Dual-Functionalized Hollow Polymer Particle as a pH-Responsive Adsorbent for Selective Removal of Basic Dye

In the present work, novel dual-functionalized hollow polymer particles (DF-HPP) with high density of carboxylate and amino dual functional groups have been specially designed and fabricated to serve as high-performance adsorbent for selective removal of basic dye (methylene blue, b-MB, as a model dye). Due to both the high surface area and the extremely high density of carboxylate and amino groups, the DF-HPPs exhibited excellent adsorption property for methylene blue (b-MB), including high adsorption capacity, fast adsorption/desorption rates, unique pH-sensitivity and easy recovery. The equilibrium adsorption data of b-MB on the DF-HPPs were evaluated using Freundlich and Langmuir isotherm models, and the equilibrium isotherm was better fit with Langmuir model with a maximum adsorption capacity of 538.8 mg/g at pH 12. More interestingly, the DF-HPPs showed a significant pH-dependent equilibrium adsorption capacity, which decreased dramatically from 516.1 mg/g to 24 mg/g as the solution pH decreased from 12 to 3. The dye-adsorbed DF-HPPs can be facilely and rapidly regenerated under mild condition (under weak acidic solution, pH 3, in 30 min) to recover both b-MB and the DF-HPPs, and the regenerated DF-HPPs can be reused for dye removal with high efficiency, indicating the exceptional recyclability of the DF-HPPs.