Now showing 1 - 10 of 13
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Exsolution enhancement of metal-support CO oxidation perovskite catalyst with parameter modification

2021-05-24 , Lew G.L. , Naimah Ibrahim , Abdullah S. , Wan Daud W.R. , Wan Khairunnisa Wan Ramli

This study aimed to further tune the capability of active metal exsolution onto the surface of the CO oxidative perovskite catalyst La0.7Ce0.1Co0.3Ni0.1Ti0.6O3 by tuning the reducing parameter. Under same calcination temperature of 800℃, XRD analysis shown that the precursors with calcination duration of 6 hours (S2T8H6) was able to achieve similar crystalline structure to those with calcination duration of 12 hours (S2T8H12). In order for the active metal (CoNi) to be exsolved onto the perovskite surface, reducing parameter such as temperature and duration are deemed crucial to the reduction process. The exsolution of the active metals was observed when the samples were treated under reducing condition with varying temperatures of 550℃ and 700℃ and duration from 200 to 300 minutes. Through comparison with their EDX readings, S2T8H6 treated under 700℃ and 300 minutes (S2T8H6-R7H5) achieved the highest weight percentage of surface Cobalt and Nickel of 3.83 and 2.81. It was clear that by tuning the temperature and duration of reduction, the exsolution of the active metals onto the surface of the perovskite could be improved resulting in better exposure and dispersion of active metals onto the surface of catalyst.

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Promoting a well-dispersion of MoO3 nanoparticles on fibrous silica catalyst via one-pot synthesis for enhanced photoredox environmental pollutants efficiency

2022-12-01 , Izzudin N.M. , Jalil A.A. , Ali M.W. , Aziz F.F.A. , Azami M.S. , Hassan N.S. , Fauzi A.A. , Naimah Ibrahim , Saravanan R. , Hassim M.H.

The coexistence of pharmaceutical compounds and heavy metals in the aquatic environment has resulted in complications in the treatment process and thus, causing uproar among the citizens. The radical-based photocatalysis technology has aroused as an excellent method to eliminate both heavy metal and pharmaceutical compounds in the water. Herein, reported the utilization of the microemulsion technique for the preparation of nanoporous fibrous silica-molybdenum oxide (FSMo) towards simultaneous photocatalytic abatement of hexavalent chromium (Cr(VI)) and tetracycline (TC). The FESEM analysis showed the spherical morphology of the FSMo catalyst with dendrimeric silica fiber. The synthesized FSMo catalyst exhibited narrowed bandgap, high crystallinity, and well Mo element dispersion for enhanced photo-redox of Cr(VI) and TC. Remarkably, simultaneous remediation of the Cr(VI) and TC over FSMo demonstrated superior photocatalytic efficiency, 69% and 75%, respectively, than in the individual system, possibly due to the effective separation of photoinduced charges. The introduction of the Mo element to the silica framework via microemulsion technique demonstrated better dispersion of Mo compared to the incipient wetness impregnation method and thus, yielded higher photocatalytic activity towards simultaneous removal of TC and Cr(VI). Besides, quenching experiments revealed the electrons and holes as the active species that play a dominant role in the simultaneous photo-redox of Cr(VI) and TC. Lastly, the FSMo catalyst demonstrated high stability after four continuous cycles of simultaneous photocatalysis reactions, implying its potential as a suitable material for practical wastewater treatments.

