Category Archives: Chemical Engineering & Technology

Properties and Phase Behavior of Water‐Tween‐Kerosene Microemulsions and Prediction of Their Viscosity

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Properties and Phase Behavior of Water-Tween-Kerosene Microemulsions and Prediction of Their Viscosity

Water-Tween-kerosene microemulsions were prepared by a titration method and characterized by droplet size, electrical conductivity, and viscosity measurements. Water-in-oil, oil-in-water, and bicontinuous Winsor IV microemulsions were obtained. A new equation to predict microemulsion viscosity as a function of the ratio of the dispersed-phase fraction to surfactant fraction is proposed.


Abstract

Microemulsion systems are of interest to researchers due to their low energy requirements and thermodynamic stability in a wide range of applications, including enhanced oil recovery, gas absorption, drug delivery, and chemical reaction environments. In this research, the viscosity of microemulsions was characterized and then predicted. Tween 20 and Tween 80 were used as surfactants and n-butanol as co-surfactant. Different types of prepared Winsor microemulsions were described using the phase diagram and then were evaluated regarding their viscosity, particle size, and electrical conductivity. The mean droplet size and viscosity of the microemulsion were 8–200 nm and 10.4–39.1 cp, respectively. Finally, a new equation is suggested to predict microemulsion viscosity as a function of the ratio of the dispersed phase fraction to the surfactant fraction.

Positioning a Measurement System for Determining the Mixing Quality in Biogas Digesters

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Positioning a Measurement System for Determining the Mixing Quality in Biogas Digesters

Proposals for positioning local flow speed sensors around the circumference of a vertical biogas digester to monitor the mixing process are provided. The installation locations are selected based on a high correlation between flow velocity at the point of installation and a corresponding global mixing parameter. This approach is demonstrated for three different types of agitators.


Abstract

Mixing quality in agricultural biogas plants is crucial for nutrition supply to the microorganisms and needs to be ensured by an energy-efficient mixing strategy. Various approaches have been proposed to determine the mixing quality in biogas digesters. Among them are magnetic-inductive or force sensors brought into vertical digesters through the concrete wall. This article presents an approach to locating these sensors effectively around the circumference of the digester to avoid positioning in dead zones and maximize information quality regarding flow and mixing behavior. Particle image velocimetry is used to measure flow fields in a transparent model digester. Finally, optimum measurement locations considering three widely used agitator geometries are suggested.

Effect of Mg/Al Oxides Supports on CaO Sorbents Prepared by Wet‐Mixing Synthesis for CO2 Capture

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Effect of Mg/Al Oxides Supports on CaO Sorbents Prepared by Wet-Mixing Synthesis for CO2 Capture

Calcium looping sorbents incorporated with MgO, Ca3Al2O6, and MgAl2O4 supports were prepared by wet-mixing synthesis and analyzed for their CO2 capture performances during the 30 cycles of carbonation/calcination reactions. At a 7:3 mass ratio of CaO to support oxides, the MgAl2O4 mixed support showed the best CO2 capture performance.


Abstract

Calcium looping is one of the effective methods for post-combustion CO2 capture. A key issue is choosing the appropriate supports to synthesize effective calcium-based sorbents. In this study, calcium looping sorbents incorporated with MgO, Ca3Al2O6, and MgAl2O4 supports were prepared by wet-mixing synthesis. Characterizations were made to determine the cyclic CO2 capture capacity, crystalline structure, porosity, and morphological changes of the sorbents over multiple cycles. The results showed that, at the mass ratio of CaO to support oxides of 7:3, the MgAl2O4 mixed support showed better CO2 capture performance than the MgO and Ca3Al2O6 supports. Moreover, the sorbent showed a porous and fluffy microstructure with a high specific surface area, making it a suitable candidate for cyclic CO2 capture.

Computational Fluid Dynamics Simulation of a Membrane Contactor for CO2 Separation: Two Types of Membrane Evaluation

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Computational Fluid Dynamics Simulation of a Membrane Contactor for CO2 Separation: Two Types of Membrane Evaluation

Two different types of hollow-fiber membrane contactors were applied for separation of CO2 from a gas stream using monoethanolamine absorbent, followed by numerical investigation. A model was proposed by solving velocity and mass transfer equations using Comsol software which was validated by experimental data. The effect of different parameters on CO2 absorption was investigated.


Abstract

Two different types of hollow-fiber membrane contactors were used for CO2 separation from the gas stream with monoethanolamine (MEA) absorbent and numerically investigated. After the model validation with experimental data, CO2 removal efficiency, MEA concentration, and pressure drop variation were examined under different conditions by variation of some effective parameters such as gas stream velocity, absorption solution velocity, membrane porosity, and membrane tortuosity. Membrane tortuosity and porosity enhancement led to light decrease and light increase in CO2 removal efficiency, respectively, but gas stream velocity enhancement significantly reduced the CO2 removal efficiency.

Modulating Catalyst‐Reactant Interface Microenvironment for Efficient Photocatalysis on Bismuth Sulfide

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Modulating Catalyst-Reactant Interface Microenvironment for Efficient Photocatalysis on Bismuth Sulfide

To improve the compatibility of the catalyst-pollutant interface, a polyvinylpyrrolidone (PVP)-capping strategy for enhanced photocatalysis of rhodamine B (RhB) on one-dimensional rod-like Bi2S3 nanocrystals was developed. This work provides an interface microenvironment modulation strategy for improving the photocatalytic performance of photocatalysts towards organic dyes.


