Prof. Ir. Dr. Nor Aishah Saidina Amin

ABSTRACT:

The photocatalytic reduction of CO2 with H2 over nickel (Ni) and indium (In) co-doped TiO2 nanocatalysts in a monolith photoreactor has been investigated. The structure and properties of catalysts, prepared via modified sol–gel method with different metal-doping levels, were characterized by XRD, SEM, TEM, N2 adsorption–desorption, XPS, UV–vis and PL spectrophotometry. Both nickel and indium, present over TiO2 as Ni2+ and In3+, promoted efficient separation of photo-generated charges (e/h+). The CO2 reduction efficiency was more significant for H2 compared to H2O vapors. TiO2 modified with 1.0 wt.% NiO and 3.5 wt.% In2O3 registered the highest CO yield. In a batch process, the maximum yield rate of CO over NiO–In2O3/TiO2 catalyst at 99.7% selectivity was 12,029 lmol g-catal.1 h1; 5.9 and 207 folds higher than In2O3/TiO2 and TiO2 catalysts, respectively. Similarly, CO2 conversion over NiO–In2O3/TiO2 (10.2%) was more substantial than In2O3/TiO2 (6.42%) and pure TiO2 (1.7%). In a continuous process, CO production rate was slightly decreased, but more CO2 was processed over the entire irradiation time.Significantly enhanced quantum efficiency of a monolith photoreactor over NiO–In2O3/TiO2 catalyst was observed compared to the cell reactor obviously due to greater mobility of charges with hindered recombination rate and higher photonic efficiency. The stability of NiO–In2O3/TiO2 catalyst was partially
reduced after several cyclic runs.

1. Muhammad Tahir and Nor Aishah Saidina Amin (2016). Performance analysis of nanostructured NiO–In2O3_TiO2 catalyst for CO2 photoreduction with H2 in a monolith photoreactor Chemical Engineering Journal, 285, 635-649. DOI: https://doi.org/10.1016/j.cej.2015.10.033

Abstract:

Experimental and theoretical studies were performed to evaluate the existence of internal and external mass transfer limitations in the gas phase glycerol dehydration to acrolein over supported HSiW catalyst. In the experimental method, the internal and external diffusions were determined by varying the gas mass flow-rate (mg), catalyst pellet size (dp), and catalytic bed volume (Vcat). In the theoretical approach the dimensionless parameters such as effectiveness factor (η), Thiele modules (ϕ1), and overall effectiveness factor () were calculated. The experimental results indicated no external mass transfer limitation due to constant glycerol conversion (94–97%) at various conditions. In addition, both the theoretical and experimental approaches confirmed no internal mass transfer limitation in glycerol dehydration reaction with catalyst pellet sizes of dp = 2–4 and 5–7 μm due to effectiveness factor equal to 1 (η = 1). Calculation of the overall effectiveness factor () also confirmed the absence of external and internal diffusion in presence of catalysts with pellet
size of dp < 13–17 μm

1. Amin Talebian-Kiakalaieh and Nor Aishah Saidina Amin (2016).Theoretical and experimental evaluation of mass transfer limitation in gas phase dehydration of glycerol to acrolein over supported HSiW catalyst Journal of the Taiwan Institute of Chemical Engineers, 59, 11-17. DOI : https://doi.org/10.1016/j.jtice.2015.07.011

ABSTRACT:

The study on immobilized titania (TiO2) nanoparticles semiconductor on stainless steel mesh for photocatalytic conversion of CO2 and CH4 has been investigated. Properties of commercial and calcinated photocatalysts on mesh surface were characterized using UV–vis spectra, BET, FESEM and XRD. The photoreduction products were identified with FTIR and GC. The process conditions was optimized using experimental design and process optimization tools to determine the maximum desired response via Response Surface Methodology (RSM) in conjunction with central composite rotatable design (CCRD). The experimental parameters were stainless steel mesh size, amount of titania nanoparticles, calcination temperature, UV light power and initial ratios of CO2:CH4:N2 in feed. Calcination of coated titania nanoparticles increased the absorption of UV–vis light while uniform photocatalyst structure commensurate with decreasing agglomeration. The optimal conditions for maximum CO2 conversion of 37.9% were determined as stainless steel mesh size of 140, coated titania nanoparticles on mesh of 4 g, calcination temperature of 600 C, UV light power of 250 W and 10% of CO2 in feed. Correspondingly, the selectivity of products were 4.7%, 4.3%, 3.9%, 41.4% and 45.7% for ethane, acetic acid, formic acid, methyl acetate and methyl formate, respectively. The kinetic model, based on Langmuir–Hinshelwood, incorporated photocatalytic adsorptive reduction and oxidation reactions over the catalyst surface, and fitted-well with the experimental data.

