Pusat Pengajian Kejuruteraan Kimia - Tesis

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Adsorption of chloramphenicol and bisphenol a using cellulosic carbonaceous fibrous strand adsorbent
(2022-04-01)
Ahammad, Nur Azian
Recently, the problem of water contamination due to organic compounds residues detected in natural wastewater streams has become more alarming. These pollutants are referred to as new emerging pollutants. New emerging pollutants such as Chloramphenicol (CPC) and Bisphenol A (BPA) have been discovered in many water resources. This study aims to synthesis carbonaceous fibrous strand adsorbent (CFSA) via Schweitzer’s reagents for the adsorption of CPC and BPA from aqueous solution. CFSA had a surface area of 650.921 m2.g-1 , a total pore volume of 0.485 cm3.g-1 and an average pore diameter of 2.930 nm. Batch and continuous adsorption study were conducted for the removal of CPC and BPA. The maximum adsorption capacity, Qmax for CPA and BPA adsorption was 234.03 mg.g-1and 118.97 mg.g-1, respectively at 50 °C. For both adsorption systems, the kinetics of adsorption followed a pseudo-second-order kinetic model. The adsorption diffusion behaviour was evaluated by intraparticle diffusion. Based on the Boyd plots, the adsorption of CPC and BPA onto CFSA was mainly governed by film diffusion. Thermodynamic findings demonstrated that CPC and BPA adsorption onto CFSA were spontaneous and endothermic in nature. Next, the adsorption profile for both CPC and BPA were best fitted Freundlich isotherm models, suggesting a heterogonous adsorption surface for both systems. From the isotherm, kinetic and thermodynamic results, we can conclude that a combination of chemisorption and physisorption takes place, i.e., physicochemical adsorption is involved in adsorption of CPC and BPA. The fixed-bed adsorption profile for CPC and BPA system were fitted well to Thomas and Yoon-Nelson.
Adsorptive Cathodic Stripping Voltammertries Of Lead In Water Samples Using 2, 2'-Bipyridyl; 1,10- Phenanthroline And Nitrite Ions
(2013-02)
Jawad, Masar Hadi
A new differential pulse adsorptive cathodic stripping voltammetric (DPAdCSV) method was developed for the determination of lead concentration in aqueous solution.. This was based on complexation of lead with combination of two complexing agents viz 2,21-hipyridyl and 1,1 O-phenanthroline with nitrite at hanging mercury drop electrode (HMDE). Variables affecting the response such as pH, supporting electrolyte, initial purge time, drop size, stirring speed, deposition potential, deposition and equilibration times, sweep rate, pulse amplitude and ligand concentration were investigated. Using the first reagent 2,2'-bipyridyl with nitrite[reagent (I)] and under optimized conditions the relationship between peak current and lead concentration was linear in the range of 10-500 ng mL-l. The limit of detection was found to be 0.48 ng mL-l. The relative standard deviation (RSD) for n= 9 determinations of standard 25 ng mL-I Pb2+ was to 1.74% with linear regression coefficient (R2) 0.9991.
Agro-Based Catalyst Systems For Converting Palm Based Oils With High Fatty Acids And Water Contents Into Methyl Esters
(0008-12)
Ganesan, Shangeetha
Present work focuses on producing a dual catalyst system to esterify fatty acids and . transesterify triglycerides into methyl esters in the presence of methanol. Firstly, boiler ash sourced from waste empty fruit bunches of the palm oil industry was characterized and used as a pseudo-homogeneous base catalyst for transesterification of palm olein. Boiler ash successfully transesterified palm olein at mild reaction conditions (3 wt.% dried boiler ash, 15: 1 methanol : oil molar ratio, methanol refluxing temperature and reaction time of 0.5 b) to produce 90% methyl esters. Calcium oxide (calcined at 900 oe for 2 h) was added to boiler ash in order to increase the free fatty acids and water tolerance of boiler ash for transesterification of low quality oils. A mixture of boiler ash-calcium oxide was found to be able to tolerate 3 wt.% water and 4 wt.% free fatty acids.
