb3O8. Fourier transform infrared (FT-IR) shows that the Nb-O bonds among the samples are different and may be attributed to the two types of silver niobates. Field emission scanning electron microscopy (FESEM) showed changes in morphologies of particles with increasing Zr-doping with average particle size ranging from 0.89 μm to 1.21 μm. The Tauc plots indicate that Zr-doped silver niobates have lower band-gap energies than their undoped counterpart. Furthermore, Zr-doped silver niobates also have a lower rate of electron-hole recombination than the undoped silver niobate as proven by the PL analysis. The photocatalytic degradation studies showed that Zr doping improved the performance of silver niobate for both Rhodamine B and methylene blue dyes. Through the present study, the link between Zr-doping and its role in dye degradation by silver niobates could be established.
This study has focused on petrography, geochemistry, radiochemical, and leaching properties of coal combustion residues (CCRs), their leachates and nearby waters from the Barapukuria coal-fired power-plant to evaluate the potential environmental impacts and human health hazards for the first in Bangladesh. The CCRs, used in this study are predominantly comprised of Al-Si-rich glassy materials (94.8%) followed by crystallites (3.6%), notably quartz, mullite, and spinel with rock-fragments (0.3%); and un-burnt organic constituents (1.3%) such as anisotropic coke (0.8%) and slightly altered inertinite (0.5%). Hematite, magnetite, cristobalite, monazite, zircon, rutile, tourmaline and sillimanite were also identified as trace minerals. Elemental contents are found to be elevated (2.1-14.2 times) in the fly-ash (FA) and bottom-ash (BA), as compared to world coal-ash average with the exceptions of Ni in FA; and of Zn, As, Cu, and Hg in BA. The sum of detected rare earth elements is significantly high as compared to the world FA, Indian and Chinese ash residues. The specific activities of CCR are comparatively higher by a factor of 3.7 (226Ra) to 6.2 (232Th) than those of the world average. The examined spheres, particles, and agglomerates of FA are predominantly comprised of C, Al, and Si as major while, K, Ca, Mg, Fe, W and Ti as minor elements. On the other hand, extractable amounts of soluble potentially toxic elements in FA leachates are 7.7% for Se, 4.8% for Zn, and in BA 5.7% for As and 3.1% for Se and others are <1%. Metals are substantially released from FA in the range of 8.5 (for Cr) to 9650 (for Zn) ppb and 0.002% (for Cr) -7.7% (for Se), while from BA below detection level (for Cr) to 940 (for Mn) ppb. The concentration of hazardous metals in the discharged waste water and water ash pond were higher than those were found in nearby pond- and ground-water sources around power-plant. Ecological and radiological risk indices suggest moderate-risk derived from FA and low-risk from BA.
Concurrent adsorptive removal of methylene blue (MB) and rhodamine B (RhB) onto durian rind (DR) agricultural waste, from an aqueous binary solution as a model of wastewater containing multiple synthetic dyes, was investigated. The concurrent adsorption of the dyes followed pseudo-second-order kinetics. The adsorption isotherm was well simulated by the Langmuir model, implying a monolayer adsorption to the surface with a homogeneous binding energy. The adsorption process was governed by external mass transfer through two-step intraparticle diffusion of the dyes onto the adsorbent surface. The adsorption efficiency of MB (96.4%) is much higher than that of RhB (56.3%). This is attributed to the higher rate constant for the adsorption of MB (0.348 g mg⁻¹ min⁻¹) as compared to that of RhB (0.151 g mg⁻¹ min⁻¹). The adsorption behavior suggested that the two cationic dyes in the binary solution diffused and adsorbed independently and randomly onto the DR surface. The adsorption capacity of MB and RhB in the binary solution (47.4 mg g⁻¹ and 32.9 mg g⁻¹, respectively) is lower than those of their single solute solutions (93.3 mg g⁻¹ and 62.8 mg g⁻¹, respectively), suggesting a competitive effect in their concurrent adsorption. This was confirmed based on the adsorption characteristics of the binary solution with different molar ratios. The competitive effect was attributed to either non-interactive or repulsive electrostatic interactions between the positively charged dyes in the binary system. The domination of MB is attributed to its smaller molecular size, higher planarity, and faster adsorption kinetics compared with RhB.
