[Adsorption Properties and Host-guest Effects of Porous Cyclodextrin Polymers for Dye Molecules in Water].

Cyclodextrin can form host-guest inclusion complexes with a variety of organic pollutants and has unique advantages in removing complex dye molecules from water. In this study, a porous cyclodextrin polymer (P-CDP) was prepared using a rigid crosslinking agent, and the structure of the P-CDP was characterized by FT-IR, XPS, SEM, BET, and other technologies. The P-CDP was studied using isothermal adsorption and kinetic adsorption experiments. The inclusion adsorption performance and host-guest effect of the P-CDP for dye molecules in water were studied using competitive experiments. The characterization results showed that the P-CDP had strong thermal stability. It had a microporous structure with a specific surface area of 108.745 m2·g-1. The Langmuir model and the pseudo-second-order kinetic model had a higher fitting degree for the adsorption process. The results of the competition experiments showed that the electrostatic effect was stronger than the host-guest effect in the adsorption process. Pollutants whose molecular configurations were highly matched with the cyclodextrin cavity could form inclusion complexes with high molecular stability. Contaminants with strong hydrophobicity were more likely to be encapsulated in the cyclodextrin cavity. After the P-CDP adsorbed the dyes, the removal efficiency after the fifth cycle of elution and regeneration remained above 80%. This study showed that P-CDP has potential application value in the treatment of dye wastewater.

Application of coagulation/flocculation in oily wastewater treatment: A review.

Volumes of oily wastewater are inevitably generated by every walk of life. The removal of oil particles from oil-contaminated wastewater which is characterized as huge amounts, intricate composition, and great threats to human health and the ecological environment is a research hotspot in water treatment fields. Due to high treatment costs and undesirable treatment efficiencies, oily wastewater treatment remains a topical and urgent issue. At present, coagulation/flocculation as an indispensable oily wastewater treatment technology receives much attention because it is very well established, economical, practical and relatively efficient. The influencing factors of oil wastewater treatment by coagulation/flocculation have also been summarized in-depth, like dosage, pH, etc. In consideration of its complex composition and treatment difficulty, this paper will also compare the treatment effects of different coagulants/flocculants used alone and combined effects in oily wastewater treatment: inorganic coagulants, organic synthetic polymeric flocculants, natural flocculants and modified polymeric flocculants. Additionally, in this review, the mechanisms of removing oily substance by coagulation/flocculation are emphasized. Given strict emission standards and the refractory nature of oily wastewater, the combination process with coagulation/flocculation, such as electrocoagulation, coagulation-membrane filtration hybrid process, and coagulation/flocculation-flotation can present better application potential and are discussed in this review. To provide a proper choice in practical application, the operating cost of coagulation and several conventional technologies are also compared. Finally, the existing challenges in the treatment of oily wastewater by coagulation are analyzed, and the feasible research direction is proposed.