An Integrative Technique Based on Synergistic Coremoval and Sequential Recovery of Copper and Tetracycline with Dual-Functional Chelating Resin: Roles of Amine and Carboxyl Groups

Abstract

A novel chelating resin (R-AC) bearing dual-functional groups (amino and carboxyl groups) was self-synthesized and it showed superior properties on synergistic coremoval of Cu(II) and tetracycline (TC) to commercial resins (amine, carboxyl, and hydrophobic types), which was deeply investigated by equilibrium and kinetic tests in binary, preloading, and saline systems. The adsorption of TC on R-AC was markedly enhanced when coexisted with Cu(II), up to 13 times of that in sole system, whereas Cu(II) uptake seldom decreased in the copresence of TC. Decomplexing-bridging, which included [Cu-TC] decomplexing and [R-Cu] bridging for TC, was demonstrated as the leading mechanism for the synergistic coremoval of Cu(II) and TC. Carboxyl groups of R-AC played a dominant role in decomplexing of [Cu-TC] complex and releasing free TC. Cu(II) coordinated with amine groups of R-AC was further proved to participate in bridging interaction with free TC, and the bridging stoichiometric ratio ([NH-Cu]: TC) possibly was 2:1. About 96.9% of TC and 99.3% of Cu could be sequentially recovered with dilute NaOH followed by HCl. Considering stable application for five cycles in simulated and practical wastewater, R-AC shows great potential in green and simple coremoval of antibiotic and heavy metal ions.

Preparation of amino-Fe(III) functionalized mesoporous silica for synergistic adsorption of tetracycline and copper

“…The adsorption amount of TC was significantly enhanced with the increasing concentration of Cu(II). The same phenomena was reported for the adsorption of TC onto chelating resin and tire powder (Lian et al, 2013;Ling et al, 2013). Lian et al confirmed that TC and Cu(II) facilitated the sorption of one another on tire powder through the formation of TC-Cu(II) complexes.…”

“…After TC uptake, only slight shifts of the two peaks were observed which attributed to the interaction between Fe(III) and amide of TC. When Cu(II) or TC/Cu(II) were added, peaks of NH 2 AFe(III) nearly disappeared, and new peaks at 400.2 eV appeared, which proved the adsorption interaction between Cu(II) and amine group (Ling et al, 2013). Due to the strong complexation between Cu(II) and amino groups of the adsorbent, the N atom donated a lone pair electrons to form the covalent bond NACu(II), causing the reduction of electron cloud density and locating at a higher binding energy (Kang et al, 2010;Ling et al, 2013).…”

“…TC and Cu(II) could facilitate the adsorption of one another, which might be attributed to the strong chelating capability of TC and Cu(II). The Cu(II) and TC, which adsorbed on different sites of Fe-N,N-SBA15, could chelate the TC and Cu(II) in the solution by formation of TC-Cu(II) complexes with higher sorption affinity (Ling et al, 2013).…”

“…The adsorption data were fitted by Langmuir and Freundlich model isotherm equations, respectively (Ling et al, 2013). The calculated parameters are listed in Table 1.…”

“…Many adsorbents have been used to adsorb antibiotics or heavy metals from water separately, but fewer were used to remove them together (Figueroa et al, 2004;Ge et al, 2012;Ji et al, 2009;Oh et al, 2007;Sassman and Lee, 2005;Vu et al, 2010;Yang and Jiang, 2014;Hasan et al, 2013). In recent years, the cosorption of antibiotics and heavy metals from water by some adsorbents has been attracting increasing concern due to the realistic demands (Kang et al, 2010;Ling et al, 2013;Wang et al, 2008). Sometimes antagonistic effects on adsorption were found when they coexist.…”