Mohamed Zulkali Mohamed Daud

Synergistic action of deep eutectic solvents and cellulases for lignocellulosic biomass hydrolysis

Abstract The increased awareness of environmental and economic issues has led many researchers to seek green and low-cost solvent for the conversion of lingocellulosic biomass to bioenergy. In this context, deep eutectic solvents, a new class of ionic liquids, have been regarded as greener substitute to conventional solvents for pretreatment of biomass. This paper is concerned with the stability and synergicity action of deep eutectic solvents for the digestion of biomass. The stability was studied by incubating commercial cellulases to different concentration of ethylene glycol–choline chloride-based deep eutectic solvent. The synergistic tests were studied by performing enzymatic saccharification after pretreatment of rice husk with deep eutectic solvent at various temperatures. The stability test showed that, the commercial cellulase activity retained more than 90% of relative activity after 1 hour of incubation in 10(%,v/v) deep eutectic solvent at 30°C. The prepared deep eutectic solvent in combination with commercial cellulases study showed that the higher pretreatment temperature improved the production of simple sugar from rice husk.

Scaling up adult stem cells for regenerative medicine

Regenerative medicine is an emerging inter-disciplinary field of research. The ultimate goal for regenerative medicine is to repair or replace damaged, dying cells, tissues or organs. Adult stem cells bioprocessing is one of the options for regenerative medicine albeit the challenges in process development. A few issues on expansion or scaling up media development, handling of cell and bioreactor are reviewed and discussed in this paper. The powerful engineering tools in process characterisation and optimisation using design of experiment (DOE) method is an excellent approach in identifying pertinent features for scaling up stem cells.

Optimization of the pyrolysis process of empty fruit bunch (EFB) in a fixed-bed reactor through a central composite design (CCD)

The production of crude palm oil from the processing of palm fresh fruit bunches in the palm oil mills in Malaysia hs resulted in a huge quantity of empty fruit bunch (EFB) accumulated. The EFB was used as a feedstock in the pyrolysis process using a fixed-bed reactor in the present study. The optimization of process parameters such as pyrolysis temperature (factor A), biomass particle size (factor B) and holding time (factor C) were investigated through Central Composite Design (CCD) using Stat-Ease Design Expert software version 7 with bio-oil yield considered as the response. Twenty experimental runs were conducted. The results were completely analyzed by Analysis of Variance (ANOVA). The model was statistically significant. All factors studied were significant with p-values < 0.05. The pyrolysis temperature (factor A) was considered as the most significant parameter because its F-value of 116.29 was the highest. The value of R2 was 0.9564 which indicated that the selected factors and its levels showed...

Preparation and characterisation of rice husk activated carbon for neutral protease adsorption

Abstract The worldwide annual production of rice husk is estimated about 500 million tonnes, and usually it was burned as one way of disposal. Despite of its high silica content, rice husk is well known as a good adsorbent for several types of compound, including protein. In order to improve its adsorption capacity, it is necessary to convert properly rice husk into activated carbon. The present paper deals with the preparation and characterisation of rice husk activated carbon followed by its utilisation for enzyme adsorption. Rice husk is initially pre-carbonised at 400°C for 4 hours before activating with NaOH at 750°C for 2 hours in the presence of nitrogen. The prepared activated carbon was further characterised with Brunauer–Emmert–Teller and scanning electron microscopy, to observe the morphology changes after treatment. It was found that the surface area has increased from 8·4228 m2 g−1 (rice husk) to become 1646·6264 m2 g−1 (rice husk activated carbon). Additionally, small pores were well developed during the process, which can be observed by scanning electron microscopy. The rice husk activated carbon was used for neutral protease adsorption. It was found that rice husk activated carbon and commercial activated carbon adsorps the enzyme more efficiently compared to rice husk. Moreover, the efficiency of prepared rice husk activated carbon is comparable with commercial activated carbon.

The Effects of Process Parameters on the Pyrolysis of Empty Fruit Bunch (EFB) Using a Fixed-Bed Reactor

Malaysia is well-known as one of the main producer and exporter of palm oil. With the high production of crude palm oil (CPO), huge amount of empty fruit bunch was generated as by-products. The abundant amount of EFB produced required careful waste management procedures. Pyrolysis is thermochemical decomposition of biomass in inert environment towards its conversion into bio-oil, bio-char and gas. In this study, the pyrolysis of empty fruit bunch (EFB) was conducted using a fixed bed reactor. The pertinent process parameters such as pyrolysis temperature, particle sizes and heating rates were investigated via the determination of the percentage product yields such as bio-oil, bio-char and gas. The first series of experiment was conducted to determine the effect of pyrolysis temperatures. The final pyrolysis temperature was varied at 300, 400, 500, 600 and 700 °C at constant heating rates and the nitrogen flowrates of 30 °C/min and 100 cm3/min respectively. It was determined that at pyrolysis temperature of 500 °C maximum bio-oil yield of 35.00 % was obtained with bio-char and gas yield of 26.98 and 38.02% respectively. In the second series of experiment, the effect of particle sizen was studied. The EFB particle was varied at <125, 125-250, 250-500, 500-710 and 710-1000 μm. The pyrolysis temperature was fixed at 500 °C with nitrogen flowrate of 100 cm3/min and heating rate of 30 °C/min. It was determined that using EFB particle size of 250-500 μm, the maximum bio-oil of 38.52% was achieved with bio-char and gas yields of 25.06 % and 36.42% respectively. In the third series of experiment to determine the effect of heating rates, the heating rates was varied at 10, 20, 30, 40, 50 and 60 °C/min towards the final pyrolysis temperature of 500 °C with constant nitrogen flowrates of 100 cm3/min. The results obtained showed that the highest amount of bio-oil of 40.81% was obtained when the heating rate of 20 °C/min was used. The bio-char and gas yield obtained were 24.69% and 34.50% respectively.

Characterizations of Hydroxyapatite - Saccharomyces cerevisiae Complex for Bioethanol Production

Immobilized cell reactor (ICR) has been used widely for bioethanol production. It has been shown to improve the performance of fermentation efficiency. The immobilization of S.cerevisiae was simply performed by enriched cells cultured media harvested at exponential growth phase. Hydroxyapatite (HAp) was found to be a suitable candidate as a solid support of surface adsorption by S.cerevisiae. The strong affinity binding of phosphate backbone of S.cerevisiae and calcium ion in HAp had been proven the effectiveness of HAp as immobiliser, thus the yield from the fermentation process has been increased. However, specific characteristics for HAp-yeast complex such as size, porosity (pore size and pore volume), surface morphology and total surface area are the important factors that were needed to control in order to avoid the detachment of the microorganisms from solid support. The characterizations performed were Mastersizer for complex size determination, Scanning Electron Microscopy (SEM) for surface morphology and Brunauer, Emmett and Teller analysis (BET) for specific surface area determination.