Abstract The present investigation was aimed to examine the percentage quantity of protein and amino acids in scales and muscles of Pampus argenteus and Parastromateus niger gathered from the local fish market of district Quetta of Balochistan. About 80 specimens of these two species, i.e., Pampus argenteus (N=40) and Parastromateus niger (N = 40), were collected from April 2017 to May 2018. In general, crude protein content was high in scales, that is, 71.03% in Parastromateus niger and 52.11% in Pampus argenteus, as well as in muscles of two Pomfret species of fishes i.e., 63.44% in Pampus argenteus and 60.99% in Parastromateus niger on a dry-weight basis, respectively. Likewise, the muscles and scales of Parastromateus niger reveal well compositions of amino acids that include proline was found to be high, and methionine was less than other amino acids, whereas threonine was found high in the scales of Pampus argenteus, but methionine was observed in lesser amount. However, the amino acids found in Pampus argenteus muscles also showed different compositions, such as lysine was found to be high, but histidine was less, respectively. In comparison, amino acids like tryptophan and cysteine were not detected in both scales and muscles of thesePomfret species of fishes. Thus, this study was based on analyzing the utilization of both Pomfret species of scales and meat whether they could have values as good supplements of both protein and certain kinds of essential amino acids in animal diets.
The latitudinal diversity gradient (LDG) is one of the most recognized global patterns of species richness exhibited across a wide range of taxa. Numerous hypotheses have been proposed in the past two centuries to explain LDG, but rigorous tests of the drivers of LDGs have been limited by a lack of high-quality global species richness data. Here we produce a high-resolution (0.025° × 0.025°) map of local tree species richness using a global forest inventory database with individual tree information and local biophysical characteristics from ~1.3 million sample plots. We then quantify drivers of local tree species richness patterns across latitudes. Generally, annual mean temperature was a dominant predictor of tree species richness, which is most consistent with the metabolic theory of biodiversity (MTB). However, MTB underestimated LDG in the tropics, where high species richness was also moderated by topographic, soil and anthropogenic factors operating at local scales. Given that local landscape variables operate synergistically with bioclimatic factors in shaping the global LDG pattern, we suggest that MTB be extended to account for co-limitation by subordinate drivers.
An intrusion detection system, often known as an IDS, is extremely important for preventing attacks on a network, violating network policies, and gaining unauthorized access to a network. The effectiveness of IDS is highly dependent on data preprocessing techniques and classification models used to enhance accuracy and reduce model training and testing time. For the purpose of anomaly identification, researchers have developed several machine learning and deep learning-based algorithms; nonetheless, accurate anomaly detection with low test and train times remains a challenge. Using a hybrid feature selection approach and a deep neural network-(DNN-) based classifier, the authors of this research suggest an enhanced intrusion detection system (IDS). In order to construct a subset of reduced and optimal features that may be used for classification, a hybrid feature selection model that consists of three methods, namely, chi square, ANOVA, and principal component analysis (PCA), is applied. These methods are referred to as "the big three." On the NSL-KDD dataset, the suggested model receives training and is then evaluated. The proposed method was successful in achieving the following results: a reduction of input data by 40%, an average accuracy of 99.73%, a precision score of 99.75%, an F1 score of 99.72%, and an average training and testing time of 138% and 2.7 seconds, respectively. The findings of the experiments demonstrate that the proposed model is superior to the performance of the other comparison approaches.
As an early crystallizing phase in the magma, apatite can accommodate a wide range of multivalent cations and has a capacity resistant to weathering and hydrothermal alteration. These features enable apatite to record the primary redox state of precursor magma. Here, we present new electron probe microanalysis (EPMA) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) geochemical data on apatite and zircon grains from the epithermal gold ore-hosting Dahalajunshan Formation volcanics in the Tulasu basin (Western Tianshan Orogen, Central Asia). Calculated zircon Ce-/Ti-based oxybarometric results and sulfur content of apatite suggest that the parental magma of the volcanics was relatively oxidized. Furthermore, we compiled a regional apatite chemical dataset to assess whether other elements (Mn, V, Eu, Ce, As and Ga) in apatite can serve as a magma redox proxy. Negative correlation between apatite Mn and whole-rock MgO is evident, implying the control of magma fractionation on apatite Mn contents. Also, oxygen fugacity (fO2) calculated by Mn-in-apatite oxybarometer correlates strongly with magma fractionation, which indicates that fractional crystallization (instead of fO2) controlled the Mn-uptake in apatite. The apatite As budget is sensitive to fO2 variation but does not show any correlation with the ratio of nonbridging oxygens to tetrahedral cations (NBO/T), whole-rock SiO2, or aluminum saturation index. In contrast, apatite V and Ga contents correlate obviously with whole-rock SiO2 and NBO/T but not fO2, and apatite Eu and Ce anomalies show no correlation with fO2. Therefore, we conclude that only the apatite As and S contents can reflect the magma redox state. The calculated fO2 of the Dahalajunshan Formation volcanic rocks is ΔFMQ+0.53 ± 0.52 (based on the fayalite+magnetite+quartz buffer), which is markedly lower than those of typical porphyry Cu ore-forming magmas worldwide. Thus, from the perspective of magma fO2, regional magma is inferred to have little potential to form the porphyry Cu deposit.
