Sheela ChandrenUniversiti Teknologi Malaysia | UTM · Department of Chemistry
Sheela Chandren
BSc, MSc (UTM), PhD (Hokkaido University)
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May 2013 - October 2015
Publications
Publications (64)
Bio-based synthetic products derived from renewable feedstock offer a more sustainable alternative to traditional non-renewable counterparts. To ensure the sustainability of thermosets, a fully bio-based thermoset poly(1,3-propanediol-co-1,12-dodecanedioate-co-itaconate) (PPDDI) via catalyst-free polyesterification was designed using commercially a...
The electronic properties of anatase titanium dioxide (TiO2) materials are of paramount importance for photocatalytic application. Ab initio calculation is performed on anatase TiO2 with various cluster sizes and shape, using Gaussian 09 program employing the standard 6-311G(d) and 3-21G basis set. Hartree-Fock (HF) theory, exchange-functional of d...
Fluency in understanding chemical kinetics is widely recognized as critical in learning further concepts of chemical reaction and chemical process. However, the traditional way of learning does not foster the desirable results, thus implementation of active learning could improve students’ achievement. In this study, we evaluate the impact of the p...
The biosynthesis procedure for nanomaterial preparation is a promising alternative due to its simplicity and environmental friendliness. In this work, TiO2 NPs were biosynthesized using the aqueous leaf extract of Azadirachta indica. The influence of the extract volumes, solvents, and acetic acid on the properties of TiO2 NPs was studied. Phytochem...
Titanium dioxide nanoparticles (TiO2 NPs) are capturing great interest worldwide with vast applications in various areas. However, their conventional synthesis methods often pose a risk to humans and the environment due to the utilization of toxic chemicals and laborious procedures. Several works have documented the biosynthesis method of TiO2 NPs...
In this study, pure phase BiFeO3 was prepared via a facile sol-gel auto-ignition route using water as a solvent. The influence of citric acid to metal nitrates molar ratio on physicochemical properties of BiFeO3 was also investigated through FTIR, XRD, PL, UV, SEM, and BET analysis. The XRD of the prepared samples revealed the rhombohedral perovski...
The past decade has observed a significant surge in efforts to discover biological systems for the fabrication of metal nanoparticles. Among these methods, plant-mediated synthesis has garnered sizeable attention due to its rapid, cost-effective, environmentally benign single-step procedure. This study explores a step-wise, room-temperature protoco...
Unprotected exposure to solar ultraviolet (UV) radiation leads to profound public health implications. Short-term physical distresses such as episodic sunburns or blistering, shockingly, could snowball into long-term hazards, including skin cancer. In an effort to suppress these damaging effects of UV radiation, photo-protective measures have been...
Biobased ternary nanocomposites can stabilize enzymes for greater stability, catalytic activity and easy recovery. This study aimed to optimize biogenic silica/magnetite/graphene oxide nanocomposite supported Candida rugosa lipase (CRL/SiO2/Fe3O4/GO) for ethyl valerate (EV) synthesis and characterize the biocatalysts’ physicochemical properties and...
The present study reports the groundwork for preparing a greener catalyst, Candida rugosa lipase (CRL), supported on biomass-based nanocellulose-silica-reinforced polyethersulfone membrane (NC-SiO2-PES) and proved its stability in synthesizing pentyl valerate. The NC-SiO2-PES/CRL-catalyzed synthesis of the ester exhibited a ping-pong bi-bi mechanis...
A greener processing route to replace the current environmentally-unfriendly esterification technique to produce biofuels such as pentyl valerate (PeVa) was explored. This study statistically optimized the covalent immobilization of Candida rugosa lipase (CRL) onto biomass-based nanocellulose-silica (NC-SiO2) reinforced polyethersulfone (PES) membr...
Nanotechnology is one of the most interesting areas of research due to its flexibility to improve or form new products from nanoparticles (NPs), and as a fast, greener, more eco-friendly and sustainable solution to technological and environmental challenges. Among metal oxides of photocatalytic performance, the use of titania (TiO2) as photocatalys...
Pure phase bismuth ferrite has been successfully prepared in this research using a modified method of sol‐gel auto‐ignition. This method is a fast and economical synthesis technique since it can produce fine as‐synthesis powder for less than 4 hours. Also, the influences of diverse chelating agents on the physicochemical properties of the synthesiz...
