Highly enhanced adsorption of methyl blue on weakly cross-linked ammonium-functionalized hollow polymer particles

Abstract

Adsorption is one of the most effective techniques for dye removal from wastewater, and advanced adsorbents with fast adsorption rate and remarkable adsorption capacity are highly desired. To attain this goal, we specially designed and synthesized a series of diethylenetriamine-modified hollow polymer particles (HPP-DETA) with varying degree of cross-linking, which exhibited highly enhanced dye-adsorption performance for selective removal of negatively charged dyes (methyl blue, as a model dye). Even though the density of ammonium groups remained almost unchanged, the sorption rate and capacity of HPP-DETAs can be significantly enhanced as their cross-linking degree decreased, which is strikingly different from conventional porous adsorbents. The adsorption isotherms are well described by Langmuir isotherm model and the calculated maximum adsorption capacity increased dramatically from 407 to 1341 mg g−1 as their cross-linking degree decreased from 26% to 3%. Most importantly, the weakly cross-linked HPP-DETA shows excellent reusability after regeneration, and the removal efficiency of methyl blue was higher than 98% after five successive adsorption-desorption process. In view of its highly enhanced adsorption rate, remarkable adsorption capacity and excellent recyclability, the weakly cross-linked HPP-DETA exhibits significant potentials as advanced adsorbents for dye removal.