Azlina Harun Kamaruddin

Continuous biosynthesis of biodiesel from waste cooking palm oil in a packed bed reactor: optimization using response surface methodology (RSM) and mass transfer studies.

This study aimed to develop an optimal continuous procedure of lipase-catalyzes transesterification of waste cooking palm oil in a packed bed reactor to investigate the possibility of large scale production further. Response surface methodology (RSM) based on central composite rotatable design (CCRD) was used to optimize the two important reaction variables packed bed height (cm) and substrate flow rate(ml/min) for the transesterification of waste cooking palm oil in a continuous packed bed reactor. The optimum condition for the transesterification of waste cooking palm oil was as follows: 10.53 cm packed bed height and 0.57 ml/min substrate flow rate. The optimum predicted fatty acid methyl ester (FAME) yield was 80.3% and the actual value was 79%. The above results shows that the RSM study based on CCRD is adaptable for FAME yield studied for the current transesterification system. The effect of mass transfer in the packed bed reactor has also been studied. Models for FAME yield have been developed for cases of reaction control and mass transfer control. The results showed very good agreement compatibility between mass transfer model and the experimental results obtained from immobilized lipase packed bed reactor operation, showing that in this case the FAME yield was mass transfer controlled.

Reactive extraction of Jatropha curcas L. seed for production of biodiesel: process optimization study.

Biodiesel from Jatropha curcas L. seed is conventionally produced via a two-step method: extraction of oil and subsequent esterification/transesterification to fatty acid methyl esters (FAME), commonly known as biodiesel. Contrarily, in this study, a single step in situ extraction, esterification and transesterification (collectively known as reactive extraction) of J. curcas L. seed to biodiesel, was investigated and optimized. Design of experiments (DOE) was used to study the effect of various process parameters on the yield of FAME. The process parameters studied include reaction temperature (30-60 degrees C), methanol to seed ratio (5-20 mL/g), catalyst loading (5-30 wt %), and reaction time (1-24 h). The optimum reaction condition was then obtained by using response surface methodology (RSM) coupled with central composite design (CCD). Results showed that an optimum biodiesel yield of 98.1% can be obtained under the following reaction conditions: reaction temperature of 60 degrees C, methanol to seed ratio of 10.5 mL/g, 21.8 wt % of H(2)SO(4), and reaction period of 10 h.

Chemoenzymatic and microbial dynamic kinetic resolutions

This review tracks a decade of dynamic kinetic resolution developments with a biocatalytic inclination using enzymatic/microbial means for the resolution part followed by the racemization reactions either by means of enzymatic or chemocatalyst. These fast developments are due to the ability of the biocatalysts to significantly reduce the number of synthetic steps which are common for conventional synthesis. Future developments in novel reactions and products of dynamic kinetic resolutions should consider factors that are needed to be extracted at the early synthetic stage to avoid inhibition at scale-up stage have been highlighted.

Modeling and simulation of enzymatic membrane reactor for kinetic resolution of ibuprofen ester

Abstract The enzymatic hydrolysis of racemic ibuprofen ester by lipase from Candida rugosa using hollow fiber membrane reactor was studied. In process modeling and simulation of the enzymatic reaction in a horizontal hollow fiber membrane reactor system, two distinctive regions were studied: (i) diffusion in the fiber lumen; and (ii) reaction in the membrane matrix support. The model equations for both regions were developed and solved numerically by different approaches. In the first part, the modeling and simulation work was based on the diffusion of ( S )-ibuprofen acid in which it leaves the reactor from the lumen side of the capillary fibers. The proposed mathematical model containing non-linear partial differential equations was solved using the orthogonal collocation technique. The second part involved an enzymatic reaction taking place with the immobilized enzyme in the porous matrix support of the membrane, at which the substrate flows in from the shell side. The driving force was predominantly induced by pressure difference across the membrane where radial convection was the only mass transport in the porous support. The model was solved using two numerical techniques, the first technique based on the orthogonal collocation of weighted residuals in solving the non-linear partial differential equations of product diffusion in the capillary fibers; and the second technique was a collocation technique for solving ordinary differential equations (ODEs) of the enzymatic reaction in the porous support structure. The simulation was studied over a wide range of process parameters to investigate their effects on separation efficiency, in terms of enantiomeric excess, ee S and enantiomeric ratio, E , respectively. The model parameters include Peclet number, weight function parameters α , β and collocation points ( n ), Thiele Modulus, Φ 2 , dimensionless Michaelis constant, Θ and Bodenstein numbers, B 0 . The performance of hollow fiber membrane reactor was found to be sufficiently effective at Θ =0.55, B 0 =0.174 and ee S =74% at Φ 2

Thermodynamics and inhibition studies of lipozyme TL IM in biodiesel production via enzymatic transesterification.

In order to characterize enzyme activity and stability corresponding to temperature effects, thermodynamic studies on commercial immobilized lipase have been carried out via enzymatic transesterification. An optimum temperature of 40 degrees C was obtained in the reaction. The decreasing reaction rates beyond the optimum temperature indicated the occurrence of reversible enzyme deactivation. Thermodynamic studies on lipase denaturation exhibited a first-order kinetics pattern, with considerable stability through time shown by the lipase as well. The activation and deactivation energies were 22.15 kJ mol(-1) and 45.18 kJ mol(-1), respectively, implying more energy was required for the irreversible denaturation of the enzyme to occur. At water content of 0.42%, the initial reaction rate and FAME yield displayed optimum values of 3.317 g/L min and 98%, respectively.