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Influence of carbonisation temperature on the surface pore characteristics of acid-treated oil palm empty fruit bunch activated carbon

2020-07-01 , Ahmad N. , Naimah Ibrahim , Fu P.Y. , Razi Ahmad

Carbonisation process affects the surface physical and chemical properties of an activated carbon. Therefore, this work aims to investigate the influence of carbonisation temperature from 400 to 550° C during activation with 85% phosphoric acid (H3PO4) on the surface pore characteristics of activated carbon produced from oil palm empty fruit bunch (EFB) for nitric oxide (NO) removal from gas streams. Pore and morphological characterisation showed that EFB carbonised at 400° C (EFBC-400) is microporous and has a uniform pore structure with 98% micropore volume. Increasing carbonisation temperature resulted in pore enlargement from 2.8 to 4.7 nm and increment in pore heterogeneity and BET surface area from 215 to 759 m2/g. However, the NO breakthrough experiment indicated that EFBC-400 is more favourable for low-temperature NO removal, due to the importance of microporosity in adsorption of NO. Further study will look at the kinetics of NO removal and the adsorbent regeneration.

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Effect of Aeration Rate on Specific Oxygen Uptake Rate (SOUR) in Treating Chemical Oxygen Demand (COD) in Domestic Wastewater

2024-01-01 , Zubir A.A.A. , Farrah Aini Dahalan , Kamarudin N.S. , Naimah Ibrahim , Ong Soon An , Nabilah Aminah Lutpi , Masitah Hasan , Nor Azizah Parmin

Specific oxygen uptake rate (SOUR) is significant parameter to determine the microbial activity and examined the effluent quality in biological wastewater treatment. Chemical oxygen demand (COD) is the major indicator in monitoring the effluent quality in relation on its removal mainly depends on the microbial activity in the activated sludge. So, this research is conducted to study the effect of aeration rate on SOUR and determined the best oxygen requirement in removing COD in domestic wastewater. The procedure was carried out by using domestic wastewater as the seed sludge in sequencing batch reactor. The reactor with working volume of 2L was operating 6 cycles in 24 hours with five phases (feeding, aeration, settle, draw and idle). The aeration time is fixed to 2.5 hours. The dissolved oxygen and COD readings were recorded with four types of aeration rate adjusted at 1L, 2L, 3L and 4L / min daily for 7 days. The result indicates that, 3L/min gives the highest SOUR which reflects that the high activity of microbial in this condition. Besides, the effluent also shows the highest COD removal efficiency on 3L/min of aeration rate. So, as a conclusion the best oxygen requirement for the microbial to carry out their activities on aeration rate of 3L/min.

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Influence of leachate matrix on oxidation performance of ozonation and aops

2022-12-15 , Kow S.H. , Fahmi Muhammad Ridwan , Che Zulzikrami Azner Abidin , Najihah Abdul Rashid , Naimah Ibrahim , Abdul Haqi Ibrahim , Ong Soon An , Wikurendra E.A. , Handayani D.

Landfill leachate is a critical environmental issue that should be adequately treated to prevent it from spreading to the environment. This study explored the influence of raw leachate matrix and treated leachate matrix on O3, O3/H2O2, and O3/PS performance. O3 and AOPs were conducted in a laboratory-scale batch reactor. The findings showed the degradation of p-cresol, COD, and humic substances was much slower in treated leachate matrix than in raw leachate matrix. However, color was found easier to remove in treated leachate. The results revealed a synergic effect between molecular O3 and dissolved organic matter in the raw leachate as the O3 performance was enhanced in the presence of raw leachate matrix, except for color removal. The highest degradation of more than 90% was achieved in O3 /H2 O2 to remove COD, p-cresol, and humic substances, although it is the most affected by the leachate matrix. This study provides vital insight into the notable performance of O3 /PS in color removal regardless of the influence of leachate matrix, suggesting that the sulfate radical-induced oxidation outperformed O3 and O3 /H2 O2 in reducing nitrogen-containing compounds.

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Influence of leachate matrix on oxidation performance of ozonation and aops

2022-12-15 , Kow Su Huan , Fahmi Muhammad Ridwan , Che Zulzikrami Azner Abidin , Najihah Abdul Rashid , Naimah Ibrahim , Abdul Haqi Ibrahim , Ong Soon An , Wikurendra E.A. , Handayani D.

