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Quantum chemical calculations were performed on ten thio compounds using semi-empirical method PM3 within program package of Material Studio 5.5. The effect of molecular structure on the corrosion inhibition efficiency was investigated using the quantum chemical calculations. The electronic properties such as highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO) energy levels, (LUMO–HOMO) energy gap, dipole moment (λ) and fraction of electron transfer (ΔN) were calculated and discussed. A relationship between the corrosion inhibition efficiency and several quantum parameters was established with coefficient correlation (R2) of 0.8894.

Recycled paper industry wastewater generates potentially persistent and toxic pollutants which can affect the ecological balance and cause aesthetic concerns. In this study, the biodegradability of recycled paper mill wastewater by a granular activated carbonsequencing batch biofilm reactor (GAC-SBBR) pilot plant system during a period of 53 days was evaluated while on-line monitoring was used to observe the influence of parameter changes during the treatment process. The effect of nitrogen (N) and phosphorus (P) addition on removal of chemical oxygen demand (COD) in four phases was investigated. The COD:N:P ratio in the nutrient medium was considered as an independent variable at a fixed value hydraulic retention time (HRT) of 24 hours. The study demonstrated that the process was unstable during the initial phase and started to stabilise during the last phase when a COD:N:P ratio of about 100:5:1 was achieved. Degradation of COD was seriously affected by variation of COD:N:P ratios, resulting in the highest removal efficiency of COD at COD:N:P ratio of 100:5:1 (80.1 %) and a minimum degradation at COD:N:P ratio of 1000:7:0.2 (33.8 %). Using the Monod model, the kinetic parameters (μm, Ks, Y and Kd) were determined as 0.1007 mg MLSS/mg COD.day, 65.917 mg COD/L, 0.5199 mg MLSS/mg COD and 0.0048 mg MLSS/mg COD.day, respectively. These findings can be used to improve the performance of the pilot GAC-SBBR system.

The inhibitive effects of 1-(2H)-phthalazinone (PTO) for aluminum alloy (2024) corrosion in 1.0 M HCl solution and the synergistic effect of KI on the corrosion inhibition efficiency were assessed using electrochemical measurements. Results showed that the inhibition efficiency increased with an increase in concentration of the PTO and synergistically increased with addition of KI. Adsorption characteristic of PTO molecules in absence and presence of KI was approximated by Freundlich and Langmuir adsorption isotherm models, respectively. The synergistic effect is found to decrease with increase in the concentration of PTO and a competitive inhibition mechanism exists between KI and PTO cations.

Zinc oxide nanoparticles were synthesized via the sol–gel method. The structures of the obtained nanoparticles were investigated by X-ray diffraction. The photocatalytic degradation of chlorophenolic compounds, namely 2-chlorophenol (CP), 2,4-dichlorophenol (DCP) and 2,4,6-trichlorophenol (TCP), was carried out using ZnO nanoparticles under solar intensity of 20–26 W m−2. The photocatalytic degradation efficiency of TCP

The effects of phthalazone (PTO) and its synergistic effect with KI on the corrosion of mild steel in 1.0 M HCl solution were studied using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements. The inhibition efficiency increases with the concentration of the inhibitor and increased further with the presence of 6.02 mM KI. The synergistic effect of 6.02 mM KI at different concentrations of PTO was determined by calculating the synergism parameters, which showed that a cooperative mechanism exists between the iodide anion and PTO cations.

Quaternary metal oxide of Ba2NiTi5O13was synthesized by using two-step sol-gel method. Excess of titanium dioxide obtained from the first step of sol-gel synthesis, were subsequently reacted in second step of sol-gel synthesis in order to produce Ba2NiTi5O13monoclinic phase. Calcination temperature of 900 °C for as long as 8 hours was needed for obtaining pure phase of Ba2NiTi5O13. Homogenous micron sized particles of Ba2NiTi5O13with average size of 0.10 μm and narrow distribution were observed using Scanning Electron Microscopy (SEM). Besides, porous structures can also be seen distributed across the surface of the particles of Ba2NiTi5O13particles. Characterization of monoclinic phase of Ba2NiTi5O13was described based on the investigations of X-Ray Diffraction (XRD), Fourier Transform Infrared (FTIR) and Thermo Gravimetric Analysis (TGA).

