Enhanced Gas Separation Prowess Using Functionalized Lignin-Free Lignocellulosic Biomass/Polysulfone Composite Membranes

Delignified lignocellulosic biomass was functionalized with amine groups. Then, the pretreated lignin-free date pits cellulose and the amine-functionalized-date pits cellulose (0–5 wt%) were incorporated into a polysulfone polymer matrix to fabricate composite membranes. The amine groups give additional hydrogen bonding to those existing from the hydroxyl groups in the date pits cellulose. The approach gives an efficient avenue to enhance the CO2 molecules’ transport pathways through the membrane matrix. The interactions between phases were investigated via Fourier transformed infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), whereas pure gases (CO2 and N2) were used to evaluate the gas separation performances. Additionally, the thermal and mechanical properties of the fabricated composites were tested. The pure polysulfone membrane achieved an optimum separation performance at 4 Bar. The optimum separation performance for the composite membranes is achieved at 2 wt%. About 32% and 33% increments of the ideal CO2/N2 selectivity is achieved for the lignin-free date pits cellulose composite membrane and the amine-functionalized-date pits cellulose composite membrane, respectively.

Insight on to Mechanical, Thermal, Long-Term, Hydrothermal, and Chemical Stability of PSf Based Membrane Systems for Separation of O2 /N2

MMMs have been opened up a new window in gas separation and purification applications, but the actual viability can be reckoned on the basis of performance achieved in realistic feed conditions. This research highlights the selection of silica decorated graphene for the first time to prepare nanocomposite membranes. In the study, XRD, Raman, and UV validated the existence of the different fillers within the host Polysulfone (PSf), while TEM authenticated their distribution. The burst strength and thermal properties were also investigated. Besides, it covered a prudent step towards resolving the dominant ingredients, which routinely appraise the stability and durability of the membranes. These indexes are long-term gas permeation up to 120 hours coupled with sustainability against hydrothermal and chemical resistance under various conditions similar to real-life separation applications. Finally, the report demonstrated that the nanohybrid integrated membrane systems displayed optimum separation performance and stability than their parent counterparts: PSf/mSiO2, PSf/GO.

Effective Gap Size Index for Determination of Optimum Separation Distance Preventing Pounding between Buildings during Earthquakes

Seismic excitations may lead to collisions between adjacent civil engineering structures, causing major damage. In this paper, an effective equation for calculating the gap size index is proposed so as to provide the optimum separation distance preventing structural pounding during different earthquakes. Evaluation of the best prediction of the required separation distance between two adjacent buildings was carried out by using the lumped mass multi-degrees of freedom models of structures. A special computer program was used to perform dynamic analyses in order to confirm the accuracy of the proposed formula. For this purpose, several different models of buildings with various properties under different earthquake excitations were analyzed. The results of the study clearly show that the proposed formula for the gap size index (based on vibration periods and damping ratios of buildings) is effective and it allows us to calculate the optimum separation between adjacent structures preventing their pounding during different earthquakes.

Interaction between surface waves on wire lines

This paper investigates coupling between electromagnetic surface waves on parallel wires. Finite-element method (FEM)-based and analytic models are developed for single- and double-wire Sommerfeld and Goubau lines. Models are validated via measurements for Goubau lines and a comparison between the analytic and the FEM-based computations for coupled Sommerfeld- and Goubau-type lines is carried out. The measurements and calculations show remarkable agreement. The FEM-based and analytic models match remarkably well too. The results exhibit new favourable effects for surface waves propagation over multiple conductors. The short-range behaviour of the coupled wires and, consequently, the existence of an optimum separation of coupled wires is one of the most significant findings of this paper. We comment on the relevance of our results, particularly in relation to applications of high bandwidth demands and cross-coupling effects.

Study on the separation of silicon from refining slag of industrial silicon

During the process of production and refining of industrial silicon, the discharged slag usually contains more than 15 mass% of metallic silicon. However, the separation of silicon from slag is very difficult due to the close density of silicon and slag as well as the high viscosity of slag, which results in the waste of resources. In the present work, the effect of Na2O addition on the separation of silicon from slag is investigated in detail. It is found that the optimum separation condition of slag and silicon is 1723 K reacting for 60 min by adding 10 mass% Na2O to the slag. Viscosity and density are two important factors affecting the separation effect of silicon from slag. The addition of Na2O reduces the viscosity of slag and promotes the separation of silicon from slag. Even if the addition of Na2O will decrease the density of slag which is detrimental to the separation of silicon, the density variation is not the determining factor affecting the separation relative to viscosity. The separation and extraction of metallic silicon from silicon slag is of great significance for improving utilization of resources and reducing environmental pollution.

Full optimization and validation of an HPLC method for the quantitative analysis of total sugars in a soft drink

Five HPLC methods were employed for the quantitative analysis of three natural sugars namely fructose, glucose and sucrose in soft drinks. HPLC-refractive index detector (RID)-AMINO proved to be the most suitable HPLC method to carry out the latter task. For the optimum separation and response of the natural sugars the best conditions employed were column oven temperature 30 oC, flow rate 0.1 mL/min, mobile phase ratio acetonitrile:water 75:25 and they were determined by studying all possible interactions among these three parameters. Full validation of HPLC-RID-AMINO was performed in terms of system suitability test, precision check, accuracy check and robustness. KEY WORDS: Sugar, Soft drink, Experimental design, Validation, HPLC, System suitability Bull. Chem. Soc. Ethiop. 2020, 34(2), 419-426 DOI: https://dx.doi.org/10.4314/bcse.v34i2.17

Diagnosis of occupational asthma from serial measurements of forced expiratory volume in 1 s (FEV1) using the Area Between Curves (ABC) score from the Oasys plotter

ObjectivesTo identify the changes in serial 2-hourly forced expiratory volume in 1 s (FEV1) measurements required to identify occupational asthma (OA) using the Oasys Area Between Curves (ABC) score.MethodsThe ABC score from 2-hourly measurements of FEV1 was compared between workers with confirmed OA and asthmatics without occupational exposure to identify the optimum separation using receiver operator characteristic (ROC) analysis. Separate analyses were made for plots using clock time and time from waking to allow for use in shift workers. Minimum record criteria were ≥6 readings per day, >4 day shifts and >4 rest days (or >9 days for controls).ResultsA retrospective analysis identified 22 workers with OA and 30 control asthmatics whose records reached the quality standards. Median FEV1 diurnal variation was 20.3% (IQR 16.1–32.6) for OA and 19.5% (IQR 14.5–26.1) for asthmatic controls. ROC curve analysis identified that a difference of 0.056 L/hour gave a ROC score of 0.821 for clock time and 0.768 for time from waking with a sensitivity of 73% and a specificity of 93% for the diagnosis of OA.ConclusionsThe diagnosis of OA requires objective confirmation. Unsupervised serial FEV1 measurements are more difficult to obtain reliably than measurements of peak expiratory flow, which are likely to remain the standard for general use. A FEV1 ABC score >0.056 L/hour provides a valid cut-off for those who wish to use FEV1 rather than peak expiratory flow.

Selection of Optimum Separation Sequence for Multicomponent Distillation

This paper considers the process of multicomponent distillation. It is shown that energy consumption (per mole of mixture being separated) depends monotonously on efficiency if the capacity is constant and separation is reversible. Authors suggest the technique for selection of distillation sequence for which the total energy consumption in the cascade of columns reaches its minimum. This sequence is determined by values of thermal coefficients. Coefficients themselves depend on temperatures in the reboiler and condenser. This paper offers the algorithm for the calculation of these coefficients.