One of mankind's biggest concerns is water pollution. Textile industry emerged as one of the main contributors with dyes as the main pollutant. Presence of dyes in water is very dangerous due to their toxicity; thus, it is important to remove them from water. In these recent years, heterogeneous advance oxidation process surfaced as a possible dyes' removal technique. This process utilizes semiconductor as photocatalyst to degrade the dyes in presence of light and zinc oxide (ZnO) appears to be a promising photocatalyst for this process. In this study, pullulan, a biopolymer, was used to produce porous ZnO microflowers (ZnO-MFs) through green synthesis via precipitation method. The effects of pullulan's amount on the properties of ZnO-MFs were investigated. The ZnO-MF particle size decreased with the increased of pullulan amount. Interestingly, formation of pores occurred in presence of pullulan. The synthesized ZnO-MFs have the surface area ranging from 6.22 to 25.65 m2 g-1 and pore volume up to 0.1123 cm3 g-1. The ZnO-MF with the highest surface area was chosen for photocatalytic degradation of methyl orange (MO). The highest degradation occurred in 300 min with 150 mg catalyst dosage, 10 ppm initial dye concentration, and pH 7 experimental conditions. However, through comparison of photodegradation of MO with all synthesized ZnO-MFs, 25PZ exhibited the highest degradation rate. This shows that photocatalytic activity is not dependent on surface area alone. Based on these results, ZnO-MF has the potential to be applied in wastewater treatment. However, further improvement is needed to increase its photocatalytic activity.
Photo-Fenton oxidation is one of the most promising processes to remove recalcitrant contaminants from industrial wastewater. In this study, we developed a novel heterogeneous catalyst to enhance photo-Fenton oxidation. Multi-composition (Fe-Cu-Zn) on aluminosilicate zeolite (ZSM-5) was prepared using a chemical process. Subsequently, the synthesized catalyst was characterized by using X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray (spectroscopy) (EDX), and Brunauer-Emmett-Teller (BET). Activity of the synthesized catalyst is analysed to degrade an azo dye, methyl orange. Taguchi method is used to optimize color removal and total carbon content (TOC) removal. The dye completely degraded, and 76% of TOC removal was obtained at optimized process conditions. The amount of catalyst required for the desired degradation of dye significantly reduced up to 92% and 30% compared to conventional homogenous and heterogeneous Fenton oxidation processes, respectively.
In this study, nano-sized ITO supported Pt-Pd bimetallic catalyst was synthesized for the degradation of methyl parathion pesticide, a common extremely toxic contaminant in aqueous solution. On the characterization with different techniques, a beautiful scenario of honeycomb architecture composed of ultra-small nanoneedles or fine hairs was found. Average size of nanocatalyst also confirmed which was in the range of 3-5 nm. High percent degradation (94%) was obtained in 30 s using 1.5 × 10- 1 mg of synthesized nanocatalyst, 0.5 mM NaBH4, and 110 W microwave radiations power. Recyclability of nanocatalyst was efficient till 4th cycle observed during study of reusability. The supported Pt-Pd bimetallic nanocatalyst on ITO displayed many advantages over conventional methods for degradation of methyl parathion pesticide, such as high percent degradation, short reaction time, small amount of nanocatalyst, and multitime reusability. Graphical abstract Schematic illustration of reaction for degradation of methyl parathion.
A novel titanium dioxide/activated carbon (TiO2/AC) composite where AC derived from oil palm empty fruit bunch (EFB) was synthesised by using sol-gel method. All the samples were characterised by using X-ray diffraction (XRD), scanning electron microscopy-energy dispersive X-ray (SEM-EDX), Fourier transformed infrared (FTIR), thermogravimetric analysis (TGA) and surface analyser. SEM analysis showed that TiO2 particles were successfully embedded and well distributed on the AC surface. The elemental composition analysis found that the TiO2/AC composite contained titanium (Ti), oxygen (O) and carbon (C) atoms. Meanwhile, the appearance of new band at about 960 cm-1 which assigned to the Ti-O stretching was observed in the FTIR spectra when the AC was incorporated into TiO2. TGA analysis showed that the weight loss of 32 wt.% from 150 to 550 °C was due to the decomposition of amorphous carbon layers and loss of hydroxyl groups on TiO2. It was found that the TiO2/AC composite had better performance in the sonocatalytic degradation of malachite green as compared to the individual AC and TiO2 because the TiO2/AC composite had dual functionality and huge number of active sites which could promote the mass transfer of dye molecules towards catalyst surface. By using 1.5 g/L of TiO2/AC composite which calcined at 700 °C on 100 mL of 200 mg/L of malachite green at solution pH of 7, a degradation efficiency of 87.11% had been achieved after 30 min of ultrasonic irradiation. A lower chemical oxygen demand (COD) removal (81.75%) was observed because the structured dye molecules underwent mineralisation process during the sonocatalytic degradation to generate intermediate compounds. The TiO2/AC composite was able to be recycled and still achieved a high degradation efficiency of 76.78% after second catalytic cycle as compared to the fresh TiO2/AC composite with degradation efficiency of 87.11%. In conclusion, the TiO2/AC composite had high reusability and promising for practical applications in textile industry.
