Process optimization and mechanism for the selective extraction of copper(ii) from polymetallic acidic solutions using a polymer inclusion membrane (PIM) with Mextral®5640H as the carrier

This study introduces a novel approach by integrating solvent extraction and polymer inclusion membrane (PIM) separation technologies to engineer an innovative PIM membrane material for the selective separation and enrichment of strategic metals, particularly copper, from polymetallic acidic solutions. The primary objectives were to streamline the technological process, reduce production costs, and enhance separation coefficients between copper and other metals. The optimal extraction conditions were determined as a mass fraction of Mextral®5640H : PVC : NPOE = 3 : 3 : 4, extraction temperature of 35 °C, and 0.9 mol L-1 H2SO4 in the stripping solution. Under these conditions, we achieved remarkable extraction efficiencies, with copper reaching 100%, and the separation coefficients between Cu2+ and Ni2+, Co2+, and Zn2+ exceeding 106. To elucidate the substantial differences in extraction performance between Cu2+ and the other metals (Ni2+, Co2+, and Zn2+), we employed an integrative analytical approach that combines FT-IR spectroscopy, BET analysis, and theoretical calculations. All extracted complexes demonstrated molecular sizes compatible with PIMs, underscoring the critical role of stability and back-extraction performance in the selective extraction of these metal ions.

Preparation and properties of phosphinic acid-functionalized polyacrylonitrile hollow fiber membrane for heavy metal adsorption

In this study, phosphorylated polyacrylonitrile hollow fiber membrane was synthesized by reacting aminated polyacrylonitrile hollow fiber membrane with phosphinic acid in a Mannich reaction. The batch single-factor measurements revealed that the phosphorylated polyacrylonitrile (PPAN) membrane had an outstanding ability for Hg²⁺ adsorption. Thermodynamic investigations indicated that the adsorption process was homogenous, and the theoretical maximum adsorption capacity predicted by the Langmuir model was 371.75 mg·g^-1. The PPAN membrane was able to successfully chelate Hg²⁺ ions and attain saturation in 4 h, demonstrating that the reaction was chemically controlled by the adsorption kinetics. Based on the FT-IR and XPS spectral characterization data, successful phosphinic acid group grafting was proven, and a plausible mechanism for Hg²⁺ adsorption by PPAN membranes was presented. Furthermore, the five adsorption-desorption cycle experiments revealed that PPAN hollow fiber membranes had outstanding reusability, indicating a possible use for removing heavy metal ions from wastewater.

Isolation of Phenolic Compounds from Raspberry Based on Molecular Imprinting Techniques and Investigation of Their Anti-Alzheimer's Disease Properties

Alzheimer's disease is the most common neurodegenerative disease, characterized by memory loss and cognitive dysfunction. Raspberry fruits contain polyphenols which have antioxidant and anti-inflammatory properties. In this study, we used molecular imprinting technology to efficiently isolate phenolic components from the raspberry ethyl acetate extracts. Six phenolic components (ellagic acid, tiliroside, kaempferol-3-o-rutoside, gallic acid, ferulic acid and vanillic acid) were identified by UPLC-Q-TOF-MS analysis. Molecular docking was used to predict the anti-inflammatory effects and anti-Alzheimer's potential of these isolated compounds, which showed a good binding ability to diseases and related proteins. However, the binding energy and docking fraction of ellagic acid, tiliroside, and kaempferol-3-o-rutoside were better than those of gallic acid, ferulic acid and vanillic acid. Additionally, by studying the effects of these six phenolic components on the LPS-induced secretion of inflammatory mediators in murine microglial (BV2) cells, it was further demonstrated that they were all capable of inhibiting the secretion of NO, IL-6, TNF-α, and IL-1β to a certain extent. However, ellagic acid, tiliroside, and kaempferol-3-o-rutoside have better inhibitory effects compared to others. The results obtained suggest that the phenolic components extracted from ethyl acetate extracts of raspberry by molecularly imprinted polymers have the potential to inhibit the progression of Alzheimer's disease.

