Removal of Copper(II) Ions from Aqueous Media by Chemically Modified MCM-41 with #-(3-(Trimethoxysilyl)propyl)ethylenediamine and Its 4-Hydroxysalicylidene Schiff-Base

摘要

The adsorption capacities of mesoporous silica modified with N-(3-(trimethoxysiIyl)propyl)ethylenediamine (MCM-41-NH_2) and its 4-hydroxysalicylidene Schiffbase, MCM-41-N-Hdhba, as sorbents for removal and recovery of copperill) ions from aqueous media have been investigated. The sorption uptake is highly dependent on the pH, contact time, temperature, diverse ions, mass of sorbent as well as initial Cu(II) ions concentration. At pH 6, the two sorbents, MCM-41-NH_2 and MCM-41-N-Hdhba, show 96.4% and 99.9% Cu(II) ions removal, respectively. Langmuir isotherm gave the best fit of the experimental data with maximum adsorption capacities 138.8 and 222.2 mg g~(-1) for MCM-41 -NH_2 and MCM-41-N-Hdhba, respectively. The uptake kinetics were modeled using a pseudo-second-order rate equation and the thermodynamic parameters (∆H~°, ∆G° and ∆S°) verified favorable, spontaneous, and exothermic for MCM-41-NH_2 and endothermic for MCM-41-N-Hdhba adsorption processes. Successive adsorption-desorption studies indicated that MCM-41-NH_2 and MCM-41-N-Hdhba maintain their adsorption and desorption efficiencies constant over five cycles. Of particular importance is the fact that MCM-41-NH, and MCM-41-N-Hdhba were able to remove 95% of Cu(II) ions from polluted river and tap water. The structures and physicochemical properties of the sorbents before and after adsorption of Cu(II) ions were characterized by using spectroscopic (FITR and XRD). morphological (TEM-EDX), thermal, elemental analysis, and magnetic susceptibility measurements.