The current work aimed to investigate the degradation of the triclocarban (TCC) in aqueous solution using a modified zeolite/TiO2 composite (MZTC) synthesized by applying the electrochemical anodization (ECA). The synthesis process was conducted at different voltages (10, 40, and 60) V in 1 h and using electrophoresis deposition (EPD) in doping zeolite. The MZTC was covered with the array ordered, smooth and optimum elongated nanotubes with 5.1 μm of the length, 120.3 nm of the inner diameter 14.5 nm of the wall thickness with pure titanium and crystalline titania as determined by FESEM/EDS, and XRD. The kinetic study by following Langmuir-Hinshelwood(L-H) model and pseudo first order, the significant constant rate was obtained at pH 11 which was 0.079 ppm/min, 0.75 cm2 of MZTC catalyst loading size achieved 0.076 ppm/min and 5 ppm of TCC initial concentration reached 0.162 ppm/min. The high-performance liquid chromatography (HPLC) analysis for mechanism study of TCC photocatalytic degradation revealed eleven intermediate products after the whole process of photocatalysis. In regard of toxicology assessment by the bacteria which is Photobacterium phosphoreum, the obtained concentration of TCC at minute 60 was less satisfied with remained 0.36 ppm of TCC was detected indicates that the concentration was above allowable level. Where the allowable level of TCC in stream is 0.1 ppm.
Tin oxide (SnO2) with versatile properties is of substantial standing for practical application, and improved features of the material are demonstrated in the current issue through the integration of nanotechnology with bio-resources leading to what is termed as biosynthesis of SnO2 nanoparticles (NPs). This review reveals the recent advances in biosynthesis of SnO2 NPs by chemical precipitation method focused on distinct methodologies, characterization, and reaction mechanism along with a photocatalytic application for dye degradation. According to available literature reviews, numerous bio-based precursors selectively extracted from biological substrates have effectively been applied as capping or reducing agents to achieve the metal oxide NPs. The major precursor obtained from the aqueous extract of root barks of Catunaregam spinosa is found to be 7-hydroxy-6-methoxy-2H-chromen-2-one that has been proposed as a model compound for the reduction of metal ions into nanoparticles due to having highly active functional groups, being abundant in plants (67.475 wt%), easy to extract, and eco benign. In addition, the photocatalytic activity of SnO2 NPs for the degradation of organic dyes, pharmaceuticals, and agricultural contaminants has been discussed in the context of a promising bio-reduction mechanism of the synthesis. The final properties are supposed to depend exclusively upon a number of factors, e.g., particle size (
Pyrolysis oil from oil palm biomass can be a sustainable alternative to fossil fuels and the precursor for synthesizing petrochemical products due to its carbon-neutral properties and low sulfur and nitrogen content. This work investigated the effect of applying mesoporous acidic catalysts, Ni-Mo/TiO2 and Ni/Al2O3, in a catalytic co-pyrolysis of oil palm trunk (OPT) and polypropylene (PP) from 500 to 700 °C. The obtained oil yields varied between 12.67 and 19.50 wt.% and 12.33-17.17 wt.% for Ni-Mo/TiO2 and Ni/Al2O3, respectively. The hydrocarbon content in oil significantly increased up to 54.07-58.18% and 37.28-68.77% after adding Ni-Mo/TiO2 and Ni/Al2O3, respectively. The phenolic compounds content was substantially reduced to 8.46-20.16% for Ni-Mo/TiO2 and 2.93-14.56% for Ni/Al2O3. Minor reduction in oxygenated compounds was noticed from catalytic co-pyrolysis, though the parametric effects of temperature and catalyst type remain unclear. The enhanced deoxygenation and cracking of phenolic and oxygenated compounds and the PP decomposition resulted in increased hydrocarbon production in oil during catalytic co-pyrolysis. Catalyst addition also promoted the isomerization and oligomerization reactions, enhancing the formation of cyclic relative to aliphatic hydrocarbon.