Adsorptive Recovery of Cu2+ from Aqueous Solution by Polyethylene Terephthalate Nanofibres Modified with 2-(Aminomethyl)Pyridine

The accumulation of plastic waste products in the environment has adversely affected wildlife and human beings. Common plastics that accumulate in the environment are plastics that are made of polyethylene terephthalate (PET) polymer. PET plastic waste products can be recycled for beneficial use, which would reduce their negative impacts. In this study, modified PET or waste PET (WPET) from plastic bottles was blended with powder commercial 2-(aminomethyl)pyridine (SiAMPy) resin and electrospun into composite nanofibres and applied for Cu2+ adsorption. PET-SiAMPy or WPET-SiAMPy composite nanofibres fibre diameters from the HRSEM images were 90–140 nm and 110–155 nm, respectively. In batch adsorption experiments, PET-SiAMPy or WPET-SiAMPy composite nanofibres achieved Cu2+ adsorption equilibrium within 60 secs of contact time with 0.98 mmol/g (89.87%) or 1.24 mmol/g (96.04%) Cu2+ adsorption capacity. The Cu2+ complex formation rate (k) with WPET-SiAMPy was 0.0888 with the mole ratio of Cu2+ and WPET-SiAMPy nanofibres 1:2. The complex molecular formula formed was Cu(WPET-SiAMPy)2 with a square planar geometry structure. The WPET-SiAMPy nanofibres’ adsorption was best fitted to the Freundlich isotherm. WPET-SiAMPy composite nanofibres were considered highly efficient for Cu2+ adsorption from aqueous solution and could be regenerated at least five times using 5 M H2SO4.

Highly efficient removal of Cu(ii) by novel dendritic polyamine–pyridine-grafted chitosan beads from complicated salty and acidic wastewaters

In this study, dendritic polyamine chitosan beads with and without 2-aminomethyl pyridine were facilely prepared and characterized. Compared to CN (without the pyridine function), more adsorption active sites, larger pores, higher nitrogen content, higher specific surface area, and higher strength could be obtained for CNP (with the pyridine function). CNP microspheres afforded a larger adsorption capacity than those obtained by CN for different pH values; further, the uptake amounts of Cu(ii) were 0.84 and 1.12 mmol g⁻¹ for CN and CNP beads, respectively, at pH 5. The CNP microspheres could scavenge Cu(ii) from highly acidic and salty solutions: the maximum simulated uptake amount of 1.93 mmol g⁻¹ at pH 5 could be achieved. Due to the strong bonding ability and weakly basic property of pyridine groups, the adsorption capacity of Cu(ii) at pH 1 was 0.75 mmol g⁻¹ in highly salty solutions, which was comparative to those obtained from the commercial pyridine chelating resin M4195 (Q_Cu(II) = 0.78 mmol g⁻¹ at pH 1). In addition, a distinct salt-promotion effect could be observed for CNP beads at both pH 5 and 1. Therefore, the prepared adsorbent CNP beads can have promising potential applications in the selective capturing of heavy metals in complex solutions with higher concentrations of H⁺ and inorganic salts, such as wastewaters from electroplating liquid and battery industries.

Dendritic polyamine chitosan (CNP) beads containing 2-aminomethyl pyridine were facilely prepared for the efficient removal of Cu(ii) ions from highly acidic and salty solutions.

Construction of a phosphate-rich polyacrylonitrile fiber surface microenvironment for efficient purification of crystal violet wastewater

Wastewater purification using fibrous adsorbents has received much attention due to their high efficiency, low cost, and recyclability. In this work, phosphate modified polyacrylonitrile fiber (B-PANEAPF) was prepared and used to remove cationic dyes. The B-PANEAPF showed the best adsorption capacity for crystal violet (CV) when compared with rhodamine B, methyl green, Victoria blue B, methylene blue, and neutral red. The adsorption tests revealed that the fiber possessed high adsorption efficiency and achieved semi-saturated adsorption within 15 min. The maximum adsorption capacity of 354.46 mg g-1 as calculated by the Langmuir adsorption model was higher than many other adsorbents. Furthermore, the B-PANEAPF was used to remove 210 mL of CV in a continuous-flow process with a high removal efficiency over 90%. Besides, the phosphate functionalized fiber could easily decrease the concentration of CV to below 0.5 mg L-1 which is below the maximum effluent discharge standard of 15 mg L-1 prescribed in China. It could also be fully recovered and easily separated from the solution to achieve re-use 10 cycles. Moreover, the adsorption mechanism indicated that the adsorption process of the fiber for CV was mainly attributed to electrostatic interaction and hydrogen bonding. In conclusion, the results suggested that the B-PANEAPF characterized by its simplicity, efficiency, eco-friendliness, and reusability, could be a promising candidate for CV removal.