Landfill leachate is a critical environmental issue that should be adequately treated to prevent it from spreading to the environment. This study explored the influence of raw leachate matrix and treated leachate matrix on O3, O3/H2O2, and O3/PS performance. O3 and AOPs were conducted in a laboratory-scale batch reactor. The findings showed the degradation of p-cresol, COD, and humic substances was much slower in treated leachate matrix than in raw leachate matrix. However, color was found easier to remove in treated leachate. The results revealed a synergic effect between molecular O3 and dissolved organic matter in the raw leachate as the O3 performance was enhanced in the presence of raw leachate matrix, except for color removal. The highest degradation of more than 90% was achieved in O3 /H2 O2 to remove COD, p-cresol, and humic substances, although it is the most affected by the leachate matrix. This study provides vital insight into the notable performance of O3 /PS in color removal regardless of the influence of leachate matrix, suggesting that the sulfate radical-induced oxidation outperformed O3 and O3 /H2 O2 in reducing nitrogen-containing compounds.

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Influence of Hydrogen Pre-treatment at Different Temperatures on Copper Oxide Supported on Carbonised Oil Palm Empty Fruit Bunch (CuO/EFBC) for Low-Temperature Nitric Oxide Removal

2020-10-01 , Ahmad N. , Zahari F.M. , Naimah Ibrahim

Low-temperature nitric oxide (NO) removal by oil palm empty fruit bunch (EFBC) modified with phosphoric acid dehydration, followed by copper oxide (CuO) impregnation is a function of both surface chemical and physical properties of CuO/EFBC resulting from hydrogen (H2) pre-treatment at different temperatures. Subjecting CuO/EFBC sample to H2 pre-treatment at 400 °C initially reduces the NO adsorption capacity (q) (at C/Co = 0.95) from 1.65 to 1.57 mg/g although the BET specific surface area (SBET) increases from 4.81 to 160 m2/g, due to surface predomination by acidic oxygenated groups (e.g. carboxyl, lactone and phenolic groups). At 500 °C, q increases to 5.67 mg/g as some of the acidic surface groups are decomposed and the SBET improves to 466 m2/g. Further increase in the temperature to 600 and 700 °C respectively enhances the SBET to 448 and 516 m2/g, and decomposes most of the acidic groups, leaving unsaturated C to react with H and form stable basic sites e.g. aldehyde, alkane, alkyl and aromatic groups more favourable for NO adsorption, thus giving rise to q (at C/Co = 0.5) to 41.01 and 62.74 mg/g, with stable performance for more than 2 h of experiment. In addition, higher pore volume, smaller pore size and smaller crystallite size of CuO, Cu2O and Cu3P sites are observed in samples pre-treated at high temperatures (600 and 700 °C), leading to a condition more auspicious for dissociative NO adsorption. Graphic Abstract: [Figure not available: see fulltext.].

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Column-based removal of high concentration microplastics in synthetic wastewater using granular activated carbon

2023-01-01 , Amirah Mohd Napi N.n. , Naimah Ibrahim , Adli Hanif M. , Masitah Hasan , Farrah Aini Dahalan , Syafiuddin A. , Boopathy R.

Microplastic (MP) is an emerging contaminant of concern due to its abundance in the environment. Wastewater treatment plant (WWTP) can be considered as one of the main sources of microplastics in freshwater due to its inefficiency in the complete removal of small MPs. In this study, a column-based MP removal which could serve as a tertiary treatment in WWTPs is evaluated using granular activated carbon (GAC) as adsorbent/filter media, eliminating clogging problems commonly caused by powder form activated carbon (PAC). The GAC is characterized via N2 adsorption–desorption isotherm, field emission scanning electron microscopy, and contact angle measurement to determine the influence of its properties on MP removal efficiency. MPs (40–48 μm) removal up to 95.5% was observed with 0.2 g/L MP, which is the lowest concentration tested in this work, but still higher than commonly used MP concentration in other studies. The performance is reduced with further increase in MP concentration (up to 1.0 g/L), but increasing the GAC bed length from 7.5 to 17.5 cm could lead to better removal efficiencies. MP particles are immobilized by the GAC predominantly by filtration process by being entangled with small GAC particles/chips or stuck between the GAC particles. MPs are insignificantly removed by adsorption process through entrapment in GAC porous structure or attachment onto the GAC surface.

