Kinetic modeling of sorption–desorption cycles for phenol removal with a cyclodextrin polymer

Francisco J. Peñas,Ana Romo,José R. Isasi,María J. San José,Sonia Alvarez 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.75 No.-

This paper examines the long-term application of a cyclodextrin hydrogel sorbent in multiple sorption–desorption cycles. Aqueous phenol was the target pollutant, whilst methanol, ethanol and isopropanolwere chosen as eluents. The experimental results were well described by empirical models: thebreakthrough curves by a two-parameter dose–response equation, and the elution curves by a pulsepeakequation with two independent parameters. The differences in polarity of solvents producedsorbent fragmentation, particularly marked for isopropanol and considerably lower for methanol, andtherefore a progressive increase in mass-transfer coefficients. In addition, a dual approach was developedfrom the proposed breakthrough model to address the mass transport of sorbate within the packed beds. Thefirst one defines an average mass-transfer coefficient as representative for each complete sorptioncycle, whereas a time-profile of this coefficient is deduced in the second method. A sorption capacity of29.6 mg-phenol/g-sorbent was found in the working conditions.

Mathematical Modeling of Drying Kinetics for Pulp Sheet Based on Fick’s Second Law of Diffusion

Lingbo Kong,Xing Yang,Zhihao Hou,Jixian DONG 한국펄프·종이공학회 2020 펄프.종이기술 Vol.52 No.2

In this study, we investigated the drying characteristics for pulp sheet at different hot air temperature (80, 90, and 100℃). The drying kinetics were modeled using one- to five-term solutions of Fick’s second law of diffusion at different drying conditions. It was found that these models underestimated the initial drying stages and overestimated the final drying stages. Meanwhile, the values of the diffusion coefficient tended to stabilize when the series terms more than three. In order to improve the accuracy of the mathematical models, the modified one- to three-term models were also used to describe the drying kinetics. The results showed that modeling data was agreed with the experiment data better than the series solution models based on Fick’s second law of diffusion. Besides, the accuracy improved dramatically as the terms of the model increased. The minimum diffusion coefficient was 0.996 for the modified three-term model. It was concluded that the modified model could simulate the pulp sheet drying process under the conditions studied.

Separation of mercury and arsenic from produced water via hollow fiber contactor: Kinetic and mass transfer analysis

Suphot Phatanasri,Ura Pancharoen,Dolapop Sribudda,Thanaporn Wannachod,Prakorn Ramakul 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.1

The separation of Hg(II) and As(V) from produced water by hollow fiber contactors was investigated. Two identical hollow fiber modules were employed. The first module was used for extraction, while the second module was used for stripping. The optimum conditions achieved were 14% (v/v) of Aliquat336, 0.07 M thiourea, volumetric flow rate of 100 mL/min for aqueous solution and 0.02 M HCl of stripping solution. At such conditions, the maximum extraction of Hg(II) and As(V) attained 100% and 78.78%, respectively. Concurrently, the maximum stripping of Hg(II) and As(V) reached 47.88% and 6.66%, respectively. The overall mass transfer coefficients of Hg(II) and As(V) extraction were 2.31×10−6 and 1.15×10−6m/s, while the Hg(II) and As(V) stripping exhibited the overall mass transfer coefficients of 8.37×10−7 m/s and 9.05×10−7 m/s, respectively. Mass transfer coefficients of the organic layer diffusion (k0) had the most effect on the overall mass transfer coefficients.

Coefficient of Restitution and Kinetic Energy Loss of Rockfall Impacts

Li-Ping Li,Shang-qu Sun,Shucai Li,Qian-qing Zhang,Cong Hu,Shao-shuai Shi 대한토목학회 2016 KSCE JOURNAL OF CIVIL ENGINEERING Vol.20 No.6

