•Inclusion complexes of Chimonanthus Praecox extract with CDs were prepared.•β-CD showed selective inclusion characters to flavonoids.•CDs significantly enhanced antioxidant activity of Chimonanthus Praecox extract.•CDs obviously enhanced thermal stability of Chimonanthus Praecox extract.•Encapsulation with CDs was a promising way in application of bioactive compounds.In this research, the inclusion complexes of Chimonanthus Praecox extract (CPE) with cyclodextrins (CDs) were prepared. The samples before and after encapsulation were analyzed by UHPLC-QTOF-MS and the variation in the contents of each identified bioactive compound were visualized in the heat maps. It was found that β-CD have selective inclusion capacity to flavonoids. Moreover, encapsulation with CDs could significantly improve the antioxidant activity and thermal stability of CPE, enabling application of Chimonanthus Praecox extract as natural antioxidants and/or food additive especially when expected to be thermally processed. Therefore, encapsulation with CDs was a promising way in further application of bioactive compounds in plants. Additionally, this study gives new insight into the inclusion behavior between the complicated guests and different hosts, which provided specific guidance on the choice of bioactive guests with appropriate hosts.Download high-res image (128KB)Download full-size image

For the simultaneous adsorption and detoxification of hexavalent chromium from water, a new titanium–chitosan (Ti–CTS) composite was synthesized through a metal-binding reaction between titanium ions and the chitosan biopolymer followed by cross-linking with glutaraldehyde. The resultant composite was characterized by FT-IR, XRD, elemental mapping, SEM and XPS. The adsorption properties toward Cr(VI) were systematically investigated as a function of pH, dosage, initial concentration, contact time, temperature and co-existing ions. Experimental data were well described by the Langmuir isotherm and the pseudo-second order model with the maximum adsorption capacity of 171 mg g−1. More attractively, the Cr(VI) could be effectively adsorbed and reduced to the less toxic Cr(III) by the Ti–CTS composite. The experimental results, FT-IR and XPS indicated that the possible removal mechanism of Cr(VI) onto the Ti–CTS composite was summarized into three steps: (i) Cr(VI) adsorption by electrostatic attraction (Ti4+ and HCrO4−) and ligand exchange (Cl− and HCrO4−); (ii) Cr(VI) partly reduced to Cr(III); (iii) the re-adsorption of Cr(III) onto the Ti–CTS composite.

In this study, zirconium-based chitosan (CTS@Zr) microcomposite was prepared and employed as an efficient adsorbent for the removal of orange II dye from aqueous solution. The microcomposite was characterized by BET, FT-IR, XRD, SEM and EDS. Various parameters including solution pH, contact time, temperature and initial dye concentration were systematically investigated. The results showed that the adsorption process was pH dependent and the optimum condition was at pH 2.0. Adsorption kinetics followed the pseudo-second order model and thermodynamic constant values demonstrated that the adsorption process of orange II dye onto CTS@Zr microcomposite was feasible, spontaneous (ΔG0 < 0) and endothermic (ΔH0 > 0) under the examined conditions. Equilibrium isotherms showed a good fit with Langmuir isotherm equation for the monolayer adsorption process and the maximum adsorption capacity was calculated for 926 mg g−1. More importantly, the removal rate was higher than 99.4% when initial dye concentration was less 100 mg L−1 (0.20 g L−1 dosage), indicating that the CTS@Zr microcomposite exhibited excellent efficiency for the removal of orange II dye. Moreover, the orange II loaded CTS@Zr microcomposite adsorbent was easily regenerated by using 0.05 M NaOH within 10 min and the adsorption capacity still remained 98% after six regeneration cycles. The mechanisms of adsorption were attributed to electrostatic attraction and ligand exchange reaction between CTS@Zr and Dye–SO3− anions. Therefore, the CTS@Zr microcomposite adsorbent possesses a great potential for the removal of orange II dyes from aqueous solution.

•UHPLC–MS/MS analysis profiled Chimonanthus praecox and presented 50 compounds.•Six markers responsible for discrimination among four varieties were indicated.•Antioxidant activities were analyzed comparatively among different varieties.•The new varieties were better than the traditional one in antioxidant activities.•Chimonanthus praecox is a good candidate for natural antioxidants.In this research, comprehensive phytochemical profile and antioxidant activities of four different varieties of Chimonanthus praecox were studied. The petal samples were analyzed by UHPLC–QTOF–MS and 50 compounds were identified. In addition, six possible markers responsible for discrimination among different varieties were indicated. Moreover, the assays such as DPPH, ABTS and FRAP revealed their high antioxidant activities. The samples of new varieties had the higher antioxidant activities than the traditional one, well correlated with their higher total flavonoid and phenolic contents. This study presents the first phytochemical profile work on C. praecox, and gives insights into its potential application as natural antioxidant in the industries related to pharmaceutical and functional ingredients.Download full-size image

•Cerium immobilized cross-linked chitosan composite was prepared and characterized.•Adsorption of fluoride by CTS-Ce composite was in high efficiency and maximum experimental qe value was 149 mg/g at 20 °C.•Mechanisms for fluoride adsorption on CTS-Ce composite were elucidated.In this present study, a bio-adsorbent based on cerium immobilized cross-linked chitosan (CTS-Ce) composite was prepared and employed for the removal of fluoride from water. This bio-absorbent was characterized by fourier transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET), energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), elemental mapping images (EMI) and X-ray photoelectron spectroscopy (XPS) analyses. Adsorption properties for fluoride removal were systematically investigated, including pH (2–11), initial fluoride concentrations (5.0–100 mg/L), contact time, temperature (10–40 °C) and co-existing ions. Besides, kinetics, isotherms, thermodynamics and regeneration were also studied to evaluate the fluoride adsorption performance on this adsorbent. Results showed the experimental data followed Langmuir isotherm and pseudo-second order kinetic model. The adsorption process was controlled by intra-particle diffusion and the maximum adsorption capacity calculated by Langmuir isotherm was 153 mg/g at 20 °C (close to experimental qe value 149 mg/g), which was higher than the raw chitosan (13.2 mg/g) and most of the reported adsorbents. The adsorption mechanisms for fluoride removal were (i) the electrostatic attraction among −NH3+ and Ce3+/4+ with F− ions, (ii) the ligand exchange between NO3− and F− and (iii) the formation of CTS-Ce-F complexation. This novel composite can be easily regenerated with NaOH solution while maintaining 78% removal efficiency after 3 cycles. It was believed that this composite had great potential to remove fluoride from contaminated water.

For the simultaneous adsorption and detoxification of hexavalent chromium from water, a new titanium–chitosan (Ti–CTS) composite was synthesized through a metal-binding reaction between titanium ions and the chitosan biopolymer followed by cross-linking with glutaraldehyde. The resultant composite was characterized by FT-IR, XRD, elemental mapping, SEM and XPS. The adsorption properties toward Cr(VI) were systematically investigated as a function of pH, dosage, initial concentration, contact time, temperature and co-existing ions. Experimental data were well described by the Langmuir isotherm and the pseudo-second order model with the maximum adsorption capacity of 171 mg g−1. More attractively, the Cr(VI) could be effectively adsorbed and reduced to the less toxic Cr(III) by the Ti–CTS composite. The experimental results, FT-IR and XPS indicated that the possible removal mechanism of Cr(VI) onto the Ti–CTS composite was summarized into three steps: (i) Cr(VI) adsorption by electrostatic attraction (Ti4+ and HCrO4−) and ligand exchange (Cl− and HCrO4−); (ii) Cr(VI) partly reduced to Cr(III); (iii) the re-adsorption of Cr(III) onto the Ti–CTS composite.