The family Sapindaceae are tropical and sub-tropical continental plants. In this study, 1,4-Benzene dicarboxyl ester (1) and 1,2-Benzene dicarboxyl ester (2) from methanolic extracts of Deinbollia pinnata leaves. The successful separation of the isomeric mixture is by freezing the sub-fraction with methanol for seventy-two hours; followed by filtra...
Herein, this study extracted nanocrystalline cellulose (NC) and silica (SiO2) from raw oil palm leaves (OPL), and employed as nanofillers in polyethersulfone (PES) to produce NC-SiO2-PES as support to immobilize Candida rugosa lipase (CRL) (NC-SiO2-PES/CRL). XRD, TGA-DTG and FTIR-ATR data affirmed that NC and SiO2 were isolated from OPL with corres...
Due to the quick advancement of automotive headlights from glass to polycarbonate (PC) plastic, ultraviolet (UV) hard coating that offers excellent properties are ideal in meeting the requirements of modern designs. However, PC is known to deteriorate upon exposure to sunlight, moisture, dirt and other environmental conditions. In this work, TiO 2...
Of late, the number of fire cases in Malaysia has been steadily increasing at a very alarming rate. One way to reduce the ability of fire ignition or spreading is by coating or doping the wood with a layer of fire-protected coating, or an insulating barrier, which is also known as Flame Retardant Coatings (FRCs). In this study, titania (TiO2) is co...
Oil palm industry is the largest contributor of biomass in Malaysia. Oil palm biomass are constantly generated in large quantities annually with a small fraction being converted into value added product while a large percentage are left underutilized. Several researchers have reported the various technologies available for the conversion of oil pal...
Currently, the chemically-assisted esterification to manufacture butyl butyrate employs corrosive homogeneous acid catalyst and liberates enormous quantities of hazardous by-products which complicate downstream treatment processes. This study aimed to identify the optimized esterification conditions, and the kinetic aspects of the enzyme-assisted s...
Carbon self-doped titanium dioxide (C/TiO2) photocatalyst was synthesized by a simple sol-gel method using titanium isopropoxide as both the titanium precursor and carbon source. The effects of calcination temperatures in the range of 300 to 700 °C to the structure and physicochemical properties of the C/TiO2 were investigated by X-ray diffraction...
The evaluation of kinetic adsorption process of sulfonated carbon-derived from Eichhornia crassipes in the adsorption of methylene blue dye from aqueous solution has been carried out. The sulfonated carbon-derived from E. crassipes (EGS-600) was prepared by carbonation of E. crassipes powder at 600 °C for 1 h, followed by sulfonation with concentra...
Depression is a common mental disorder that may lead to major mental health problems, and antidepressant drugs have been used as a treatment of choice to mitigate symptoms of major depressive disorders by ameliorating chemical imbalances of neurotransmitters in brain. Since abusing ADs such as selective serotonin reuptake inhibitors and tricyclic a...
The demonstration of the structure–properties relationship of shape-dependent photocatalysts remains a challenge today. Herein, one-dimensional (1-D)-like titania (TiO2), as a model photocatalyst, has been synthesized under a strong magnetic field in the presence of a magnetically responsive liquid crystal as the structure-aligning agent to demonst...
The present study reports on Candida rugosa lipase (CRL) supported on magnetized nanosilica from oil palm leaves (CRL/Gl-A-SiO2-MNPs) and its utilization in the catalytic synthesis of butyl butyrate. Statistical optimization of process parameters, viz: enzyme loading, incubation time, temperature and substrate molar ratio (1-butanol:n-butyric acid)...
The study reports the preparation of a composite consisting of magnetite coated with nanosilica extracted from oil palm leaves (OPL) ash as nanosupports for immobilization of Candida rugosa lipase (CRL) and its application for the synthesis of butyl butyrate. Results of immobilization parameters showed that ~ 80 % of CRL (84.5 mg) initially offered...
The contribution of chitosan/nanocellulose (CS-NC) to the enzymatic activity of Candida rugosa lipase covalently bound on the surface of CS-NC (CRL/CS-NC) was investigated. Cellulosic material from oil palm frond leaves (OPFL) were bleached, alkaline treated and acid hydrolyzed to obtain the purified NC and used as nano-fillers in CS. XRD, Raman sp...
