Structure-photocatalytic activity relationship of carbon doped titanium dioxide analyzed by density functional theory and fuzzy logic graph

Carbon doping is a promising way to modify the properties of TiO2 for enhancing its photocatalytic performance. Although there are many publications about the enhancement of photocatalytic activity of TiO2, the relationship between the structural and physical properties with the photocatalytic activity of TiO2 is still not clearly understood. A new approach has been proposed to evaluate the structurephotocatalytic activity relationship with the aim to better understand the dominant properties that determine the photocatalytic activities of C-doped TiO2. Fuzzy logic graph has been used as a new approach in determining the dominant factor for the structure-photocatalytic activity relationship of C-doped TiO2. Characterization results from experimental study were used in the fuzzy logic graph. For the experimental study, two types of C-doped TiO2 were successfully synthesized by the sol-gel method with addition of cetyltrimethylammonium bromide (CTAB) surfactant and without the addition of CTAB, at different calcination temperatures, to compare with commercial TiO2. The synthesized photocatalysts were characterized using several characterization techniques. Photooxidation of styrene with aqueous hydrogen peroxide has been used as the model reaction for organic pollutants to study the structure-photocatalytic activity relationship under UV and visible light irradiation. Xray photoelectron spectroscopy (XPS) spectra show that C was doped into TiO2’s lattice with the amount of C of about 2.5 at% for CTAB-C/TiO2-500 samples and about 10.5 at% for C/TiO2-500 samples at interstitial and substitutional positions of anatase TiO2. Energy dispersive X-ray spectroscopy (EDX) and XPS results for CTAB-C/TiO2 samples show a lower amount of C incorporated into TiO2 as compared to C/TiO2 without the addition of CTAB, which may be caused by the removal of C impurity by the CTAB surfactant. Furthermore, the effects of calcination temperature from 300 to 700°C on the physicochemical properties of the C-doped TiO2 were also studied. Calcination temperature affected the phase, morphology, surface area, porosity, crystallite size and amount of C. The surface area of CTAB-C/TiO2 and C/TiO2 samples is shown to decrease as the calcination temperature increased. Additionally, the confirmation on the effect of C on the band gap energy of the anatase TiO2 was investigated using density functional theory (DFT). Total density of states (TDOS) shows that the C affects the band gap energy of TiO2 by introducing the mid gap states between the band gap. Based on DFT analysis and photocatalytic experiment, six physical properties have been chosen to be used for fuzzy logic graph, i.e. surface area, phase, amount of electron-hole recombine, band gap energy, existence of sub-band gap and amount of C. Fuzzy logic graph analysis shows that surface area is a dominant factor for the photooxidation of styrene under UV and visible light irradiations, followed by phase , amount of C and amount of electron-hole recombine. This study demonstrated that the combination of photocatalytic experiment, DFT and fuzzy logic graph analysis can be used to clarify the structure-photocatalytic activity relationship in TiO2 photocatalytic systems

Synthesis of carbon self-doped titanium dioxide and its activity in the photocatalytic oxidation of styrene under visible light irradiation

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 (XRD), field emission scanning electron microscopy (FESEM) coupled with energy dispersive X-ray (EDX), Fourier transform infrared (FTIR) spectroscopy, UV-visible diffuse reflectance (UV-Vis DR) spectroscopy, photoluminescence spectroscopy, N2 adsorption-desorption and X-ray photoelectron spectroscopy (XPS). XPS results proved the presence of self-doped carbon at the interstitial and substitutional lattice of TiO2. The C/TiO2 calcined at 300 and 400 °C (C/TiO2-300 and C/TiO2-400, respectively) showed mesoporous characteristic and large surface area of about 100 m2 g-1. The C/TiO2 photocatalysts were then tested in the photo-oxidation of styrene under visible light irradiation with aqueous hydrogen peroxide as the oxidizing agent. The C/TiO2 photocatalysts were successfully activated under the irradiation of visible light, where C/TiO2-300 and C/TiO2-400 showed the highest total concentration of products (benzaldehyde and styrene oxide) at 1.1 mmol and 1.0 mmol, respectively

Toughening of ceramic shell mould with rice husk fiber (CSm-RH) to improve strength property and mould performance

For ages, ceramic shell mould (CSm) have been extensively applied in investment casting industry. The formation of CSm requires multiple steps of dipping, layering drying and firing stages. The later steps are very crucial as the solidification thin layer CSm that consist of loose ceramic particles easily cracks when exposed to the higher thermal effect. The inclusion of fiber or any reinforces phases is able to enhance fired ceramic body and also strengthen the green ceramic structure. Thus, the feasibility of rougher NaOH treated rice husk fiber (RHT) prior embedded into composited structure has shown a significant CSm improvement by induced a better adhesion properties and larger bonding area with brittle ceramic matrix, resulted in increased green strength (1.34 MPa) and fired body strength (4.32 MPa). Owing to the decomposed of lignin layer in CSm with untreated rice husk fiber (CSm-RHU) exhibited a higher porosity that provide a better permeation paths of air flow during molten metal pouring as increased 30 % from the standard CSm permeability, giving an enormous benefit for investment casting cooling process. Overall, the incorporation of RHT fiber in a CSm matrix of both green and fired body governed in toughening of brittle ceramic body, hence avoid failure to the casting mould

Tahap kreativiti di kalangan pelajar program sains di Fakulti Pendidikan, Universiti Teknologi Malaysia