This paper presents the results of the coefficient of restitution and the kinetic energy loss rate obtained by lab experiment, two parameters that are crucial for rockfall impact. However, various definitions of coefficient of restitution exist and the most appropriate one is still not formed and obtained. In addition, the energy variation during the rockfall impacts has important significance in practical design. In this research, two kind shapes of blocks including plate and strip were adopted in the laboratory testing and the block material was tested before, indicating that the material has sufficient strength to prevent shattering during the impact. Furthermore, an apparatus specifically built for this study was established including a base, a slope and a releasing device. The falling testing was performed using plate and strip block while the falling height as well as the slope angle and releasing height were altered during the tests in order to estimate the effect of each parameter on the coefficients of restitution and energy loss rate. It was observed that collision reflection angle is less than impact angle for all, suggesting energy loss in collision. Impact angle decreases with increasing slope angle while there was no obvious effect of releasing height and releasing angle on impact angle. The relevant coefficient of restitution was found to decrease with impact angle, and the kinetic energy loss rate increased. Finally, the kinetic energy before and after the impact was found to significantly affect the COR and energy loss rate and the results can provide basis for mitigation measures.

Study of the Quantum Magneto-Thermoelectric Effect in the Two-Dimensional Compositional Superlattice GaAs/AlGaAs under the influence of an Electromagnetic Wave by Using the Quantum Kinetic Equation

Nguyen Quang Bau,Dao Thu Hang,Do Tuan Long 한국물리학회 2019 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.75 No.12

The quantum magneto-thermoelectric effect in a two-dimensional compositional superlattice under the influence of an electromagnetic wave (EMW) in two cases is investigated. Two cases of the electron scattering mechanism are considered: the electron-acoustic phonon scattering and electron-optical phonon scattering. Analytical expressions for the quantum Ettingshausen coefficient (EC), the thermopower tensor, the thermoelectric tensor and the kinetic tensor are obtained by using a quantum kinetic equation. These expressions are numerically solved for the two-dimensional compositional superlattice GaAs/AlGaAs and the results are discussed. The results show that in the case of electron-acoustic phonon scattering, the Shubnikov-de Haas oscillations appear when we examine the dependences of the quantum EC, the thermopower tensor and the thermoelectric tensor on the magnetic field. In the case of electron-optical phonon scattering, resonance peaks that satisfy the condition of the inter-subband magneto-phonon resonance appear. In the two cases, the superlattice period (a parameter specific to the material) strongly affects the quantum magneto-thermoelectric effect. When the superlattice period is small, quantum EC oscillations (in the case of electron-acoustic phonon interaction) and quantum EC resonance peaks (in the case of electron-optical phonon interaction) appear. However, when the superlattice period is large, these oscillations and resonance peaks are not observed. Especially, the influence of electromagnetic waves on the quantum magneto-thermoelectric effect is also clarified. The quantum theory of the magneto-thermoelectric effect has been studied from low temperature to high temperature. This overcomes the limitations of the Boltzmann kinetic equation which was studied at high temperature. The results are new and can serve as a basis for further development of the theory of quantum magneto-thermoelectric effects in low-dimensional semiconductor systems.

Moisture-dependent Physical Properties of Detarium microcarpum Seeds

Aviara, Ndubisi A.,Onaji, Mary E.,Lawal, Abubakar A. Korean Society for Agricultural Machinery 2015 바이오시스템공학 Vol.40 No.3

Purpose: Physical properties of Detarium microcarpum seeds were investigated as a function of moisture content to explore the possibility of developing bulk handling and processing equipment. Methods: Seed size, surface area, and 1,000-seed weight were determined by measuring the three principal axes, measuring area on a graph paper, and counting and weighing seeds. Particle and bulk densities were determined using liquid displacement and weight in a measuring cylinder, respectively. Porosity was computed from particle and bulk densities. Roundness and sphericity were measured using shadowgraphs. Angle of repose and static and kinetic coefficients of friction were determined using the vertical cylindrical pipe method, an inclined plane, and a kinetic coefficient of friction apparatus. Results: In the moisture range of 8.2%-28.5% (db), the major, intermediate, and the minor axes increased from 2.95 to 3.21 cm, 1.85 to 2.61 cm, and 0.40 to 1.21 cm, respectively. Surface area, 1,000-seed weight, particle density, porosity, and angle of repose increased from 354.62 to $433.19cm^2$, 3.184 to 3.737 kg, 1060 to $1316kg/m^3$, and 30.0% to 53.1%, respectively, whereas bulk density decreased from 647.6 to $617.2kg/m^3$. Angle of repose increased from $13.9^{\circ}$ to $28.4^{\circ}$. Static and kinetic coefficients of friction varied between 0.096 and 0.638 on different structural surfaces. Conclusions: Arithmetic mean, geometric mean, and equivalent sphere effective diameters determined at the same moisture level were significantly different from each other, with the arithmetic mean diameter being greatest. Surface area, 1,000-seed weight, particle density, porosity, and angle of repose all increased linearly with moisture content. Bulk density decreased linearly with moisture content. The coefficients of friction had linear relationships with moisture content. The highest values of static and kinetic coefficients of friction were observed on galvanized steel and hessian fabric, respectively, whereas the lowest values were observed on fiberglass.

