A New Approach for Removing Anionic Organic Dyes from Wastewater Based on Electrostatically Driven Assembly

A conceptually new approach for an efficient removal of anionic organic dyes from wastewater using layered double hydroxides (LDHs) through their formation is presented. Acid yellow 25 (AY25) was used as anionic organic dye model molecules. As a result of the electrostatic induction, the removal mechanism involved a concurrent incorporation of AY25 molecules into the interlayer of LDHs during their structural arrangement, where Mg²⁺ and Al³⁺ ions were utilized to construct the base of LDHs in an alkaline solution. It was found that the molar stoichiometry of all precursors was a key factor affecting the removal efficiency. Within 5 min removal time, this method still maintained high removal efficiency of over 97% and provided a removal capacity of ∼186 mg g^–1, comparable to that of other LDH-based methods. Also, almost complete dye recovery was simply achieved by anionic exchange with common anions (Cl^–, NO₃^–, and CO₃^2–). Additionally, the present technique is straightforward, cost-effective, and environmentally friendly since it avoids the synthesis step of sorbents, thus significantly saving time, chemicals, and energy. Hence, this strategy not only exhibits the alternative exploitation of LDHs, but also provides new insights into the removal of contaminants from wastewater

A sensitive and selective spectrophotometric method for 2-chlorophenol based on solid phase extraction with mixed hemimicelle magnetic nanoparticles

The first study of a sensitive and selective spectrophotometric detection of 2-chlorophenol (2-CP) was reported. The method is based on derivatization of 2-CP with 4-aminoantipyrine (4-AAP) and subsequent preconcentration by solid phase extraction (SPE) using mixed hemimicelles adsorbent of cetyltrimethylammonium bromide coated magnetic nanoparticles (CTAB coated Fe3O4 NPs) before its detection by spectrophotometry at 510 nm. The adsorption capacity was evaluated using the Langmuir adsorption isotherm model, with high correlation coefficients (R2 = 0.9983). The optimum conditions for SPE were CTAB coated Fe3O4 NPs 20 mg under vortex 60 s and methanol as the desorption solvent under sonication for 7 min. The linearity of the method was in the range of 0.05–1.0 mg L−1 with correlation coefficient (0.9970). The limit of detection (LOD) and limit of quantitation (LOQ) were 0.01 mg L−1 and 0.05 mg L−1, respectively. Good precision with relative standard deviation (%RSD, n = 5) less than 3.7% was obtained. The method was successfully applied for the determination of 2-CP in soil samples with satisfactory recoveries (81.7–95.2%)