Giant Microgels with CO₂-Induced On–Off, Selective, and Recyclable Adsorption for Anionic Dyes

Abstract

Adsorbents that are capable of controllable pollutants adsorption and release without secondary pollution are attractive in water treatment. Here, we propose eco-friendly CO2 as a trigger to switch the charge states and collapse–expansion transition of giant microgels consisting of hydrophilic acrylamide and hydrophobic 2-(diethylamino)­ethyl methacrylate and demonstrated the on–off, selective, and recyclable adsorption of anionic dyes on microgels under CO2 stimulation. Apart from easy-handling separation from the water by a simple filtration process, the maximum adsorption capacity is as high as 821 mg g–1, and the adsorption isotherms and kinetics obeyed Langmuir isotherm and the pseudo-second-order kinetics models, respectively. The anionic dye can also be separated from the mixture solution using CO2-treated microgels. Moreover, a wastewater treatment prototype with microgel-packed column was fabricated. Under continuous flow condition, the dye was removed and recovered by alternative bubbling CO2 and flushing with aqueous alkali (pH 12). Thus, this type of microgels with CO2-induced protonation–deprotonation transition can serve as a cost-effective, environmentally friendly, and efficient adsorbent for water purification applications.

Adsorption of Anionic Dyes Using a Poly(styrene-block-4-vinylpyridine) Block Copolymer Organogel

“…This may also prohibit secondary contamination. 61 To investigate the regeneration of the organogel, the dye absorbed mass was immersed in 5 mL of ethanol solution. After ensuring that no detectable dye remains on the gel (by recoding the UV−vis spectrum), the dye adsorption experiments were repeated.…”

“…Also, the recovered dyes can be reused for the further dyeing process, and this will significantly reduce the continuous feed of dyes required for textile dyeing. This may also prohibit secondary contamination . To investigate the regeneration of the organogel, the dye absorbed mass was immersed in 5 mL of ethanol solution.…”

Monodispersed polymer particles with tunable surface structures: Droplet microfluidic‐assisted fabrication and biomedical applications

“…Polymer particulate materials have attracted much attention due to their wide applications in wastewater treatment, 1 drug delivery, 2 colloidal crystals, 3 chromatographic columns, 4 pigments, 5 liquid crystal displays (LCDs), 6 biochemical analysis/sensors/detectors, etc 7 . Among the various polymer particles, those with surface microstructures (e.g., bubbles, tentacles, wrinkles, pores and pits) are more attractive due to their increased specific surface area, as well as dramatically enhanced surface/interface performance.…”

pH-Sensitive Membranes with Smart Cleaning Capability for Efficient Emulsion Separation and Pollutant Removal

“…However, the photocatalytic degradation of dyes is a time-consuming and laborious process, which largely depends on the power of the light source [27] and the nanoparticles composited to the membranes have low instability, which may become a potential source of water contamination. Additionally, most of the current studies focus on dye removal, but the capability of surfactant removal has rarely been investigated [28]. Since surfactants are unlikely to be decomposed by light, it is more difficult for us to remove them from water.…”