Abstract

Pollution by organic dyes has received extensive attention due to their high toxicity, biohazard, and high stability in the natural environment, and the development of high-efficiency dye degradation and heavy metal ion reduction technologies is urgently needed in photocatalysis. However, the interface microenvironment between catalyst and pollutant is often ignored, and the poor compatibility of the catalyst-pollutant interface constrains further efficient catalysis. Herein, to improve the compatibility of the catalyst-pollutant interface, a surfactant-capping strategy for enhanced photocatalysis of rhodamine B (RhB) on one-dimensional rod-like Bi2S3 nanocrystals was investigated. Specifically, polyvinylpyrrolidone (PVP)-capped Bi2S3 (Bi2S3-PVP) showed enhanced RhB degradation rate compared with pure Bi2S3, and further studies suggested enhanced reaction interface compatibility at the Bi2S3-PVP-RhB interface. This work provides an interface microenvironment modulation strategy for improving photocatalytic performance towards organic dyes.

Nanomaterial‐Incorporated Membrane Distillation Membranes: Characteristics, Fabrication Techniques, and Applications

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Nanomaterial-Incorporated Membrane Distillation Membranes: Characteristics, Fabrication Techniques, and Applications

A thorough overview of the recent developments in membrane modification by incorporation of different types of nanoparticles in polymeric membranes resulting in improved fouling resistance and membrane wettability is given. Membrane modifications and membrane fabrication techniques, advanced membrane preparation using nanoscale materials, and future research are evaluated and discussed.


Abstract

Membrane distillation (MD), a temperature-driven membrane separation process, is used for various applications due to its less complicated design. MD operations encounter major issues such as permeate flux decrease, membrane fouling, and wetting. A lot of research has been conducted in the past years on the modification of MD membranes by incorporating nanomaterials to overcome these obstacles and considerably increase their performance. Nanomaterials incorporated into the membranes improve the water permeability, mechanical strength, and fouling. The incorporation of next-generation nanomaterials like metal oxide nanoparticles, carbon-based nanomaterials, graphene-based membranes, quantum dots, and metal-organic frameworks in the MD membranes is investigated. Essential membrane properties for MD operations are comprehensively studied, including higher liquid entry pressure, permeability, porosity, hydrophobicity, thermal stability, mean pore size, and low fouling rate. Significant advances in the application of nanomaterials to the modification of MD membranes as well as other membrane fabrication techniques adopted for the incorporation of nanoparticles like surface grafting, interfacial polymerization, plasma polymerization, and dip coating are reviewed. Important future aspects are discussed.

Density Functional Theory Computations and Experimental Analyses to Highlight the Degradation of Reactive Black 5 Dye

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Density Functional Theory Computations and Experimental Analyses to Highlight the Degradation of Reactive Black 5 Dye

Oxidative degradation of Reactive Black 5 (RB5) in aqueous solution was studied for Fenton process (FP), photo FP, sono FP, and sono photo FP. Reactivities of the studied chemical systems were analyzed by DFT calculations. Especially the calculated chemical hardness reflects the reactivity of dye and dye-Fe2+ complex. The experimental method used here provides high efficiency in the removal of RB5.


Abstract

The oxidative degradation of Reactive Black 5 (RB5) in aqueous solution was investigated using Fenton (FP), photo Fenton (P-FP), sono Fenton (S-FP), and sono photo Fenton (S-P-FP) processes. Degradation experiments showed efficient dye degradation for FP, P-FP, S-FP, and S-P-FP under optimal conditions. The half-life values of the reaction calculated for first-order reaction kinetics showed that the S-FP process is faster than the FP and P-FP processes. Using DFT calculations, the chemical reactivities of the studied chemical systems were analyzed. Especially the calculated chemical hardness values reflect the reactivities of the dye and the dye-Fe2+ complex. The calculated binding energy between the Fe2+ ion and RB5 of 15.836 eV is compatible with the prediction made in the light of the principle of hard and soft acids and bases. The computed data supported the experimental observations.

Biomass Simulation: Orange and Eucalyptus Waste as a Source of Essential Oils Using Solar Energy

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Biomass Simulation: Orange and Eucalyptus Waste as a Source of Essential Oils Using Solar Energy

Residues from orange processing and wood production industries wastes can be valorized as feedstocks for the production of essential oils. A simultaneous extraction process of essential oils from orange peels and eucalyptus leaves by integrating solar thermal energy was designed and simulated. Scaling the process according to waste availability in the region of interest became possible.


Abstract

Orange processing and wood production industries generate wastes in the form of orange peel and eucalyptus leaves. These residues can be valorized as feedstocks to produce essential oils. Therefore, a simultaneous orange peel and eucalyptus leaves essential oil extraction process integrating solar energy was simulated. Biomass and essential oils were simulated by using equivalence models. The coupling of solar collectors allowed the extraction of eucalyptus essential oil, with a saving of 10 % in the total energy load.