This work was aimed at providing a comprehensive physicochemical characterization of the Malaysian oil palm leaves (OPL) that may be useful for industrial applications as well as providing new insights on minimizing the environmental impact of oil palm biomass wastes. The leaves of discarded oil palm fronds were collected, dried and ground. The lea...
This paper describes the approach by using a magnetic field as a technique in order to synthesize well-aligned materials. The magnetic field technique could be a potential method because it has advantage that all of the materials could be aligned by magnetic field as long as they have magnetic anisotropy. The aim of this research is to explore the...
High voltage powder spray coating (HVPSC) is one of the methods used for coating substrate with polymer powder in industries. This study utilizes HVPSC as a new deposition method of carbon-based powdered materials on stainless steel. Carbon-titania (C/TiO2) coated stainless steel was successfully prepared from the mixture of epoxide and titania pow...
In this study, nanocellulose (NC) was successfully extracted from oil palm frond leaves (OPFL) using a combination of bleaching, alkaline treatment and acid hydrolysis. X-ray diffractogram revealed the extracted NC was crystalline with a crystallinity index of 70.2%. This indicates its suitability as nano-fillers for preparing the chitosan/nanocell...
One of the methods used to produce buffer layers for thin film solar cells is the Spray ion layer gas reaction (SPRAY-ILGAR). This method has exhibited astonishing efficiencies in the fabrication of homogenous compact metal chalcogenide films. The same approach can be applied in the preparation of photocatalyst on a substrate, in order to acquire a...
Titania-loaded coal char catalyst was successfully prepared. The preparation steps involved pyrolysis of low rank coal at different temperatures and durations, sulfonation, impregnation of titanium(IV) isopropoxide, and then heating at 110 °C. It is found that the coal chars’ surfaces were rough after sulfonation and impregnation, while large pore...
Titanium-silica (TiO2-SiO2), a type of semiconductor metal oxide cluster compound, has been widely used as oxidative catalysts and dye agents. In this research, TiO2-SiO2 on cotton textile has been utilized as self-cleaning agents by cross linking with acrylic acid compound. The clusters of TiO2-SiO2was modified by a series of Ti:Si molar compositi...
Titania, as one of the most widely used material for heterogeneous semiconductor photocatalysts, shows exceptional characteristics such as high chemical stability, nontoxicity, low cost, and capacity to induce various kinds of chemical reactions. A common drawback, however, is its lack of selectivity. This problem has been addressed through the syn...
Improving the antimicrobial activity and radical scavenging ability of textile-based nanocomposite (textile/TiO2, textile/Al2O3/TiO2, textile/Al2O3 and textile/Al2O3-TiO2 bimetal oxide nanocomposite) is the key issue in developing good and flexible wound dressing. In this work, flexible textile attached with Al2O3-TiO2 nanoparticles was prepared by...
This research work describes the effect of hydrophobicity in inducing the diffusion of alkene substrates to the catalytic active sites. The aim of this research is to improve the catalytic activity by tailoring the degree of hydrophobicity of the catalyst. Silica functionalized with solid non-silylated Ti-salicylaldimine complex was prepared at roo...
Titania (TiO2) has been an important renewable material that is able to convert solar energy into chemical energy in recent years. Therefore, the main focus of this paper centers around different strategies and precursors to prepare TiO2 with various shapes, e.g. perforated hollow TiO2, anatase hollow TiO2 spheres, well-aligned TiO2 and rambutan-li...
Hollow anatase titania spheres have been synthesized using hydrothermally–prepared carbon spheres as the template. Here, the combination of hydrothermal process with sol–gel followed by calcination in air was done in order to obtain hollow anatase TiO2 spheres by utilizing fructose and tetrabutyl titanate (TBT) as the precursors. The structure and...
Hollow anatase titania (TiO2) spheres were synthesized using fructose and tetrabutyl titanate (Ti(OC4H9)4, TBT) as the precursors via the conventional hard template method. The morphological, structural and thermal properties of the products were characterized using scanning electron microscopy (SEM), field emission scanning electron microscopy (FE...
The drug-delivery field has been an attractive as well as challenging area for research. With the emerging of new formulated drugs and pharmaceutical compounds, development of good drug-delivery system (DDS) is crucially required. This study aims to utilize albumin as the drug template in silica/albumin/drug (S/A/D) system. Prior to designing this...