Environmentally friendly manufacture of organic compounds has been intensively reexamined in recent years. Many excellent methods have been devised to produce organic compounds from renewable resources. Azelaic acid has been produced by ozonolysis of oleic acid. The reaction was performed in a Bach bubbling reactor, with fine bubbles, at high temperature (150 °C) without utilizing any catalyst or any solvent. Yield of the reaction was 20% after 2 h. Production of azelaic acid was confirmed by use of FT-IR and 1H NMR spectroscopic data and high-performance liquid chromatography of both synthesized and reference azelaic acid. A theoretical study was performed to obtain quantum chemical data for azelaic acid and to optimize the molecule’s geometry.

The inhibition of mild steel corrosion in a 2.5 M H2SO4 solution by 4,4-dimethyl-3-thiosemicarbazide (DTS) was studied at 30 °C using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Quantum chemical parameters were calculated for DTS using PM3-SCF method. The molecular dynamic method was performed to simulate the adsorption of the DTS molecules on Fe surface. Results showed that DTS performed excellent as inhibitor for mild steel corrosion in a 2.5 M H2SO4 solution and indicated that the inhibition efficiencies increase with the concentration of inhibitor. Theoretical results indicated that DTS could adsorb on the mild steel surface firmly through heteroatoms.

The inhibition ability of phthalhydrazide (PTD) for mild steel in 1 M HCl at 30 °C was investigated by electrochemical measurements [impedance spectroscopy (EIS) and potentiodynamic polarization techniques] and quantum chemical calculations. The frontier molecular orbital energy E HOMO (highest occupied molecular orbital), E LUMO (lowest unoccupied molecular orbital), and the Mulliken charge distribution were calculated and are discussed. Results showed that the inhibition efficiency of PTD increased with inhibitor concentration. The maximum corrosion inhibition efficiency was 77.6% at 2 mM PTD. Adsorption of the inhibitor followed the Langmuir adsorption isotherm. Adsorption of inhibitor molecules on mild steel surface occurred spontaneously and chemically. Quantum chemical calculations showed that the low performance of PTD as a corrosion inhibitor is due to the large energy gap (E HOMO − E LUMO).

New coumarin derivatives, namely 7-[(5-amino-1,3,4-thiadiazol-2-yl)methoxy]-2H-chromen-2-one (4), 5-[(2-oxo-2H-chromen-7-yloxy)methyl]-1,3,4-thiadiazol-2(3H)-one (5), 2-[2-(2-oxo-2H-chromen-7-yloxy)acetyl]-N-phenylhydrazinecarbothioamide (7), 7-[(5-(phenylamino)-1,3,4-thiadiazol-2-yl)methoxy]-2H-chromen-2-one (8) and 7-[(5-mercapto-4-phenyl-4H-1,2,4-triazol-3-yl)methoxy]-2H-chromen-2-one (9) were prepared starting from the natural compound umbelliferone (1). The newly synthesized compounds were characterized by elemental analysis and spectral studies (IR, 1H-NMR and 13C-NMR).

3-Aminocoumarin (L) has been synthesized and used as a ligand for the formation of Cr(III), Ni(II), and Cu(II) complexes. The chemical structures were characterized using different spectroscopic methods. The elemental analyses revealed that the complexes where M=Ni(II) and Cu(II) have the general formulae [ML(2)Cl(2)], while the Cr(III) complex has the formula [CrL(2)Cl(2)]Cl. The molar conductance data reveal that all the metal chelates, except the Cr(III) one, are non-electrolytes. From the magnetic and UV-Visible spectra, it is found that these complexes have octahedral structures. The stability for the prepared complexes was studied theoretically using Density Function Theory. The total energy for the complexes was calculated and it was shown that the copper complex is the most stable one. Complexes were tested against selected types of microbial organisms and showed significant activities. The free radical scavenging activity of metal complexes have been determined by measuring their interaction with the stable free radical DPPH and all the compounds have shown encouraging antioxidant activities.

The organic material named 4-amino-5-phenyl-4H-1, 2, 4-trizole-3-thiol (APTT) was studied as inhibitor for mild steel corrosion in 1.0 M HCl at 30 °C. The effects of turbulent flow on the inhibition process were characterized using open circuit potential (OCP), potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). Turbulent flow condition experiments were simulated by Rotating Cylinder Electrode (RCE). Results obtained from changes of open circuit potential (OCP) with immersion time, potentiodynamic polarization, and impedance measurements all are in good agreement and indicated that the formation and the development of the inhibitor film were flow rate dependence. The scanning electron micrograph confirmed film structure is dependence of flow condition.