Bioregenera Tion Of Granular Activated Carbon Loaded With Phenol And Ocresol By Immobilized Biomass: Quantification And Kinetic Studies
(2013-11)
Toh, Run Hong
The objectives of this study were to (i) develop a novel approach to bioregenerate GAC loaded with phenol and a-cresol, respectively, using immobilized biomass as well as immobilized PAC-biomass, (ii) quantify and compare the bioregeneration efficiencies of GAC loaded with phenol and a-cresol, respectively using suspended and immobilized biomasses as well as immobilized PAC-biomass, and (iii) develop kinetic models to describe the bioregeneration process of GAC loaded with phenol and a-cresol, respectively, using the immobilized biomass.
Biotransformation Of Ferulic Acid Extracted From Biomass To Biovanillin By Amycolatopsis Sp. Atcc 39116
(2014-11)
Abu Sepian, Noor Raihana
This study focuses on the biotransformation of synthetic and extracted ferulic acid (FA) from lignocellulosic biomass using growing cells of Amyco/alopsis sp. ATCC 39116 as a biocatalyst. Preliminary alkaline hydrolysis showed that the hydrolyzate from oil palm empty fruit bunch (OPEFB) contained the highest amount of FA (199.4 mg/l) among the other three lignocellulosic wastes (i.e. oil palm frond, coconut fiber and sheIl). Optimization of extraction was carried out using Response Surface Methodology (RSM) via Central Composite Design (CCD) on the effect of three independent variables, i.e. concentration of NaOH (1.5-5 M), solid/liquid ratio (0.03-0.084 g/ml) and time (16-32 h). The optimum FA concentration of 2.04 mg/g OPEFB (365.19 mg/l) was obtained under the optimal conditions of 1.5 M ofNaOH concentration, 0.03 g/ml of solid/liquid ratio and 32 h of extraction time. The extracted FA was further purified using polyvinylpolypyrrolidone (PVPP) and activated carbon, and about 97.26% was successfully recovered from the extract using PVPP. The partially purified FA was converted into 38.47% molar yield of vanillin, showing the ability of Amyco/alopsis sp. ATCC 39116 to convert the extracted FA from lignocellulosic waste.
Catalytic co-pyrolysis of high-density polyethylene/polypropylene mixture and oil palm fibre to liquid fuel
(2022-09-01)
Abel Williams Gin
Green House Gas (GHG) emission and environmental pollution remain the two main issues of concern in the globe today because of the continuous and unrestricted dumping of both plastic and agricultural biomass residues across the globe. Hence, a conversion of these solid wastes into highly valuable liquid fuel could be a potential solution to alleviate this environmental issue. In this work, oil palm fibre (OPF), a major agricultural biomass in Malaysia, was mixed with an equal mass of high-density-polyethylene (HDPE) and polypropylene (PP) and converted to liquid fuel via non-catalytic and catalytic co-pyrolysis in a fixed-bed-reactor. The synthesized catalysts, SBA-15 exhibited a highly ordered mesoporous structure while ladle furnace derived - hydroxyapatite (HAP-LF) demonstrated metal-rich microporous structure, respectively. The influence of process parameters (temperature, feedstock ratio, catalyst/feedstock ratio) indicated that the maximum composition of the desirable compounds (alcohol and hydrocarbons) using HAP-LF was 71.65 % (Temperature = 450 oC, OPF-plastic mixture ratio = 1:3). The yield of these compounds was higher than maximum value of 60.54 % obtained using SBA 15 (600 oC, OPF-plastic mixture ratio = 1:1). The HAP-LF catalyst/feedstock ratio of 1:8 produced the maximum composition of the desired compounds in oil while SBA 15 catalyst/feedstock ratio of 1:6 produced maximum composition of the desired compounds. These results indicated that HAP-LF is a more suitable catalyst for the catalytic co-pyrolysis of the feedstock mixture. The heating value of the produced oil was found to be 44.5 kJ/mol. Recyclability studies of the HAP-LF catalyst indicated that it could be used up four consecutive recycle times without serious deactivation. The kinetic studies using thermogravimetric analyzer showed a reduction in activation energy from 13.98 - 92.11kJ/mol to 21.58 - 59.33 kJ/mol across the three degradation stages of the feedstock mixture.
