Microcapsule dispersion of poly(calix[4]arene-piperazine) for hazardous metal cations removal from waste water

Abstract

Microcapsule of 500 nm was fabricated through non-agitation solution polymerization, used 5, 11, 17, 23-tetra-t-butyl- 25, 26, 27, 28-tetrakis(chlorocarbonyl-methoxy) calix [4] arene (C4C) and piperazine (PIP) with or without agitation. It was the amphiphilic self-assembly of C4C that made microcapsule the unique product for C4C/PIP couple in chloroform. Fourier transform infrared spectrometry (FTIR) and the X-ray photoelectron spectroscopy (XPS) proved the successful preparation of microcapsule. Transmission electron microscope (TEM) showed that microcapsules uniformly scattered in chloroform as a colorless dispersion. Absorption-C4C/PIP ratio curve indicated that the optimum ratio is 1:3 by ultraviolet–visible spectroscopy (UV–Vis). Microcapsule was almost uniform and intact at the optimum concentration of 3\u2009×\u200910−4 mol L−1 under the optimum ratio of C4C/PIP. TEM and dynamic light scattering (DLS) illustrated that non-agitation solution polymerization is a better method to prepare a dispersion of microcapsules. This dispersion can extract heavy metal cations from their aqueous solution and fixed them over the interface of the two liquid phases through the formation of floccule layer. Inductively coupled plasma optical emission spectroscopy (ICP-OES) data showed that extraction efficiencies of Pb(II), Zn(II), Cu(II), and Ce(II) ions were 98.85%, 100.00%, 99.56%, and 98.97%, respectively. Dilute nitric acid can dissociate floccule layer and release cations into water, meanwhile, renewing the dispersion. The recovery ratio was 77.50%, 62.96%, and 68.42% for Pb(II), Cu(II), and Ce(II) ions, respectively. For Zn(II) ions, the recovery efficiency was more than 99.99%.