Inhibition of corrosion of nickel–aluminum bronze alloy (NAB) by use of 4-amino-5-phenyl-4H-1,2,4-triazole-3-thiol (APTT) was investigated by monitoring weight loss and open-circuit potentials (OCP), and by use of electrochemical impedance spectroscopy (EIS). Quantum chemical data were calculated by use of the density functional theory (DFT) model. Results showed that APTT inhibits corrosion of NAB alloy fairly well. The efficiency of inhibition increases with increasing concentration of APTT, and adsorption of the inhibitor obeys the Langmuir adsorption isotherm model. Negative values of adsorption free energy indicate chemical adsorption is spontaneous. The theoretical study showed that sulfur and nitrogen atoms (S, N7 and N8) were the reactive sites.

Electrode performance is the most important part in proton exchange membrane fuel cell system because all electrochemical processes and chemical conversions into energy occur via electrode interface. However the main problem in widespread proton exchange membrane fuel cells (PEMFCs) applications is the cost of the catalyst and life time of electrode, due to different parameters effects. Intense research imply in reducing the cost with increase the activity of catalyst in additional to other parameters (components) to make electrode for PEM more efficient with reasonable cost. This paper review recent research for the most parameters affecting performance of (Pt/C and Pt/C/M ) electrode for proton exchange membrane fuel cells (PEMFCs) such as Catalyst oxidation (degradation), and life time of the electrode using Pt/C, gas diffusion layer (GDL) thickness, and loading of PTFE in the diffusion layer, Nafion@ solution in the catalyst layer, methods of fabrication of electrode as spraying, casting, and electro deposition methods. Then the link between these parameters to achieve high performance and avoid the electrode degradation by optimized these parameters.

Catalysis is the major process involved in fuel cell technology to generate electricity which is known renewable. Generally, fuel cell electrodes utilize platinum supported carbon to catalyze the reactions at both cathode and anode. However, cheaper substitution materials such as nitrogen-doped carbon catalyst have attracted greater attention in recent year due to its significant catalytic activity at cathode in fuel cell. Nitrogen-doped CNT (N-CNT) is believed to allow oxygen reduction reaction (ORR) at cathode to take place which play a role as n-type dopant for electrical conductivity. The objective of this paper is to understand the mechanism of oxygen adsorption on N-CNT using the density-functional theory (DFT). N-CNT with two configurations involve sp2 and sp3 hybridized nitrogen are studied and compared in order to find the most thermodynamically stable N-CNT for sustainable ORR activity in fuel cell. The structural stability is studied through the binding energies of each configurations and the metallic behavior is examined through the energy gaps from the HOMO-LUMO studies. Finally, the adsorption energies and deformation energies of oxygen on N-CNT is discussed. Results revealed that sp3 hybridized N-CNT gives the most stable structure with compatible oxygen adsorption ability.

The solar photocatalytic degradation of 2,4-dicholrophenol in aqueous solution was carried out direct solar radiation without any collector. A slurry reactor with TiO2 nanoparticles catalyst was used. The catalyst sample was prepared by sol-gel method from titanium tetra-isopropoxide as raw material and calcinated at 400°C. The photocatalytic activity of TiO2 nanoparticles were evaluated by photocatalytic degradation of initial concentration (50 mgl-1) 2,4-dicholrophenol under solar irradiation. The average solar intensity of ultra violet (UV) was recorded as 23 Wm-2. HPLC was used for monitoring the concentration of 2,4-dicholrophenol in solution at different time intervals during the experiment. The degradation efficiency of 2,4-dicholrophenol removal was 93.8% at pH solution of 6, irradiated for 1 h and using optimum amount of catalyst 2gl-1 .

Polymer electrolyte membrane based on Nafion and zirconium oxide (ZrO2) was developed via film casting method. The content of ZrO2 (1.0, 2.0, and 3.0 wt.%) was incorporated with Nafion solution to prepare Nafion-ZrO2 composite membranes. Recast Nafion membrane was used as reference material. All of the prepared membranes have been subjected to both physical and chemical characterizations such as Fourier transform infra-red (FT-IR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) analysis, water uptake rate (WUR) and conductivity measurements. The Nafion-ZrO2 composite membranes were found to possess high thermal stability (Tg= 188 - 192°C) and conductivity (0.30 – 0.93 S cm-1). This study demonstrates the possibility of developing Nafion-ZrO2 composite membrane as promising polymer electrolyte membrane for fuel cell operated at medium temperature and low humidity.