Copper-Tannate Complexes As Antifoulant In Antifouling Paint For Fish-Cage Nets
(2014-05)
Usol Ghafli, Nurul Azwin
Tannin extracted from mangrove bark, Rhizophora apiculata (R. apiculata) was used as a natural-origin source to be complexed with copper(U) salt. The copper-tannate (Cu-T) produced was used as an antifoulant in antifouling paint. Mangrove bark was extracted using 70% (v/v) aqueous acetone and gives 31.1 % extraction yield. The total phenolic content (TPC) of mangrove tannin extract (MT) was 186.0 mg gallic acid equivalent per gram sample, total flavonoid content (TFC) was 96.0 mg catechin equivalent per gram sample and condensed tannin content (CTC) was 95.5% weight content. The optimum condition of copper-tannate complexes (Cu-T) was studied using precipitation curve on varies parameters which were copper dosage, reaction temperature, reaction time and pH of Cu-T solution. The optimum conditions were taking into account of Cu-T percentage yield and IR spectrum analysis. Three derivatives ofCu-T at different pH, which were Cu-T pH 3.5, Cu-T pH 5.0 and Cu-T pH 8.0, were chosen for further analysis. The concentration of copper element in CuT and commercialized antifoulant, Cu-Oma was measured using AAS analysis and shown that Cu-T complexes had lower amount of copper content which are almost 50% lower than Cu-Oma.
Data driven technique for boiler water quality monitoring in palm oil mills
(2022-07-01)
Rusdi, Muhammad Rufaizal Izham
Steam boilers widely used in oil palm mills are intended to generate steam in the factory for process use. Based on the statistical data from DOSH Perak Section Analysis and Process, repair work for boilers in Perak for Palm Oil showed that the number of cases increased between 2014 and 2018. The increasing of repaired cases reported to DOSH need to be studied to help facilitate the operator and in the future as the lesson learn to avoid unscheduled shutdown due to increasing numbers of repaired jobs for boilers failure. In this work, the data was collected from 39 palm oil mills from the year 2017 to 2019. Data driven analysis methods of the data collected were carried out for the parameter namely total hardness, pH, total dissolved solid (TDS), total Iron, hydrate alkalinity, silica, sulphite, phosphate, chloride and cycle of concentration. A centralised data-driven technique for boiler water monitoring systems using statistical process control (SPC) was developed in this study. The application of toolboxes like box plots and correlation coefficients adequate in providing profiles and analysis for all parameters and the correlations between the parameters. From the results of the analysis, 6 parameters that being investigate which are hardness, pH, chloride, silica, total iron and sulfite are not within the recommended ASME guidelines. Total Dissolved Solid (TDS), silica, hardness, and total iron are four factors that have a significant impact on the treatment of boiler water. Therefore, proper monitoring and treatment of boiler feedwater based on ASME guidelines and performing blowdown based on the cycle of concentration for boiler water effectively protect from scaling and corrosion of boiler. As a conclusion, the finding from this study can be introduced to DOSH and it can facilitate DOSH in improving the enforcement of boiler operators to properly monitor and control parameters according to the ASME guidelines in reducing the number of boiler repair jobs, enhance and prolong the life of the boiler.
