Removal of copper(II) ions from Aqueous Media by Chemically Modified MCM‐41 with N‐(3‐(trimethoxysilyl)propyl)ethylenediamine and Its 4‐hydroxysalicylidene Schiff‐base

Abstract

The adsorption capacities of mesoporous silica modified with N‐(3‐(trimethoxysilyl)propyl)ethylenediamine (MCM‐41‐NH2) and its 4‐hydroxysalicylidene Schiff‐base, MCM‐41‐N‐Hdhba, as sorbents for removal and recovery of copper(II) 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‐NH2 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‐NH2 and MCM‐41‐N‐Hdhba, respectively. The uptake kinetics were modeled using a pseudo‐second‐order rate equation and the thermodynamic parameters (ΔH°, ΔG° and ΔS°) verified favorable, spontaneous, and exothermic for MCM‐41‐NH2 and endothermic for MCM‐41‐N‐Hdhba adsorption processes. Successive adsorption–desorption studies indicated that MCM‐41‐NH2 and MCM‐41‐N‐Hdhba maintain their adsorption and desorption efficiencies constant over five cycles. Of particular importance is the fact that MCM‐41‐NH2 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 (FTIR and XRD), morphological (TEM‐EDX), thermal, elemental analysis, and magnetic susceptibility measurements. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 746–760, 2018

Efficient adsorption of Cd(ІІ) ions from aqueous media onto a semi‐interpenetrating bio‐composite

“…Figure displays the plot of the equilibrium concentration ( C e ) versus adsorbance. The adsorption of Cd(ІІ) ions onto s‐IPNs‐3 increases gradually up to 50 ppm of Cd(II) ions, and begins to decrease upon further increasing the concentration of Cd(ІІ) ions as a result of saturation of the surface …”

“…Next, s‐IPN (50 mg) was added to each bottle and the bottles were allowed to equilibrate at 25 ± 0.05°C for 24 hr followed by stirring, filtering, and remeasuring the equilibrium pH value (pH e ). In addition, the zeta potentials of each the equilibrated NaCl aqueous solution were measured at different pHs using a zeta potential analyzer …”

“…The initial pH of a 50 ppm Cd(ІІ) solution was adjusted using 0.1M HCl or NaOH solutions. Then, 50 mg of s‐IPN was then added into the solutions and the mixture was shaken at 250 rpm for 2 hr.…”

“…The adsorption of Cd(ІІ) ions onto s‐IPN was studied in the 15–45°C temperature range at pH 6 using 50 mg of s‐IPN and 50 ppm Cd(ІІ) solution with shaking at 250 rpm for 2 hr.…”

“…To examine the uptake efficiency, 50 mg L −1 of interfering cations (Co 2+ , Cu 2+ , Zn 2+ , and Ca 2+ ) and 3,000 mg L −1 of K + ions in the form of nitrates, chlorides, or sulfates were added to the Cd(II) solution containing 50 mg of s‐IPNs‐3 …”