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Articles by Duduku Krishnaiah
Total Records ( 14 ) for Duduku Krishnaiah
  Duduku Krishnaiah , Awang Bono , Rosalam Sarbatly and Siti Fadhilah
  Supercritical fluid carbon dioxide (SC-CO2) at pressure 19.8 MPa and temperature 51°C with different amount of ethanol (0-100 mL) was studied the extraction of palm kernel oil from palm kernel cake. The amount of oil produced from SFE and Modified ethanol-CO2 are proportional to the amount of ethanol. It was found that α-tocopherol, α-tocotrienol, sterols and fatty acid such lauric acid, myristic acid and oleic acid were present in all of the palm kernel oil sample.
  Duduku Krishnaiah , Rosalam Sarbatly , D.M.R. Prasad and Awang Bono
  The mineral content of some species Caulerpa, Ulva, Sargassum, Eucheuma, Gracilaria, Gelidiella and Kappaphycus was investigated. These are the major variety of seaweeds available in Sabah South China Sea (Malaysia) and contained high proportions of ash content (20.56- 40.5%). The green and brown seaweeds ash content (37.27-40.5%) was higher than the red seaweeds (20.56-22.41%). The iron content was rich in the sequence of Gelidiella>Caulerpa> Sargassum> Eucheuma and its range was found to be 6.6-10.94 mg/100 g dry weight. The major seasonal deviation was found to be 9.25% Mg, 6.44% Ca and 5.3% Fe. This study was conducted to create a nutritional data for consumption and utilization in the industry.
  Rosalam Sarbatly , Duduku Krishnaiah , Richard England , Sariah Abang and Jeanette Jeffery
  In this study, the boundary-resistance layer model and solution-diffusion model were used to investigate the applied driving pressure force technique and the concentration driving force technique, respectively, for the production of intravenous drip solution. A 5 kD monolithic membrane coated with Al2O3 and TiO and NaCl aqueous solution as the feed solution was used. The results show that the boundary-resistance layer model diffusivity coefficient, D = 1.8x10–9 m2 sec–1 and the mass transfer coefficient, k = 1.1910–4 m sec–1 which were both slightly higher than the solution-diffusion model. Applying Fick`s law for the solution diffusion model, the calculated operating pressure inside the lumen was 15 kPa. Clearly, the findings suggested that the boundary-resistance layer model should be chosen for the production of pure and sterile intravenous salt solution as it provided higher diffusivity and mass transfer coefficient than the solution-diffusion model.
  Collin G. Joseph , Awang Bono , Duduku Krishnaiah , Chow Yee Ling and Ng Chiew Ban
  The aim of this investigation was to study the morphology and sorption kinetic studies of an L-type activated carbon prepared from Oil Palm Shells (OPS) by way of the two stage activation method in self-generated atmosphere using a muffle furnace. Both L-type dehydrating agents, zinc chloride and phosphoric acid were used as the chemical activation agent. For the ZnCl2 samples, the optimum adsorption capacity was obtained when the samples were subjected to semi-carbonization of 400°C, 5 M ZnCl2 impregnating solution, followed by pyrolysis at 400°C. Whereas for the H3PO4 samples, semi-carbonization of 400°C followed by 4.5 M H3PO4 impregnating solution and pyrolysis at 400°C has shown to produced the optimum adsorption capacity. All activated carbons were fitted well in the Langmuir adsorption isotherm and the pseudo-second-order kinetics. These results demonstrated that this agricultural waste has the potential to be converted into high-capacity adsorbent for the remediation of waste waters.
  Duduku Krishnaiah , Siva Kumar Kumaresan , Matthew Isidore and Rosalam Sarbatly
  This study outlines the artificial neural networks application to improve the prediction capability by investigating the effect of data sampling, network type and configuration as well as the inclusion of past data at the neural network input. Multi layered perception and Elman network were used. Validation results using input data based on 5 min and 1 h sampling was compared. It was found that the 1 h sampling yielded better prediction. Different network configurations were also compared and it was observed that although the larger network showed better prediction capability during the training phase, it was the smaller network that demonstrated better prediction in the validation stage. The inclusion of past data into the neural network was also studied. The generalisation degraded as more past data were included.