Development Of A Catalytic Membrane Reactor For The Production Of Ethylene Using Oxidative Coupling Of Methane (Oem)
(2006-09)
Chua, Yen Thien
A catalytic membrane reactor resembles shell and tube heat exchanger integrated with a tubular ceramic membrane was developed for the application in oxidative coupling of methane (OCM) reaction. A 3-components catalyst system (Na-W-Mn/Si02) was used to study the OCM reaction in a packed bed catalytic reactor. The effects of various operating parameters were studied using design of experiments method. The interaction effects of each parameter were obtained and response surface methodology coupled with central composite design was applied in determining the optimum condition. The predicted optimum condition of temperature 850oe, gas hourly space velocity at 23,947cm3/g.hr, catalyst pretreatment period of 2 hrs, CH" to O2 ratio 7 and dilution ratio 0.2 gave 40.55% methane conversion, 79.51 % C2+ selectivity and 32.24% C2+ yield. The experimental value of with 43.05% methane conversion, 70.62% C2+ selectivity and 30.40% C2+ yield was obtained at an optimum condition.
Development of guar gum-based polymer for water shutoff treatment
(2021-11-01)
Kamarulizam, Siti Nuraffini
This research was conducted to introduce a new polymeric water shutoff agent (PWSA) developed from the combination of Guar Gum (GG), Acrylonitrile (AN), Acrylic Acid (AA), and Chitosan (CHI) to stop water entrance experienced in the mature oil well. This graft copolymerisation of vinyl monomers (AN and AA) into natural polymers (GG and CHI). The efficiency of the synthesised polymer as a polymeric water shutoff agent (PWSA) was studied at targeted gelation time (GT), rigid gel time (RGT), and temperature. For this study, the GT was targeted in 120 minutes and RGT of 720 minutes at 60°C. Safer approaches in making PWSA using Ce4+ instead of Cr3+ and natural polymer to replace synthetic was the essence for synthesising this polymer. This polymer was attained to stop water entrance through porous features to prevent excessive water-borne problems with water-like initial viscosity. The synthesised polymer was validated as PWSA by the polymer characteristic. The relationship among materials was expressed in the stable empirical model by the statistical analysis approach. Synthesised PWSA was evaluated in typical and extreme wellbore conditions and mimicking wellbore conditions for polymer effectiveness. Polymer synthesis was started with the selection of backbone polymer, polymer strengthener, and time delay agent. Selected (GG, AA, CHI) materials were polymerised in a single batch at a given temperature to obtain the optimised composition. The optimised composition PWSA were 0.1%v/v GG, 4%v/v AN, 0.03%v/v CAN, 4%v/v AA, and 20%v/v CHI. This formulation was agreed with targeted GT, RGT, with accepted polymer strength at 0.68 bar. This polymer showed a swelling water capacity of 557% with an initial viscosity of 0.0009 Pa.s. The elastic properties were a good PWSA indication. The thermal profile of the polymer also showed that weight loss ranging from 50% to 90% was detected at temperature 80°C to 110°C. For the heat flow curves, the polymer showed the reaction was started at 78°C, and the final degradation was at 120°C to 130°C. Approached with the statistical method, the mathematical model showed the summarised estimation of the gelation process, and the expression was fit to resemble the whole experiment. The polymer also reacted to elevated temperature, added salts, and pH variation during polymerisation and reacted polymer. The elevated temperature at 110°C showed the most influence on PWSA behaviour. This PWSA had successfully reduced water permeability throughout the Berea sandstone core from 186 mD to 0 mD. This polymer was succeeded in blocking 100% water entrance.
Development Of Model Based Decoupler For Multi Input Multi Output Distillation Column
(2013-01)
Lee, Qiao Hui
Distillation column is a complex multivariable system and exhibits nonlinear dynamic behaviour due to the complex processing configurations and high product purities. The strong coupling among control loops often invalidates conventional loop controllers. Coupling is a very common phenomenon in multiple input multiple output (MIMO) systems. During processes, multiple control loops are designed for a process plant to control and guarantee the product quality. However, the control loops interact with other significantly. Due to the interaction between the loops, the stability and the product quality of the process may be compromised. Therefore, decoupling control was introduced to reduce the coupling problem in the nonlinear system.