This review paper discusses the temperature behavior and thermal event of cesium dihydrogen phosphate (CsH2PO4) in both ambient and high pressure atmosphere. A complete transition from the room-temperature to a high-temperature of CsH2PO4 (monoclinic to cubic phase) occurs between 230 to 240 °C, even in the absence of humid conditions and the superprotonic transition precedes the onset of the dehydration/chemical decomposition of the title compound. Decomposition or dehydration can be avoided by either keeping the sample under a H2O-saturated atmosphere, or subjecting the sample to a pressure of 1.0 ± 0.2 GPa.

The relatively inexpensive SiO2 layer was studied as the silicon etch mask in a KOH etching process for the fabrication of a flow field pattern that consists of channels as well as through-holes on the substrate of a fuel cell. The SiO2 layer was grown in a wet thermal oxidation process to obtain a thickness of up to 6.5 μm and the growth was predicted using the Deal–Grove model. The flow fields on the cathode and anode sides were done using a wet etch process with KOH as etchant. Etching time was utilized to control the depth of the required pattern and the pattern shape was found to have an influence over the etch rate. With constant monitoring of the conditions and parameters used throughout the micro-fabrication process, the thick SiO2 layer was found to be a reliable masking material for a long KOH etching.

Hot-pressing conditions for fabricating a membrane-electrode assembly (MEA) were optimized. The key parameters were time, temperature, and pressure, varying from 1 to 5 min, 100 to 170°C, and 21 to 93 kg cm ―2 , respectively. The MEAs were fabricated with 50 cm 2 active electrode area and their performance was investigated using a fuel cell test station. The most suitable hot-pressing time for MEA was 3 min, the optimized pressure and temperature for MEA fabrication were 21 kg·cm ―2 and 130 °C with 1.6 A and 0.56 V. At 100 °C, the current and voltage of the produced MEAs were low due to the trapped liquid formed inside the electrode. However, at more than 150°C, the obstructed/distorted polytetrafluor-oethylene (PTFE) will block the pores inside the gas diffusion layer (GDL) and cause a loss of performance of the fuel cell. Physical properties of the GDL were observed using scanning electron microsopy (SEM). The GDL exhibited a uniform pore distribution after application of hot-pressing.

Questionnaire of prospective university graduates have been identified as one of the effective methods for the strength and weakness assessment of the program curriculum. It is based on student feedbacks regarding on their performance and satisfaction in Department of Chemical & Process Engineering (JKKP) in order to determine the effectiveness of the Chemical and Biochemical Engineering Program at Faculty of Engineering and Built Environment, UKM. The questionaire include a general information of future graduates, information on program outcomes over 4 years and acquiring skills, career preparation and student-lecturer relationship. The results of the evaluation process and recommendations for improving the curriculum were also studied. The study was conducted over two sessions (semester 2009/2010 and 2010/2011) for two batches of students. Overall, mostly all the prospective graduates are satisfied with the current system of teaching and learning in JKKP as well as also willing to involve into the working environment. Achievement of the 12 program outcomes indicates a satisfactory performance with an average of more than 70% and 57% for respective Chemical and Biochemical Engineering Program. Based on this study, approximately more than 27% graduate in Chemical Engineering believes that the theoritical-practical and technical oriented projects should be adopted, while 19% of Biochemical Engineering graduates thinks that the project design should be separated and should be more focused to the field of biochemical engineering area.

Exposure to real life industries is one of the key elements implicitly emphasized in the Program Outcomes (PO) for students graduated from Chemical and Biochemical Engineering programs. The Department of Chemical and Process Engineering (JKKP) has implemented the Industrial Talk and Industrial Visit activities since 2006, following suggestions from the program external assessors. The activities are important for students to relate their theoretical knowledge to practical aspects of the studied courses, in terms of industrial unit operations, process and design concepts, and impact of its activities on health, safety, environment and society. Recently, the Faculty of Engineering and Built Environment has proposed that students from each academic year should be exposed to industrial talks (twice a year) and industrial visits (once a year). This paper elaborates on the objectives and experiences gained by the JKKP in implementing these activities. The strengths, weaknesses and opportunities for improvement are also identified and discussed. It can be concluded that a good coordination and a proper assessment methods, selection of industrial sites for visit as well as speakers or topics for talks are important for enhancing students’ practical learning.

