Herein, we studied the adsorption behaviors of organic micropollutants, such as anticonvulsant carbamazepine (CBZ) and antibiotic tetracycline hydrochloride (TC), on zirconium metal-organic framework UiO-66 in water. The maximum adsorption capacities of CBZ and TC on the UiO-66 were 37.2 and 23.1 mg·g at 25 °C, respectively. The adsorption isotherms and kinetics of CBZ and TC were well described by using the Langmuir model and pseudo-second-order model, respectively, and the adsorptions on UiO-66 are endothermic reactions. The adsorption capacities of CBZ and TC on UiO-66 were decreased with the increase of solution pH. The presence of humic acid could improve the adsorption of CBZ and TC on UiO-66, but K ion inhibited their adsorption obviously. In addition, Ca and Al ions also suppressed the adsorption of TC on UiO-66. The competitive adsorption suggested that the adsorption sites for CBZ on UiO-66 were different from those for TC. The surface interactions between UiO-66 and the two micropollutants were demonstrated by powder X-ray diffraction, Fourier transform infrared (FT-IR) spectra, scanning electron microscopy, nitrogen adsorption/desorption isotherms, and X-ray photoelectron (XPS) spectra. The characterizations showed that the adsorption of CBZ on UiO-66 is mainly a physisorption, and the hydrophobic effect played a crucial role during the adsorption of CBZ; meanwhile weak π-π electron donor-acceptor interaction and electrostatic attraction also existed. However, the adsorption of TC on UiO-66 is mainly a chemisorption; in addition to the strong electrostatic attraction and π-π electron donor-acceptor interaction forces, the nitrogenous groups of TC played an important role, which can replace the carboxylic groups coordinated with Zr-O clusters. The obtained results will aid us to comprehend the surface interaction between organic micropollutants and UiO-66 and expand the application of UiO-66 as sorbent for removal of pollutants from water.

Magnetic Fe–Cx as heterogeneous Fenton-like catalysts were synthesized by the pyrolysis of Fe-MOF, and the catalytic activity of Fe–Cx for removal of 4-NP was significantly affected by pyrolysis temperature.

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In this study, calcium-alginate microgels coated with a polyelectrolyte multilayer (PEM) were fabricated as a controlled-release system. This system was constructed via an electrostatic droplet generation technique followed by a layer-by-layer (LbL) self-assembly technique. The electrostatic droplet generation technique was reported as an easy method of preparing microgels, due to their mild preparation conditions and ability to preserve the biological activity of the encapsulated drugs. With the LbL self-assembly technique, the PEM could be fabricated on the microgels attributed to the electrostatic attraction between positive-charged chitosan (Chi) and negative-charged dextran sulfate (Dex). The properties of the prepared microgels were investigated using dynamic laser scattering (DLS), scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectrum and zeta potential analyzer. In vitro release study indicated that the initial burst release of the bovine serum albumin (BSA) from PEM-coated microgels was less compared to the uncoated microgels (19% versus 31% in 24 h). In addition, the sustained release of BSA from the PEM-coated microgels was recorded up to 1 month without any damage to BSA integrity. Thus, our results demonstrated that the PEM-coated microgels not only prolonged the release time, but also relieved the initial burst problem to some degree and preserved the biological activity of the encapsulated drugs. Moreover, the release rate of BSA could be regulated by controlling the number of deposited layers. In conclusion, this study presented an easy yet effective method for the controlled, sustained release of biological macromolecules.

In recent years, the application of biochar to remove contaminants from aqueous solutions has become interesting due to favorable physical/chemical properties and abundant feedstocks.