Adsorption properties of halloysite nanotubes/poly(m-phenylenediamine) composites for Cr(Ⅵ)

In order to obtain a high-performance heavy metal Cr(Ⅵ) adsorption material, the halloysite nanotubes/poly(m-phenylenediamine) (HNTs/PmPD) composite was synthesized through in situ chemical polymerization under the regulation of Na₂CO₃ at room temperature. The surface structure and properties of HNTs/PmPD composite were characterized by SEM, TGA, EDS, Brunauer-Emmett-Teller specific surface area analysis (BET), inductively coupled plasma mass spectrometry (ICP-MS), FTIR and Zeta potential analysis (Zeta). The effects of experimental conditions such as pH value, time, initial concentration and temperature on the removal of Cr(Ⅵ) have been also analyzed. In addition, the experimental data of Cr(Ⅵ) adsorption by HNTs/PmPD composite were fitted and evaluated by kinetic and isotherm models. The HNTs/PmPD composite shows excellent removal ability for Cr(Ⅵ), good sedimentation separation and cycle regeneration performance, moreover, the adsorption capacity can reach above 855.66 mg·g^-1 at room temperature. The results show that amino and imine groups presented on the surface of the HNTs/PmPD composite are the main adsorption sites for the removal of Cr(Ⅵ). HNTs/PmPD composite has excellent performance and application prospects in the field of chromium-containing wastewater treatment.