  Duduku Krishnaiah
  ICCBPE-2005/SOMChE conference discussed the recent developments in chemical and bioprocess engineering. In this introduction to the special issue dedicated to the conference, an overview of selected papers outlined.
  Reddy Prasad , Duduku Krishnaiah , Awang Bono , Paulraj Pandiyan , Rosli Bin Mohd Yunus and Naveena Lakshmi
  The application of Artificial Neural Networks in chemical engineering field is being under immense research. One of the physical properties of every material has its own intensity to absorb the sound waves. Carrageenans are water-soluble gums, which occur in certain species of red seaweeds. They are sulfated natural polymers made up of galactose units. Carrageenan consists of a main chain of D-galactose residues linked alternately α - (1→3) and β - (1→4). The decibel frequency analyzer dbFA - 32 has been used for this analysis. The sound signals are captured using the hydrophone. The analog signals are then digitized at different octave frequencies. These are used to generate the frequency power spectrum. The change in the spectrum is proportional to the concentration of the material in the solution. The normalized data is used as a input to a feed forward neural network model. In this study, a simple scheme is proposed to estimate the amount of carrageenan present in a solution using under water acoustics and Artificial Neural Networks. This method is useful for the direct estimation of carrageenan in food, pharmaceutical and cosmetic industries. It can be useful for online measurement of compound in the industries.
  Reddy Prasad , Muhammad Syaddad Bin Zainol , Iqbal Ahmad and Duduku Krishnaiah
  Microwave-Assisted Extraction (MAE) was used to extract total triterpenoids from Ceriops Decandra sp. The extraction procedure was optimized and compared with the Soxhlet extraction technique. Triterpenoids were quantified by UV-VIS Spectrophotometer via colorimetric method without any further treatment. MAE shows the highest extraction efficiency with lower time compared with Soxhlet extraction method. MAE requires 20 min to get the yield of triterpenoids at 1.1785% while the Soxhlet extraction methods need several hours and gives lower yield. The other factors affecting the MAE extraction rate were also discussed, such as extraction time, temperature and ratio of solvent to material. Optimal conditions of MAE from this research can be concluded as follows: 20 min at 80°C, the ratio of solvent to material is 15 by using 95% ethanol as the solvent. The developed MAE method provided a good alternative for the extraction of triterpenoids in Ceriops Decandra sp. as well as other herbs species.
  Duduku Krishnaiah , Rosalam Sarbatly , S.M. Anisuzzaman and Rendy Kasin
  Dense ceramic membrane has become a major selection for its potential to give high oxygen enrichment from surrounding air. The separation through dense ceramic membrane has overcome several limitations of polymeric membrane material and therefore it is capable of performing efficient means of oxygen production. Experiments were carried out to study the potential of ceramic membrane for oxygen system on oxygen/nitrogen mixtures, where the effects of operating pressure and temperature were observed and discussed. The oxygen concentration in the permeate stream increases when the operating pressure increased for each set of air flow rate of 20, 30 and 40 LPM. The permeate oxygen concentration at 40 LPM and 25 psi was found to be 5.30 ppm where as at 20 LPM and 150°C and was 5.13 ppm.
  S.M. Anisuzzaman , Awang Bono , Duduku Krishnaiah , Norazwinah Azreen Hussin and Hong Ying Wong
  The objective for this work was to study the characteristics of Semi Refined Carageenan (SRC) which extracted from Kappaphycus alvarezii. The production of SRC was conducted by alkali treatment of seaweed and to obtain the powder used spray drying technique. This analysis based on two independent parameter which are concentration of potassium hydroxide (KOH) and extraction time. Extraction temperature during alkali treatment process was fixed as constant which was 70-80°C. The optimization of extraction process parameters and the experimental design were done based on Central Composite Design (CCD) of Response Surface Methodology (RSM). Gel viscosity, powder weight of SRC, particle size and gel strength were studied as responses. The bounds of all these factors keyed in the RSM to get the predicted number of experiments. Optimum process extractions for spray drying technique result showed at 6.70% of KOH concentration and 74.70 minute extraction time. At optimum conditions the viscosity of the SRC gel was found as 111.80 cP and the particle size of SRC powder was found as 86.88 μm. Gel strength was optimize at 85.60 g cm-2 and SRC powder production as 5.01 g.
