Rapid ion pair-based surfactant-assisted liquid-liquid microextraction with solidification of floating organic drop for simultaneous spectrophotometric determination of selected anionic dyes in food samples.

Ion pair-based surfactant-assisted liquid-liquid microextraction with solidification of floating organic drops has been developed to extract Allura red (AR), tartrazine (TAR), and fast green (FG) prior to spectrophotometric determination. Cetyltrimethylammonium bromide (CTAB) was employed as ion-pairing agent to enhance the hydrophobic behavior of anionic dyes. 1-undecanol and ethanol were used as the extraction and dispersion solvents, respectively. The dyes were quantitatively extracted in the presence of KCl (0.15 mol L-1) at pH 4.0. The method exhibits wide linearity (15.0-1500.0 µg L-1 for AR, 35.0-2000.0 µg L-1 for TAR, and 3.0-1200.0 µg L-1 for FG) with preconcentration factors of 19.6, 20.1, and 19.9, respectively. The detection limit was 3.7. 9.5, and 0.83 µg L-1 for AR, TAR, and FG, respectively. The relative standard deviation did not exceed 2.1 %. The procedure was applied for the determination of these dyes in food samples.

Fractional Kinetic Strategy toward the Adsorption of Organic Dyes: Finding a Way Out of the Dilemma Relating to Pseudo-First- and Pseudo-Second-Order Rate Laws.

Recently, there has been debate about using a pseudo-second-order model in adsorption kinetics and its ability to fit experimental data, especially at the initial stages. This paper introduces a generalized fractional kinetic model obtained via a fractional reaction-diffusion equation with a time-dependent reaction rate. This model is presented as a dependable approach to understanding chemical adsorption kinetics. It offers insights into the adsorbate history and extends classical kinetic models, such as pseudo-first-order and pseudo-second-order models. The generalized fractional kinetic model accounts for memory effects with long-range interactions, heterogeneity, and nonequilibrium dynamics, leading to more accurate predictions of adsorption rates, capacities, and equilibrium values. As an applied context, we use the fractional kinetic model to analyze experimental data on the adsorption of anionic acid yellow-17 and cationic brilliant green dyes in single and binary systems. The fractional kinetic model is employed to fit the data by incorporating waiting times into the adsorption process and correlating macroscopic properties, such as the pH, with adsorption dynamics.

Silver sulfide decorated carbonaceous sawdust/ES-PANI composites as salt-resistant solar steam generator.

Solar steam generation (SSG) is a potential approach for resolving the global water and energy crisis while causing the least amount of environmental damage. However, using adaptable photothermal absorbers with salt resistance through a simple, scalable, and cost-effective production approach is difficult. Herein, taking advantage of the ultra-fast water transportation in capillaries, and the large seawater storage capacity of wood, we develop a highly efficient natural evaporator. The wood wastes (sawdust) were carbonized at low temperatures to fabricate a green and low-cost carbonaceous porous material (CW). To enhance the salt resistance in high saline water, this evaporator was coated with polyaniline emeraldine salt (ES-PANI) which was synthesized through facile and cost-effective one-step oxidation of aniline. Furthermore, the composite was decorated with silver sulfide to increase the evaporation rate which reached up to 1.1 kg m-2 h-1 under 1 sun irradiation with 91.5% efficiency. Besides, the evaporator performs exceptionally well over 10 cycles due to the salt resistance capability of ES-PANI which generates a "Donnan exclusion" effect against cations in saline water. The Ag2S@PANI/CW evaporator may be a viable large-scale generator of drinking water due to its high efficiency for energy conversion, simple and low-cost fabrication approach, salt-resistance, and durability.

Fabrication of poly(maleic acid)-grafted cross-linked chitosan/montmorillonite nanospheres for ultra-high adsorption of anionic acid yellow-17 and cationic brilliant green dyes in single and binary systems.

In this contribution, poly(maleic acid)-grafted cross-linked chitosan/montmorillonite composite nanospheres (PMAL-CTS/MMT) were synthesized via a facile approach for adsorption of organic dyes. The adsorption capacity of PMAL-CTS/MMT towards anionic acid yellow-17 (AY17) and cationic brilliant green (BG) was compared to PMAL-CTS, CTS/MMT, and MMT to emphasize the role of surface functional groups introduced by poly(maleic acid) and montmorillonite. Interestingly, the adsorption efficiency of PMAL-CTS/MMT nanocomposite towards both dyes in the single and binary systems was extremely high due to plenty of functional groups. The affinity of PMAL-CTS/MMT towards cationic and anionic dyes resulted from the feasible modulation of the surface charges as a function of the solution pH. The PMAL-CTS/MMT nanocomposite exhibited a maximum adsorption capacity of 518 and 1910 mg g-1 for AY17 and BG, respectively, which is higher than most of the adsorbents reported in recent literature studies. The proposed mechanism based on the characterization of PMAL-CTS/MMT after the adsorption highlighted that the adsorption is mainly controlled by electrostatic interaction, π - π interactions, and hydrogen bonding. More importantly, the PMAL-CTS/MMT nanocomposite was successfully applied to separate the AY17 and BG dyes from real-life aquatic environments. Collectively, the simple fabrication and superior adsorption performance reveal that PMAL-CTS/MMT has the potential to treat concomitant organic dyes effectively.