Intermolecular interactions in mixed dye systems and the effects on dye wastewater treatment processes.

Dye wastewater discharge is a critical concern across textiles, paper, cosmetics, and other industries. This study explores the impact of dye-dye interactions on chemical coagulation and ultrafiltration process. Using basic and reactive dyes, representing cationic and anionic compounds, the intricate interplay between these dyes was examined through spectroscopic analysis. Remarkably, interactions between dyes of opposite charges exhibited significant effects on both techniques. Electrostatic attractions played a key role. Positive coagulant hydrolysates selectively attracted negative dyes, while negatively charged membranes effectively captured positive dyes. Combining dyes with opposite charges resulted in enhanced removal efficiency, addressing challenging dyes collectively. This discovery offers a novel approach to improving dye removal, utilizing opposite-charged dye mixtures can tackle stubborn dyes unmanageable by conventional methods.

Efficiently Removing Heavy Metals from High-Salinity Wastewater via Ionic Liquid-Based Aqueous Biphasic Systems.

For the separation of metal ions, ionic liquid-based aqueous biphasic systems (IL-ABSs) offer a promising alternative to solvent extraction. However, the incorporation of an extensive quantity of inorganic salts restricts their practical application. Because heavy metal wastewater often contains high concentrations of inorganic salts, it offers good prospects for the application of IL-ABSs in the separation of heavy metals. In this work, an IL-ABS was formed by tributyltetradecylphosphonium chloride ([P44414]Cl), and simulated high-salinity wastewater (NaCl and Na2SO4 as the main inorganic salts) was used for the separation of heavy metals. The phase diagram results indicated that the formation of a two-phase system required a relatively high salt concentration. The extraction process followed the mechanism of anion exchange; thus, heavy metals such as zinc and cadmium that formed complexes with chloride ions could be effectively extracted (extraction rate >99.5%) with a very fast rate (extraction time <1 min) at a wide pH range (pH = 2-7). After extraction, the metals could be stripped well (stripping rate >99.5%) after contact with the NaOH solution. This research provided a new approach for treating heavy metals in high-salinity effluents, which has the advantages of IL-ABS and avoids the disadvantages of adding large amounts of inorganic salts at the same time.

Eggshell membrane-templated gold nanoparticles as a flexible SERS substrate for detection of thiabendazole.

The authors describe a three-dimensional (3D) flexible interconnected porous nanocomposite membrane for use in surface-enhanced Raman scattering (SERS). It was obtained via in -situ deposition of gold nanoparticles (AuNPs, ca. 10 nm) on eggshell membranes (ESM). The AuNP/ESM nanocomposites were used as a SERS substrate for detection of the pesticide thiabendazole (TBZ) with prominent Raman bands at 1180, 1280, and 1580 cm-1. The abundant "hot spots" are generated by the closely arranged AuNPs in the 3D geometry of the ESM networks. This makes the SERS substrate highly sensitive because of remarkable signal amplification. The substrates were applied to the rapid detection of TBZ in Oolong tea. The limit of detection for TBZ is 0.1 ppm. Graphical abstract Schematic presentation of a three-dimensional flexible interconnected porous nanocomposite membrane as surface-enhanced Raman scattering (SERS) substrate for detection of thiabendazole (TBZ) in tea.