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In this study, a novel bamboo activated carbon (BAC) with ethylene diamine tetraacetic acid (EDTA) functionality was prepared by direct grafting in the presence of tetraethyl orthosilicate (TEOS) as a crosslinking agent. The BAC@SiO 2 -EDTA was characterized by SEM, TEM, TGA, FTIR, XPS and its adsorption property for removal of Pb(II) and Cu(II) under various experimental conditions was also investigated. The characterization results reflected that EDTA was successfully assembled on the surface of the BAC and average pore size increased from 4.10 to 4.83 nm as BAC grafted with EDTA. Adsorption data fitted very well in Langmuir isotherm model and pseudo-second-order kinetic model. As compared with the raw BAC, the maximum adsorption capacities of BAC@SiO 2 -EDTA for the Pb(II) and Cu(II) increased from 45.45 to 123.45 mg g −1 and from 6.85 to 42.19 mg g −1 , since the existence of EDTA on modified BAC promoted the formation of chemical complex. The removal of heavy metal ions mainly depended on the complexation with EDTA and the electrostatic attractions with negatively charged surface of BAC@SiO 2 -EDTA. The adsorption of Pb(II)/Cu(II) on the BAC@SiO 2 -EDTA was pH dependent and pH 5–6 was considered an optimum. However, lower temperature favored the adsorption and the maximum adsorption was recorded at 20 °C. In addition, BAC@SiO 2 -EDTA had an excellent reusability with about 40% decline in the adsorption capacity for Pb(II) after fifth reuse. Insignificant influences of co-existing cations and natural organic matter (NOM) were found on the adsorption of Pb(II) and Cu(II). All the results demonstrate that BAC@SiO 2 -EDTA is a potential adsorbent for metal ions in wastewater. [ABSTRACT FROM AUTHOR]

In this study, EDTA-functionalized Fe 3 O 4 (Fe 3 O 4 @SiO 2 -EDTA) was prepared by silanization reaction between N-(trimethoxysilylpropyl) ethylenediamine triacetic acid (EDTA-silane) and hydroxyl groups for Pb(II) and Cu(II) removal from aqueous solutions. Fe 3 O 4 @SiO 2 -EDTA composites were characterized using SEM, TEM, EDX, FTIR, XPS, TGA and saturated magnetization techniques. Maximum Pb(II) adsorption capacity was found to be 114.94 mg g −1 with SiO 2 /EDTA molar ratio of 2.5:1. The adsorption rate was significantly fast and the equilibrium was reached within 10 min. The optimum pH was recorded to be 5.0. The maximum adsorption capacity of the studied heavy metal ions calculated by Langmuir model followed the order: Cu(II) (0.58 mmol g −1 ) > Pb(II) (0.55 mmol g −1 ) ≈ Ni(II) (0.55 mmol g −1 ) > Cd(II) (0.45 mmol g −1 ). Moreover, Pb(II) and Cu(II) adsorption capacities were not significantly affected by co-existing cations and NOM. These results suggested that this adsorbent can be considered as a promising adsorbent to remove Pb(II) and Cu(II) from wastewaters. [ABSTRACT FROM AUTHOR]