Zaki Yamani Zakaria

Review: Parametric Study on the Performance of Progressive Cryoconcentration System

Progressive cryoconcentration (PC) is gaining acceptance in solution concentration process as it could provide an easy separation and ice purification with relatively low energy. In fact, the advantages of PC process as compared to the other concentration methods have led the growth of related studies that aim to provide the best system or condition for the separation process involved. Apart from the provision of appropriate equipment, the PC process should also be conducted at its optimum conditions of operating parameters involved, which could give the highest separation efficiency. Hence, relationship between the parameters, which covers both manipulated and determinant parameters should be studied first. This review summarizes the previous conducted studies on the effect of various operating parameters on the PC performance, which includes effect of coolant temperature, solution flowrate, initial solution concentration, freezing time, ice crystal front growth rate, and stirring rate.

The Effect of Coolant Temperature and Stirrer Speed for Concentration of Sugarcane via Progressive Freeze Concentration Process

Progressive freeze concentration system engaging an anti-supercooling holes crystalliser was used to concentrate sugarcane juice in order to increase its sugar content and achieve highly concentrated sugarcane juice without initial supercooling or ice lining process. The other function of this process is to retain the aromatic compound, quality and avoid operating pressure compared to using another separation process like evaporation and reverse osmosis. The process was conducted with a specific process condition including coolant temperature, stirrer speed, constant initial concentration and process time. The parameter of coolant temperature and stirrer speed was in the range of -6 to -14 °C and 150 to 350 rpm, meanwhile the constant process time was set at 180 min and constant initial concentration at 12 - 13 % Brix. The effects of coolant temperature at stirrer speed were evaluated and observed based on the value of effective partition constant, Kvalue, and concentration efficiency of the sugarcane juice. This system achieved its best performance at intermediate coolant temperature which is -8 °C and stirrer speed of 300 rpm, referring to the best K value and concentration efficiency with the values of 0.438 and 51.15 %. The heat transfer analysis was done by determination of overall heat transfer coefficient, where the highest overall heat transfer coefficient, Uo was found at coolant temperature of -8 °C and stirrer speed of 350 rpm, implying that the smallest thickness of ice was formed on the wall of the crystalliser at this condition, which favours the heat transfer in the process.

Adsorption of Free Fatty Acid in Biodiesel from Palm Fatty Acid Distillate Using Koh-activated Starch

The elimination of free fatty acids (FFA) from biodiesel is usually performed in industrial practice using different units for neutralization with caustic, washing and drying of the fuel. However, adjustment of the free fatty acids can be performed in only one operation using bleaching tanks and commercial adsorbents. In this work, purification of crude biodiesel fuel from palm fatty acid distillate (PFAD) has been done by employing dry washing method for the removal of FFA using modified potato and cassava starch and compared with commercial magnesium silicate. The molar ratios of KOH/starch in modified potato and cassava, i.e. 0.10:1, 0.15:1 and 0.25:1 were obtained by varying concentrations of KOH: starch samples. The morphology, crystal structures, surface area and pore size of the adsorbents were characterized by scanning electron microscopy (SEM), X-ray diffraction method (XRD) and Brunauver-Emmett-Teller technique (BET). The adsorption efficiency of the synthesized adsorbents in biodiesel was studied by varying dosage of adsorbents for 50 g of biodiesel at 30 oC for 30 min. The results showed that the modified potato and cassava at 0.25:1 KOH/starch molar ratio at room temperature presented the highest efficiency in adsorption of residual FFA at 69.46 % and the highest adsorption capacity of modified cassava and potato starch was 233 mg and 228 mg of FFA per gram of adsorbent. The comparison of dry washing with commercial magnesium silicate, presented good efficiency in the removal of FFA and depicted similar behaviour independent of the kind of adsorbent employed.

Renewable Coconut Shell Activated Carbon Based for Ethyl Orange Dye Removal

A study on the performance of a renewable activated carbon towards concentration reduction for ethyl orange dye was conducted. The coconut shell activated carbon was prepared by varying the carbonization temperature and impregnation ratio of chemical activation agent and coconut shell. The effect of adsorbent dosage and temperature on performance of the synthesized AC was determined. The finding showed that the impregnation ratio of 2 and carbonization temperature of 800 °C were the best condition to synthesis the activated carbon. The result also showed that the increment in adsorbent dosage increased the sorption capacity for coconut shell AC. However, the temperature changes caused the fluctuation in reduction of dye concentration. Comparison with commercial activated carbon indicated that coconut shell AC had proved to be a low cost and efficient adsorbent in this research.

Developing teamwork skills among first year chemical engineering students using cooperative problem-based learning in "introduction to engineering" course

This study was conducted to investigate the development of teamwork skills among first year chemical engineering students using Cooperative Problem-Based Learning in “Introduction to Engineering” course. A pre and post-test questionnaire using Team Assessment Tool (TAT) established by Moore and colleagues was administered to 52 first-year chemical engineering undergraduates. This instrument is useful to measure individuals’ rate on team’s performance using 24 Likert-scale items. The main constructs for this instrument consist of interdependency, potency, goal-setting and learning. The descriptive analysis provides the mean, standard deviation and frequency to see the significance of the pre and post-test results. The paired sample t- test was used to determine the significant differences of teamwork level between at the beginning and end of the course. The results from paired sample t-test shows that there was significant increment (p < 0.05) for teamwork in its constructs like interdependency, potency, goal-setting and learning. This shows that the students have developed teamwork skills after undergoing the “Introduction to Engineering” course.