  Duduku Krishnaiah , Rosalam Sarbatly , S.M. Anisuzzaman , Rajesh Nithyanandam and Phong Ming San
  This study conducted adsorption experiments on azeotropic and non-azeotropic mixtures at a constant temperature in the presence and absence of ultrasound. Ultrasound waves were applied at a frequency of 21 kHz and amplitude of 25% at atmospheric pressure. The adsorption of azeotropic and non-azeotropic mixtures was evaluated according to Gibbs dividing plane theory. The results indicated that the adsorptive capacity of azeotropic and non-azeotropic mixtures on activated carbon decreased in the presence of ultrasound.
  Duduku Krishnaiah , Rosalam Sarbatly , Awang Bono , S.M. Anisuzzaman and Sharmila Subramaniam
  Transesterification of methyl ester is a reversible reaction and requires excess methanol to drive the reaction forward. In this study, Polyethylene Glycol (PEG) membrane reactor was used to separate glycerol during reaction, to attain high conversion of palm oil at lower methanol to oil ratio. Thus reduces the amount of methanol used. The transesterification of palm oil was performed using base catalyst. Experiments were performed in the membrane reactor in batch mode at different catalyst concentrations and different molar ratio (methanol/oil). Asymmetric polyethersulfone ultrafiltration flat sheet membranes with Polyethylene Glycol (PEG) of different molecular weight as additive were prepared by phase inversion process from casting solution containing Polyethersulfone (PES) as polymer, N,N-porylydone (NMP) as solvent and PEG of different molecular weights namely PEG 200, PEG 300 and PEG 400 as additives. The results show that PES with different PEG as additive are suitable for separation of glycerol during the reaction.
  Duduku Krishnaiah , Awang Bono , S.M. Anisuzzaman , Collin Joseph and Teo Bee Khee
  Carbon dioxide (CO2) among other air pollutants is a major culprit to the greenhouse gases that is fueling global warming. To mitigate global warming, Kyoto Protocal urges 37 industrialized nations and European Union to reduce their greenhouse gas emissions to a level of 5.2% on average lower than those of 1990 during the period of 2008-2012. It is therefore essential to develop the CCS technologies to cope with the global demand of CO2 reduction. In this study the technologies of CO2 removal are reviewed.
  Awang Bono , NurAbidah Ramlan , Duduku Krishnaiah , Norina Yadin , Yan Yan Farm and Chi Ming Chu
  Adsorption isotherm is essential component in the understanding of the adsorption process. Several methods of the measurements, analysis and interpretation of adsorption from solution have been reported in the literature. Most of the measurements of adsorption isotherm from solution were involved the measurement of excess isotherm conducted at low region of sorbates concentration. Direct interpretation of excess adsorption isotherm as adsorption isotherm is always been practice. Therefore, in this study, on the measurement of the adsorption isotherm from solution of non-azeotropic organic solvent mixture onto porous adsorbents for whole range of liquid concentration was conducted. The study included the measurement of excess adsorption isotherm using conventional technique. Theoretical analysis and interpretation of adsorption isotherm from the excess isotherm were conducted using Pseudo Ideal Adsorption, Gibbs Dividing Plane Model and Langmuir-Fruendlich binary isotherm model. For organic solvents, acetone and propanol were chosen as the adsorbates due to the non-azeotropic properties in the mixture. Activated carbon and silicalite were chosen as adsorbents due to the different in their porosity such as macro porous and micro porous structure. The result of the study has revealed that the adsorption isotherm of non-azeotropic mixture onto activated carbon and silicalite can be interpreted as monolayer type of adsorption.
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