Recent Innovations in Chemical Engineering (Formerly Recent Patents on Chemical Engineering) - Volume 16, Issue 4, 2023

The exponential concern about environmental concerns has heavily driven the development of green technology. In light of these needs, Deep Eutectic Solvent (DES) emerged as a green solvent and additive, characterized by its minimal toxicity, volatility, biodegradability, and biocompatibility, as well as the simplicity of synthesis, high yields, purity, and the availability of its precursors. This review is intended to summarise and discuss polymer electrolytes based on DES for better insight into the potential of replacing conventional organic solvents or ionic liquids for energy storage applications in the aspect of their electrical and structural properties. Therefore, an examination of dielectric studies is conducted as they hold significance in establishing a correlation between the rise in ionic conductivity and the augmentation of freely movable ions, thereby highlighting the importance of investigating the dielectric properties of an electrolyte. Besides, XRD and morphological studies in this work can show how ionic conductivities can influence the size of pores in DES-based polymer electrolytes.

Lithium, with its exceptional properties, such as remarkable redox activity and high specific heat capacity, finds widespread applications in thermonuclear fusion reactors, ceramics, batteries, aerospace, glass, metal additives, and photo-electricity. The growing demand for clean technology, especially electric cars and energy storage, has led to a significant rise in global lithium production. Brines now constitute a major portion of the world's lithium output, driving research in lithium extraction and purification methods. This study examines recent innovative research and patents, including various extraction techniques, sorbents, electrolysis-based approaches, and costeffective methods. The study identifies gaps and limitations in existing lithium extraction technology and proposes future research areas to advance the field. The bibliographic analysis underscores the importance of further investigation to overcome current obstacles and drive progress in lithium extraction.

Landfill leachate contains organic compounds like amines, ketones, carboxylic acid, alcohols, aldehydes, phenols, phosphates and inorganic pollutants such as ammonia, phosphorous, sulphate, emerging contaminants like per-and polyfluoroalkyl substances (PFAS) and also the toxic heavy metals like Mn, Cd, Pb, Fe, Ni, Zn and As. In young landfill leachate, the concentration of volatile acid and simply degraded organic matter is high while pH is low. However, in mature landfills, there is more leachate production with high pH. The age of landfill and determination of parameters like BOD, COD, COD/BOD ratio are important to know the appropriate treatment methods. Physicochemical, biological and combined methods are the most reported landfill leachate treatment methods. Advanced oxidation process, adsorption, coagulation-flocculation, bioremediation, phytoremediation, bioreactor, membrane process and air striping are some of the common categories of effective treatment of landfill leachate. For better apprehension, it has been reviewed that treatment efficiencies of different kinds of leachate depend on their composition and method adopted. Studies related to the removal of organic matter and heavy metals are predominant which reported excellent removal efficiency ranging from 80-100%. In addition, physical parameters like color and turbidity can also be removed effectively using appropriate treatment methods. The present article deals with a concise review of existing literature on sustainable landfill leachate treatment technologies which include physical, chemical, biological and combined techniques.

Background: Bubbly suspensions can be often run into natural and industrial processes. The addition of bubbles with different sizes can lead to a significant change in the rheological properties of a matrix liquid. It is extremely significant to fully understand the rheological properties of bubbly suspensions for improving process efficiencies and optimizing productive processes. 

Objective: The objective of this study is to explore qualitatively the physical law and internal mechanism of the apparent viscosity of suspensions formed by a Newtonian liquid containing different bubbles. 

Methods: Based on the parallel plate model of shear flow, the volume of fluid method (VOF) was used to investigate the effect of bubble arrangement and volume fraction on the apparent viscosity of bubbly suspensions at low volume fractions. The piecewise linear interface calculation (PLIC) method was applied to reconstruct the interface based on the phase function. 

Results: The present results show that the relative viscosity (ηr) of bubbly suspensions shows a nonlinear change with an increase in bubble volume fraction (ϕ). When the capillary number (Ca) is less than 0.6, ηr shows a nonlinear increase with an increase in ϕ (ηr increases from 1 to 1.03 with an increase in ϕ from 0 to 2.94% at Ca=0.1). However, Ca is greater than or equal to 0.6, ηr shows a nonlinear decrease with an increase in ϕ (ηr decreases from 1 to 0.92 with an increase in ϕ from 0 to 2.94% at Ca=2.5). Even if ϕ is the same, different arrangements of bubbles can lead to different magnitudes of apparent viscosity of bubbly suspensions.

 Conclusion: As ϕ increases, the region of low shear rate increases, which leads to a non−linear decrease in the relative viscosity. When ϕ is the same, the different arrangements of bubbles can lead to different effects on bubble dynamics and flow fields. This results in different viscous dissipation in bubbly suspensions. Thus, the apparent viscosity of bubbly suspensions is different