Manganese Removal from Aqueous Solution by Ozonation Process Designed by Box-Behken Design (BBD)

The aim of this research was to investigate interactions in the removal of manganese from contaminated water by oxidation through an ozonation process. The manganese oxidation was used to oxidize manganese ions (Mn2+) in solution to manganese dioxide (MnO2) in its brown solid form, in order to reduce levels of manganese ions in the water to below the acceptable limit for drinking water (0.05 mg L-1). In this study, the independent effects such as the initial concentration of manganese (5, 10 and 15 mg L-1), initial pH of solutions (3, 4 and 5) and ozone concentrations (10.970, 21.945 and 32.920 mg L-1) designed Box-Behnken Design (BBD) as a one of the design of experiments were examined for  optimal conditions and including main effects and their interactions. The ozone concentration in the reactor was increased with increasing operating time of an ozone generator and linearly increased at the rate about 2.194 mg O3 L-1 min-1. The experimental results indicated that all factors significantly affected manganese removal rate. Initial manganese concentration was negatively correlated, while pH and ozone concentration were both positively correlated with removal percentage. Main, square and interaction effects were significant on percent manganese removal. Additionally, percent removal was reduced with increasing ozone concentrations because at higher ozone levels, MnO2 in solid form was converted to MnO4- and redissolved into solution- a process known as over-oxidation. The maximal condition, the removal efficiency of manganese in oxidation reaction by ozonation process in initial manganese concentration 5 mg L-1, pH 4.0 and ozone concentration 21.945 mg L-1 was appeared more than 100 %. The present study indicates that manganese ions can be effectively removed from drinking water by ozonation

Time-varying sliding mode controller for heat exchanger with dragonfly algorithm

This article proposes the design of a sliding mode controller with a time-varying sliding surface for the plate heat exchanger. A time-varying sliding mode controller (TVSMC) combines the benefit of the control system’s robustness and convergence rate. Using Lyapunov stability theory, the stability of the designed controller is proved. In addition, the controller parameters of the designed controller are specified optimally via the dragonfly algorithm (DA). The input constraint’s effect is considered in the controller design process by applying the concept of the auxiliary system. The bounded disturbances are applied to investigate the robustness of the proposed techniques. Moreover, the quasi-sliding mode controller (QSMC) is developed as a benchmark to evaluate the convergence behavior of the proposed TVSMC technique. The simulation results demonstrate the proposed TVSMC with the optimal parameters provided by the DA algorithm (TVSMC+DA) can regulate the temperature to the desired level under bounded disturbances. When compared to the QSMC method, the TVSMC+DA performs significantly faster convergence speed and greater reduction in chattering occurrence. The results clearly indicate that the proposed controller can enhance convergence properties while being robust to disturbances

A Smart Wristband Integrated with an IoT-Based Alarming System for Real-Time Sweat Alcohol Monitoring

Breathalyzer is a common approach to measuring blood alcohol concentration (BAC) levels of individuals suspected of drunk driving. Nevertheless, this device is relatively high-cost, inconvenient for people with limited breathing capacity, and risky for COVID-19 exposure. Here, we designed and developed a smart wristband integrating a real-time noninvasive sweat alcohol metal oxide (MOX) gas sensor with a Drunk Mate, an Internet of Thing (IoT)-based alarming system. A MOX sensor acquired transdermal alcohol concentration (TAC) which was converted to BAC and sent via the IoT network to the Blynk application platform on a smartphone, triggering alarming messages on LINE Notify. A user would receive an immediate alarming message when his BAC level reached an illegal alcohol concentration limit (BAC 50 mg%; TAC 0.70 mg/mL). The sensor readings showed a high linear correlation with TAC (R2 = 0.9815; limit of detection = 0.045 mg/mL) in the range of 0.10–1.05 mg/mL alcohol concentration in artificial sweat, achieving an accuracy of 94.66%. The sensor readings of ethanol in water were not statistically significantly different (p > 0.05) from the measurements in artificial sweat and other sweat-related solutions, suggesting that the device responded specifically to ethanol and was not affected by other electrolytes in the artificial sweat. Moreover, the device could continuously monitor TAC levels simulated in real-time in an artificial sweat testing system. With the integration of an IoT-based alarming system, the smart wristband developed from a commercial gas sensor presented here offers a promising low-cost MOX gas sensor monitoring technology for noninvasive and real-time sweat alcohol measurement and monitoring

ผลของปริมาณโลหะโครเมียมบนตัวรองรับไดอะตอมไมต์ต่อการสังเคราะห์ไดเมทิลอีเทอร์จากเมทานอลEffect of Chromium Loading on Diatomite for the Synthesis of Dimethyl Ether from Methanol

งานวิจัยนี้ได้ศึกษาผลการเร่งปฏิกิริยากำจัดน้ำของเมทานอลเพื่อผลิตไดเมทิลอีเทอร์ โดยใช้ตัวเร่งปฏิกิริยาโครเมียมบนตัวรองรับไดอะตอมไมต์ที่มีปริมาณโลหะที่แตกต่างกัน ถูกทดสอบในเครื่องปฏิกรณ์แบบเบด-นิ่ง ณ ความดันบรรยากาศในช่วงอุณหภูมิ 250 ถึง 350°C จากผลการทดลองการเพิ่มปริมาณโครเมียมในตัวเร่งปฏิกิริยาส่งผลให้ร้อยละการแปลงผันเมทานอลสูงขึ้นที่ทุกสภาวะอุณหภูมิ และให้ค่าการเลือกเกิดเป็นไดเมทิลอีเทอร์สูงถึงร้อยละ 99 ทุกสภาวะ อีกทั้งการเพิ่มปริมาณโลหะโครเมียมทำให้ค่าความเป็นกรดบนพื้นผิวสูงขึ้น แต่พื้นที่ผิวของตัวเร่งปฏิกิริยาลดลง พบว่าปริมาณโลหะออกไซด์และความเป็นกรดมีผลต่อปฏิกิริยามากกว่าพื้นที่ผิวของตัวเร่งปฏิกิริยา โดยตัวเร่งปฏิกิริยา 15%Cr/DM ให้ร้อยละการแปลงผันเมทานอลสูงที่สุดถึงร้อยละ 91.7 และมีเสถียรภาพคงที่ในขณะทำการทดลองเป็นเวลา 12 ชั่วโมง แสดงให้ว่าเป็นตัวเร่งปฏิกิริยานี้เหมาะสมสำหรับการนำไปใช้ในการสังเคราะห์ไดเมทิลอีเทอร์จากเมทานอล This research investigates the results of catalytic methanol dehydration for synthesis of dimethyl ether using chromium on diatomite catalyst with different the metal loading. The reactions were performed in pack-bed reactor at temperature between 250 to 350°C. According to the experimental results, the conversion of methanol increased with the increase of chromium loading on diatomite catalyst. DME selectivity was up to 99 percent. The surface acidity increased due to chromium loading, whereas the surface areas decreased. It was found that metal oxide loading and surface acidity affected reaction rates more than the surface area of the catalyst. Finally, 15%Cr/DM catalyst give high methanol conversion at 91.7 percent and it has exhibited good stability during the 12 hour experiment. The catalyst has shown efficient synthesis of dimethyl ether from methanol