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Articles by R.M. Yunus
Total Records ( 6 ) for R.M. Yunus
  M. Jusoh , R.M. Yunus and M.A. Abu Hassan
  Freeze concentration freezes or crystallizes water component in a solution out as ice crystals and leaves behind a highly concentrated solution. Conventional Suspension Freeze Concentration (SFC) system has to deal with difficult separation of ice formed in a suspension of the mother liquor, which leads to a high cost of operation. Scraped surface heat exchanger used to form seed ice to ensure production of large ice crystals also hiked up the capital cost involved. Progressive Freeze Concentration (PFC) is believed to be able to reduce the capital and operation cost by eliminating some unit operations used. In PFC, ice crystals were formed progressively as a single block of ice, on the surface where cooling is supplied. In this particular study, a new helical structured copper Crystallization Chamber (CC) was designed and fabricated. Three operating parameters which affect the performance of the system were investigated namely the circulation period, circulation flow rate and coolant temperature. Effective partition constant, K was used as an indication of the system efficiency and to assess its performance, calculated from the volume and concentration of the solid and liquid phase. Circulation period was found to produce a constant value of K at each period tested with the CC. It was also discovered that higher flowrate resulted in a lower K, which translated into high efficiency. The efficiency is the highest at 1000 mL min-1. The process also gives the highest efficiency at a coolant temperature of -6°C.
  Maryudi , R.M. Yunus , A.H. Nour and M.H. Abidin
  The explorations of prodegradant additives for plastics from trans-metals organic salts have been being conducted. This study reports a method of synthesis of manganese carboxylates and their characterization. The new method involves reaction between molten carboxylic acid with sodium hydroxide in alcoholic solution to produce sodium carboxylate and continued by reacting sodium carboxylate with chloride salt of manganese. First reaction and second reaction were conducted at 80-85°C and under perfect agitation. Second reaction took place well in the low concentration of manganese chloride, about 0.25 M or less. Manganese carboxylates (manganese laurate, manganese palmitate, manganese stearate) densities are 0.376, 0.227 and 0.201 g cm-3, respectively. Their onset melting points are 104.95, 111.27 and 114.69°C, respectively, obtained by Differential Scanning Calorimeter (DSC) test. Thermogravimetric Analyzer (TGA) test have been done on manganese carboxylates to investigate their thermal stabilities. The results obtained in this study have exposed the capacity of manganese carboxylates stability at processing temperature of polyethylene. It was also found that manganese carboxylates were insoluble in water, ethanol, acetone, n-hexane, cyclohexane, benzene and toluene.
  N. Nadir , M. Mel , M.I.A. Karim and R.M. Yunus
  The two-step enzymatic hydrolysis of sweet sorghum and cassava were performed by commercially available α-amylase and glucoamylase and further ethanol fermentation of the obtained hydrolyzates by Saccharomyces cerevisiae were studied. For both sweet sorghum and cassava, the hydrolysis and fermentation were done in a 2 L stirred tank bioreactor, B-Braun fermenter, by using the same conditions. The amount of glucose obtained after hydrolysis process was greater in sweet sorghum compared to cassava, which are 50.07 and 40.00 g L-1, respectively. Also, sweet sorghum gave higher ethanol concentration than cassava at the 64 h of fermentation process, which are 40.11 and 34.07 g L-1, respectively.
  M.N. Razali , R.M. Yunus , Z. Jemaat and S. Alias
  This research was conducted to evaluate the feasible methods to recycle and reuse the monoethanolamine (MEA) in the CO2 removal unit and at the same time, maintaining the amine concentration level. The adsorption performance of chitosan was compared to activated carbon, alum and zeolite. Amine contaminated waste water contains about 230,000 mg L-1 of COD, 69,000 mg L-1 of suspended solid, 596 mg L-1 of residue oil and 41% of amine concentration. Preliminary results showed that application of chitosan managed to reduce the COD by up to 83%, suspended solid by up to 57 and 95% for residue oil removal at the defined optimum experimental condition (weight of absorbent: 5%, contact time : 1 h, mixing rate: 100 rpm, ambient temperature : 25-30°C and pH 11). For activated carbon, alum and zeolite, the results showed reduction of COD by up to 80, 73 and 70%, suspended solid by up to 49, 43 and 38%, respectively. For residue oil removal, activated carbon was 87%, alum was 64% and zeolite was 46% at the same experiment conditions. In conclusion, chitosan showed the best adsorption performance followed by activated carbon, alum and zeolite.
  S.S. Suradi , R.M. Yunus , M.D.H. Beg , M. Rivai and Z.A.M. Yusof
  The incorporation of lignocellulosic materials as a reinforcing component in polymer composites has received increased attention, particularly for price driven and high volume applications. This development reflects several advantages of lignocellulosic fibbers over their inorganic counterparts, including lower density, reduced abrasiveness to expensive moulds and mixing equipment, as well as being less expensive. Moreover, lignocellulosic based fibers are derived from renewable resources. The major challenge for natural fiber composites is their inherent poor adhesion between fiber and the matrix, high moisture absorption and UV degradation. Lignin and hemicelluloses are the components of natural fiber which are mostly responsible for moisture absorption and UV degradation. In this study, the lignocelluloses (Oil Palm Empty Fruit Bunch) were treated with alkaline peroxide to remove lignin and hemicelluloses. Composites were produced with treated and untreated fiber using up to 50% fiber with polypropylene (PP) matrix using twin-screw extruder followed by injection molding. Composites were characterized using tensile and flexural testing, SEM and TGA. The tensile and flexural modulus were found to be higher for alkaline peroxide treated fiber composites compared to untreated fiber composites. To improve interfacial bonding, additional of coupling agents also found to provide higher strength and modulus of composites. The treated fiber and their composites provided higher thermal stability compared to untreated fiber and their composites, respectively.
  B. Wiyarno , R.M. Yunus and M. Mel
  This study aims at describing the characteristics of the microalgae oil extraction from Nannochloropsis sp. using soxhlet and ultrasonic. There were two extraction processes that were investigated, Soxhlet-assisted Extraction (SE) and Ultrasonic-assisted Extraction (UE) and both used ethanol solvent. A combination of several criteria was selected to find the characteristics of each extraction. In the SE, a variety of ethanol concentration and time were used; whereas in the UE, a variety of ethanol volume, time and temperature were applied. The given frequency for all UE treatments was 40 kHz. The quality of algae oil proceeded by SE was shown by the level of FFA (Free Fatty Acid) and saponification number. In the SE study, the best combination was gained when the ethanol concentration was 70% and the given time was 200 min in which the FFA level was 9.4% and the saponification number was 286.8. While in the UE study, 51.6 min, 98% of ethanol concentration and 69.62°C were the best circumstance in which the quantity of the oil yield got its maximum. In SE, the higher solvent concentration, the higher FFA level and saponification number were gained. However, after reaching the peak at particular circumstance, the saponification number decreased gradually. Meanwhile, UE reduced the length of extraction time.
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