The development of highly efficient and robust cathodes is crucial for intermediate temperature solid oxide fuel cells (IT-SOFC). Perovskite type SrCo0.9Ta0.1O3-δ (SCT91) is a promising cathode but its instability against CO2 limits the practical application. In this work, a new medium-entropy SrCo0.5Fe0.2Ti0.1Ta0.1Nb0.1O3-δ (SCFTTN52111) cathode is designed and evaluated. The effect of configuration entropy on electrical conductivity, physical and electrochemical properties are studied in detail. The SCFTTN52111 cathode exhibits a lower polarization resistance of 0.033 Ω cm² at 700 °C, superior to 0.040 Ω cm² of SCT91 parent. The higher oxygen reduction activity is attributed to its larger surface exchange coefficient and smaller particle size. More importantly, SCFTTN52111 displays outstanding stability and high CO2 tolerance, due to a more negative value of average metal-oxygen bond energy and significantly reduced surface Sr segregation. Our study provides a feasible and effective entropy engineering approach to design high-active and durable cathode materials for SOFCs.
The Yidun Terrane, sandwiched between the Qiangtang and Songpan-Ganze terranes, hosts important information on the tectonic evolution of the eastern Tibetan Plateau. However, its tectonic link with adjacent terranes and East Gondwana remains equivocal. Here, we present U-Pb-Hf isotopes of detrital zircons from the upper Neoproterozoic-lower Paleozoic clastic rocks in the Yidun Terrane. The results show that detrital zircons from the Neoproterozoic rocks are mainly of ca. 821 – 890 Ma, 1714 – 1977 Ma, and 2317 – 2520 Ma, with εHf(t) values of each group comparable to coeval magmatic rocks in the nearby South China Block. This suggests that the Yidun Terrane and South China were possibly connected in the late Neoproterozoic, with the latter being the main sedimentary provenance. In contrast, the five Paleozoic samples have markedly different detrital zircon age spectra at ca. 2600 – 2300 Ma, 1100 – 900 Ma, 900 – 740 Ma, and 690 – 480 Ma, which were interpreted to have derived from Pan-African and Grenville-age provinces in the East Gondwana, as well as the South China Block and Songpan-Ganze Terrane. Such a major change on provenance suggests that after prolonged isolation in the Proto-Tethys, the Yidun Terrane began to collide with the East Gondwana in late Ediacaran to early Paleozoic. Integrated with published works, we consider that the Yidun Terrane, along with Songpan-Ganze Terrane and Yangtze Block, was located on the northern margin of East Gondwana during the early Paleozoic.
Hybrid minimum quantity lubrication and compressed carbon dioxide (MQL + CO2) lubri-coolant can play a crucial role in advancing machinability as well as sustainability. However, it is also the fact that the high-pressure throttling of CO2 produces fog and hinders the low-pressure MQL mist to touch the cutting zone adequately. Therefore, a low-pressure novel hybrid MQL-dry ice blasting lubri-coolant technology is anticipated to improve the machinability by providing the cooling and lubrication simultaneously in milling AISI-52100. This low-pressure hybrid dry ice blasting not only reduces an abundance of smog to reduce the cutting zone visibility, but the dry ice grains also behave as carriers to bring MQL-mist to the cutting zone perfectly. In this proposed study, the surface roughness, residual stresses, cutting temperature, surface hardness, tool wear, and cutting forces are measured by varying the cutting speed (75-300 m/min) and feed per tooth (0.04–0.12 mm/z) under hybrid MQL-dry ice blasting lubri-cooling condition in milling AISI52100 tool steel. The results of this study highlighted that as the cutting speed raised from 100 m/min to 300 m/min, an increase in cutting temperature was 22 % at a constant feed per tooth of 0.08 mm/z. Similarly, the decrease in surface roughness was 42 %, tool life reduced to 57 %, surface hardness increased to 9 %, and across-the-feed surface hardness increased to 58 % by the increase of cutting speed from 75 to 300 m/min and constant feed per tooth of 0.08 mm/z. The proof-of-the-concept study showed the machinability advancement under hybrid lubri-cooling technology due to precise penetration of MQL mist and dry ice grains into the cutting zone in terms of ease in chip evacuation, excellent lubrication, and cutting heat dissipation by sublimation of dry ice.