Kajian yang dijalankan adalah bertujuan untuk mengukur tahap kreativiti di kalangan pelajar program sains di Fakulti Pendidikan, Universiti Teknologi Malaysia. Jumlah responden yang terlibat seramai 161 orang pelajar program sains iaitu 19 orang pelajar lelaki dan 142 orang pelajar perempuan. Instrumen kajian yang digunakan adalah set borang soal selidik yang diubahsuai berdasarkan Ujian Pemikiran Kreatif Guilford dan Torrance untuk menguji empat kriteria kreativiti iaitu keaslian, kefasihan, kelenturan dan penghuraian. Data yang diperolehi disemak dan pemarkahan diberikan berdasarkan skema yang dicadangkan oleh Guilford dan Torrance seterusnya dianalisis mengunakan Statistical Package for the Social Science (SPSS). Dapatan kajian menunjukkan bahawa secara keseluruhannya pelajar program sains di Fakulti Pendidikan mempunyai pemikiran tidak kreatif iaitu sebanyak 85.10% daripada keseluruhan responden. Keputusan Ujian-t menunjukkan tidak terdapat perbezaan signifikan antara tahap kreativiti merentasi jantina (p=0.519). Hasil analisis statistik ANOVA pula menunjukkan tidak terdapat perbezaan yang signifikan antara tahap kreativiti merentasi pencapaian akademik (p=0.419). Daripada dapatan kajian mendapati tahap kreativiti yang rendah di kalangan pelajar program sains di Fakulti Pendidikan yang merupakan bakal-bakal guru akan menjejaskan proses penyampaian ilmu di dalam kelas kelak. Oleh itu, usaha-usaha yang berkaitan perlu dilakukan bagi meningkatkan kreativiti bakal guru sains supaya dapat menggalakkan persekitaran pembelajaran yang kreatif di dalam kelas seterusnya dapat melahirkan pelajar-pelajar yang kreatif dan boleh menjadi pewaris agama, bangsa dan negara

The effectiveness of the procedures in granting halal logo by JAKIM to Malaysian caned food products / Amirah Azhari and Siti Hajar Alias.

Recently there has been an increasing demand for halal food in Malaysia markets. This may be due to the increasing number of Muslim population or an increase in their purchasing power. Furthermore, with the advancement of science and technology, it is now possible for various typed of food products to be in the form of canned food products and they are now abundantly available in the supermarkets. These increased in variety of canned food products raised concerned on Muslim consumers with regards to its manufacturing process. The issue is whether these canned food products bearing "halal logo" on their packaging really signifies that the food has been processed according to the actual "halal" process as prescribed by JAKIM in accordance with the Trade Description Act 1972 and The Use of Halal Expression Order 1975. The "halal logo" plays a very important role in certifying the authenticity of JAKIM certification on halal process on the canned food products sold in supermarkets. This is because the Muslim consumers would not be able to access the halal making process of these canned foods are actually complied with except to rely solely on the "halal logo" whenever it appear on the cover of the canned food products. Since there are more than one "halal logo" appearing on the cover of canned food products in Malaysia, it is aims of this research to study how effective is the JAKIM procedures in granting " halal logo" to canned food products. Can these procedures secure that the "halal process" has been observed before the logo was issued either by them of by other authorized body in issuing the "halal logo" to these canned food products. This research will also survey various other "halal logo" available in Malaysian supermarkets

Effects of feedstock and catalyst concentration on biodiesel production

In this study, production of biodiesel from new and used palm and soybean oils was carried out using a transesterification method. The effect of catalyst amount used towards the percentage yield, soap content and heat of combustion of the biodiesel produced was investigated. The soap content and heat combustion of the biodiesel were determined using titration (AOCS Cc-95) and heat calorimeter bomb (ASTM D240-09), respectively. The results showed that catalyst concentration of 0.5 w/w% gave the best result in terms of yield of biodiesel produced from both palm and soybean oils. However, the quality of biodiesel (i.e. soap content and heat of combustion) produced from palm and soybean oils behaved differently towards catalyst concentration. Overall, both oils (palm and soybean), either new or used oil apparently showed no significant difference in term of yield or qualities of biodiesel produced. This indicates that the used oil has high potential as an economical and practical future source of biodiesel

Removal of Iron (Fe) by adsorption using activated Carbon Moringa oleifera (ACMO) in aqueous solution / Nurul Zawani Alias et al.

Activated carbon has been widely developed as an adsorbent to adsorb heavy metal in wastewater due to its high efficiency and low cost. Activated carbon of Moringa oleifera (ACMO) was prepared from the woods for the removal of iron in aqueous solution. The ACMO was produced using chemical activation process impregnation with phosphoric acid as the activating agent. The surface morphology of ACMO was characterized using SEM, and the functional group present was determined using FTIR. Effects of various operating variables namely the carbon dose, adsorbate concentration and contact time on the removal of iron ions have been studied. The adsorption capacity was determined as a function of carbon doses (0.1, 0.2, 0.3, 0.4 and 0.5 g), adsorbate concentration (2, 4, 6, 8 and 10 mg/L) and the contact time between ACMO and aqueous solution (30, 60, 90 and 120 min) with constant parameters of temperature 303 K, agitation at 180 rpm and pH 8. From the data obtained, percent of moisture present in ACMO and raw M. oleifera (RMO) were 6.752% and 9.512% respectively. Meanwhile, amount of ash in ACMO was 1.451% and in RMO was 7.592%. In addition, the volatile matter present in ACMO was replaced from RMO about 28.431% and 23.715% respectively. The percentage of fixed carbon of ACMO and RMO were 63.366% and 59.181% respectively. The highest adsorption capacity obtained was at 8.043 mg/g with the amount of carbon dosage of 0.1 g, concentration of iron solution of 10 mg/L and contact time of 120 min