Dissolution Of Natural Fiber Using Ionic Liquid For Production Of Cellulose Nanoparticles
(2014-04)
Yahya, Nadzirah
Natural fiber (NF) exhibits desirable properties such as renewability, biodegradability, environment-friendly, lightweight, low density, high specific mechanical performance, good electrical and thermal conductivities, and low cost. Cellulose nanoparticles (CNPs) embedded in NF possess even greater properties caused by the high crystallinity of cellulose fiber. In this study, dissolution process was used in order to extract these CNPs from NF source; coconut fiber (CF). The process was done using an ionic liquid (IL) 'green solvent' that are best known for their capabilities in chemical reaction and extraction! separation processes. IL is known to be non-volatile, non-flammable, and recyclable, with low toxicity and vapor pressure. The properties of CNPs extracted was further determined using fourier transform infrared (FTIR) analysis, thermogravimetric analysis (TGA), scanning electron microscope (SEM) analysis, high resolution thermal electron microscope (HRTEM) analysis and dynamic light scattering (DLS) analysis. An optimization studies on the ultrafine CNPs extraction resulted in an optimum operating condition of 74.90min, 10S.06°C and O.OS wt% of CF:IL.
Effect of coating of polypropylene on polyvinylidenefluoride hollow fiber membrane via non-solvent for membrane gas absorption
(2022-09-01)
Hassan, Amir Ikmal
Emissions of greenhouse gases mainly CO2 are mostly sourced from industries and automations. Conventional equipments such as scrubbers and absorbers were applied in plants to deal with excess gas emissions. This leads to implementation of membrane gas absorber (MGA) which has the potential as an alternative. Polyvinylidenefluoride (PVDF) or polypropylene (PP) material as base substrate was not sufficient to achieve the highest performance. Therefore, surface modification involving dip-coating was implemented. Coating steps involved PP layer coated on commercial PVDF hollow fiber membrane via dip-coating with and without non-solvent, hand-dip and automated dip to understand the effect of coating on its interaction, parameters and evaluated using MGA. Pre-coating of non-solvent using MEK improved membrane contact angle to 116.75' as opposed to ethanol, 105.84' proved MEK having better affinity and interaction to the substrate used. Study of PP concentration (10 – 55 mg/ml) and drying temperature (30 – 70'C) was studied with MEK which MP25 and MP40 at 50'C achieved the two highest contact angle at 116.75'and 118.35'. Study of coating speed (1 – 15 mm/s) and dipping time(10 – 60 s) were optimized at 5 mm/s and 10 s. Multilayer coating method (M1, M2 and M3) at increasing dipping cycle (2x and 3x) was addressed and M1 achieved the higher contact angle, 135.75' owing to its high average surface roughness (Ra), 0.0809 µm via AFM compared to single dipping and other methods. MGA evaluation proved that pre-coated membranes with non-solvent have better CO2 flux. Besides, single coated membrane achieved higher overall flux as compared to 2x and 3x dipping cycle membranes. However, MP25 at 3x dipping cycle have lower wetting tendencies owing to 13.79% flux reduction while 1x dipping cycle experienced 20.59% flux reduction. In conclusion, interactions between components, dip-coating parameters and performance of each membrane was optimized, addressed and elucidated.
Establishment Of The Callus And Cell Suspension Cultures For The Growth Of Pogostemon Cablin
(2014-12)
Che Saad, Norlia
In this study, plant cell culture technique was used in order to investigate the production of patchouli alcohol in callus and cell suspension cultures. The callus cultures were induced from the intact Pogostemon cablin leaves called explants. Different types, concentration of plant growth regulators (PGRs) and different culture conditions (light, carbon source and inoculum size) were studied in order to produce a rapid-growing callus cultures and well-dispersed cell suspension cultures or P. cublin. The best condition for callus cultures growth was obtained in the Murashige and Skoog (MS) basal medium containing I mg/L picloram (MS I d) which was maintained in the dark for 21 days. Callus cultures were healthy with whitish and friable features. However, the cultured explants showed negative response to MS medium supplemented with 2, 4- D and all combination of picloram and 2, 4-0. The healthy, fast growing and friable callus cultures were then used to establish the cell suspension cultures. Under the influences of different concentrations and combinations of PGRs and light, rapid growth of cell suspension cultures were observed in the MDI medium.