The corrosion of aluminum alloy (6262) in artificial sea water under flow condition was evaluated using electrochemical impedance spectroscopy (EIS) and potentiodynamic methods. The flow condition experiments were simulated using rotating cylinder electrode (RCE). Results showed that the increasing of the flow velocity enhances the corrosion kinetic of the system and changes the corrosion mechanism. Limiting current density was increased with increasing in the flow velocity. This behavior was due to the presence of a mixed control on the corrosion process related with the formation and stabilization of corrosion product layers on the electrode surface.

A relationship between quantum chemical parameters for three triazole compounds and their inhibition ability was studied using electrochemical measurements (potentiodynamic polarization and EIS), molecular dynamic method and quantum chemical calculations. Electrochemical measurements results revealed that the inhibition efficiencies increased with the concentration of inhibitors. The molecular dynamic method results showed that the higher interaction potential between the inhibitor and metal surface, the higher the inhibition efficiency. The quantum chemical calculation results showed that the triazole ring is the active site in these inhibitors and they can absorb on Fe surface by donating electrons to Fe d-orbital.

The main goal of this paper was to introduce an environmental fate and risk assessment methodology for comparing and establishing the general features of new and existing non-volatile organic chemicals (NVOCs) used in agricultural activities, based on simple and readily available properties. This methodology is a computer program called the multimedia agricultural fate and risk assessment model (MAFRAM). This model is a combination of the EQC-2V model, which describes the fate of NVOCs, with the ecological relative risk (EcoRR) approach, which assesses the ecotoxicological risk to agro-ecosystems. MAFRAM divides the agricultural environment into two main zones, which are the on- and off-farm zones. Each zone is subdivided into six compartments, including the air, water, soil, sediment, aboveground plants, and roots. The required input data are the chemical-physical properties of the pesticide, biota data, and environmental properties. The MAFRAM output includes the inter-compartmental transport and transfer rates, the primary loss mechanisms, chemical concentration, amount, residence time, and the rank of risk in each compartment. In addition, it can provide several secondary results. The MAFRAM application was illustrated using typical homogenous region properties and was run with an illustrative emission rate of 1 kg/h into air, using spinosad as a case study.

The corrosion inhibition of Al-Alloy (Al2024) in 0.5 M nitric acid solution at 30 °C was achieved using 4-4-dimethyloxazolidine-2-thione (DMT) as a corrosion inhibitor. The electrochemical performance of the DMT was studied by electrochemical impedance spectroscopy (EIS), potentiodynamic polarization measurements, and scanning electron microscopic study (SEM). The results indicated that DMT acts as an inhibitor for Al2024 in 0.5 M nitric acid. Polarization curves indicated that DMT was a mixed-type inhibitor. Inhibition efficiencies were observed to be increased with an increase in DMT concentration and attains approximately to 93.4% at 2 mM of DMT in 0.5 M nitric acid. The adsorption of DMT model on Al2024 surface obeyed in accordance with Langmuir adsorption isotherm model. The value of the free energy of adsorption ΔG ads indicated that the adsorption of DMT molecule was a spontaneous process and was typical of physical and chemical adsorption.

The inhibition ability of 4,4-dimethyloxazolidine-2-thione (DMT) for mild steel corrosion in a 1 M HCl solution at 30 °C was studied by means of potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) technique, and scanning electron microscopy (SEM). Quantum chemical calculation based on PM3 method was performed on DMT. The molecule structural parameters, such as the frontier molecular orbital energy HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital), the charge distribution and the fraction of electrons (ΔN) transfer from inhibitor to mild steel were calculated and discussed. Results showed that DMT performed as good inhibiting effect for the corrosion of mild steel in a 1 M HCl solution and inhibition efficiency is higher than 82% at 4 × 10−3 M DMT. Results indicate that the inhibition efficiencies increased with the concentration of DMT and the area containing S atom is most possible site for bonding the mild steel surface by donating electrons to the metal. Adsorption of the inhibitor on the mild steel surface followed Langmuir adsorption isotherm and the value of the free energy of adsorption ΔG○ads indicated that the adsorption of DMT molecule was a spontaneous process and was typical of chemisorptions.