Protected areas (PAs) are key tools to prevent extinction and preserve ecosystem functions. As countries reiterated their commitment to expand the reach of PAs by up to 30 % by 2030, stronger purpose and pertinence in the establishment of PAs is needed to ensure effective conservation. In this study, we used Dipterocarpaceae as a proxy for threatened and ecologically important trees to determine the role of PAs in tree conservation and the potential shortfalls at a global scale. We quantified the overlap between the geo-referenced occurrence data of 433 Dipterocarpaceae species and the distribution of global PAs, followed by a conservation gap analysis on Borneo, the center of diversity of the family. We found that while Southeast Asia is the hotspot for species diversity and threat to Dipterocarpaceae, a high proportion of threatened species were found at the range edges of Dipterocarpaceae. Half of all the countries with Dipterocarpaceae met the Aichi Target 11 of designating at least 17 % of their land area as PAs, and most had <10 % of their total number of PAs being relevant to Dipterocarpaceae conservation. Our conservation gap analysis demonstrated that only 5.02 % of the total area of habitat (AOH) of endemic and Critically Endangered dipterocarps was formally protected, while 18.6 % of the total AOH was included in the Heart of Borneo complex. Our data highlights the need for a more effective global conservation gap analysis for threatened trees that could inform area-based conservation post-2020.
Tropical estuarine environments have been rapidly changing due to deforestation and urbanization. To understand the unique water properties of pristine tropical estuaries and utilize information for future conservation and management, spatial and temporal variations in basic water properties were measured in the Brunei estuary (Brunei Bay and Brunei River) on Borneo, where most of the estuary is still rimmed with humid primary forests such as mangroves. The vertical section profiles of the estuarine water showed a clear gradient of salinity, pH, and dissolved oxygen (DO) from the upstream Brunei River to Brunei Bay. In the Brunei River, a clear halocline and pycnocline were observed at a 1–4 m depth in the dry season (May and July), and a pH and DO minimum layer was also observed at a 1–2 m depth, indicating the supply of acidic, oxygen-depleted freshwater from the surrounding forests. In the wet season (January), the surface water pH was much lower than that in the dry season and was the lowest recorded for estuaries in Southeast Asia. This low pH is most likely caused by aerobic and/or anaerobic microbial processes in the surrounding wetlands and forests. These findings showed the unique environmental gradients of the fundamental water properties in this tropical estuary, which is supported by ambient primary forest and mudflat ecosystems. For the sustainable management of tropical estuarine ecosystems, it is important to monitor and maintain this gradient of water quality, while also conserving the surrounding terrestrial ecosystem.
Background Early administration of intravenous (IV) caffeine (initiation within 2 days of life) is an effective treatment strategy for the management of apnoea of prematurity among infants. However, the safety and effectiveness of early administration of oral caffeine treatment is not be fully established. Aim We aimed to compare the effectiveness and safety of early versus late caffeine therapy on preterm infants’ clinical outcomes. Method A retrospective matched cohort study was conducted using data of patients admitted to neonatal intensive care units of two tertiary care hospitals between January 2016 and December 2018. The clinical outcomes and mortality risk between early caffeine (initiation within 2 days of life) and late caffeine (initiation ≥ 3 days of life) were compared. Results Ninety-five pairs matched based on gestational age were included in the study. Compared to late initiation, preterm infants with early caffeine therapy had: a shorter duration of non-invasive mechanical ventilation (median 5 days vs. 12 days; p < 0.001); shorter length of hospital stay (median 26 days vs. 44 days; p < 0.001); shorter duration to achieve full enteral feeding (median 5 days vs. 11 days; p < 0.001); and lower frequency of bronchopulmonary dysplasia (BPD) (4.5% vs. 12.9%; p = 0.045). They also had a reduced risk of osteopenia of prematurity (OP) (OR 0.209; 95% CI 0.085–0.509; p = 0.001). Conclusion Early oral caffeine therapy can potentially improve respiratory outcomes among infants with apnoea of prematurity. However, an increase in mortality associated with early caffeine therapy requires further investigation.
