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A dynamic mathematical model was used in this study to describe the mass transfer and reaction kinetics of a fouled α-CGTase-CNF layer in a biocatalytic membrane reactor (BMR) system. BMR performance was evaluated based on the effect of substrate concentration and pneumatic gauge pressure on the permeate flux, total permeate volume, starch conversion, and α-CD production. A model is introduced based on the layer of mass limit as the resistance blocking mechanism with reaction kinetics on the fouled α-CGTase-CNF layer. Important unknown parameters of the constants describing the layer resistance, KML0 and the kinetic constant of Michaelis-Menten, kcat, for mass transfer and its reaction kinetics, were successfully estimated at 3.9 × 107 min/mL and 216.18 mg-starch/cm3⋅U⋅min, respectively, using the proposed models. The study found that the kcat value corresponding to the maximum efficiency of the enzyme on starch cyclisation was a critical parameter in the prediction of the BMR dynamic profiles. Thus, the proposed model in this study can be used for further development of the BMR system, with excellent hydrodynamic and reaction performance.

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This research mainly focuses on developing a natural cellulose nanofibre (CNF) from kenaf bast fibre and its potential for enzyme immobilization support. CNF was isolated by using a combination between chemical and mechanical treatments such as alkaline process and high-intensity ultrasonication process to increase the efficiency of hemicellulose and lignin removal, and to reduce its size into nano-order. The morphological study was carried out by using scanning electron microscope (SEM), indicating most of CNF diameter in range of 50-90 nm was obtained. The result of chemical analysis shows that cellulose content of raw bast fibre, bleached pulp fibre and CNF are 66.4 %, 83.7 % and 90.0 %, respectively. By decreasing the size of cellulose fibre, it increases the number of (O-H) group on the surface that plays as important role in enzyme immobilization. Covalent immobilization of cyclodextrin glucanotransferase (CGTase) onto CNF support resulted in about 95.0 % of protein loading with 69.48 % of enzyme activity, indicating high immobilization yield of enzyme. The enzymatic reaction of immobilized CGTase was able to produce more than 40 % yield of α-CD. Reusability profile of immobilized CGTase resulted in more than 60 % of retained activity up to 7 cycles. Therefore, the CNF is highly potential to be applied as enzyme immobilization support.Keywords: cellulose nanofibre (CNF), kenaf, enzyme immobilization; cyclodextrin glucanotransferase (CGTase), chemical and mechanical treatments Abstrak Kajian ini memberi tumpuan terutamanya kepada penghasilan nano-gentian selulosa (CNF) semulajadi daripada gentian lapisan kulit kenaf dan potensinya sebagai penyokong pemegunan enzim. CNF dihasilkan dengan menggunakan gabungan antara rawatan kimia dan mekanikal seperti proses alkali dan proses ultrasonikasi berintensiti tinggi untuk meningkatkan kadar kecekapan penyingkiran hemiselulosa dan lignin, dan pengurangan saiz kepada nano. Kajian morfologi menggunakan mikroskop imbasan elektron (SEM), menunjukkan sebahagian besar daripada saiz diameter CNF diperolehi dalam julat 50-90 nm. Hasil kajian analisis kimia menunjukkan bahawa kandungan selulosa daripada gentian mentah, gentian pulpa dan CNF masingmasingnya adalah 66.4 %, 83.7 % dan 90.0 %. Dengan mengurangkan saiz diameter gentian selulosa, ia meningkatkan bilangan kumpulan (O-H) di permukaan sokongan yang mana memainkan peranan yang penting dalam pemegunan enzim. Pemegunan ISSN -2506 Safwan et al: DEVELOPMENT OF CELLULOSE NANOFIBRE (CNF) DERIVED FROM KENAF BAST FIBRE AND IT'S POTENTIAL IN ENZYME IMMOBILIZATION SUPPORT 310Siklodektrin Glukanotransferase (CGTase) secara kovalen pada CNF menunjukkan kira-kira 95.0 % muatan protein dengan 69.48 % aktiviti enzim, menunjukkan pemegunan enzim yang tinggi terhasil. Tindak balas berenzim CGTase terpegun juga mampu menghasilkan lebih daripada 40 % pengeluaran α-CD. Kitaran kebolehulangan enzim terpegun menunjukkan lebih daripada 60 % daripada aktivitinya dapat dikekalkan selama 7 kitaran. Oleh itu, CNF sangat berpotensi untuk ...