The adsorption kinetics of cellulase and xylanase immobilized on magnetically separable, hierarchically ordered mesocellular mesoporous silica (M‐HMMS) was investigated. The adsorption of cellulase ...on M‐HMMS followed pseudo‐second‐order kinetics while the xylanase adsorption followed the Avrami model. Intraparticle and film diffusion also affected this process. These results enable in‐depth knowledge of the cellulase and xylanase adsorption mechanisms on M‐HMMS for better future applications by improving the stability of the immobilization.
Cellulase and xylanase were co‐immobilized in magnetically separable hierarchically ordered mesocellular mesoporous magnetic silica (M‐HMMS) through adsorption. The adsorption mechanism was investigated. Cellulase and xylanase adsorption took place on the external surface and inside the pores of M‐HMMS.
A novel greener MNC/PES membrane was developed through an electrospinning technique for lipase immobilization to catalyze the synthesis of ethyl valerate (EV). In this study, the covalent ...immobilization of
lipase (AOL) onto an electrospun nanofibrous membrane consisting of magnetic nanocellulose (MNC) and polyethersulfone (PES) to produce EV was statistically optimized. Raman spectroscopy, Fourier-transform infrared spectroscopy: attenuated total reflection, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, thermal gravimetric analysis (TGA), and differential thermal gravimetric (DTG) of MNC/PES-AOL demonstrated that AOL was successfully immobilized onto the fibers. The Taguchi design-assisted immobilization of AOL onto MNC/PES fibers identified that 1.10 mg/mL protein loading, 4 mL reaction volume, 250 rpm stirring rate, and 50 °C were optimal to yield 72.09% of EV in 24 h. The thermal stability of MNC/PES-AOL was improved by ≈20% over the free AOL, with reusability for up to five consecutive esterification cycles while demonstrating an exceptional half-life of 120 h. Briefly, the electrospun MNC/PES fibers that immobilized AOL showed promising applicability in yielding relatively good EV levels. This study suggests that using MNC as fillers in a PES to improve AOL activity and durability for a longer catalytic process could be a viable option.
The adsorption kinetics of laccase immobilization on magnetically-separable hierarchically-ordered mesocellular mesoporous silica (M-HMMS) as the support was studied. Past studies on the ...immobilization of laccase through adsorption have gradually increased, but the kinetics and mechanism of laccase adsorption on magnetic support have been poorly investigated, specifically on M-HMMS. Thus, the adsorption process was analyzed to understand the distribution and nature of laccase molecules on the M-HMMS and the rate-limiting step based on the intraparticle diffusion model. The adsorption kinetics of laccase corresponded to the pseudo-second-order and exhibited two stages of intraparticle diffusion. This study clearly indicates that the immobilization of laccase on M-HMMS is chemical adsorption with a strong covalent bond and that chemisorbed types are difficult to remove from the solid surface due to the greater bond strength in chemisorption. These results provide a deeper knowledge of the adsorption mechanisms of laccase on M-HMMS for better future applications.
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•High temperatures impact the adsorption process of laccase on the magnetic support.•The adsorption kinetics of laccase fitted well with pseudo-second-order.•Adsorption of laccase on the solid surface creates greater bonding strength.•The rate-limiting step exhibited two intraparticle diffusion stages.
Magnetically-separable enzyme system has been developed by adsorption, precipitation and cross-linking of enzymes in superparamagnetic hierarchically ordered mesoporous mesocellular silica (M-HMMS). ...The immobilization of xylanase within M-HMMS were compared between enzyme adsorption (EA), enzyme adsorption and cross-linking (EAC), and enzyme adsorption, precipitation and cross-linking (EAPC). EAPC includes higher enzyme activity immobilized within the matrix in comparison with the other methods. Furthermore, the immobilized enzyme is predicted to be prevented from leaching out of the matrix when exterior blow is being tested on the structure. Thus, the stability of the EAPC of this invention is anticipated to be maintained even after a long time passed since high enzyme activity compared with known method can be supported and immobilized within the matrix. Consequently, it is possible to improve performance of the enzymes by manipulating the preparation and operation condition.
Electrochemical immunosensors based PEDOT/MWCNT hybrid composite for detection of clenbuterol antibiotic has been developed. It shows promising properties as biosensors platform with combination of ...high conductive properties of poly(3,4-ethylenedioxythiophene) (PEDOT) and high surface area of carbon nanotube (CNT). Based on cyclic voltammetry (CV) measurement in potassium ferricyanide (K3Fe(CN)6), lower peak potential separation (90.33mV) and higher peak current (0.197mA) were obtained compared with unmodified electrode (114.75mV and 0.163mA).This immunosensor, which was based on direct competitive method, was examined with standard clenbuterol hydrochloride for detection of clenbuterol through chronoamperometry at -0.1V.
The key performance of any drilling operation depends heavily on the choice of drilling fluid used as well as how good it can overcome the drill pipe friction. It is essential that the drilling fluid ...be able to reduce bit wear, torque and drag. Drilling with oil-based drilling fluid offer less torque and drag. However, water based drilling fluid are cheaper and environmental friendly compared to oil-based and synthetic-based drilling fluids. Lubricants are added to drilling fluid to produce a thin film of liquid that separates the solid surfaces in contact to reduce the friction to an acceptable range. This study focused on the performance evaluation of two different commercial lubricants, which are EBL and EME salt to improve the lubricity of water based drilling fluid. The performances of lubricants were evaluated by ranging the concentrations from 1%, 2% and 3%. Fann Lubricity Tester is used to test the lubricity of these lubricants. The results reveal that the coefficients of friction for all lubricants were reduced after reaching the optimum concentration at the range of 1 - 2%. Some improvements were observed on the rheological properties such as plastic viscosity, yield point and gel strength when the lubricants were added to the drilling fluid. The values satisfy the requirement accepted by the industry. This study also showed that the applicants of EBL lubricant is better than EME salt in term of reducing the coefficient of friction in drilling fluid.
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