The current study assessed the ecological-health risks of potentially toxic arsenic (As) and antimony (Sb) in the vegetable Centella asiatica, topsoils, and mangrove sediments sampled from Peninsular Malaysia. The As concentrations ranged from 0.21 to 4.33, 0.18 to 1.83, and 1.32 to 20.8 mg/kg dry weight, for the leaves, stems, and roots of the vegetable, respectively. The ranges of Sb concentrations were 0.31-0.62, 0.12-0.35, and 0.64-1.61 mg/kg dry weight, for leaves, stems, and roots of the vegetable, respectively. The children's target hazard quotient (THQ) values indicated no non-carcinogenic risks of As and Sb in both leaves and stems, although children's THQ values were higher than those in adults. The calculated values of estimated weekly intake were lower than established provisional tolerable weekly intake of As and Sb for both children and adult consumers. The carcinogenic risk (CR) values of As for children's intake of leaves and stems of vegetables showed more public concern than those of adults. The levels of Sb and As in the topsoils were generally higher (although not significantly) than those in the mangrove sediments, resulting in a higher geoaccumulation index, contamination factor and ecological risk, hazard index, THQ, and CR values. This indicated that the anthropogenic sources of Sb and As originated from the land-based activities before reaching the mangrove near the coast. The CR of As signifies a dire need for comprehensive ecological-health risks exposure studies, as dietary intake involves more than just vegetable consumption. Therefore, risk management for As and Sb in Malaysia is highly recommended. The present findings of the ecological-health risks of As and Sb based on 2010-2012 samples can be used as an important baseline for future reference and comparison.
Visible light-driven photocatalysts have attracted considerable attention as these photocatalysts can effectively utilize visible light and are cost-effective. This study reports the synthesis of silver phosphate (Ag3PO4) and 1, 3, and 5% La, Zr co-doped Ag3PO4 via precipitation method. The synthesized materials were characterized using powder X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), UV-Visible diffuse reflectance spectra (DRS), photoluminescence spectroscopy (PL), scanning electron microscopy (SEM), and energy dispersive X-ray analysis (EDX). No impurities were observed in all the synthesized materials as shown by the XRD analysis. FTIR measurements of the synthesized materials displayed the presence of several functional groups in the synthesized materials. The band gap energy of Ag3PO4 decreases as more La and Zr were incorporated into the Ag3PO4 lattice. The SEM images of Ag3PO4 displayed tetrapod-shaped particles whereas La, Zr co-doped Ag3PO4 showed irregular particles. The photocatalytic activities of the synthesized materials were determined through photocatalytic degradation of methylene blue (MB) and methyl orange (MO) dyes as well as photoreduction of Cr(VI). Results showed that 1% La, Zr co-doped Ag3PO4 exhibited superior photocatalytic properties in both photocatalytic processes when compared to Ag3PO4.
Ciprofloxacin (CIP) has been listed in the last version of the surface water due to its ability to kill human cells by inhibiting the activity of DNA topoisomerase IV. Thus, CIP, along with other antibiotic pollution has become a serious threat to the environment and public health. Ozonation has been used as an advanced technique that is applied in wastewater treatment to remove CIP, but the primary limitation of this method is the low solubility of ozone in water. This study is the first report of CIP removal in a scale-up of its aqueous solution using a self-developed aerator pump-enhanced ozonation (APO) system, which only employs a propeller and a zigzag arrangement of meshes. This aerator pump decreased the size of ozone bubbles by 90% and increased the effective ozone solubility to 0.47 ppm. The mechanism of degradation of CIP is attributed to an oxidation reaction of the antibiotic with reactive oxygen species, such as hydroxyl, oxygen, and hydroperoxyl radicals, generated on the surface of the ozone microbubbles. It was found that the rate and efficiency of degradation of CIP using the APO system were 3.64×10‒3/min and 83.5%, respectively, which is higher compared with those of conventional flow ozonation (FO) systems (1.47×10‒3/min and 60.9%). The higher degradation efficiency of CIP by the APO system was also revealed by its higher electrical energy efficiency (0.146 g/kWh), compared to that of the FO system (0.106 g/kWh). The degradation of CIP was also monitored by the resulting antibacterial activity against Escherichia coli and Staphylococcus aureus.
