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Bisphenol AF (BPAF) was used as a model compound to investigate the binding mechanism between the endocrine disrupting compound and human serum albumin (HSA) using multispectroscopic techniques and molecular modeling method at the protein level. The results indicated that BPAF was indeed bound to HSA and located in the hydrophobic pocket of HSA on subdomain IIA through hydrogen bond and van der Waals interactions. The fluorescence quenching data showed that the binding of BPAF and HSA quenched the intrinsic fluorescence of HSA, and the static quenching constants were acquired.

Recent studies have shown the presence of endocrine disrupting compounds (EDCs) in surface water and sewage samples. A study on rapid removal of endocrine disrupting compounds (EDCs)-bisphenol AF (BPAF) on multi-walled carbon nanotube (MWCNT) is significant for understanding how wastewater containing trace recalcitrant or hazardous BPAF was treated. Besides, the sorption behavior and mechanisms remain largely unknown. In this study, it was found the adsorption kinetics equilibrium followed the pseudo-second-order model, while the adsorption isotherms fitted better with Langmuir equation, and the adsorption is a spontaneous and exothermic process. The adsorption process was controlled simultaneously by external mass transfer and intraparticle diffusion, but the external mass transfer processes played an important role in sorption of BPAF. Hydrogen bonds was the main driving force for the adsorption, and π–π stacking and hydrophobic interactions were probably extra important mechanisms to the adsorption of BPAF. The MWCNT have higher stability within eight removal–regeneration recycles and up to 95% of recovery could be obtained using ethanol elution. The results of the experiment verified effectiveness for the recovery and removal of BPAF from wastewater samples.

The interaction between olaquindox (OLA) and bovine serum albumin (BSA) was investigated using fluorescence, UV–vis absorption and circular dichroism (CD) spectroscopy. The results showed that the fluorescence quenching of BSA by OLA was a static quenching process induced by the formation of OLA–BSA complex. The binding constant of OLA–BSA complex was calculated to be 1.299 × 104 L mol−1 (293 K). The negative values of ΔH0 and ΔS0 indicated that hydrogen bond and van der Waals interactions played major roles in stabilizing the complex. Site probe competition experiments and number of binding sites (n) revealed that OLA could bind to site I in subdomain IIA of BSA, and the binding distance (r) was evaluated to be 3.643 nm according to Forster’s non-radiative energy transfer theory. The results of CD and three-dimensional fluorescence spectra suggested some conformational changes of BSA after OLA binding.

Multi-walled carbon nanotubes (MWCNTs) were used for the sorption of tetracycline (TC) from aqueous solution. A systematic study of the adsorption process was performed by varying pH, ionic strength, sorbent amount, sorption time and temperature. The adsorption mechanism is probably the non-electrostatic π–π dispersion interaction and hydrophobic interaction between TC and MWCNT. The adsorption efficiency could reach 99.8%, suggesting that MWCNT is excellent adsorbents for TC removal from water. TC adsorption kinetics were found that the equilibrium was reached within 20 min following the pseudo-second-order model with observed rate constants (k2) of 0.026–0.032 g mg−1 min−1 (at varied temperatures). The whole rate process appeared to be influenced by both intraparticle diffusion and boundary layer diffusion. The sorption data could be well interpreted by the Langmuir model with the maximum adsorption capacity of 269.54 mg g−1 (293 K) of TC on MWCNT. The mean energy of adsorption was calculated to be 0.029 kJ mol−1 (293 K) from the Dubinin–Radushkevich adsorption isotherm. Moreover, the thermodynamic parameters for the adsorption were estimated, and the ΔH° and ΔG° values indicated the endothermic and spontaneous nature of the sorption process.