Heterogeneous Photo-Fenton Decolorization Of Acid Green 25 Using Local Natural Clays And Dolomite Based Catalysts
(2012-09)
Mohammad Azmi, Nur Hidayah
In this research work, three different type of catalysts from natural mineral resources were developed as heterogeneous catalyst support for the decolorization of Acid Green 25 (AG25) dye using photo-Fenton process in a batch system. Fe-Ipoh clay (Fe-IC), Fe-Bandar Baru clay (Fe-BBC) and Fe-Dolomite (Fe-DOL) were successfully synthesized by immobilized iron ions derived from ferric nitrate nonahydrate (Fe(N03)3.9H20) on the catalyst support, Ipoh clay (IC), Bandar Baru clay (BBC) and Dolomite (DOL), respectively through impregnation process. Preliminary studies on effect of calcination temperature ancl duration of time by all catalysts on decolorization of AG25 were investigated.
Hydrocracking And Hydrodesulphurization Activities Of Nimo Catalyst Supported On Alumina And Activated Carbons For Petroleum
(2023-09)
Ahmed Alsobaai, Ahmed Mubarak
This study aims to improve petroleum residual oil quality by converting it into lighter products over different types of catalysts. The process was conducted in a batch mode under various operating conditions, temperature in range 250-350 °C, reaction time 90- 230 min and catalyst ratio 0.3-1.30 using a high-pressure stirred reactor in the presence of hydrogen and catalyst. At first commercial NiMo/Ah03 catalyst was used to find the range of operation conditions for catalytic hydrocracking of petroleum residual oi). Statistical design of experiment, (DOE), was used to obtain the range of operating conditions. It was found that the range of operating conditions for catalytic hydrocracking of petroleum residual oil over commercial NiMo/Ah03 sulphided catalyst are: temperature of 330°C, time of 200 min and catalyst ratio of 1.1.
Identification Of Chemical Markers And Quality Assessment In Malaysian Stingless Bee Honey Using Chemometric Techniques
(2023-09)
Manickavasagam, Ganapaty
Heterotrigona itama (H. itama) honey is stingless bee honey produced by stingless bee species of H. itama. For H. itama honey to be commercialised in local and international markets, the adherence of honey to the quality assessment parameters is vital. In this study, moisture content, ash content, electrical conductivity, pH, free acidity, total dissolved solids, and 5-hydroxymethylfurfural (5-HMF) content in H. itama honey collected from three different provinces (Pulau Pinang, Kedah, and Perak) were assessed during its fresh state and after six months at two different storage temperatures (4 and 30 °C) and the obtained values were compared with Malaysian and international standards. In addition to quality assessment parameters, total phenolic and flavonoid contents, and multi-element compositions also were investigated. Subsequently, a geographical discrimination study was carried out using data from the mentioned analysis incorporated with volatile organic compounds in honey using multivariate analysis. The quality assessment analysis during fresh condition revealed that moisture content, ash content, free acidity, and total dissolved solids of most samples failed to meet the requirement set by international standards. In terms of the Malaysian Standard, the ash content of all samples exceeded the limit. Besides, although toxic minor elements (Cd, Ni, and As) were present in some samples, the estimated daily/weekly intake of these multi-elements was still below tolerable daily/weekly intake.
