Khairuddin Md Isa
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Preferred name
Khairuddin Md Isa
Official Name
Md Isa, Khairuddin
Alternative Name
Isa, K. Md
Md Isa, Khairuddin
Md. Isa, Khairuddin
Isa, K. M.
Main Affiliation
Scopus Author ID
36188321600
Researcher ID
Y-7078-2019

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Sulfur dioxide removal by calcium-modified fibrous KCC-1 mesoporous silica: kinetics, thermodynamics, isotherm and mass transfer mechanism

2022-04-01 , Hanif M.A. , Naimah Ibrahim , Khairuddin Md Isa , Umi Fazara Md Ali , Tuan Abdullah T.A. , Jalil A.A.

The removal of sulfur dioxide from industrial flue gas through dry flue gas desulfurization method commonly involves the use of adsorption process with porous sorbent. The efficiency of this process is highly dependent on the adsorption capacity and the adsorption rate of SO2 onto the sorbent materials. The use of KCC-1 mesoporous silica modified with calcium metal additives (Ca/KCC-1) in SO2 adsorption is examined in a fixed bed reactor system. The adsorption capacity of Ca/KCC-1 is found to be critically governed by the reaction temperature and inlet SO2 concentration where low values of both parameters are favorable to achieve the highest adsorption capacity of 3241.94 mg SO2/g sorbent. SO2 molecules are adsorbed on the surface of Ca/KCC-1 by both physisorption and chemisorption processes as assumed by the Avrami kinetic model. Thermodynamic study shows that the process is exothermic and spontaneous in nature, and changes from an ordered stage on the surface of KCC-1 towards an increasingly random stage. The process is well explained by Freundlich isotherm model indicating a slightly heterogeneous process and moderate adsorption capacity. The adsorption stage is limited by film diffusion at the initial stage and by intraparticle diffusion during the transfer of SO2 into the network of pores before adsorption takes place on the active sites.

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Sulfur dioxide removal by mesoporous silica KCC-1 modified with low-coverage metal nitrates

2021-01-01 , Muhammad Adli Hanif , Naimah Ibrahim , Khairuddin Md Isa , Tuan Abdullah T.A. , Abdul Jalil A.

The removal of sulfur dioxide (SO2) from flue gas using fibrous mesoporous silica KCC-1 synthesized via microwave-assisted hydrothermal method was observed. The sorbent was modified by introducing nitrate salts of sodium (Na) and calcium (Ca) at 5 wt. % metal loading via incipient wet impregnation method. The SO2breakthrough experiment was conducted in a vertical quartz-column reactor at atmospheric pressure and temperature of 323 K in the presence of 0.3 % SO2/N2. The SEM micrograph of KCC-1 exhibited a well-defined fibrous morphology consisting of colloidal spheres of 240-1160 nm in diameter. Addition of metal nitrates resulted in the reduction of surface area, total pore volume and minor breakage of the silica framework. The adsorption capacities of all samples were measured at C/C0= 0.5, where the addition of sodium (Na5/KCC-1) and calcium (Ca5/KCC-1) enhanced the removal capacity by 1.88 and 2 times higher than the parent KCC-1 respectively. Even though sodium is expected to achieve better removal capacity due to its higher basicity and dispersion related to the lower crystallite size, its performance ultimately suffered from significant agglomeration of sodium oxide which created pore blockage, subsequently resulting in poor accessibility to the active sites.

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Comparative Study of Sulfur Dioxide Removal Using Mesoporous Silica KCC-1 and SBA-15

2022-01-01 , Muhammad Adli Hanif , Naimah Ibrahim , Khairuddin Md Isa , Masitah Hasan , Tuan Abdullah T.A. , Jalil A.A.

