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Institution

Universiti Teknologi Malaysia

EducationJohor Bahru, Malaysia
About: Universiti Teknologi Malaysia is a education organization based out in Johor Bahru, Malaysia. It is known for research contribution in the topics: Membrane & Control theory. The organization has 21644 authors who have published 39500 publications receiving 520635 citations.


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Journal ArticleDOI
TL;DR: In this article, the limitations and implications of using KOH in the activation process are highlighted, and the selection of appropriate potassium salts for activated carbon preparation is also recommended; however, the adverse drawbacks of employing KOH have been overlooked in many of the published studies.
Abstract: Copyright © Korean Carbon Society http://carbonlett.org Over the years, the furnace has been used as a common heating method to manufacture activated carbon. In a furnace, heat is transferred through conduction and convection. The outer surface of the sample is in contact with the generated heat, which slowly diffuses inwards as a result of the thermal gradient between the surface and the core of the material’s particles. Another method of heating employs microwave irradiation. Even though it is less energyand time-consuming, the microwave method has several critical issues with respect to temperature control and thermal runaway, especially in the scaling-up of the microwave heating process [1]. Generally, the activation of a carbonaceous precursor can be performed through physical (steam, air or CO2) or chemical activation (activators such as ZnCl2, KOH, etc.) or a combination of both. The chemical activation is normally preferable over physical activation since it is a faster process with a lower activation temperature. Moreover, the activated carbon produced via chemical activation usually possesses high specific surface area (as determined by the Brunauer-Emmett-Teller, BET method), good pore development and high carbon yield [2,3]. In recent years, potassium salts such as KOH and K2CO3 have been widely used in the manufacture of low cost activated carbon. It has been found that activated carbon prepared by KOH activation is highly microporous when compared to that produced through ZnCl2 or H3PO4 activation [4-6]. Besides, KOH also enhances the specific surface area and the formation of—OH functional groups on the carbon surface [7]. Over the past 5 years, many advantages of KOH activation have been revealed in the literature [8]. However, the adverse drawbacks of employing KOH have been overlooked in many of the published studies. In this paper, the preparation of activated carbon by KOH activation using conventional heating is reviewed and discussed. The limitations and implications of using KOH in the activation process are highlighted. The selection of appropriate potassium salts for activated carbon preparation is also recommended. The physical preparation of activated carbon is comprised of two major processes, namely, carbonization and activation of the carbonized sample [4]. Chemical activation is a single step process, as both carbonization and activation occur simultaneously at temperatures ranging between 400oC and 700oC, which is lower than that of physical activation [9]. However, in some cases, additional carbonization or a pre-carbonization step is performed to produce char prior to chemical impregnation and activation [5,4,10-13]. Thus, potassium hydroxide activation can be achieved through either direct chemical activation or char-impregnated chemical activation. In direct chemical activation, a selected carbonaceous precursor is first dried overnight to remove moisture and then chemically treated at a desired impregnation ratio (weight of KOH over weight of precursor). The impregnated solid is then heated in a furnace at a specified temperature and time. Carbonization of the precursor is often omitted when the impregnated solid is already suitable for activation. Table 1 exhibits recently developed activated carbon preparation methods using various precursors and KOH activation with conventional heating. From Table 1, it can be seen that DOI: http://dx.doi.org/ DOI:10.5714/CL.2015.16.4.275

158 citations

Journal ArticleDOI
TL;DR: The findings indicated that the RF-NBT model showed an increased prediction accuracy relative to the NBT model using both the training and validation datasets, and theRF-N BT model exhibited a greater capability for landslide susceptibility mapping.
Abstract: The main objective of this study was to produce landslide susceptibility maps for Langao County, China, using a novel hybrid artificial intelligence method based on rotation forest ensembles (RFEs) and naive Bayes tree (NBT) classifiers labeled the RF-NBT model. The spatial database consisted of eighteen conditioning factors that were selected using the information gain ratio (IGR) method. The model was evaluated using quantitative statistical criteria, including the sensitivity, specificity, accuracy, root mean squared error (RMSE), and area under the receiver operating characteristic curve (AUC). Furthermore, the new model was compared with the NBT, functional tree (FT), logistic model tree (LMT) and reduced-error pruning tree (REPTree) soft computing benchmark models. The findings indicated that the RF-NBT model showed an increased prediction accuracy relative to the NBT model using both the training and validation datasets, and the RF-NBT model exhibited a greater capability for landslide susc...

