Grafted polymer membranes with extractive agents for the extraction process of VO2+ions

Kinetic control aspects and mechanisms in oriented membrane processes for extraction and recovery of ascorbic acid compound

Ascorbic acid comprises four enantiomers, with only one of them, L-ascorbic acid, recognized as vitamin C. The modern industries place significant importance on obtaining this compound in its purest form. The challenge is to recover L-ascorbic acid, which requires specific processes within these industries. To satisfy this condition, purification is needed, a process that requires large quantities of solvents and high energy consumption. To overcome these limitations, we conducted a study on the facilitated extraction of L-ascorbic acid using three affinity polymer membranes, including supported liquid membrane (SLM), polymer inclusion membrane (PIM), and grafted polymer membranes (GPM) with cholic acid as the extractive agent. Following the characterization of the membranes using IR spectroscopy and SEM techniques, we investigated various parameters associated with substrate diffusion through the organic membrane phase. Regarding the biologically active L-ascorbic acid, our research findings indicated that kinetic factors drove the mechanisms of the studied processes.

Vanadium for Green Energy: Increasing Demand but With Health Implications in Volcanic Terrains

The transition to a clean energy future may require a very substantial increase in resources of vanadium. This trend brings into focus the potential health issues related to vanadium in the environment. Most vanadium enters the Earth's crust through volcanic rocks; hence, vanadium levels in groundwaters in volcanic aquifers are higher than in other aquifers and can exceed local guidance limits. The biggest accumulation of volcanogenic sediment on the planet is downwind of the Andes and makes up much of Argentina. Consequently, groundwaters in Argentina have the highest vanadium contents and constitute a global vanadium anomaly. The high vanadium contents have given rise to health concerns. Vanadium could be extracted during remediation of domestic and other groundwater, and although the resultant resource is limited, it would be gained using low-energy technology.

Kinetic control concept for the diffusion processes of paracetamol active molecules across affinity polymer membranes from acidic solutions

Background

Paracetamol compound remains the most used pharmaceutical as an analgesic and antipyretic for pain and fever, often identified in aquatic environments. The elimination of this compound from wastewater is one of the critical operations carried out by advanced industries. Our work objective was to assess studies based on membrane processes by using two membranes, polymer inclusion membrane and grafted polymer membrane containing gluconic acid as an extractive agent for extracting and recovering paracetamol compound from aqueous solutions.

Result

The elaborated membrane characterizations were assessed using Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Kinetic and thermodynamic models have been applied to determine the values of macroscopic (P and J₀), microscopic (D* and K_ass), activation and thermodynamic parameters (E_a, ΔH^#, ΔS^#, ΔH^#_diss, and ΔH^#_th). All results showed that the PVA–GA was more performant than its counterpart GPM–GA, with apparent diffusion coefficient values (10⁷D*) of 41.807 and 31.211 cm² s⁻¹ respectively, at T = 308 K. In addition, the extraction process for these membranes was more efficient at pH = 1. The relatively low values of activation energy (Ea), activation association enthalpy (ΔH^≠_ass), and activation dissociation enthalpy (ΔH^≠_diss) have indicated a kinetic control for the oriented processes studied across the adopted membranes much more than the energetic counterpart.

Conclusion

The results presented for the quantification of oriented membrane process ensured clean, sustainable, and environmentally friendly methods for the extraction and recovery of paracetamol molecule as a high-value substance.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13065-021-00794-7.

Parameters and mechanism of membrane-oriented processes for the facilitated extraction and recovery of norfloxacin active compound

In the present work, a polymer inclusion membrane (PIM) using an amphiphilic molecule Tween 20 (TW20) as the carrier was developed and characterized to hinder environmental contamination caused by norfloxacin (NRF), an antibiotic widely used in veterinary and human medicines. Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) coupled with energy X-ray dispersion spectroscopy (EDS) were used to reveal the composition, porosity, and morphology of the elaborated membrane. In order to measure the performance of the as-developed membrane, the influences of NRF initial concentration (C₀ = 0.04 mol L^-1, 0.02 mol L^-1, 0.01 mol L^-1, and 0.005 mol L^-1), pH (2.6, 4.5, and 10.5), and temperature (T = 298 K, 303 K, and 305 K) were investigated. The evolution of macroscopic (permeability (P) and initial flux (J₀)), microscopic (association constant (K_ass) and apparent diffusion coefficient (D*)), and activation parameters (activation energy (E_a), enthalpy (∆H^≠_ass), and entropy (∆S^≠)) was analyzed. It was found that TW20 was an effective agent for the extraction and recovery of different forms of NRF, especially the zwitterion form appeared at pH = 4.5. On the other hand, for the biologically active NRF compound, the mechanisms of the studied processes were controlled by the kinetic aspect rather than the energetic counterpart. Graphical abstract.