Infuence of mass transfer towards pilot-scale semi-continuous cultivation of chlorella vulgaris
(2020-06-01)
Khoo, Choon Gek
Microalgae, well-known for their prominent photosynthetic efficiency and rapid growth rate emerge as a great feedstock for bio-energy production of third-generation biofuel. In this study, Chlorella vulgaris was chosen as the subject of investigation. The aim was to maximize the biomass production by investigating both the kinetic and mass transfer phenomena in a pilot-scale bubble column photobioreactor (BC-PBR) cultivation system. To account for the maximum microalgal biomass accumulation, the microalgae growth condition was optimized in the semi-continuous cultivation mode. Each cultivation cycle was carried out with 15 days of batch cultivation mode, followed by 3 cycles of 5 days each during semi-continuous cultivation mode. One-factor-at-a-time (OFAT) method was employed to investigate the effects of inoculum concentration of microalgae cells, photoperiod, and aeration rate towards microalgal growth performance, in the range of 0.1 – 0.35 g L-1, 12 and 24 h, and 0.12 – 0.19 vvm, respectively. The underlying mass transfer mechanism between gaseous CO2 and the culture medium were investigated under the optimized growth conditions. In addition, the reusability of the recycled water from the harvesting process was evaluated. To convert the microalgae into application biofuel, the harvested microalgal biomass was then converted into hydrochar via hydrothermal carbonization (HTC) reaction. The effects of hydrothermal temperature and retention time and the properties of hydrochar were studied at the range of 180 – 250 oC and 0.5 – 4 h, respectively. The research results showed that the optimum biomass accumulation was at 0.9819 g L-1, with cultivation conditions of: inoculum concentration of 0.3 g L-1, exposed under continuous (24 h) illumination with light intensity 60 – 70 μmol m-2 s-1, and supplied with compressed air at aeration rate of 0.16 vvm. The cultivation system underwent a bubble breakup mechanism during the transportation of gaseous CO2 into the culture medium with gas-liquid mass transfer coefficient, kLaL(CO2) of 0.45 s-1. Higher CO2 concentration environment did not affect the biomass accumulation due to the solubility limitation of CO2 in the microalgae culture. Based on optimized growth conditions for microalgae, a mathematical model for microalgae growth was developed. By incorporating the mass transfer parameter into the modified growth model, which was validated through an extended 120 days (21 cycles) of semi-continuous cultivation. In addition, the microalgae cells were proven to be able to grow in the recycled harvesting water. On the other hand, the highest energy yield of hydrochar was achieved at 76.59%, at the HTC under 210 oC for 0.5 h. Comparatively, higher heating value (HHV) of hydrochar produced was measured to be 24.51 kJ g-1, which is higher than that of raw biomass (12.58 kJ g-1). Moreover, the HTC process produced an aqueous phase that could be used as an alternative nutrient source for microalgae cultivation, yielding an average biomass accumulation of 0.8483 g L-1, demonstrating the feasibility of close loop cultivation. To conclude, mass transfer was a dominant factor affecting the kinetic growth of microalgae in pilot-scale semi-continuous BC-PBR cultivation system. It further affected the quality of produced biomass, and thus affected the downstream processing route chosen for optimal conversion of bioenergy.
Isoamyl acetate production via miniaturized intensified reactor: a non-enzymatic and solvent free synthesis route
(2022-09-01)
Yusoff Azudin, Nurhazwani
Process intensification refers to technologies that replaces large, expensive, energy-intensive equipment or processes with smaller, cheaper, efficient plants that combine multiple operations into one or fewer devices. This can be applied to isoamyl acetate production, which may provide positives value in economic, sustainability, and inherent safety factors within the overall process. Conventionally, this ester which has a characteristic of banana flavours were produced by extraction from its crops. Limitation in raw material and low yield making it unviable. Fischer esterification mechanism was introduced however consumers are concerned about environmental and health issues resulted from the procedure. Biotechnology route via enzymatic esterification seems to have high potential and industrially sensible however there is still room for improvement via process intensification. The production of isoamyl acetate was