Analysis of threshed rice mixture separation through vibration screen using discrete element method

The discrete element method was utilized to construct three-dimensional discrete element models for the rice mixture,and their motions were analyzed numerically on a planar vibration screening device.The results showed that,after falling onto the vibrating screen surface,the mixture undergoes a reciprocating motion within the same cycle.During the screening process,the mixture undergoes segregation,slides along the screen surface,passes through the screen and then falls.In comparing the movement of grains and shriveled grains,it can be seen that the velocity of shriveled grains experiences cyclical changes,which is consistent with the grains’motion cycle.The impact on grains is shown to be greater than that on shriveled grains,and the average speeds of shriveled grains and grains converge.The curve shows that the screening of repetitive movements has a significant effect on the average velocity of shriveled grains,but also the velocity of shriveled grains and the vibration parameters can be well represented by a fitting equation.It is beneficial for the separation of grains from shriveled grains to choose a greater vibration frequency and screen surface inclination in the range of commonly used.

Membrane materials in the pervaporation separation of aromatic/aliphatic hydrocarbon mixtures—A review

The separation of aromatic/aliphatic hydrocarbon mixtures is a significant process in chemical industry, but challenged in some cases. Compared with conventional separation technologies, pervaporation is quite promising in terms of its economical, energy-saving, and eco-friendly advantages. However, this technique has not been used in industry for separating aromatic/aliphatic mixtures yet. One of the main reasons is that the separation performance of existed pervaporation membranes is unsatisfactory. Membrane material is an important factor that affects the separation performance. This review provides an overview on the advances in studying membrane materials for the pervaporation separation of aromatic/aliphatic mixtures over the past decade. Explored pristine polymers and their hybrid materials(as hybrid membranes) are summarized to highlight their nature and separation performance. We anticipate that this review could provide some guidance in the development of new materials for the aromatic/aliphatic pervaporation separation.

SEPARATION OF FORMIC ACID-WATER AZEOTROPIC MIXTURES BY MEMBRANE DISTILLATION

The azeotrope disappeared when the formic acid-water mixtures were treated by membrane distillation. Membrane distillation were used for separation of formic acid-water azeotropic mixtures for the first time.

A WEIGHTED GENERAL DISCRETE FOURIER TRANSFORM FOR THE FREQUENCY-DOMAIN BLIND SOURCE SEPARATION OF CONVOLUTIVE MIXTURES

This letter deals with the frequency domain Blind Source Separation of Convolutive Mixtures (CMBSS). From the frequency representation of the "overlap and save", a Weighted General Discrete Fourier Transform (WGDFT) is derived to replace the traditional Discrete Fourier Transform (DFT). The mixing matrix on each frequency bin could be estimated more precisely from WGDFT coefficients than from DFT coefficients, which improves separation performance. Simulation results verify the validity of WGDFT for frequency domain blind source separation of convolutive mixtures.

Distinguished discriminatory separation of CO2 from its methane-containing gas mixture via PEBAX mixed matrix membrane

Highly selective separation of CO_2 from its methane-containing binary gas mixture can be achieved by using Poly(ether-block-amide)(PEBAX)mixed matrix membranes(MMMs).According to FESEM and AFM analyses,silica-based nanoparticles were homogenously integrated within the polymer matrix,facilitating penetration of CO_2 through the membrane while acting as barrier for methane gas.The membrane containing 4.6 wt% fumed silica(FS)(PEBAX/4.6 wt%FS)exhibits astonishing selectivity results where binary gas mixture of CO_2/CH_4 was used as feed gas.As detected by gas chromatography,in the permeate side,data showed a significant increase of CO_2 permeance,while CH_4 transport through the mixed matrix membrane was not detectable.Moreover,PEBAX/4.6 wt%FS greatly exceeds the Robeson limit.According to data reported on CO_2/CH_4 gas pair separation in the literature,the results achieved in this work are beyond those data reported in the literature,particularly when PEBAX/4.6 wt%FS membrane was utilized.

The effects of science,technology,society,environment(STSE)interactions on teaching chemistry

This study aimed to investigate the effects of making Science, Technology, Society and En-vironment relations on students’ comprehen-sion of chemistry topics through teaching che-mistry using STSE approach at secondary level. The study made use of the research model where pre and post tests were administered to control and treatment groups. The Chemistry Achievement Test (CAT) was used in the study. The sampling consisted of Grade 9 students studying at Anatolian High School and Voca-tional High School. Since the sampling had not been equated, in order to determine students’ logical and spatial thinking skills, they were administered Logical Thinking Skill Test and Mental Rotation test as pretests. Students were chosen randomly to take part in two control and two treatment groups. This experimental study was applied to the treatment group in teaching of “Separation of Mixtures” topic in Grade 9 Chemistry course during a four-week period. Students in the control group were taught through the traditional teaching methods. The data obtained were analyzed through the SPSS Software. As a result of the study, statistically significant increases were observed in the achievement levels of treatment group which received instruction using STSE relations. The change observed in the achievement levels of the control group was not statistically signifi-cant. The difference between the achievement levels of control and treatment groups in the posttests were favoring the treatment groups.

Optimization of the separation of a mixture of unknown composition by reversed-phase HPLC

A method is presented for the computer-assisted optimization of mobile phase selection for the separation of a synthetic intermediate of unknown composition by reversed- phase HPLC.The method is based on recognition of the order of the peaks by comparison of peak area ratio and followed by the BSOS-L(Binary Solvent Optimization System for HPLC)method.Excellent agreement was obtained between predicted data and experimental results.