Selection of metal oxides in the preparation of rice husk ash (RHA)/CaO sorbent for simultaneous SO2 and NO removal.

In this work, the removal of SO(2) and NO from simulated flue gas from combustion process was investigated in a fixed-bed reactor using rice husk ash (RHA)/CaO-based sorbent. Various metal precursors were used in order to select the best metal impregnated over RHA/CaO sorbents. The results showed that RHA/CaO sorbents impregnated with CeO(2) had the highest sorption capacity among other impregnated metal oxides for the simultaneous removal of SO(2) and NO. Infrared spectroscopic results indicated the formation of both sulfate (SO(4)(2-)) and nitrate (NO(3)(-)) species due to the catalytic role played by CeO(2). Apart from that, the catalytic activity of the RHA/CaO/CeO(2) sorbent was found to be closely related to its physical properties (specific surface area, total pore volume and average pore diameter).

Evaluation of various additives on the preparation of rice husk ash (RHA)/CaO-based sorbent for flue gas desulfurization (FGD) at low temperature.

This paper examines the effectiveness of 10 additives toward improving SO2 sorption capacities (SSC) of rice husk ash (RHA)/lime (CaO) sorbent. The additives examined are NaOH, CaCl2, LiCl, NaHCO3, NaBr, BaCl2, KOH, K2HPO4, FeCl3 and MgCl2. Most of the additives tested increased the SSC of RHA/CaO sorbent, whereby NaOH gave highest SSC (30mg SO2/g sorbent) at optimum concentration (0.25mol/l) compared to other additives examined. The SSC of RHA/CaO sorbent prepared with NaOH addition was also increases from 17.2 to 39.5mg SO2/g sorbent as the water vapor increases from 0% RH to 80% RH. This is probably due to the fact that most of additives tested act as deliquescent material, and its existence increases the amount of water collected on the surface of the sorbent, which played an important role in the reaction between the dry-type sorbent and SO2. Although most of the additives were shown to have positive effect on the SSC of the RHA/CaO sorbent, some were found to have negative or insignificant effect. Thus, this study demonstrates that proper selection of additives can improve the SSC of RHA/CaO sorbent significantly.

Enantioseparation of (R,S)‐ketoprofen using Candida antarctica lipase B in an enzymatic membrane reactor

An enzymatic membrane reactor (EMR) for enantioseparation of (R,S)-ketoprofen via Candida antarctica lipase B (CALB) as biocatalyst was investigated. A comparative study of free and immobilized CALB was further conducted. The catalytic behaviour of CALB in an EMR was affected by the process parameters of enzyme load, substrate concentration, substrate molar ratio, lipase solution pH, reaction temperature, and substrate flow rate. Immobilization of CALB in the EMR was able to reduce the amount of enzyme required for the enantioseparation of (R,S)-ketoprofen. Immobilized CALB in the EMR assured higher reaction capacity, better thermal stability, and reusability. It was also found to be more cost effective and practical than free CALB in a batch reactor.

Sorption of SO2 and NO from simulated flue gas over rice husk ash (RHA)/CaO/CeO2 sorbent: Evaluation of deactivation kinetic parameters

In this study, the kinetic parameters of rice husk ash (RHA)/CaO/CeO(2) sorbent for SO(2) and NO sorptions were investigated in a laboratory-scale stainless steel fixed-bed reactor. Data experiments were obtained from our previous results and additional independent experiments were carried out at different conditions. The initial sorption rate constant (k(0)) and deactivation rate constant (k(d)) for SO(2)/NO sorptions were obtained from the nonlinear regression analysis of the experimental breakthrough data using deactivation kinetic model. Both the initial sorption rate constants and deactivation rate constants increased with increasing temperature, except at operating temperature of 170 °C. The activation energy and frequency factor for the SO(2) sorption were found to be 18.0 kJ/mol and 7.37 × 10(5)cm(3)/(g min), respectively. Whereas the activation energy and frequency factor for the NO sorption, were estimated to be 5.64 kJ/mol and 2.19 × 10(4)cm(3)/(g min), respectively. The deactivation kinetic model was found to give a very good agreement with the experimental data of the SO(2)/NO sorptions.

The feasibility study of crude palm oil transesterification at 30 °C operation.

The objective of this research is to investigate the potential of transesterification of crude palm oil (CPO) to biodiesel at 30 degrees C. The mass transfer limitations problem crucial at 30 degrees C due to the viscosity of CPO has been addressed. The process parameters that are closely related to mass transfer effects like enzyme loading, agitation speed and reaction time were optimized. An optimum methanol to oil substrate molar ratio at 6.5:1 was observed and maintained throughout the experiments. The optimum operating condition for the transesterification process was found at 6.67 wt% of enzyme loading and at 150 rpm of agitation speed. The corresponding initial reaction and FAME yield obtained at 6 h were 89.29% FAME yield/hr and 85.01%, respectively. The 85% FAME yield obtained at 30 degrees C operation of CPO transesterification shows that the process is potentially feasible for the biodiesel synthesis.