Photophysical properties of a perylene derivative for use as catalyst in ethanol eletrooxidation

A Simple Isoniazid-Based N-Acylhydrazone Derivative as Potential Fluorogenic Probe for Zn2+ Ions

This study evaluated three isoniazid-based N-acylhydrazone derivatives (HL1, HL2, and HL3) varying their substituting groups (-H, -N(CH₃)₂, and -NO₂) as potential chemosensors for Zn²⁺ ions. To this end, the absorption and emission properties of these derivatives were investigated in the presence of Zn²⁺ ions. Results point to the derivative HL2 as the best chemosensor for Zn²⁺ ions because of its comparatively higher sensitivity. The color of this derivative changed from colorless to strong yellow with zinc addition, as indicated by the shift in UV-vis spectrum. Moreover, HL2 was the only derivative to emit fluorescence in the presence of Zn²⁺ ions, attributable to PET inhibition and bond isomerization promoted by coordination with this metal. LOD, LOQ, and binding constant values for HL2 + Zn²⁺ were 0.43 μmol.l^-1, 0.93 μmol.l^-1, and 5.04 × 10¹² l.mol^-1, respectively. The fluorescence of HL2 with other metal ions (Fe³⁺, Mg²⁺, Na⁺, Cd²⁺, Cu²⁺, Co²⁺, Ni²⁺, Ca²⁺, and K⁺) was also investigated. Zn²⁺ yielded the best result without Cd²⁺ interferences. Job's Plot showed that the stoichiometric ratio of the complex formed by HL2 and Zn²⁺ ions is 2:1 (ligand:metal). The strip test with adsorbed HL2 indicated fluorescence in the presence of zinc ions under 365 nm UV irradiation.

Removal of rhodamine 6G from synthetic effluents using Clitoria fairchildiana pods as low-cost biosorbent

Many organic dye pollutants have been identified in rivers and lakes around the world, and concern is growing with them as they cause serious changes in the ecological balance of aquatic environments. One of these dyes is rhodamine R6G, which is very water-soluble and has a high corrosive power. Therefore, Clitoria fairchildiana (CF) pods were used as a biosorbent to remove R6G from synthetic dye effluents. CF was characterized by infrared spectroscopy, thermogravimetric analysis, x-ray diffraction, elemental analysis, Boehm titration, and zero charge point measurements. The influence of various factors, such as solution pH, contact time, adsorbent mass, and concentration of R6G, was studied using batch equilibrium experiments. The optimum contact time to reach equilibrium was found to be 15 min, while the optimum adsorbent dose was 8 g L^-1. The maximum adsorption capacity of CF (73.84 mg g^-1) was observed at pH 6.4 and 298.15 K. Adsorption kinetics followed a pseudo-second-order law, and the isotherm could be best fitted with a Liu model. The obtained thermodynamic parameters indicate that the adsorption of R6G is spontaneous and enthalpy-driven. We thus conclude that CF is an efficient, green, and readily available biosorbent for dye removal from wastewater.