Various treatments of choice are available to overcome contamination of bisphenol A (BPA) in the environment including membrane technologies; however, the treatment still releases contaminants that threaten the human being. Therefore, the present study is conducted to investigate the degradation of BPA by recently developed visible-light-driven photocatalytic nitrogen-doping titanium dioxide (N-doped TiO2) dual-layer hollow fibre (DLHF) membrane and its efficiency in reducing the level of BPA in contaminated water. Fabricated with suitable polymer/photocatalyst (15/7.5 wt.%) via co-extrusion spinning method, the DLHF was characterized morphologically, evaluated for BPA degradation by using submerged photocatalytic membrane reactor under visible light irradiations followed by the investigation of intermediates formed. BPA exposure effects were accessed by immunohistochemistry staining of gastrointestinal sample obtained from animal model. BPA has been successfully degraded up to 72.5% with 2 intermediate products, B1 and B2, being identified followed by total degradation of BPA. BPA exposure leads to the high-intensity IHC staining of Claudin family which indicated the disruption of small intestinal barrier (SIB) integrity. Low IHC staining intensity of Claudin family in treated BPA group demonstrated that reducing the level of BPA by N-doped TiO2 DLHF is capable of protecting the important component of SIB. Altogether, the fabricated photocatalytic DLHF membrane is expected to have an outstanding potential in removing BPA and its health effect for household water treatment to fulfil the public focus on the safety of their household water and their need to consume clean water.
Natural enzymes possess several drawbacks which limits their application in industries, wastewater remediation and biomedical field. Therefore, in recent years researchers have developed enzyme mimicking nanomaterials and enzymatic hybrid nanoflower which are alternatives of enzyme. Nanozymes and organic inorganic hybrid nanoflower have been developed which mimics natural enzymes functionalities such as diverse enzyme mimicking activities, enhanced catalytic activities, low cost, ease of preparation, stability and biocompatibility. Nanozymes include metal and metal oxide nanoparticles mimicking oxidases, peroxidases, superoxide dismutase and catalases while enzymatic and non-enzymatic biomolecules were used for preparing hybrid nanoflower. In this review nanozymes and hybrid nanoflower have been compared in terms of physiochemical properties, common synthetic routes, mechanism of action, modification, green synthesis and application in the field of disease diagnosis, imaging, environmental remediation and disease treatment. We also address the current challenges facing nanozyme and hybrid nanoflower research and the possible way to fulfil their potential in future.
Carbon-integrated binary metal oxide semiconductors have gained prominence in the last decade as a better material for photocatalytic wastewater treatment technology. In this regard, this research describes the investigation of the binary metal oxide TiO2@Fe3O4 embedded on reduced graphene oxide (rGO) nanosheets synthesized through a combination of sol-gel, chemical precipitation, and Hummer's processes. Besides, the catalyst is applied for the photocatalytic degradation of organic chlorophenol pollutants. The characterized diffraction results showed the peak broadening of the rGO-TiO2@Fe3O4 composite formed with tetragonal and cubic structures having small crystallite sizes. The TEM observation shows an enormous miniature of TiO2@Fe3O4 nanospheres spread on the folded 2D-rGO nanosheets with a large BET surface area. The XPS result holds the mixed phases of Fe3O4 and Fe2O3. Finally, the catalyst demonstrated a low band gap with extended light absorption towards visible light irradiation. The synergistic interactions between Fe3+ and Fe2+ improved the visible light activity due to the incorporation of rGO, and also possessed good recycling capacity. The increased mobility of electrons at the interfaces of TiO2 and Fe3O4 due to the mixing of rGO results in the separation of charge carriers by elevating the photocatalytic degradation efficiency of chlorophenol.
