The present work deals with the equilibrium adsorption of Hg(II) onto carbonized Rosmarinus officinalis leaves (ACROL) as a new adsorbent from aqueous solution and it has been investigated. ACROL samples were prepared by physical carbonization at 773 K for 1 h. Titration method was used to determine the concentration of Hg(II) before and after adsorption onto ACROL by ethylenediaminetetraacetic acid, EDTA, as chelating agent. Batch equilibrium studies were carried out under different experimental conditions such as Hg(II) concentration and temperature. The relationship between the amount of Hg(II) onto ACROL can be described using four tow-parameter isotherm models. The equilibrium sorption data were analyzed using Freundlich, Langmuir, Dubinin-Ra-dushkevich (DRK) and Temkin isotherms. The experimental results were found to fit the Langmuir isotherm model with a monolayer adsorption capacity of 588.2 mg/g at 318 K, while they were found to fit the Freundlich isotherm model at 298 K. The KL was decreased with increasing temperature, indicating a bond strength between Hg(II) and ACROL decreased with increasing temperature and sorption is exothermic. From DRK isotherm, free energy, E, was higher than 31 kJ/mol suggesting the Hg(II) adsorption onto ACROL chemical sorption. The thermodynamic studies revealed that the process is spontaneous nature of Hg(II) adsorption by ACROL and exothermic. The findings from this research show that ACROL has capability to remove Hg(II) from aqueous solutions.

The protonation constants of the free ligands and the stability constants of binary and ternary complexes of bivalent metal ions of Ni(II) and Cu(II) with a biologically important amino acid of L-valine, Val, and paracetamol, Para, were studied potentiometrically in aqueous solutions at 313.15 ± 0.1 K and a fixed ionic strength of I = 0.10 M NaCl. The complexation model for each system was established using the Irving-Rossotti equation. The formation of the 1:2 or 1:1 binary complexes and 1:1:1 ternary complexes in which the amino acid Val was used as the primary ligand and Para as the secondary ligand, as inferred from the corresponding potentiometric pH-metric titration curves, and their relative stabilities compared to the corresponding ML and ML2 binary complexes are expressed in terms of statistical parameters ∆logK, logK1 and logK2. The complex stability was found to follow the order of Cu(II) > Ni(II). Through these diagnostic studies, it was possible to give the general formula of compounds prepared from amino acids and paracetamol. Amino acid binds to the central ion through oxygen in the hydroxyl group and nitrogen atom in the amine group (-NH2), whereas paracetamol forms a unipolar bond by binding to the concentrated ion through the oxygen atom in the hydroxyl group. Most of the nickel complexes had octahedral symmetry with valine and paracetamol ligands, while the copper complexes had square or hierarchical to square base symmetry.

Amberlite LA-2 was used as an ion exchanger to remove Congo red dye from aqueous solution. The effect of the initial concentration of dye and the initial concentration of Amberlite LA-2 on the efficiency of dye removal from the aqueous phase to the organic phase at different contact times, temperatures and pH values was studied. this research aims to study the potential of using Amberlite LA-2 as an extracting material for Congo red dye removal. UV-visible Spectrophotometer were used to assay the dye concentration in the aqueous solution before and after removal. Distribution coefficients (KD), loading capacity (Z), and extraction efficiency (E%) were computed using experimental data. The maximum extraction efficiency of 99.69 % was obtained with a loading capacity of 384.366 mol/kg. The obtained results also indicated that the removal of dye increases with the increase in the concentration of Amberlite LA-2. The best removal was obtained in a neutral medium (pH = 7), a temperature of 20 oC. A mechanism of extraction by Amberlite LA-2 was also proposed.