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Novel zwitterionic inorganic–organic hybrids: Synthesis of hybrid adsorbents and their applications for Cu²⁺ removal

Dong, Qiang, Liu, Junsheng, Song, Long, Shao, Guoquan
Journal of hazardous materials 2011 v.186 no.2-3 pp. 1335-1342
Fourier transform infrared spectroscopy, absorbents, adsorbents, adsorption, anion exchange, cation exchange capacity, copper, ethylene, models, polymerization, temperature, water pollution, zwitterions
A series of zwitterionic hybrid adsorbents were prepared via the ring-opening polymerization of pyromellitic acid dianhydride (PMDA) and N-[3-(trimethoxysilyl)propyl] ethylene diamine (TMSPEDA), and a subsequent zwitterionic process as well as sol–gel reaction. Their applications for Cu²⁺ removal by adsorption were performed. FTIR spectra confirmed the step products. TGA revealed that the initial decomposition temperature (IDT) of these zwitterionic hybrid adsorbents could arrive at near 150°C. DSC showed that Tg values decreased with an increase in PMDA content in the hybrid matrix. Ion-change capacity (IEC) revealed that the cation-exchange capacities (CIECs) and anion-exchange capacities (AIECs) of these hybrid adsorbents were within the range of 9.13–11.49 and 4.97–6.28mmolg⁻¹, respectively. Meanwhile, the CIECs and AIECs exhibit an opposite change trend as PMDA content increases. Adsorption experiment indicated that their adsorptions for Cu²⁺ ions followed Lagergren second-order kinetic model, surface adsorption and intraparticle diffusion mechanisms might be the major process. These findings demonstrated that they are promising absorbents for the separation and recovery of Cu²⁺ ions from contaminated water.