Agricultural Process and Food Engineering ; Moisture-dependent Physical Properties of Detarium microcarpum Seeds

( Ndubisi A. Aviara ),( Mary E. Onaji ),( Abubakar A. Lawal ) 한국농업기계학회 2015 바이오시스템공학 Vol.40 No.3

Purpose: Physical properties of Detarium microcarpum seeds were investigated as a function of moisture content to explore the possibility of developing bulk handling and processing equipment. Methods: Seed size, surface area, and 1,000-seed weight were determined by measuring the three principal axes, measuring area on a graph paper, and counting and weighing seeds. Particle and bulk densities were determined using liquid displacement and weight in a measuring cylinder, respectively. Porosity was computed from particle and bulk densities. Roundness and sphericity were measured using shadowgraphs. Angle of repose and static and kinetic coefficients of friction were determined using the vertical cylindrical pipe method, an inclined plane, and a kinetic coefficient of friction apparatus. Results: In the moisture range of 8.2%-28.5% (db), the major, intermediate, and the minor axes increased from 2.95 to 3.21 cm, 1.85 to 2.61 cm, and 0.40 to 1 .21 cm, respectively. Surface area, 1,000-seed weight, particle density, porosity, and angle of repose increased from 354.62 to 433.19 cm 2 , 3.184 to 3.737 kg, 1060 to1316 kg/m 3 , and 30.0% to 53.1%, respectively, whereas bulk density decreased from 647.6 to 617.2 kg/m 3 . Angle of repose increased from 13.9° to 28.4°. Static and kinetic coefficients of friction varied between 0.096 and 0.638 on different structural surfaces. Conclusions: Arithmetic mean, geometric mean, and equivalent sphere effective diameters determined at the same moisture level were significantly different from each other, with the arithmetic mean diameter being greatest. Surface area, 1,000-seed weight, particle density, porosity, and angle of repose all increased linearly with moisture content. Bulk density decreased linearly with moisture content. The coefficients of friction had linear relationships with moisture content. The highest values of static and kinetic coefficients of friction were observed on galvanized steel and hessian fabric, respectively, whereas the lowest values were observed on fiberglass.

Friction Characteristics of DLC and WC/C

김동욱,김경웅 한국트라이볼로지학회 2011 한국윤활학회지(윤활학회지) Vol.27 No.6

In this study, friction tests were performed in order to investigate the effect of sliding velocity and normal load on the friction characteristics of DLC (a-C:H) and WC/C (a-C:H:W) using a ball-on-disk type friction tester. DLC and WC/C were deposited on AISI 52100 steel balls. Friction tests against carburized SCM 415 Cr-Mo steel disks were carried out under various sliding velocity (0.1, 0.78, 1.56, 3.13, 6.25, 12.5, 25, 50 and 100 mm/s) and normal load (2.4, 4.8 and 9.6 N) conditions while the relative humidity was 20~40 % R.H. and air temperature was 16~24 ℃. As results, kinetic friction coefficients of DLC and WC/C were obtained under each test condition. The results show that the kinetic friction coefficients of DLC and WC/C generally increase with the increase in sliding velocity. And, under the same sliding velocity condition, the kinetic friction coefficients are almost constant regardless of normal load. In addition, the kinetic friction coefficients of DLC are lower than those of WC/C under the same test conditions.

