N-(((2-((2-Aminoethyl)amino)ethyl)amino)methyl)-4-sulfamoylbenzamide Impregnated Hydrous Zirconium Oxide as a Novel Adsorbent for Removal of Ni(II) from Aqueous Solutions: Optimization of Variables Using Central Composite Design

In this study, N -(((2-((2-aminoethyl)amino)ethyl)amino)methyl)-4-sulfamoylbenzamide was impregnated into the hydrous zirconium oxide matrix to yield N -(((2-((2-aminoethyl)amino)ethyl)amino)methyl)-4-sulfamoylbenzamide/hydrous zirconium oxide composite (AESB/HZO). The composite material was used to remove Ni(II) from aqueous environment. AESB/HZO was characterized using Fourier transform infrared, scanning electron microscopy with energy dispersive X-ray, and thermogravimetry-differential thermal analyses. An experimental design approach was utilized to model and optimize the variables of adsorption of Ni(II) onto the AESB/HZO composite. Four experimental parameters were selected as independent variables: contact time, pH, adsorbent dose, and initial Ni(II) concentration. A multivariable experimental design was used to establish quadratic model to describe the relationship between percent removal of Ni(II) and four independent variables. At the optimum conditions (contact time: 85 min, pH: 6, adsorbent dose: 10 mg/20 mL, and initial Ni(II) concentration: 20 mg L -1 ), high removal efficiency (99.35%) was achieved, which is reasonably well predicted by the quadratic model. The sorption of Ni(II) is dependent on pH and ionic strength at pH < 6.0. At low pH, -NH and -NH 2 groups are protonated, whereas the -SO 2 - group is available for binding with Ni(II) and the sorption of Ni(II) is mainly governed by outer sphere surface complexation. In the pH range 6.0-7.5, -NH, -NH 2 , and -SO 2 - groups are available for binding with Ni(II) and the sorption is mainly governed by inner-sphere surface complexation. Adsorption isotherm data fitted well to the Langmuir model and the maximum adsorption capacity was found to be 96.03 mg g -1 at 303 K. The results of present investigation demonstrated that AESB/HZO has a good potential for Ni(II) removal from aqueous solution.