The inhibition ability of 4-amino-5-phenyl-4H-1, 2, 4-trizole-3-thiol (APTT), ethylenediaminetetra-acetic acid (EDTA) and thiourea (TU) for mild steel corrosion in 1.0 mol/L HCl solution at 30 ℃ was investigated. Tafel polarization and electrochemical impedance spectroscopy (EIS) were used to investigate the influence of these organic compounds as corrosion inhibitors of mild steel in 1.0 mol/L HCl solution at 30 ℃. The inhibition mechanism was discussed in terms of Langmuir isotherm model. Results obtained from Tafel polarization and impedance measurements are in a good agreement. The inhibition efficiency increases with the increase of the inhibitor concentration. The adsorption of the inhibitors on the mild steel surface follows Langmuir adsorption isotherm and the free energy of adsorption ∆Gads indicates that the adsorption of APTT, EDTA, and TU molecules is a spontaneous process and a typical chemisorption.

The corrosion inhibition of mild steel in a 2.5 M H2SO4 solution by 4-amino-5-phenyl-4H-1, 2, 4-trizole-3-thiol (APTT) was studied at different temperatures, utilising open circuit potential, potentiodynamic and impedance measurements. The results indicate that APTT performed as an excellent mixed-type inhibitor for mild steel corrosion in a 2.5 M H2SO4 solution and that the inhibition efficiencies increased with the inhibitor concentration but decreased proportionally with temperature. The kinetic and thermodynamic parameters for adsorption of APTT on the mild steel surface were calculated. A chemisorption mechanism of APTT molecules on the mild steel surface was proposed based on the thermodynamic adsorption parameters.

This paper attempts to explore the level of religious integration in counselling practicum among practicum students in public university. 173 practicum students from three public universities were involved in this study and questionnaires were sent by post to the selected sample. Descriptive analysis (percentage, mean and standard deviation) and inferential (t-test) was used to analyze the data. Research finding shows that the religious integration among counselling practicum students are moderate. Based on the findings of the study, the recommendations made are standard training and constant exposure on the integration of religious understanding in the practice of counselling should be established to improve the competency level of spirituality and religiousity among counselling practicum students.

Electrochemical polarization and electrochemical impedance spectroscopy (EIS) were involved to study the corrosion inhibition of aluminum alloy 2024 in 2.5M H2SO4 solution by 4-amino-5-phenyl-4H-1, 2, 4-triazole-3-thiol (APTT) at 30 ○C. Potentiodynamic polarization results were comparable with those obtained by impedance measurements. Results showed that APTT performed as inhibitor for aluminum alloy 2024 corrosion in 2.5M H2SO4 solution and it attains an efficiency of more than 32% at 4×10- 4 M at 30 ○C . The inhibition efficiency increases with an increase in the concentration of APTT. Polarization curves show that APTT is a mix-type inhibitor. Changes in impedance parameters (charge transfer resistance, Rct, and double layer capacitance, Cdl) were indicative of adsorption of APTT on the aluminum alloy 2024 surface, leading to the formation of protective films

A study concerned to thermogravimetric analy- sis is performed in cesium dihydrogen phosphate (CsH2PO4) that was synthesized, using cetyltrimethylammonium-bro- mide (CTAB), polyoxyethylene-polyoxypropylene (F-68) and mixture of (F-68:CTAB) with two mole ratio 0.06 and 0.12 as surfactant. The dehydration behavior of particles was studied using thermal gravimetric analysis and differential scanning calorimetric. Subsequently, the experimental results indicated that the first dehydration temperature in the range of 237-239 C upon heating, the second peaks occur at temperature range 290-295 C and overlapping in the ther- mogravimetric events is observed. The mass loss values are obtained in the range of 6.62-6.97 wt% that is less than reported theoretical value 7.8 wt%. These values show well compatibility of reaction CsH2PO4 to Cs2H2P2O7 with 3.92 wt% whereas mass loss value of CsH2PO4 to CsPO3 is less than theoretical value 7.8 wt%. The activation energy of two steps dehydration are calculated using Kissinger equa- tion for the samples synthesized via CTAB and (F-68) with minimum value mass loss 6.62% and maximum value mass loss 6.97%, respectively. The calculation results reveal that the reaction rate in the first step (CsH2PO4 ? Cs2H2P2O7 )i s faster than the second step (CsH2PO4 ? CsPO3). The weight loss values of the samples demonstrate that existence of CTAB can be considered as effective factor which pre- vents more weight loss during the dehydration process.