1. Saeed Delavari and Nor Aishah Saidina Amin (2016). Photocatalytic conversion of CO2 and CH4 over immobilized titania nanoparticles coated on mesh_ Optimization and kinetic study: Optimization and kinetic study. Applied Energy, 162, 1171-1185. DOI: https://doi.org/10.1016/j.apenergy.2015.03.125

ABSTRACT:

The glucose conversion using Fe/HY zeolite catalyst in a batch reactor has been investigated. The main products within the temperature range between 120 and 200 C were 5-hydroxymethylfurfural (5-HMF) and levulinic acid (LA). The highest LA yield of 66% was obtained from 100% glucose conversion at 180 C. After eliminating the influence of internal and external diffusions, a kinetic model was developed based on the pseudo homogeneous model. The kinetic model consisted of four key steps: (1) glucose dehydration to form 5-HMF; (2) glucose degradation to produce humins; (3) 5-HMF rehydration to form LA; and (4) 5-HMF degradation to form humins. The first-order model and the experimental data fitted-well. The reactions rates increased with temperature, and the activation energies of glucose conversion to 5-HMF and 5-HMF conversion to LA were 64 and 61 kJ mol1, respectively, comparativelylower than previously reported values.

1. Ramli, N.A.S., Amin, N.A.S. (2016) .Kinetic study of glucose conversion to levulinic acid over Fe_HY zeolite catalyst. Chemical Engineering Journal. 283, 150-159. DOI: https://doi.org/10.1016/j.cej.2015.07.044

ABSTRACT:

The performance of highly ordered nitrogen-doped titania (TiO2) nanotube arrays, fabricated by anodization method, was tested for photocatalytic CO2 conversion with CH4. Nitrogen-doped titania nanotube arrays were characterized using field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), BrunauereEmmetteTeller (BET), X-ray photoelectron spectroscopy (XPS) and Ultravioletevisible (UVevis) spectra. The photoreduction products were identified using residual gas analyzer (RGA) and GC spectra. The effects of important parameters such as UV light power, initial ratios of CO2:CH4:N2 in feed and distance between UV lamp and reactor on CO2 and
CH4 conversions were analyzed using response surface methodology (RSM). FESEM images of titania nanotube arrays indicated highly ordered and vertically oriented morphology with inside diameter ranging from 3 to 50 nm. The optimal conditions for maximum CO2 conversion of 41.5% were determined as 250 W UV light power, 10% CO2 initial ratio and 2 cm distance between UV lamp and reactor. H2 and CO were the main products with selectivities being 80.5% and 18.9%, respectively. CO2 and CH4 molecules were competitively activated by the charge transfer excited complexes and the values of feed ratios influenced the selectivity for the formation of the desired products. The kinetic model based on Langmuir eHinshelwood, incorporated photocatalytic adsorptive reduction and oxidation reactions over the catalyst surface fitted-well with the experimental data

1. Delavari, S., Amin, N.A.S., Ghaedi, M. (2016). Photocatalytic conversion and kinetic study of CO2 and CH4 over nitrogen-doped titania nanotube arrays Journal of Cleaner Production. 111, 143-154. DOI: https://doi.org/10.1016/j.jclepro.2015.07.077

ABSTRACT:

The discharge of silver ions from nanosilver-based product into the environment has raised the ecological and human health concern due to the toxicity of silver ion, particularly on the release behaviour of ionized nanosilver from the wastage. Therefore, recovery of ionized nanosilver is highly necessary. In this research, emulsion liquid membrane technique was employed for ionized nanosilver recovery from the domestic waste. The liquid membrane consists of kerosene, Span 80, Cyanex 302 and acidic thiourea as the diluent, surfactant, carrier and stripping agent, respectively. The emulsion stability was investigated at different surfactant concentrations, agitation and homogenizer speeds. Response surface methodology (RSM) was applied for the optimization of process variables including treat ratio, sulphuric acid (H₂SO₄) and thiourea concentration in the recovery process. The results showed that the most stable emulsion was observed at 3% w/v of surfactant, 10,000 and 150 rpm of homogenizer and agitation speed, respectively. The optimum conditions obtained for the recovery process using RSM were: treat ratio (0.256), H₂SO₄ concentration (0.75 M) and thiourea concentration (0.85 M). At the optimized condition, the maximum recovery of ionized nanosilver was 84.74%.