Highly selective and efficient adsorption of Hg2+ by a recyclable aminophosphonic acid functionalized polyacrylonitrile fiber

Mercury ions, even an ultra-trace amount in water, present a serious environmental concern. Hence, searching for cost-effective and high-performance Hg²⁺ adsorbents has acquired increasingly attention but still remained challenging. In this work, aminophosphonic acid was immobilized onto polyacrylonitrile fiber by chemical grafting approaches. The functionalized fiber (PAN_APF) possessed high adsorption selectivity and efficiency for Hg²⁺ when compared with other coexisting ions viz. Pb²⁺, Cd²⁺, Ag⁺, Zn²⁺, Cu²⁺, Ni²⁺, Co²⁺, Ca²⁺ and Mg²⁺. The adsorption results revealed that PAN_APF exhibited high removal capacities for Hg²⁺ over a wide pH range from 3 to 11. The adsorption process was better described by the pseudo second-order kinetic model, indicating the chemical interaction between Hg²⁺ and active groups on the PAN_APF. Moreover, the maximum adsorption capacity as calculated from the Langmuir adsorption model of 358mgg^-1 was higher than that of many other adsorbents. The PAN_APF could be reused more than 10 times and it is able to decrease Hg²⁺ below 50μgL^-1 which is the maximum discharge standard for mercury containing wastewater in China. A continuous-flow process was also implemented to remove Hg²⁺. The results suggested the environmentally friendly PAN_APF could be a promising candidate for Hg²⁺ removal in wastewater treatment.

Platinum Nanoparticle Encapsulated Metal-Organic Frameworks for Colorimetric Measurement and Facile Removal of Mercury(II)

Pt nanoparticle (Pt NP)@UiO-66-NH₂ composites were synthesized and encompassed the benefits of permanent porosity, high thermal and chemical stability of metal-organic frameworks (MOFs), together with the functional behavior of isolated Pt NPs. The PVP-stabilized Pt NPs with the average diameter of 2.48 nm were well dispersed and confined within the framework of UiO-66-NH₂. Pt NPs possess highly peroxidase-like activities and make the composites oxidize 3,3',5,5'-tetramethylbenzidine in the presence of H₂O₂. Moreover, the specific interaction between Hg²⁺ and Pt NPs leads to the effective suppression of the peroxidase-like activity of Pt NP@UiO-66-NH₂, which endows excellent selectivity for Hg²⁺ measurement over the interfering metal ions. Based on the colorimetric sensing system, Hg²⁺ is linearly measured over the range from 0 to 10 nM with a detection limit of 0.35 nM. Moreover, the as-obtained Pt NP@UiO-66-NH₂ nanocomposites exhibit high capacity and good selectivity for Hg²⁺ adsorption, which is successfully applied to treat Hg²⁺ in water with removal efficiency over 99%. With these findings, Pt NP@UiO-66-NH₂ composites can be used to develop a simple and rapid colorimetric sensing system and are utilized as nanoadsorbents for facile removal of Hg²⁺. This work not only expands the scientific researches on MOFs but also provides practical application in environmental, biological, and relative fields.

A novel tetraethylenepentamine functionalized polymeric adsorbent for enhanced removal and selective recovery of heavy metal ions from saline solutions

A novel tetraethylenepentamine functionalized polymeric adsorbent with polymethacrylate–divinylbenzene as the substrate was facilely prepared for the enhanced removal and selective recovery of Cu(ii) and Ni(ii) from saline solutions.