A Flocculation–Adsorption Self-Coupled System for Wastewater Treatment with the Aim of Water Reuse

Abstract

In this work, a unique flocculation–adsorption self-coupled system with a tunable coupling ratio is constructed based on an ultra-salt-sensitive polymer (USSP). USSP exhibits unique ultra-salt-sensitive properties, and distinct phase transition can be observed at a very low salt concentration of 30 g/L, which provides a straightforward strategy for coupling flocculation and adsorption processes. The self-coupling ratio between flocculation and adsorption can be finely controlled by adjusting the external stimuli. USSP shows a high adsorption capacity for the anionic dye (991.7 mg/g) in a short contact time (5 min) through the unique self-coupled flocculation–adsorption mechanism. More importantly, stimulus-triggered self-cleaning behavior of USSP can be achieved by a flocculation–adsorption self-coupled system, thereby minimizing the residual flocculant in treated water. Wastewater and salt can be easily reclaimed and reused for three cycles without any post-processing, which minimizes the total salt and water consumption in the textile dyeing industry