Peatlands are important carbon sinks, therefore their degradation mainly due to lowering of the water table, has an adverse effect to the carbon cycle and largely burden the atmosphere. Annually, extensive areas of these peatlands are affected by wildfires, therefore large peatland areas have been degraded, directly or indirectly related to anthropogenic activities, largely contributing to greenhouse gas emissions. Some of the most pristine tropical peatlands worldwide occur primarily at the coastal lowlands of Southeast Asia. In terms of their geological features and evolution, these sites are generally understudied despite covering more than half of the global area of tropical peatlands. This review compiles geological data from 52 peatlands from insular and continental Southeast Asia, providing a comprehensive geological dataset for future research. The Southeast Asian peatlands are mostly ombrogenous and hence poorly supplied by nutrients. During the Last Glacial Period (ca. 115,000–11,000 years ago), extensive areas were exposed because of the lowering of the seawater level, which caused a consequent lowering of the groundwater table landwards; the forests were under severe threat, mainly due to dry conditions, thus resulting in the retreat of the forest boundaries inland. This was an unfavourable environment for peatland formation and hence, most of the Southeast Asian peatlands were formed right after that period. Almost 40% of the reviewed sites are located on Borneo Island, highlighting the importance of Bornean peatlands, where many peatlands are already deforested and drained and converted to plantations. Overall, the available geological data from the Southeast Asian peatlands is incomplete and non-comparable to each other because each study has a different focus. Details, such as the type of peat-forming plants, age of peat, peat thickness, substrate type and the pH value are not reported systematically in approximately 30% of the reviewed sites, while other important geological data, such as the ash yield and the carbon content of peat are only reported in 30% and 10% of the reviewed sites, respectively. Characterisation of peatlands using data imputation and principal component analysis (PCA) is based on three physical parameters (maximum ash yield, maximum thickness and oldest age), and includes the study of their relation in terms of climatic periods, peatland type, region and substrate. It is observed that peatlands which were developed in warming periods share similar physical parameters (such as accumulation rates, ash yield, peatland type, and environment of the substrates). With better data reporting on these parameters, the PCA analysis can provide a more accurate reflection of peatland characteristics and their relationships. The study aims to raise awareness on the importance and vulnerability of the Southeast Asian peatlands and to highlight their role in the global climate fluctuations.
In this study, AgNbO3, 1%, 5%, and 10% La, Zr-codoped AgNbO3 photocatalyst were synthesized by the solid state method. The synthesized AgNbO3 was codoped with La and Zr to enhance its effectiveness in photocatalytic dye degradation. The as-synthesized materials were also characterized via XRD and SEM analysis to determine their structural and morphological properties. The vibrational bands of the photocatalysts observed in FT-IR spectroscopy confirmed the presence of NbO6 octahedra which can be found in AgNbO3. Furthermore, all the photocatalysts showed high crystallinity and are single-phase materials with an orthorhombic crystal structure. It was observed that the particle size decreased with the increasing concentration of La and Zr codopants. The calculated lattice parameters showed that codoping AgNbO3 with 10% La and Zr had caused its unit cell volume to expand. The UV-Vis absorption spectra showed a slight band gap widening and a decrease in surface plasmonic resonance (SPR) effect with increasing La, Zr-codoping. The photocatalytic RhB and MB degradation results of undoped AgNbO3 and La, Zr-codoped AgNbO3 were compared and they showed that there are improvements in the photocatalytic performance. The highest degradation (98.1%) of RhB was achieved by 5% La, Zr-codoped AgNbO3 while the highest MB degradation (48.3%) was achieved by 1% La, Zr-codoped AgNbO3. Last but not least, La, Zr-codoped AgNbO3 is a promising material for water remediation application as it showed enhanced performance for photocatalytic dye degradation under visible light irradiation.
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Owais Ahmed Malik
  • Computer Science
AS Kamariah
  • Environmental and Life Sciences
Dr Mamunur Rashid
  • Accounting and Finance
Jalan Tungku Link, BE1410, Bandar Seri Begawan, Brunei