Enhanced Removal of Pb²⁺, Cu²⁺, and Cd²⁺ by Amino-Functionalized Magnetite/Kaolin Clay

Abstract

The amino-functionalized magnetite/kaolin clay (MKC) was synthesized via a simple solvothermal method and used to remove Pb 2+ , Cu 2+ , and Cd 2+ from aqueous solutions. In comparison, the kaolin clay (KC) and MKC were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and scanning and transmission electron microscopy with energy dispersive spectrometry. The results indicated amino-functionalized MKC was formed with Fe 3 O 4 particles adhering to the surface by interactions with negatively charged KC. The optimal experimental conditions were evaluated, and the adsorption performance of MKC for Pb 2+ , Cu 2+ , and Cd 2+ was far better than that of KC. This was mainly caused by adding an amino group, in which the amino group displayed complexing ability toward metal ions. In kinetic data representation, the pseudo-first-order, pseudo-second-order, and Elovich models were employed, and the second one gave the better fitting. Langmuir, Freundlich, and Dubinin−Radushkevich models were chosen for isotherm data correlation, of which the first one showed better suitability. The X-ray photoelectron spectroscopy analysis of MKC before and after adsorption further revealed that the adsorption mechanisms of Pb 2+ , Cu 2+ , and Cd 2+ could be a combined reaction of complexation between functional groups and metal ions and electrostatic attraction. In addition, MKC can be rapidly separated using only a magnet after the adsorption process.

Thiourea modified hyper‐crosslinked polystyrene resin for heavy metal ions removal from aqueous solutions

“…The chorine content of the TM-HPS adsorbent was measured by the Volhard method. 31 Fourier transform infrared (FTIR) spectra were recorded on a Fourier transform infrared spectrometer (PerkinElmer 2000, USA) using KBr as background over the range of 400-4000 cm 21 under ambient conditions. The specific surface area was measured by N 2 adsorption isotherm with a Micromeritics ASAP 2020 accelerated surface area and porosimetry analyzer (Micromeritics, Norcross, GA, USA).…”

“…Heavy metal ions i.e., Pb 21 , Cd 21 , and Cu 21 are potential hazards to aquatic, animal, and human life because of their toxicity, even at low concentrations. 1 Various treatment methods i.e., chemical precipitation, 2 adsorption, 3 ion-exchange, 4 membrane filtration, 5,6 coagulation and flocculation, 7 and electrochemical treatment 8 have been widely used for the removal of heavy metal ions from aqueous medium.…”

“…[16][17][18] However, it is necessary to introduce some specific functional groups on the surface of adsorbents, with the aim to improve their adsorption performance toward heavy metal ions. [19][20][21] Adsorbents containing the amino groups (ANH 2 ), hydroxyl groups(AOH), sulfonic (ASO 3 H), and carboxylic (ACOOH) groups have been developed for the removal of heavy metal ions from aqueous solutions because these introduced functional groups can significantly improve their adsorption properties after modification of the chemical composition.…”

“…of Cd 21 ions from aqueous solution. The surface functional groups of adsorbents significantly affect the adsorption performance, and dominate the adsorption mechanism.…”

“…The results indicated that the prepared resin was effective for the removal of the heavy metal ions from aqueous solutions. The isotherm data could be better fitted by Langmuir model, yielding maximum adsorption capacities of 689.65, 432.90, and 290.69 mg/g for Pd 21 , Cd 21 , and Cu 21 , respectively. And the adsorption kinetics of the three metal ions followed the pseudo-second-order equation.…”