LİGAND KATKILI MEZOGÖZENEKLİ SİLİKA KULLANARAK Cu(II) İYONLARININ KOLORİMETRİK TAYİNİ VE ADSORPSİYONU

Abstract

The aim of this work is to evaluate the effectiveness of the ligand dopped mesoporous silica as conjugate materials for Cu(II) ions detection and removal from water samples. In this work, mesoporous monolithic silica was synthesized in acidic medium by using tetraethylorthosilicate (TEOS) and nonionic surfactant Brij 56. The water-soluble indicator Pyrocatechol Violet was lipophilized with N-cetyl pyridinium chloride in the form of an ion-pair (PC-CP) and subsequently immobilized into mesoporous silica (Si- PV-CP). The resulting material was characterized by FT-IR, SEM, BET, elemental analysis and X-ray microtomography. The prepared Si-PV-CP particles was exhibited an obvious color change from yellowish to dark blue in the presence of Cu(II) ions. In Cu(II) adsorption experiments, several affecting factors, including the solution pH, contact time, initial Cu(II) ions concentration, foreign ions and reuses were investigated. From the experimental data, the maximum adsorption capacity of Si-PVCP particles was found to be 41.6 mg/g Cu(II) at pH of 6.0. The adsorption equilibrium was achieved within a short contact time (30 min). The results demonstrated that Cu(II) ion loaded conjugate materials was effectively regenerated using 0.05 M HCl and 0.05 M EDTA solution. The Cu(II) adsorption efficiency was not affected in the presence of foreign ions. iv In the third part of this study, an optical test strip was prapared for visual detection of Cu(II) ions. In the preparation of the test strip, the spectrophotometric reagent PV-CP was immobilized in the sol-gel, and then the filter papers were coated with sol-gel thin film using the dip coating method. The test strip color was changed quickly to the addition of Cu(II) ions, which was visualized through naked-eye. The selectivity of the test strip was determined by Uv–Vis reflectance spectra. Under optimum conditions, trace level of Cu(II) ions recognized, and the limit of detection was calculated to be 3,2 μg/L. A linear calibration graph was obtained in the range of 10–750 μg/L of Cu(II). The presence of foreign ions did not interfere detection of Cu(II) ions. Furthermore, the test strip was applied to certified reference water samples for the detection of Cu (II) ions and satisfactory results were obtained. The method developed requires no prior treatment such as concentrating and extraction process.