In recent years, previously reported studies revealed a high efficiency of pollutant degradation by coupling photocatalysis and electrochemical processes (PECs) using titanium dioxide (TiO2) photoelectrode rather than using photocatalysis or electrocatalysis alone. However, some of the TiO2 photoelectrodes that have been reported were not cost-effective. This is due to the use of expensive chemicals and certain expensive equipment in the fabrication process, other than involving complicated preparation steps. Therefore, this study is aimed at investigating the PEC performance and stability of low-cost TiO2-polyvinyl chloride (TiO2-PVC) composite photoelectrode for Reactive Orange 16 (RO16) degradation. The materials characterisation using the ATR-FTIR, XRD and UV-Vis DRS proved that TiO2 and TiO2-PVC were successfully synthesised. The micrograph obtained for the surface characterisation using the FESEM showed that the smooth surface of freshly prepared photoelectrodes turned slightly rough with tiny pits formation after five continuous PEC processes. Nevertheless, the photoelectrode retained its original shape in good condition for further PEC processes. By PEC process, the fabricated photoelectrode showed 99.4% and 51.1% of colour and total organic carbon (TOC) removal, respectively, at optimised PEC parameters (1.0 mol L-1 NaCl concentration, 10 V applied voltage, 120 min degradation time and initial pH 2). Moreover, the fabricated photoelectrode demonstrated sufficient reusability potential (~ 96.3%) after five cycles of PEC processes. In summary, a low-cost and stable composite photoelectrode with high efficiency in RO16 degradation was successfully fabricated and could be potentially applied for other emerging pollutants degradation via the PEC degradation technique.
The current research concentrated on the Co-precipitation synthesis of g-C3N4 (CN), ZnO, ZnO/CN, and Co-doped ZnO/CN nanocomposite, as well as the solar light enhanced photocatalytic treatment of Reactive Red 120 (RR120) from genuine wool textile effluent. The 3D flower-like structure of Co-doped ZnO distributed on the surface of CN thin sheets, according to structural studies employing XRD and SEM examinations Electrochemical experiments exhibited that the Co-doped ZnO/CN nanocomposite has a large electroactive surface area. The optical band-gap values of CN, ZnO, ZnO/CN, and Co-doped ZnO/CN nanocomposites were 2.68, 3.13, 2.38, and 2.23 eV, respectively, according to optical characterizations. The synergistic effects and heterojunction produced by Co-doped ZnO and CN can be linked to the narrow gap in nanocomposites. After 75, 60, 50, and 40 min of exposure to solar light, photocatalytic degradation assays for 250 mL of 20 mg/L RR120 solution in the presence of CN, ZnO, ZnO/CN, and Co-doped ZnO/CN nanocomposites demonstrated 100% dye treatment. The applicability of photocatalysts for decolorization of 250 mL of 10 mg/L RR120 prepared from actual wool textile wastewater was investigated, and the results showed that Co-doped ZnO/CN nanocomposites for treatment of RR120 from actual wool textile wastewater were highly efficient at photocatalytic degradation.
UV and solar-based photocatalytic degradation of 2,4-dichlorophenol (2,4-DCP) as an organic contaminant in ceramics industry wastewater by ZnS and Fe-doped ZnS NPs was the focus of this research. Nanoparticles were prepared using a chemical precipitation process. The cubic, closed-packed structure of undoped ZnS and Fe-doped ZnS NPs was formed in spherical clusters, according to XRD and SEM investigations. According to optical studies, the optical band gaps of pure ZnS and Fe-doped ZnS nanoparticles are 3.35 and 2.51 eV, respectively, and Fe doping increased the number of carriers with high mobility, improved carrier separation and injection efficiency, and increased photocatalytic activity under UV or visible light. Doping of Fe increased the separation of photogenerated electrons and holes and facilitated charge transfer, according to electrochemical impedance spectroscopy investigations. Photocatalytic degradation studies revealed that in the present pure ZnS and Fe-doped ZnS nanoparticles, 100% treatment of 120 mL of 15 mg/L phenolic compound was obtained after 55- and 45-min UV-irradiation, respectively, and complete treatment was attained after 45 and 35-min solar light irradiation, respectively. Because of the synergistic effects of effective surface area, more effective photo-generated electron and hole separation efficiency, and enhanced electron transfer, Fe-doped ZnS demonstrated high photocatalytic degradation performance. The study of Fe-doped ZnS's practical photocatalytic treatment capability for removing 120 mL of 10 mg/L 2,4-DCP solution made from genuine ceramic industrial wastewater revealed Fe-doped ZnS's excellent photocatalytic destruction of 2,4-DCP from real industrial wastewater.
