Mohd Zaki Sulaiman

The effects of carbonization temperature on pore development in palm-shell-based activated carbon

A series of experiments have been conducted to study the effects of carbonization temperature on pore development in palm shell activated carbon. Activation of char prepared at 500, 800 and 900°C was performed at 820°C in a fluidized bed reactor. Activated carbon prepared from high temperature char had a significant amount of micropore volume. For all carbonization temperatures investigated, both micropore and macropore volumes showed maximum values at intermediate carbon burn-off. Only a small amount of mesopore was developed in the initial stage of activation. However, as the level of burn-off increased, a rapid development in mesopore was observed. No clear pattern was demonstrated on the effects of carbonization temperature on the development of mesopore and macropore volumes.

Limiting permeate flux in the clarification of untreated starfruit juice by membrane ultrafiltration

Abstract This paper describes the limiting flux of untreated starfruit juice obtained during clarification using membrane ultrafiltration. Experiments were conducted in a stirred cell unit using membranes of 25,000 MWCO at 30°C for a range of juice concentration varying from 0.46 to 6.5 wt.%. In addition to the limiting flux behaviour, he relationship between the concentration of solute in the bulk solution and the gel layer was also established. The measured experimental data was analysed using the gel model. In general, it was concluded that the gel model could not satisfactorily describe the clarification of starfruit juice. The observed deviation from the model was mainly due to the high pectin content of the juice.

Prediction of dynamic permeate flux during cross-flow ultrafiltration of polyethylene glycol using concentration polarization-gel layer model

Abstract A tubular ultrafiltration model which couples the formation of a cake layer on the membrane surface and the presence of a polarized layer above the cake has been developed, which contains a single constant and the cake layer resistance to be evaluated from experiments. In the model, the tangential flow of feed material is assumed to induce a shearing effect on the cake layer resulting in the re-entrainment the particles into the bulk stream. The validity of the model over a range of cross-flow velocity, transmembrane pressure (TMP) and solute concentration was confirmed using experimental permeate fluxes obtained from the ultrafiltration of polyethylene glycol. Excellent prediction is observed for solute concentrations above some critical value at which a well developed cake layer is believed to have been formed. For concentrations below this value, the model under predicted the steady-state permeate fluxes. By ignoring the presence of the polarized layer, the model always over predict the dynamic fluxes.

Temperature control for chemical reactor using adaptive neural network control strategy

A pilot scaled chemical reactor is constructed and commissioned to study various conventional and advanced control strategies. One of the approaches is the use of neural network inverse model based controller to control the temperature of the chemical reactor. Neural network control was chosen due to its capabilities to overcome the hassle in periodically tuning the conventional controller to obtain a good process response for a certain set point. Tests in a form of load disturbance and set point tracking are carried out to evaluate the neural network controller. The neural network controller exhibits satisfactory performance. Simulation work prior to the planned online implementation is vital to predict the control strategy performance and behavior. With the expected performance in hand, one has the prior knowledge of the control strategy.

Cross flow ultrafiltration studies on solutions of pectin with pulsatile flow in-situ cleaning.

A study was conducted to evaluate the cross flow tubular ultrafiltration behavior of aqueous solutions of pectin. The effectiveness of pulsatile flow as a cleaning-in-place (CIP) technique to improve permeate flux was undertaken on the above mentioned solution. This investigation is part of a study to apply membrane filtration in the clarification of tropical fruit juice. The main variables, which were investigated, include the concentration of pectin, pulse frequency and amplitude. It was found that the amount of pectin in the solution significantly affects its ultrafiltration behavior. From the observed profiles, it is evident that the formation of gel layer on the membrane surface is responsible for the leveling of flux at high pressures. The presence of pectin was found to affect the properties of the solution such as viscosity, pH and the size of pectin colloid. Improvements in the permeate flux for pectin solution were obtained by employing pulsatile flow cleaning-in-place technique. Both pulse frequency and amplitude are important parameters that can improve the improvement of in-situ cleaning method. Similar to several findings reported in the literature, pulsatile flow showed significant effectiveness of about 60% higher flux when the ultrafiltration process is operated under laminar condition.