Amino piperazine vermiculites as adsorbents for copper cations from aqueous solutions

Full text: Several treatments are available for the removal of heavy metals such as copper from water and wastewaters [1]. Adsorption is an effective and economical separation process for removing copper ions. Therefore, in recent years, novel adsorbents have been developed, and clay minerals have received special attention because of their affinity for heavy metal ions, which makes them potential sorbents for the removal of pollutants, such as copper from wastewater. Vermiculite sample was initially leached with nitric acid solution at three concentrations, 0.3, 0.5 and 0.8 mol dm-3. The suspension was refluxed under mechanical stirring for 4 h at 353 K, yielding leached solid named V0.3, V0.8 and V1.0. Organically modified vermiculites were synthesized by previous silylation of three lixiviated vermiculites with chloropropyltrimethoxysilane under anhydrous conditions following reaction with 1-(2-aminoethyl)piperazine (AMP), which acted as chelating agent for copper retention. Elemental analysis, X-ray diffractometry, infrared spectroscopy, scanning electronic microscopy and nitrogen gas adsorption/desorption measurements were used to characterize pristine, lixiviated and organo functionalized solids. Such factors as contact time, pH and initial copper(II) concentration for the adsorption of Cu(II) ions were investigated. Under the optimum conditions, the equilibrium was reached for sorption of Cu(II) ions followed the order V0.3AMP < V0.5AMP < V0.8AMP, with times of 30, 60 and 80 min, respectively. The adsorption capacities were 1.49, 1.54 and 1.26 mmol/g for V0.3AMP, V0.5AMP and V0.8AMP, respectively. References: [1] Wang, N.X., Zhang, X.Y., Wu, J., Xiao, L., Yin, Y., Miao, A.J., Ji, R., Yang, L.Y., Effects of microcystin-LR on the metal bioaccumulation and toxicity in Chlamydomonas reinhardtii. Water Res. 46, 369-377, 2012.(author)