Lignocellulosic biomass contains lignin, an aromatic and oxygenated substance and a potential method for lignin utilization is achieved through catalytic conversion into useful phenolic and aromatic monomers. The application of monometallic catalysts for lignin hydrogenolysis reaction remains one of the major reasons for the underutilization of lignin to produce valuable chemicals. Monometallic catalysts have many limitations such as limited catalytic sites for interacting with different lignin linkages, poor catalytic activity, low lignin conversion, and low product selectivity. It is due to lack of synergy with other metallic catalysts that can enhance the catalytic activity, stability, selectivity, and overall catalytic performance. To overcome these limitations, works on the application of bimetallic catalysts that can offer higher activity, selectivity, and stability have been initiated. In this review, cutting-edge insights into the catalytic hydrogenolysis of lignin, focusing on the production of phenolic and aromatic monomers using bimetallic catalysts within an internal hydrogen donor solvent are discussed. The contribution of this work lies in a critical discussion of recent reported findings, in-depth analyses of reaction mechanisms, optimal conditions, and emerging trends in lignin catalytic hydrogenolysis. The specific effects of catalytic active components on the reaction outcomes are also explored. Additionally, this review extends beyond current knowledge, offering forward-looking suggestions for utilizing lignin as a raw material in the production of valuable products across various industrial processes. This work not only consolidates existing knowledge but also introduces novel perspectives, paving the way for future advancements in lignin utilization and catalytic processes.
In this work, the direct electrochemistry of hemoglobin (Hb), which was immobilized on carbonyl functionalized single walled carbon nanotube (SWCNT) and deposited onto a gold (Au) electrode has been described. The synthesis of the network of crosslinked SWCNT/Hb was done with the help of crosslinking agent EDC (1-ethyl-3-(3-dimethylaminopropyl) carbodiimide). The UV-Vis and FTIR spectroscopy of SWCNT/Hb networks showed that Hb maintained its natural structure and kept good stability. In addition with this, scanning electron microscopy (SEM) illustrated that SWCNT/Hb networks had a featured layered structure and Hb being strongly liked with SWCNT surface. Cyclic voltammetry (CV) was used to study and to optimize the performance of the resulting modified electrode. The cyclic voltammetric (CV) responses of SWCNT/Hb networks in pH 7.0 exhibit prominent redox couple for the FeIII/II redox process with a midpoint potential of -0.46 V and -0.34, cathodic and anodic respectively. Furthermore, SWCNT/Hb networks are utilized for the detection of hydrogen peroxide (H2O2). Electrochemical measurements reveal that the resulting SWCNT/Hb electrodes display high electrocatalytic activity to H2O2 with high sensitivity, wide linear range, and low detection limit. Overall, the electrochemical results are due to excellent biocompatibility and excellent electron transport efficiency of CNT as well as high Hb loading and synergistic catalytic effect of the modified electrode toward H2O2.
In this work, SrCrxFe12-xO19 (x = 0.0, 0.5, 1.0, 1.5) nanostructures were successfully synthesized by sol-gel auto-combustion method, and different aminoacids were used as green reductants. Various analysis results show that SrCrxFe12-xO19 nanoparticles synthesized successfully.The present study shows that SrCrxFe12-xO19 nanoparticle could be used as adsorbent for the desulfurization of liquid fuels. Increasing of nanoparticles concentration was caused to increase the adsorption rate of sulfur contents of fuel. The adsorption rate of sulfur contents of fuel in various concentrations 4.5, 9.5, and 18.5 g. L -1 of SrCrxFe12-xO19 nanoparticles in solution was estimated about 39, 50, and 62% for 30 min, respectively. The results of catalytic tests reveals that SrCrxFe12-xO19 nanoparticles have the potential to be used as a new kind of semiconductor catalysts for the desulfurization of liquid fuels. Magnetic property of the final sample was measured at room temperature by a vibration sample magnetometer (VSM) and shown that the intrinsic coercivity of product is about 6000 Oe and it exhibits characteristics of single magnetic domains (Mr/ Ms = 0.53).
