Systematic Investigation on the Adsorption Performance and Mechanism of MnO₂/TA Nanoflowers for Cu(II) Removal from Aqueous Solution

Abstract

In this work, a nanoflower-type manganese dioxide composite with tannic acid (MnO 2 /TA) was prepared using a facile hydrothermal method. The maximum adsorption capacity of nanoflower MnO 2 /TA for Cu(II) removal from aqueous solution was 194.3 mg⋅g À 1 , and this illustrated the excellent adsorptive activity of nanoflower MnO 2 /TA. Adsorption kinetics and isotherm investigations showed that pseudo second order kinetics and the Langmuir isotherm model fit the experimental data well. The surface complex formation model (SCFM) was used to study the adsorptive process and mechanism of Cu(II) adsorption on the surface of MnO 2 /TA. Further investigation indicated that the adsorption energies for various forms of Cu (II) were negative which indicated that Cu(II) adsorption on MnO 2 /TA was a spontaneous process. Electrostatic interactions and chemical complexation were involved in Cu(II) removal by MnO 2 /TA from aqueous solution. The decline of adsorption capacity was about 10% for MnO 2 /TA after being reused five times, and this showed that the adsorbent might be reused in Cu(II) removal. The MnO 2 /TA nanocomposite has been proven to be a low-cost and efficient adsorbent that could be a potential material for use in environmental treatment. Understanding the adsorption mechanism might provide a technical basis for the processual design of heavy metal adsorbents.[a] Prof.

Natural polyphenol tannin-immobilized composites: rational design and versatile applications

“…Other inorganic materials, for example, SiO 2 , 235,236 TiO 2 , 237–239 MnO 2 , 240 clay, 241,242 glass fabric, 243 hydrotalcite, 244 hydroxyapatite, 245,246 and Ag, 10 have been commonly used the supports for the immobilization of tannins or their derivatives.…”