The x–y robotic spraying technique developed in the Universiti Kebangsaan Malaysia is capable of fabricating various sizes of thickness and porosity of gas diffusion layer (GDL) used in the proton exchange membrane fuel cell (PEMFC). These parameters are obtained by varying the characteristic spray numbers of the robotic spraying machine. This investigation results were adequately represented with mathematical equations for hydrogen gas distribution in GDL. Volumetric modulus ( M ) parameter is used to determine the value of current density produced on the electrode of a single cell PEMFC. Thus the M parameter can be employed as indicator for a successful GDL fabrication. GDL type 4 has three variables of layer design that can be optimized to function as gas distributor, gas storage, flooding preventer on GDL surface, to evacuate water from the electrode and to control the electrical conductivity. The gas distribution in GDL was mathematically represented with average error of 15.5%. The M value of GDL type 4 according to the model was 0.22 cm 3 /s and yielded a current density of 750 A/m 2 .

Many pesticides used in agricultural activities are considered environmentally non-volatile. The main purpose of this paper is to develop multimedia model to be used as a tool to predict the overall fate and transport of non-volatile organic chemicals (NVOCs) dynamic in the agro-ecosystem. The model was developed based on the EQuilibrium Criterion (EQC) model for type 2 chemicals introduced by Mackay and colleagues in 1996. Mackay’s model only considered four environmental compartments, which are air, water, soil and sediment. The present model adds the vegetation compartment, in addition to previous compartments that shape the agro-ecosystem. The vegetation compartment is described by two sub-compartments consisting of the above ground plant (AGP) and roots. The model was parameterized for the Cameron Highlands region, Malaysia, and runs with an illustrative emission rate of 1 kg h −1 into the air for three selected pesticides, namely, mancozeb, spinosad and chlorosulfuron. The simulation results with and without vegetation compartment were compared. The estimated results indicating that the AGP captures 99.9% of introduced NVOCs (i.e., of 100% or 1 kg h −1 ) and transfers them to the ground below due to the slight degradation losses of 10 −4 % and the non-volatility property of the evaluated chemicals. Root uptake of chlorosulfuron accounted the highest removal process from soil while degradation of spinosad in the soil is the major loss mechanism. Leaching to groundwater loss for mancozeb is about 2-fold greater than that of degradation, which together accounted the major removal process from soil. Based on the estimated results of mass distribution on the overall system, vegetation compartment accumulates 0.04%, 0.5% and 2.02% of the mancozeb, spinosad and chlorosulfuron, respectively.

Adsorption of CO and CO2 in mixtures of H2/CO/CO2 was achieved using compact pressure swing adsorption (CPSA) system to produce purified hydrogen for use in fuel cell. A CPSA system was designed by combining four adsorption beds that simultaneously operate at different processes in the pressure swing adsorption (PSA) process cycle. The overall diameter of the cylindrical shell of the CPSA is 35 cm and its height is 40 cm. Several suitable adsorbent materials for CO and CO2 adsorption in a hydrogen stream were identified and their adsorption properties were tested. Activated carbon from Sigma–Aldrich was the adsorbent chosen. It has a surface area of 695.07 m2/g. CO adsorption capacity (STP) of 0.55 mmol/g and CO2 at 2.05 mmol/g were obtained. The CPSA system has a rapid process cycle that can supply hydrogen continuously without disruption by the regeneration process of the adsorbent. The process cycle in each column of the CPSA consists of pressurization, adsorption, blowdown and purging processes. CPSA is capable of reducing the CO concentration in a H2/CO/CO2 mixture from 4000 ppm to 1.4 ppm and the CO2 concentration from 5% to 7.0 ppm CO2 in 60 cycles and 3600 s. Based on the mixture used in the experimental work, the H2 purity obtained was 99.999%, product throughput of 0.04 kg H2/kg adsorbent with purge/feed ratio was 0.001 and vent loss/feed ratio was 0.02. It is therefore concluded that the CPSA system met the required specifications of hydrogen purity for fuel cell applications.

