APPLICATION OF ORANGE XYLENOL DYE TO NICKEL ADSORPTION COMPLEXIOMETRY

Purpose: The objective of this work was to evaluate the adsorption of nickel (Ni 2+ ) by complexiometry in different natural clays - in natura kaolin (KaONP), purified kaolinite (KaO) and bentonite (Ben). Methods: For the kinetic study, 100 mL of the NiCl 2 solution with initial concentration of 1000 mg L -1 was placed in an Erlenmeyer with 1 g of each clay sample: KaONP, KaO and Ben. Aliquots were removed at specified times. Initially, the kinetic study was performed under static conditions to evaluate the ideal time to reach equilibrium. At the end of the assay, the Ni 2+ concentration in the supernatant was determined by complexiometry with the Orange Xylenol dye, one of the techniques commonly available in the analysis is the quantification by molecular absorption spectroscopy in the visible ultraviolet (UV-vis), Ni 2+ and orange xylenol form comparatively stable complexes with little affected color intensity. The maximum absorption of the complex is between 583 nm. The materials were dried at 60 ° C for 24 hours and designated as KaONPNi, KaON1 and BenNi. Results: from the data obtained in the (UV-vis) it was possible to determine the amount of Ni 2+ absorbed, in relation to time. The equilibrium time for the clays was 24 hours. The adsorption capacity (qt) was 86.4 (mg g -1 ) for KaONPNi, 72.1 (mg g -1 ) for KaONi and 73.0 (mg g -1 ) for Ben. Conclusion: (qt) for KaONP is more efficient because it presents organic matter in its structure, since these organic groups bind cationically to the Ni 2+ ions.