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Microplastics and nanoplastics: Recent literature studies and patents on their removal from aqueous environment

2022-03-01 , Muhammad Adli Hanif , Naimah Ibrahim , Farrah Aini Dahalan , Umi Fazara Md Ali , Masitah Hasan , Jalil A.A.

The presence of microplastics (MP) and nanoplastics (NP) in the environment poses significant hazards towards microorganisms, humans, animals and plants. This paper is focused on recent literature studies and patents discussing the removal process of these plastic pollutants. Microplastics and nanoplastics can be quantified by counting, weighing, absorbance and turbidity and can be further analyzed using scanning electron microscopy (SEM), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, surface-enhanced Raman spectroscopy and Raman tweezers. Mitigation methods reported are categorized depending on the removal characteristics: (i) Filtration and separation method: Filtration and separation, electrospun nanofiber membrane, constructed wetlands; (ii) Capture and surface attachment method: coagulation, flocculation and sedimentation (CFS), electrocoagulation, adsorption, magnetization, micromachines, superhydrophobic materials and microorganism aggregation; and (iii) Degradation method: photocatalytic degradation, microorganism degradation and thermal degradation; where removal efficiency between 58 and 100% were reported. As these methods are significantly distinctive, the parameters which affect the MP/NP removal performance e.g., pH, type of plastics, presence of interfering chemicals or ions, surface charges etc. are also discussed. 42 granted international patents related to microplastics and nanoplastics removal are also reviewed where the majority of these patents are focused on separation or filtration devices. These devices are efficient for microplastics up to 20 μm but may be ineffective for nanoplastics or fibrous plastics. Several patents were found to focus on methods similar to literature studies e.g., magnetization, CFS, biofilm and microorganism aggregation; with the addition of another method: thermal degradation.

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Microplastics and nanoplastics: Recent literature studies and patents on their removal from aqueous environment

2022-03-01 , Hanif M.A. , Naimah Ibrahim , Farrah Aini Dahalan , Umi Fazara Md Ali , Masitah Hasan , Jalil A.A.

The presence of microplastics (MP) and nanoplastics (NP) in the environment poses significant hazards towards microorganisms, humans, animals and plants. This paper is focused on recent literature studies and patents discussing the removal process of these plastic pollutants. Microplastics and nanoplastics can be quantified by counting, weighing, absorbance and turbidity and can be further analyzed using scanning electron microscopy (SEM), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, surface-enhanced Raman spectroscopy and Raman tweezers. Mitigation methods reported are categorized depending on the removal characteristics: (i) Filtration and separation method: Filtration and separation, electrospun nanofiber membrane, constructed wetlands; (ii) Capture and surface attachment method: coagulation, flocculation and sedimentation (CFS), electrocoagulation, adsorption, magnetization, micromachines, superhydrophobic materials and microorganism aggregation; and (iii) Degradation method: photocatalytic degradation, microorganism degradation and thermal degradation; where removal efficiency between 58 and 100% were reported. As these methods are significantly distinctive, the parameters which affect the MP/NP removal performance e.g., pH, type of plastics, presence of interfering chemicals or ions, surface charges etc. are also discussed. 42 granted international patents related to microplastics and nanoplastics removal are also reviewed where the majority of these patents are focused on separation or filtration devices. These devices are efficient for microplastics up to 20 μm but may be ineffective for nanoplastics or fibrous plastics. Several patents were found to focus on methods similar to literature studies e.g., magnetization, CFS, biofilm and microorganism aggregation; with the addition of another method: thermal degradation.