intensified by using a miniaturised intensified reactor (MIR) in a non enzymatic and solvent-free condition. Optimized reaction conditions between acetic anhydride and isoamyl alcohol in MIR was found to be at 80'C reaction temperature and 0.5 acid-alcohol molar ratio, with reaction rate constant equals to 1.3x10-4 L s-1 mol-1, 9.00x10-8 L s-1 mol-1 and -1.50x10-4 L s-1 mol-1for k1, k2 and k-2 respectively. Simulation of isoamyl acetate reaction was done via COMSOL Multiphysics ® with a grid independence study conducted giving an optimum mesh of 32.12x103 number of elements with 33s of computational period for 2-D analysis of this MIR study. The esterification reaction between acetic anhydride and isoamyl acetate that took place in this system was found to be a diffusion-controlled reaction. Simulation of reaction in a miniaturized intensified reactor was found to have a regression value of 0.9980 for isoamyl acetate concentration in comparison to the experimental value in the system. Optimization was done via adjustment of MIR by adding multi-inlet at three different locations and three different inlet flowrates. Adjusted MIR at inlet location-1 and location-2 with inlet velocity 1x10-5 m s-1 resulted in a conversion value equal to 0.97. similar as for the unmodified MIR. Inlet location-3 with inlet velocity 1x10-5 m s-1 has a conversion value of 0.96, whereas other inlet location at inlet velocity 2.5x10-5 m s-1and 7.00x10-5 m s-1 have conversion rate lower than the unmodified MIR. It was found that the increase in inlet number only increases a small amount of isoamyl acetate produced at the end of MIR, therefore the original unmodified MIR in this study is the best design with optimum isoamyl acetate production in a non-enzymatic and solvent-free system.
Lanthanum strontium cobalt ferrite-nickel oxide as cathode for intermediate temperature solid oxide fuel cell
(2022-03-01)
Mohamed Rosli, Ahmad Zaki
Solid Oxide Fuel Cell (SOFC) is a device to produce high amount of energy with elevated conversion efficiency that produces water as by-product. Generally, SOFC is operated at a high temperature 1000 ºC with multiple types of fuel for the oxygen reduction reaction process. However, high capital and operating cost hinder SOFC application. Reducing operating temperature to intermediate temperature (600-800 ºC) also known as IT-SOFC can suppress the component degradation as well as improve cell durability and reduce system cost. Lowering the operating temperature decreases the electrode kinetics and increases interfacial polarization resistance and the effects is more prominent for the oxygen reduction reaction (ORR) at cathode side. To minimize the polarization resistance of the cathode, a favourable electronic and ionic conductivity along with excellent catalytic activity for oxygen reduction must be developed. In this research, NiO was added to the state-of-art cathode for IT-SOFC, which is lanthanum strontium cobalt ferrite (LSCF) forming a composite cathode LSCF-NiO. NiO was selected to be added to the LSCF because previous studies suggest that it can improve the performance by enhancing the oxygen reduction reaction (ORR). This thesis focusing on the study regarding the impact on the physical, chemical, and electrochemical performance by utilizing the modified Pechini method. Thermogravimetric analysis (TGA) result suggests that LSCF can form a complete perovskite structure as low as 650 ºC. Further analysis from Fourier transform infrared spectroscopy (FTIR) confirms the complete perovskite structure formation achieved after calcined at 700 ºC. X-Ray diffraction (XRD) also showed the crystal size increase as calcination temperature increases. These findings align with scanning electron microscopy (SEM) and Brunauer–Emmett–Teller (BET) analysis where the particle size increase as increased in calcination temperature. BET result reveals the decrement of specific surface area from 18.3 to 7.9 m2/g when sintered at 700 ºC and 800 ºC, respectively. High purity and well-spread of NiO were confirmed by elemental analysis. There is no trace of gadolinium-doped ceria (GDC) in composite cathode LSCF-NiO via Energy Dispersive X-ray (EDX) indicating good chemical compatibility between the LSCF-NiO and GDC. The Electrochemical Impedance Spectroscopy (EIS) result shows that the LSCF-NiO 800 has a low polarization resistance, Rp of 0.07 Ω cm2 when tested at 800 ºC. The activation energy, Ea obtained was 159.5 kJ/mol. This suggests that LSCF-NiO 800 is suitable to be used as a cathode for IT-SOFC.

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