Nafion-silicon oxide (SiO 2 )-phosphotungstic acid (PWA) composite membrane has been synthesized to improve Nafion based proton exchange membrane fuel cell (PEMFC) performance. The objective of the study is to fabricate Nafion-SiO 2 -PWA nanocomposite membrane using sol–gel reaction. The composite is composed of the mixture of Nafion solution, tetra ethoxy orthosilane (TEOS) and PWA solution. The mixed solution was casted at certain temperature until transparent membrane is obtained. Peaks of SiO 2 and PWA in the infrared spectra revealed that both inorganic and organic components are present in the modified Nafion based nanocomposite membrane. Analysis with fuel cell test station showed that higher current density was produced by nanocomposite membrane (82 mA cm −2 at 0.6 V for NS15W) than with the Nafion membrane (30 mA cm −2 at 0.2 V) at 90 °C and 40% relative humidity. The internal resistance was seen to increase with the inorganic content. The internal resistances of the commercial Nafion (N112), NS10W, NS15W and NS20W are 6.33, 4.84, 1.33 and 3.6 Ω cm 2 , respectively and their Tafel constants are 93.4, 84.4, 11.25 and 26.6 mV, respectively. While the nanocomposite membrane results were shown to be better than the commercial Nafion, the overall performances are comparable to those in the open literature.

A Multimedia Agricultural Model (MAM) for predicting the fate and transport of Non- Volatile Organic Chemicals (NVOCs) in the agricultural environment was presented. It is an expanded and modified version of the three compartmental model introduced by Batiha and co-authors in 2007, which is an aquivalence-based level IV. MAM considered five environmental compartments to include the air, water, soil, sediment and vegetation. It calculates the complete steady-state mass budgets for the air, water and particulate organic carbon between the model compartments. MAM compartments were connected by advective and intermedia transport processes. Degradation can take place in every compartment. The mass balances for each of the compartments result in a system of five differential equations, solved numerically to yield estimates of concentrations, masses, transport fluxes and reaction rates as a function of time. All the equations required for MAM calculations were provided.

Multimedia dynamic model of the fate of non-volatile organic chemicals (NVOC) in the agricultural environment is described. The modeled environment, consisting of up to three major surfaces environmental compartments, includes air, agricultural soil, and surface water. This model is based on the aquivalence approach suggested by Mackay and co-workers in 1989. As the movement of chemicals in the environment is closely associated with the movement of air, water and organic matter, the complete steady state mass budgets for air, water and particulate organic carbon (POC) between the model compartments are described. All of the model equations, which are expressed in aquivalence notation, the mass balance for NVOC in the environmental surfaces compartments at dynamic state, and equations for the calculation of partitioning, overall persistence, total amount, total concentrations at dynamic state and intermedia fluxes of organic chemicals between air, water, and soil at steady-state are provided.

Stabilization standards of PVC films are fundamentally depend on essential laws: solvation and "reverberation" Stabilization. The photo-stabilization of poly(vinyl chloride) (PVC) films by epoxidized oleic acid was investigated. Photo-stabilization activities were determined by monitoring the carbonyl, polyene and hydroxyl indices with irradiation time. The changes in viscosity average molecular weight of PVC with irradiation time were also tracked using tetrahydrofuran as a solvent. The quantum yield of the chain scission (Φcs) was evaluated and found with range 4.53´10-8 and 8.12´10-8. Postulated mechanisms were outlined depending on the structure of the additive.

The rational design of 4-hydroxycoumarins with tailor-made antioxidant activities is required nowadays due to the wide variety of pharmacologically significant, structurally interesting of coumarins and researcher orientation toward green chemistry and natural products. A simple and unique coumarins have been achieved by reaction of 4-hydroxycoumarin with aromatic aldehyde accompanied with the creation of a macromolecules have 2-aminothiazolidin-4-one. The molecular structures of the compounds were characterized by the Fourier transformation infrared and Nuclear magnetic resonance spectroscopies, in addition to CHN analysis. The scavenging abilities of new compounds against stable DPPH radical (DPPH•) and hydrogen peroxide were done and the results show that the compounds exhibited high antioxidant activates.

New derivatives of 7-hydroxy-4-methylcoumarin were synthesized using a chemical method and a microwave-assisted method to compare the feasibility, reaction times, and yields of the product. The newly synthesized coumarins were characterized by different spectroscopic techniques (FT-IR and NMR) and micro-elemental analysis (CHNS). In vitro antioxidant activities of these compounds were evaluated against hydrogen peroxide and were compared with standard natural antioxidant, vitamin C. Our results reveal that these compounds exhibit excellent radical scavenging activities.