Raja Sulaiman, R.N., Othman, N., Saidina Amin, N.A. (2016). Recovery of ionized nanosilver by emulsion liquid membrane process and parameters optimization using response surface methodology. Desalination and Water Treatment. 57(8), 3339-3349. DOI: 10.1080/19443994.2014.985724

Abstract:

Palm shells, which are agricultural by-products from palm oil processing, were used to produce low-cost activated carbons. Effect of different carbonization times (1–4 h) on the biochar and activated carbon properties was investigated. The carbonization was carried out at 700°C followed by CO₂ activation. Carbons were characterized using Fourier transform infrared spectroscopy, ultimate analysis, scanning electron microscopy (SEM), proximate analysis and nitrogen adsorption. The proximate analysis of the palm shell showed low moisture content (5.5%), high percentage of volatile matter (70%), average contents of fixed carbon (23%) and ash content (4.28%). Carbonization times (1–4 h) within the range investigated have little influence on the char yield, thermal and chemical properties of the material but had more effect on the textural properties. SEM micrographs revealed that more pore networks and cavities were formed after carbonization and activation of the palm shells. The textural characteristics of the biochars and activated carbon reveal that the pore size is predominantly mesoporous. The properties of the palm shell activated carbon prepared at 700°C for 2 h indicated its ability to be used in volatile organics removal from wastewater and in gas-related adsorption applications.

1. Hamza, U.D., Nasri, N.S., Amin, N.S., Mohammed, J., Zain, H.M. (2016). Characteristics of oil palm shell biochar and activated carbon prepared at different carbonization times. Desalination and Water Treatment. 57(17), 7999-8006. DOI: http://dx.doi.org/10.1080/19443994.2015.1042068

ABSTRACT:

Pharmaceuticals and personal care products are recognized as emerging pollutants in water resources. Various treatment options have been investigated for the removal of pharmaceuticals that include both conventional (e.g., biodegradation, adsorption, activated sludge) and advanced (e.g., membrane, microfiltration, ozonation) processes. This article reviews literature for adsorptive removal of pharmaceuticals from water sources. Adsorbents from various origins were reviewed for their capacity to remove pharmaceuticals from water. These adsorbents include carbonaceous materials, clay minerals, siliceous adsorbents, and polymeric materials. The adsorption capacity of adsorbents to adsorb pharmaceuticals from water is discussed in this study. The review discusses the mechanism for adsorption of pharmaceuticals onto adsorbents as well. Finally, effectiveness of processing parameters during adsorption processes is presented.

1. Akhtar, J., Amin, N.A.S., Shahzad, K. (2016). A review on removal of pharmaceuticals from water by adsorption. Desalination and Water Treatment. 57(27), 12842-12860. DOI: http://dx.doi.org/10.1080/19443994.2015.1051121

ABSTRACT:

Photocatalysis is a promising method for the disinfection of potable water in developing countries. Water treatment using nanocrystalline titanium dioxide photocatalytic oxidation is a well-known, enhanced and advanced oxidation process for environmental remediation. In this article, the bactericidal properties of TiO₂ nanoparticle suspension irradiated with ultraviolet (UV) light for the disinfection of a water sample contaminated with Escherichia coli (E. coli) are investigated. Degussa P25 TiO₂nanoparticles are used as photocatalyst at concentrations ranging from 0.25 to 1 g/l. The optimal photocatalyst concentration is 0.5 g/L. The kinetics of the photocatalytic degradation rates are studied using established kinetic models available in the literature, such as the Hom model. After reviewing the data, it was observed that with increasing the light intensity and system aeration, the effectiveness of the photocatalytic reaction increased. Also, the Hom kinetic model exhibited greater bacteria inactivation reaction speed in case when laboratory data were placed in middle inactivation state.

1. Mojtaba Khani, Nor Aishah Saidina Amin, Sayed Nezamedin Hosseini, Mahshid Heidarrazaei (2016). Kinetic study of the photocatalytic inactivation of Escherichia coli, International Journal of Nano and Biomaterials. DOI: 10.1504/IJNBM.2016.086106

Abstract :

As the world’s second-largest palm oil producer and exporter, Malaysia could capitalize on its oil palm biomass waste for power generation. The emission factors from this renewable energy source are far lower than those from fossil fuels. This study applies an integrated carbon accounting and mitigation (INCAM) model to calculate the amount of CO2 emissions from three Malaysian biomass power plants. CO2 emissions released from biomass plants utilizing empty fruit bunch (EFB) and palm oil mill effluent (POME) as alternative fuels for powering steam and gas turbines were determined using the INCAM model. Each section emitting CO2 in the power plant—called a “carbon accounting center,” or CAC—was measured for its carbon profile (CP) and carbon index (CI) from each center. The carbon performance indicators (CPI) included electricity, fuel and water consumption, and solid waste and waste-water generation. The carbon emission index (CEI) and carbon emission profile(CEP), based on total monthly carbon production, were determined across the CPIs. We developed various innovative strategies that resulted in a 20 to 90 percent reduction of CO2 emissions. The implementation of reduction strategies significantly reduced the CO2 emission levels. Based on the model, utilization of EFB and POME in the facilities could significantly reduce CO2 emissions.

1. Amin Talebian-Kiakalaieh and Nor Aishah Saidina Amin (2017).Reduction of CO2 emission by INCAM model in Malaysia biomass power plants during the year 2016. Waste Management DOI: https://doi.org/10.1016/j.wasman.2017.11.019