Titanium dioxide supported sulfonated low rank coal catalyst possesses high catalytic activity in liquid phase oxidation of styrene with aqueous hydrogen peroxide at room temperature. The catalysts were prepared by sulfonation with concentrated sulfuric acid and impregnation of titanium dioxide (500-2500 μmol). The effect of titanium dioxide impreg...
Cobalt Schiff base complex is widely used in many reactions such as reduction process, carbonylation of alcohol and oxidation of alkenes. Generally, this catalyst is in the powder form. It is difficult to separate the catalyst from the reaction mixture due to the small particles size of the catalyst. One way to easily separate the catalyst is by ap...
In this study, a hierarchically porous carbon was prepared from a natural material, Averrhoa bilimbi, also known as bilimbi. The bilimbis were cut into preferred shape and size before drying by freeze drying method. The bilimbis were then subjected to pyrolysis at temperature of 400°C and transformed to porous carbon. Scanning electron microscopy (...
The design and synthesis of particulate materials for new catalyst systems with novel properties remain a big challenge today. Here an attempt has been made to synthesize particulate materials for several heterogeneous catalytic systems, which contain examples from our recent research projects in this area. The particulate catalysts have been desig...
A possible approach for photocatalytic selective organic synthesis is utilization of photocatalysts of or in defined microstructures. We have reported [1,2] fabrication of a novel core-shell photocatalyst which consisted of commercially available titania (TiO 2 ) particles incorporated in a hollow silica shell (SiO 2 / void /TiO 2 ) showing size-se...
Octahedral manganese oxide molecular sieves (OMS-2) was prepared by precipitation method and modified by impregnation of titanium with different titanium/manganese (Ti/Mn) ratio. It was discov-ered that Ti/Mn ratio of less than 0.5 still retains the original pure cryptomelane structure of OMS-2. However, for sample with Ti/Mn ratio of more than 0.5...
Controlled removal of carbonaceous component in low rank coal by sulfonation followed by calcination demonstrated that it is a simple and effective method to utilize this material as catalyst in the oxidation of styrene. Low rank coal is one of the least utilized categories of coal. However, it shows excellent potential as a catalyst due to high co...
Hollow core–shell particles of a titania core and a silica shell, the latter of which was highly porous, water-swollen and not directly connected to the former, were synthesized by a multistep process including carbon and silica coatings followed by calcination of the carbon-layer combustion. The core–shell particles suspended in aqueous solutions...
Hollow core shell particles of titania core and silica shell were synthesized by multistep process, and the core shell particles showed improved stereoselectivity in the photocatalytic redox-combined synthesis of L-pipecolinic acid from L-lysine in an aqueous suspension without reducing the original activity of the bare titania core.
The role of Lewis and Brönsted acidities in alkylation of resorcinol is demonstrated through the gallium-zeolite beta by varying the amount of Lewis and Brönsted acid sites. The synergism of Lewis and Brönsted acid sites takes place heterogeneously in Friedel-Crafts alkylation of resorcinol with methyl tert-butyl ether to produce 4-tert-butyl resor...
Due to the potential environmental applications, photocatalytic reactions occurring on the surface of photoirradiated titanium (IV) oxide (TiO2) have garnered a wide interest. Despite displaying high photocatalytic activity, the utilization of TiO2 is limited by its lack of selectivity. This paper presents the synthesis of platinized TiO2 core and...
Mesoporous alumina which contains only Lewis acidity was synthesized by sol-gel method and was then impregnated with sulfuric acid to generate Brnsted acidity. The catalyst was used in Friedel-Crafts alkylation of resorcinol with methyl tert-butyl ether to produce 4-tert-butylresorcinol and 4,6-di-tert-butylresor- cinol as the major and minor produ...
With the development of large molecule hydrocarbon processes, mesoporous alumina which possesses high surface area with narrow pore size distribution has received a great deal of attention. However, its acid properties lack Bronsted acidity and showed only Lewis acid sites, making it an inactive solid catalyst in the alkylation of resorcinol, a rea...
Organized mesoporous materials represent a class of molecular sieves because of its high potential for commercial applications in adsorption and catalysis. In this study, organized mesoporous alumina was synthesized by the sol-gel method using various organic templates, i.e. cationic, neutral and anionic surfactants. Surface porosity of the synthes...