The controllable intensified process has received immense attention from researchers in order to deliver the benefit of process intensification to be operated in a desired way to provide a more sustainable process toward reduction of environmental impact and improvement of intrinsic safety and process efficiency. Despite numerous studies on gain and phase margin approach on conventional process systems, it is yet to be tested on intensified systems as evidenced by the lack of available literature, to improve the controller performance and robustness. Thus, this paper proposed the exact gain and phase margin (EGPM) through analytical method to develop suitable controller design for intensified system using Proportional-Integral-Derivative (PID) controller formulation, and it was compared to conventional Direct Synthesis methods (DS), Internal Model Control (IMC), and Industrial IMC method in terms of the performance and stability analysis. Simulation results showed that EGPM method provides good setpoint tracking and disturbance rejection as compared to DS, IMC, and Industrial IMC while retaining overall performance stability as time delay increases. The Bode Stability Criterion was used to determine the stability of the open-loop transfer function of each method and the result demonstrated decrease in stability as time delay increases for controllers designed using DS, IMC, and Industrial IMC, and hence control performance degrades. However, the proposed EGPM controller maintains the overall robustness and control performance throughout the increase of time delay and outperform other controller design methods at higher time delay with [Formula: see text] uncertainty test. Additionally, the proposed EGPM controller design method provides overall superior control performance with lower overshoot and shorter rise time compared to other controllers when process time constant is smaller in magnitude ([Formula: see text]) than the instrumentation element, which is one of the major concerns during the design of intensified controllers, resulting overall system with a higher order. The desired selection of gain margin and phase margin were suggested at 2.5 to 4 and 60 °-70 [Formula: see text], respectively, for a wide range of control conditions for intensified processes where higher instrumentation dynamic would be possible to achieve robust control as well. The proposed EGPM method controller is thought to be a more reliable design strategy for maintaining the overall robustness and performance of higher order and complex systems that are highly affected by time delay and high dynamic response of intensified processes.
Over the past decade, L-homophenylalanine is extensively used in the pharmaceutical industry as a precursor for production of angiotensin-converting enzyme (ACE) inhibitor, which possesses significant clinical application in the management of hypertension and congestive heart failure (CHF). A number of chemical methods have been reported thus far for the synthesis of L-homophenylalanine. However, chemical methods generally suffer from process complexity, high cost, and environmental pollution. On the other hand, enantiomerically pure L-homophenylalanine can be obtained elegantly and efficiently by employing biocatalytic methods, where it appears to be the most attractive process in terms of potential industrial applications, green chemistry and sustainability. Herein we review the biocatalytic synthesis of vital L-homophenylalanine as potentially useful intermediate in the production of pharmaceutical drugs in environmentally friendly conditions, using membrane bioreactor for sustainable biotransformation process. One envisages the future prospects of developing an integrated membrane bioreactor system with improved performance for L-homophenylalanine production.
This study examined the performance of nanofiltration membranes to retain atrazine and dimethoate in aqueous solution under different pH conditions. Four nanofiltration membranes, NF90, NF200, NF270 and DK are selected to be examined. The operating pressure, feed pesticide and stirring rate were kept constant at 6x10(5) Pa, 10 mg/L and 1000 rpm. It was found that increasing the solution's pH increased atrazine and dimethoate rejection but reduced the permeate flux performance for NF200, NF270 and DK. However, NF90 showed somewhat consistent performance in both rejection and permeate flux regardless of the solution's pH. NF90 maintained above 90% of atrazine rejection and approximately 80% of dimethoate rejection regardless of the changes in solution's pH. Thus, NF90 is deemed the more suitable nanofiltration membrane for atrazine and dimethoate retention from aqueous solution compared to NF200, NF270 and DK.
Polymeric vanadium pentoxide gel was formed via the reaction of V2O5 powder with hydrogen peroxide. The polymeric vanadium pentoxide gel was then dispersed in alumina gel. Different vanadium loading composites were coated on alumina support and calcined at 500 degrees C for 1 hr. These composite layers were characterized using TGA, FT-IR, XRD, SEM, and Autosorb. It was found that the lamellar structure of polymerized vanadium pentoxide was retained in the inorganic matrix. Crystalline alumina in gamma phase was formed after calcinations. However, the vanadium-alumina mixed oxides are lack of the well defined PXRD peaks for polycrystalline V2O5. This is possibly because the vanadia species are highly dispersed in the alumina matrix or the vanadia species are dispersed as crystalline which is smaller than 4 nm. In addition, the imbedded polymeric vanadium oxide improved the specific area and average pore diameter of the composite layer.