Most substrate for esterification has the inherent problem of low miscibility which requires addition of solvents into the reaction media. In this contribution, we would like to present an alternative and feasible option for an efficient solvent-free synthesis of menthyl butyrate using a novel thermostable crude T1 lipase. We investigated the effects of incubation time, temperature, enzyme loading and substrate molar ratio and determined the optimum conditions. The high conversion of menthyl butyrate catalyzed by crude T1 lipase in a solvent-free system is greatly affected by temperature and time of the reaction media. The highest yield of menthyl butyrate was 99.3% under optimized conditions of 60 °C, incubation time of 13.15 h, 2.53 mg, 0.43% (w/w) enzyme to substrate ratio and at molar ratio of butyric anhydride/menthol 2.7:1. Hence, the investigation revealed that the thermostable crude T1 lipase successfully catalyzed the high-yield production of menthyl butyrate in a solvent-free system. The finding suggests that the crude T1 lipase was a promising alternative to overcome shortcomings associated with solvent-assisted enzymatic reactions.
Titanium dioxide (TiO2) is one of the most widely investigated metal oxides due to its extraordinary surface, electronic and catalytic properties. However, the large band gap of TiO2 and massive recombination of photogenerated electron-hole pairs limit its photocatalytic and photovoltaic efficiency. Therefore, increasing research attention is now being directed towards engineering the surface structure of TiO2 at the most fundamental and atomic level namely morphological control of {001} facets in the range of microscale and nanoscale to fine-tune its physicochemical properties, which could ultimately lead to the optimization of its selectivity and reactivity. The synthesis of {001}-faceted TiO2 is currently one of the most active interdisciplinary research areas and demonstrations of catalytic enhancement are abundant. Modifications such as metal and non-metal doping have also been extensively studied to extend its band gap to the visible light region. This steady progress has demonstrated that TiO2-based composites with {001} facets are playing and will continue to play an indispensable role in the environmental remediation and in the search for clean and renewable energy technologies. This review encompasses the state-of-the-art research activities and latest advancements in the design of highly reactive {001} facet-dominated TiO2via various strategies, including hydrothermal/solvothermal, high temperature gas phase reactions and non-hydrolytic alcoholysis methods. The stabilization of {001} facets using fluorine-containing species and fluorine-free capping agents is also critically discussed in this review. To overcome the large band gap of TiO2 and rapid recombination of photogenerated charge carriers, modifications are carried out to manipulate its electronic band structure, including transition metal doping, noble metal doping, non-metal doping and incorporating graphene as a two-dimensional (2D) catalyst support. The advancements made in these aspects are thoroughly examined, with additional insights related to the charge transfer events for each strategy of the modified-TiO2 composites. Finally, we offer a summary and some invigorating perspectives on the major challenges and new research directions for future exploitation in this emerging frontier, which we hope will advance us to rationally harness the outstanding structural and electronic properties of {001} facets for various environmental and energy-related applications.
Electrochemical dechlorination of chlorobenzenes in the presence of various arene mediators such as naphthalene, biphenyl, phenanthrene, anthracene, and pyrene, was studied. The amount of mediator required was able to be reduced to 0.01 equiv. for all mediators except for anthracene, with the complete dechlorination of mono-, 1,3-di- and 1,2,4-trichlorobenzene still achieved. This catalytic amount of mediator plays an important role in accelerating the dechlorination through the rapid formation of radical anions prior to reduction of the chlorobenzenes.
Lipase-catalyzed production of palm esters by alcoholysis of palm oil with oleyl alcohol in n-hexane was performed in 2L stirred-tank reactor (STR). Investigation on the performance of reactor operation was carried out in batch mode STR with single impeller mounted on the centrally located shaft. Rushton turbine (RT) impellers provide the highest reaction yield (95.8%) at lower agitation speed as compared to AL-hydrofoil (AL-H) and 2-bladed elephant ear (EE) impellers. Homogenous enzyme particles suspension was obtained at 250 rpm by using RT impeller. At higher impeller speed, the shear effect on the enzyme particles caused by agitation has decreased the reaction performance. Palm esters reaction mixture in STR follows Newtons' law due to the linear relation between the shear stress (tau) and shear rate (dupsilon/dy). High stability of Lipozyme RM IM was observed as shown by its ability to be repeatedly used to give high percentage yield (79%) of palm esters even after 15 cycles of reaction. The process was successfully scale-up to 75 L STR (50 L working volume) based on a constant impeller tip speed approach, which gave the yield of 97.2% after 5h reaction time.