Sulfur dioxide (SO2) emitted into the atmosphere by fossil fuel burning in the industries posed significant negative effects on humans and the environment. SO2 removal performance of two mesoporous silica: KCC-1 and SBA-15, are compared through breakthrough experiments on a lab-scale fixed bed reactor. The mesoporous silicas were characterized via nitrogen (N2) adsorption-desorption isotherm and field emission scanning electron microscopy (FESEM). KCC-1 demonstrates characteristics of capillary condensation and non-uniform slit-shaped pores while SBA-15 displays characteristic of a narrow range of mesopores with minimal network effects. Surface area, total pore volume and average pore diameter of KCC-1 are significantly greater than SBA-15 due to the presence of dendrimeric fibrous morphology. Under tested conditions, SO2 adsorption capacities of KCC-1 and SBA-15 are 614.01 mg/g and 274.64 mg/g, respectively. Superior performance by KCC-1 can be attributed to better accessibility of SO2 towards the active sites due to higher surface area provided by the dendrimer fibers.

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Sulfur dioxide removal by calcium-modified fibrous KCC-1 mesoporous silica: kinetics, thermodynamics, isotherm and mass transfer mechanism

2022-04-01 , Muhammad Adli Hanif , Naimah Ibrahim , Khairuddin Md Isa , Umi Fazara Md Ali , Tuan Abdullah T.A. , Jalil A.A.

The removal of sulfur dioxide from industrial flue gas through dry flue gas desulfurization method commonly involves the use of adsorption process with porous sorbent. The efficiency of this process is highly dependent on the adsorption capacity and the adsorption rate of SO2 onto the sorbent materials. The use of KCC-1 mesoporous silica modified with calcium metal additives (Ca/KCC-1) in SO2 adsorption is examined in a fixed bed reactor system. The adsorption capacity of Ca/KCC-1 is found to be critically governed by the reaction temperature and inlet SO2 concentration where low values of both parameters are favorable to achieve the highest adsorption capacity of 3241.94 mg SO2/g sorbent. SO2 molecules are adsorbed on the surface of Ca/KCC-1 by both physisorption and chemisorption processes as assumed by the Avrami kinetic model. Thermodynamic study shows that the process is exothermic and spontaneous in nature, and changes from an ordered stage on the surface of KCC-1 towards an increasingly random stage. The process is well explained by Freundlich isotherm model indicating a slightly heterogeneous process and moderate adsorption capacity. The adsorption stage is limited by film diffusion at the initial stage and by intraparticle diffusion during the transfer of SO2 into the network of pores before adsorption takes place on the active sites.

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Tailoring the properties of calcium modified fibrous mesoporous silica KCC-1 for optimized sulfur dioxide removal

2022-01-01 , Muhammad Adli Hanif , Naimah Ibrahim , Khairuddin Md Isa , Fahmi Muhammad Ridwan , Tuan Abdullah T.A. , Jalil A.A.

Dry regenerative flue gas desulfurization (FGD) is a promising method to tackle industrial issues regarding SO2 emission into the atmosphere due to its sorbent being highly accessible, the lack of water dependency and reduction in waste management. This study examined the feasibility of using fibrous mesoporous silica KCC-1 which has been reported to possess better properties than several other predecessor mesoporous silica as alternative sorbents for dry FGD. Calcium metal was introduced to overcome the lack of active sites available on KCC-1 while simultaneously providing sufficient basicity to counter the increase in acidity brought by SO2 adsorption. Three sorbent modification parameters were analyzed: metal loading (5–15 wt %), calcination temperature (823–973 K) and calcination time (5.5–7 h), and the prepared samples were characterized using BET surface area and pore analyzer, FESEM-EDX, XRD and H2-TPR. The breakthrough experiment was conducted using a lab scale fixed bed reactor system with 1500 ppm SO2/N2 at 200 mL/min. SO2 removal was optimized by sorbent prepared with calcium loading of 5 wt %, calcination temperature of 923 K and calcination time of 6.5 h with adsorption capacity of 3241.94 mg SO2/g KCC-1. The optimized sorbent demonstrated highest surface area, good pore development, high dispersion of calcium metal, appropriate impregnation of calcium oxide which caused only minor distortion to the silica framework of KCC-1. Subjecting the optimized sample to five consecutive regeneration cycles by heating at 773 K while simultaneously flowing N2 gas for an hour shows good regeneration performance with a total final reduction of only 25% from the initial adsorption capacity obtained from a fresh sample.

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