158 citations

Proceedings Article
01 Mar 2011
TL;DR: In this paper, a review of the existing web caching and prefetching approaches is presented and some studies that take into consideration the impact of integrating both Web caching and web pre-fetching together.
Abstract: Web caching and prefetching are the most popular techniques that play a key role in improving the Web performance by keeping web objects that are likely to be visited in the near future closer to the client. Web caching can work independently or integrated with the web prefetching. The Web caching and prefetching can complement each other since the web caching exploits the temporal locality for predicting revisiting requested objects, while the web prefetching utilizes the spatial locality for predicting next related web objects of the requested Web objects. This paper reviews principles and some existing web caching and prefetching approaches. The conventional and intelligent web caching techniques are investigated and discussed. Moreover, Web prefetching techniques are summarized and classified with comparison limitations of these approaches. This paper also presents and discusses some studies that take into consideration impact of integrating both web caching and web prefetching together.

158 citations

Journal ArticleDOI
TL;DR: The effect of antenna losses due to rain on a 26 GHz microwave link and the technique of extracting the losses from the measured rain attenuation will provide useful information in the microwave link planning and design in tropical regions.
Abstract: This letter discusses the effect of antenna losses due to rain on a 26 GHz microwave link and the technique of extracting the losses from the measured rain attenuation A 2-feet parabolic dish antenna with horizontal polarization has been used in the study The measurement results have been compared with those obtained from other locations in Malaysia and some other Published Research works The study will provide useful information in the microwave link planning and design in tropical regions; and it can also be adapted to satellite communication operating at ka-band

158 citations

Journal ArticleDOI
TL;DR: In this paper, the role of inorganic nanomaterials in advancing the characteristics and separation performance of polymeric ultrafiltration membranes is discussed, where metal oxides, metals and carbon-based materials are incorporated into polymeric membranes to render the desired properties for ultra-filtration separations.
Abstract: Due to the rapid expansion of nanotechnology and the increasing range of nanomaterials under production and development, a significant amount of research interest has been dedicated to the innovative exploitations of various inorganic nanomaterials in environmental applications. The incorporation of inorganic nanomaterials as fillers within a polymeric matrix has expanded opportunities to produce a multifunctional nanocomposite membrane that is capable of performing tasks beyond separation alone. The architectures and performances of these nanocomposite membranes have triumphed over polymeric membranes to overcome the underlying conspicuous drawbacks. This review aims to shed more light on the roles of inorganic nanomaterials in advancing the characteristics and separation performance of polymeric ultrafiltration membranes. Inorganic nanofillers such as metal oxides, metals and carbon-based materials are incorporated into polymeric membranes to render the desired properties for ultrafiltration separations...

157 citations


Authors

Showing all 21852 results

NameH-indexPapersCitations
Xin Li114277871389
Muhammad Imran94305351728
Ahmad Fauzi Ismail93135740853
Bin Tean Teh9247133359
Muhammad Farooq92134137533
M. A. Shah9258337099
Takeshi Matsuura8554026188
Peter Willett7647929037
Peter C. Searson7437421806
Ozgur Kisi7347819433
Imran Ali7230019878
S.M. Sapuan7071319175
Peter J. Fleming6652924395
Mohammad Jawaid6550319471
Muhammad Tahir65163623892
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
202371
2022347
20212,811
20203,003
20193,148
20182,980