Water purification of lake water using progressive freeze concentration method

Progressive freeze concentration method using stainless steel coil crystallizer was performed to concentrate and purify water from lake in Universiti Teknologi Malaysia, UTM. The study focused on the effect of operation time in range of 5 to 25 min and coolant temperature in range of -5 to -17 °C with constant pump rotation (450 rpm), initial biological oxygen demand (16.83 mg/L), total suspended solid (566 mg/mL) and turbidity (300 NTU). In water treatment using this progressive freeze concentration setup, a layer of pure ice crystal is produced on the inner wall of the crystallizer, leaving behind concentrated mother liquor. In order to determine the efficiency of the process, values of parameters such as biological oxygen demand (BOD5), total suspended solids (TSS) and water turbidity were measured. High system efficiency was observed at coolant temperature of -11 °C and operation time of 10 min giving BOD: 2.23 and 2.47 mg/L TSS: 28 and 36 mg/L and turbidity 1.22 and 1.25 NTU, respectively. The current technology of crystallizer design was found to be relevant to reduce BOD5, TSS and turbidity of water lake.

Electrical conductivity, thermal, rheological and morphological Characteristics of Grafted Blend of Polypyrole and Polypropylene

Grafted blends of polypyrole (PPy) and polypropylene (PP) were prepared by melt mixing in assisted sonicator twin screw extruder. Dicumyl peroxide (DCP) was used as grafting agent. Electrical conductivity, thermal, rheological and morphological properties of the blend were investigated as a function of PPy composition. Electrical conductivity of PPy-g-PP increased with increasing PPy content. Thermal analysis shows a decrease in melting temperature and crystallinity values as the PPy content increased. This indicates a strong interaction between PPy and PP phase while DCP has successfully acted as crosslinking and grafting agent. Scanning electron microscopy observations on tensile fracture shows an agglomeration behaviour become obvious as PPy content was increased. Despite of that, PPy particles were highly dispersed in the PP matrix indicating a good interaction between the component polymers.

Preparation and characterisation of microwave assisted chlorinated glucose for biodiesel production from palm fatty acid distillate

Biodiesel has a remarkable potential in substituting petroleum based fuel because it is non-Toxic, biodegradable, renewable and sulphur free. In this work, the esterification of palm fatty acid distillate (PFAD) over microwave assisted chlorinated glucose catalysts was investigated. PFAD is being chosen due to its lower cost compared to palm oil and stable its properties. Incomplete carbonised glucose (ICG) was prepared by heating the D-(+)-Glucose in microwave and crushed into powder form. The ICG powder was mixed with concentrated HCl acid and heated for 5, 7 and 9 min in microwave. The catalyst was then diluted with distilled water and washed using hot distilled water. The catalyst was then dried prior to the catalytic activity. Esterification conditions were molar ratio methanol: oil of 10 : 1, temperature at 70 °C, 2.5 wt% of catalyst loading and 90 min reaction time. Characterisation of catalyst was carried out by using Brunauer-Emmett-Teller (BET), Scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform-infrared (FTIR). The maximum biodiesel yield obtained was 91.78 % using the optimal chlorinated glucose catalyst which was heated for 5 min in the microwave. It can be deduced that microwave assisted chlorinated glucose acid catalyst could potentially reduce substantial amount of time, energy and cost to produce low cost feedstock biodiesel.

Dielectric properties for extraction of orthosiphon stamineus (Java Tea) leaves

A dielectric properties study was performed at ISM frequencies and a range of temperatures (25 – 45 °C) on the extraction of Orthosiphon Stamineus (Java Tea) leaves system in order to relate their dielectric properties to microwave heating mechanisms and design of microwave applicator quantitatively. The main results concluded that the heating mechanism of the extraction mixture in an electromagnetic field was controlled by the dielectric properties of solvent (water), where the solvent was the major component (> 90 % v/v) as well as the component with highest dissipation factor (tan d). The penetration depths of extraction mixture at ambient temperature (25 °C) are 3.8 cm, 3.2 cm and 1.4 cm at ISM frequencies of 0.433 GHz, 0.915 GHz and2.45 GHz. These tiny penetration depths limit the potential to achieve the successful scale up of a microwave- assisted extraction of Orthosiphon Stamineus leaves in batch mode at ISM frequencies. This will lead to inhomogeneous bulk temperature distribution within the extraction mixture and irreproducible extraction yield without sufficient stirring and stirrer compatible with microwave system. A fast heating rate based on a high value of tan d of the extraction mixture revealed that the microwave heating technique has a great potential in reducing the processing time especially at heating up stage compared to conventional thermal heating technique in extraction of Orthosiphon Stamineus leaves. The dielectric properties of extraction mixture are worth to be considered to certify the consistency and reproducibility of the microwave-assisted extraction at large scale production.

Effect of Coolant Temperature on Desalination Process via Progressive Freeze Concentration

The world is still suffering from a shortage of clean water supply and the problem is expected to become more serious in the future. Consequently, researchers have been trying to find the best solution to address this problem by introducing new desalination technologies that are able to accommodate the demand for clean water which is increasing from time to time. One of the new technologies introduced is the desalination of seawater through freeze concentration. In this study, progressive freeze concentration (PFC) is implemented to produce pure water in the form of ice crystal block and leave behind a higher concentration solution. The effect of coolant temperature was investigated and the efficiency of the system was reviewed based on the value of effective partition constant, K which is defined by the ratio of solute in ice and liquid phase. The low value of K leads to the best efficiency for the system. Apart from that, the efficiency, E% and salinity reduction were also calculated in order to determine the system performance.