Doped Two-dimensional Semiconductor Superlattice: Photo-stimulated Quantum Thermo-magnetoelectric Effects under the Influence of a Confined Phonon

Bau Nguyen Quang,Quynh Nguyen Thi Lam,Ba Cao Thi Vi,Hung Le Thai 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.77 No.12

Photo-stimulated quantum thermo-magnetoelectric effects in doped two-dimensional semiconductor superlattices, including the photo-stimulated quantum Ettingshausen effect and the photo-stimulated quantum Peltier effect, have been theoretically studied by using the quantum kinetic equation method. In this work, we assume that the electron-confined acoustic phonon scattering is essential. Moreover, the presence of the laser radiation (LR) is also taken into account to determine the influence of confined phonons on the aforementioned effects. We have defined the analytical expressions for the kinetic tensors and the Ettingshausen and the Peltier coefficients, presented the numerically calculated the theoretical results for the GaAs:Si/GaAs:Be doped semiconductor superlattice and compared them with these for the case of an unconfined acoustic phonon. The results obtained indicated that the formulas for the kinetic tensors, the Ettingshausen coefficient (EC) and the Peltier coefficient (PC) contain the quantum number m specifying the confinement of a phonon and approach the results for an unconfined phonon as m goes to zero. We found that the kinetic tensors, the EC and the PC oscillate with changing magnetic field and that the confinement of a phonon causes a shift of the peaks in these oscillations to lower energy. The dependences of both EC and PC on the temperature were found to be nonlinear. Moreover, all the coefficients level off when the temperature was less than 4.5 K or greater than 5.5 K. The EC also depended on the doping concentration in a nonlinear way and reaches a positive constant value when the semiconductor superlattice was doped with a high concentration. Most of the numerical results showed that the magnitude of the tensors, the EC as well as the PC, within a confined acoustic phonon varie significantly in comparison with the unconfined phonon case. This means that the confinement of the phonon affects the thermo-magnetoelectric effect quantitatively and qualitatively. These results contribute to completing the theory of the thermo-magnetoelectric effects in the low-dimensional semiconductor systems.

Friction Characteristics of DLC and WC/C

Dong-Wook Kim(김동욱),Kyung-Woong Kim(김경웅) 한국트라이볼로지학회 2011 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.27 No.6

본 연구에서는 수직 하중과 미그럼 속도가 DLC(a-C:H)와 WC/C (a-C:H:W)의 마찰 특성에 미치는 영향을 파악하기 위해 ball-on-disk 형태의 마찰 실험 장치를 이용하여 실험을 수행하였다. 연구 대상 고체 윤활막인 DLC와 WC/C는 AISI 52100 steel ball의 표면에 증착되었으며, 상대 마찰면의 재질은 침탄 경화된 SCM 415 Cr-Mo steel이다. 실험은 상대 습도가 20~40% 이고 온도가 16~24℃인 대기 분위기에서 다양한 미끄럼 속도 (0.1, 0.78, 1.56, 3.13, 6.25, 12.5, 25, 50, 100 ㎜/s) 및 수직하중 (2.4, 4.8, 9.6 N) 조건에 대해 수행되었다. 실험 결과로 각각의 실험 조건에서의 DLC와 WC/C의 운동 마찰 계수를 얻었다. 실험 결과 DLC 와 WC/C의 운동 마찰 계수는 미끄럼 속도가 증가할수록 대체로 증가하였으며, 수직 하중에 관계없이 거의 일정한 갑을 보였다. 그리고 동일한 실험조건에서 DLC의 마찰 계수가 WC/C의 마찰 계수애 비해 대체로 낮은 값을 보였다. In this study, friction tests were performed in order to investigate the effect of sliding velocity and normal load on the friction characteristics of DLC (a-C:H) and WC/C (a-C:H:W) using a ball-on-disk type friction tester. DLC and WC/C were deposited on AlSI 52100 steel balls. Friction tests against carburized SCM 415 Cr-Mo steel disks were carried out under various sliding velocity (0.1, 0.78, 1.56, 3.13, 6.25, 12.5, 25, 50 and 100 ㎜/s) and normal load (2.4, 4.8 and 9.6 N) conditions while the relative humidity was 20~40 % R.H. and air temperature was 16~24 ℃. As results, kinetic friction coefficients of DLC and WC/C were obtained under each test condition. The results show that the kinetic friction coefficients of DLC and WC/C generally increase with the increase in sliding velocity. And, under the same sliding velocity condition, the kinetic friction coefficients are almost constant regardless of normal load. In addition, the kinetic friction coefficients of DLC are lower than those of WC/C under the same test conditions.