In this study, a green adsorbent made of corn leaf powder was applied in the removal of Cu(II) and Cd(II) from water samples. The material was characterized by Fourier transform infrared (FTIR) spectroscopy, which indicated the existence of amine (1375 and 1249 cm -1 ) and carboxylic groups (1730 cm -1 ). Elemental analysis corroborated the results of FTIR, indicating that the substance consisted of 0.63% sulfur and 0.46% nitrogen. The NMR results indicated that thiamine and methionine may be present in the corn leaf substances, which can act in coordination with metal species. Scanning electron microscopy (SEM) indicated the existence of pores of approximately 15 µm in diameter and a homogeneous particle size. Equilibrium adsorption was attained in 5 min, and the obtained data were applied to a pseudo-second-order kinetic model (r 2 = 0.999 for Cu(II) and Cd(II)). Selective adsorption of Cu(II) was attained at pH 3.0, and the maximum adsorption capacities were attained at pH 6.0. Adsorption isotherms were adjusted to a modified Langmuir equation and the maximum number of moles adsorbed of Cu(II) and Cd(II) were 0.089 and 0.071 mmol g -1 , respectively. The results are superior to many materials currently employed in metal removal from aqueous samples.
The synthesis of an organofunctionalized mesoporous silica was accomplished by a two-step process involving (1) the co-condensation of a silylant agent at the surface of silica, followed by (2) the immobilization of Purpald (ligand) at the organic termination of the silytant agent. The characterization of the organofunctionalized material indicated the presence of NH2 groups, and the immobilization of the ligand was confirmed by 29Si- and 13C-nuclear magnetic resonance. The material’s surface area was determined as 370 m2 g−1. Batch adsorption experiments enabled the determination of optimum pH conditions for the adsorption of Cu(II) and Cd(II). Under optimal pH, the pseudo-second-order kinetic model and Langmuir model provided the best correlations to describe the materials adsorption behavior, suggesting a chemisorption mechanism. When tested in continuous-flow preconcentration experiments, the flow rate and eluent concentration demonstrated to affect the removal of Cu(II) and Cd(II), while the buffer concentration had an effect only over the adsorption of Cu(II). Under optimized preconcentration conditions, it was possible both to determine the concentrations of Cu(II) and Cd(II) in samples such as mineral water, ground water, tap water and river water. Ions commonly found in drinking and natural waters (Na+, K+, Ca2+, Mg2+, Fe3+, Ba2+, Cl−, SO42−, HCO3−, and H2PO4−) did not affect the preconcentration of any of the studied analytes. Reutilization experiments indicated that the adsorbent material can withstand at least 40 adsorption/desorption preconcentration cycles with no efficiency loss.
Modo de acesso: World Wide Web Inclui bibliografia 1. Meio ambiente 2. Gestão. I. Toledo, Fabiane dos Santos CDD-577 O conteúdo dos artigos e seus dados em sua forma, correção e confiabilidade são de responsabilidade exclusiva dos seus respectivos autores.
Cocondensation and postfunctionalization methods were employed to synthesize a mesoporous silica with large surface area (795.1 ± 1.1 m 2 g −1) modified with 4-amino-5-hydrazino-1,2,4-triazole-3-thiol, which was successfully applied to adsorb and preconcentrate Cu(II), Co(II), and Cd(II) from aqueous media. Infrared spectroscopy of the adsorbent material demonstrated N-H stretching bonds related to primary amines existing in the ligand molecule, elemental analysis revealed the presence of 0.132 mmol g −1 of nitrogen, scanning electron microscopy indicated globularly shaped particles with average size of 10 µ m, and the point of zero charge was found to be 7.2. Kinetic data were applied to the pseudo-second-order model, indicating that a chemisorption mechanism is probably involved in the uptake of metal ions from aqueous solutions. According to the Langmuir model, the adsorption capacities for the different ions obey the following order: Cu(II) > Co(II) > Cd(II). Through a preconcentration system, a preconcentration factor of 18-, 15-, and 20-fold was attained for Cu(II), Cd(II), and Co(II), respectively. The proposed method was applied in the determination of trace metals in natural river water (Tietê River) and the results were validated through standard reference material analysis. The results also indicated that the packed column proved to be stable over 24 adsorption/desorption cycles, demonstrating that the developed material is potentially suitable for the determination of trace-level metal ions in aqueous samples.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.