Preparation of Molecularly Imprinted Microspheres as Biomimetic Recognition Material for In Situ Adsorption and Selective Chemiluminescence Determination of Bisphenol A

Bisphenol A (BPA) is an endocrine disrupter in environments which can induce abnormal differentiation of reproductive organs by interfering with the action of endogenous gonadal steroid hormones. In this work, the bisphenol A (BPA) molecularly-imprinted microspheres (MIMS) were prepared and used as biomimetic recognition material for in situ adsorption and selective chemiluminescence (CL) determination of BPA. Through non-covalent interaction, the BPA-MIMS was successfully prepared by Pickering emulsion polymerization using a BPA template, 4-vinylpyridine (4-VP) monomer, ethylene glycol dimethacrylate (EGDMA) cross-linker, and a SiO2 dispersion agent. The characterization of scanning electron microscopy (SEM) and energy-disperse spectroscopy (EDS) showed that the obtained MIMS possessed a regular spherical shape and narrow diameter distribution (25–30 μm). The binding experiment indicated BPA could be adsorbed in situ on the MIMS-packing cell with an apparent maximum amount Qmax of 677.3 μg g−1. Then BPA could be selectively detected by its sensitive inhibition effect on the CL reaction between luminol and periodate (KIO4), and the inhibition mechanism was discussed to reveal the CL reaction process. The CL intensity was linear to BPA concentrations in two ranges, respectively from 0.5 to 1.5 μg mL−1 with a detection limit of 8.0 ng mL−1 (3σ), and from 1.5 to 15 μg mL−1 with a limit of detection (LOD) of 80 ng mL−1 (3σ). The BPA-MIPMS showed excellent selectivity for BPA adsorption and the proposed CL method has been successfully applied to BPA determination in environmental water samples

Mesoscopic Simulations of Adsorption and Association of PEO-PPO-PEO Triblock Copolymers on a Hydrophobic Surface: From Mushroom Hemisphere to Rectangle Brush

The dissipative particle dynamics (DPD) method is used to investigate the adsorption behavior of PEO-PPO-PEO triblock copolymers at the liquid/solid interface. The effect of molecular architecture on the self-assembled monolayer adsorption of PEO-PPO-PEO triblock copolymers on hydrophobic surfaces is elucidated by the adsorption process, film properties, and adsorption morphologies. The adsorption thicknesses on hydrophobic surfaces and the diffusion coefficient as well as the aggregation number of Pluronic copolymers in aqueous solution observed in our simulations agree well with previous experimental and numerical observations. The radial distribution function revealed that the ability of self-assembly on hydrophobic surfaces is P123 > P84 > L64 > P105 > F127, which increased with the EO ratio of the Pluronic copolymers. Moreover, the shape parameter and the degree of anisotropy increase with increasing molecular weight and mole ratio of PO of the Pluronic copolymers. Depending on the conformation of different Pluronic copolymers, the morphology transition of three regimes on hydrophobic surfaces is present: mushroom or hemisphere, progressively semiellipsoid, and rectangle brush regimes induced by decreasing molecular weight and mole ratio of EO of Pluronic copolymers

Mesoscopic Simulations of Adsorption and Association of PEO-PPO-PEO Triblock Copolymers on a Hydrophobic Surface: From Mushroom Hemisphere to Rectangle Brush

The dissipative particle dynamics (DPD) method is used to investigate the adsorption behavior of PEO-PPO-PEO triblock copolymers at the liquid/solid interface. The effect of molecular architecture on the self-assembled monolayer adsorption of PEO-PPO-PEO triblock copolymers on hydrophobic surfaces is elucidated by the adsorption process, film properties, and adsorption morphologies. The adsorption thicknesses on hydrophobic surfaces and the diffusion coefficient as well as the aggregation number of Pluronic copolymers in aqueous solution observed in our simulations agree well with previous experimental and numerical observations. The radial distribution function revealed that the ability of self-assembly on hydrophobic surfaces is P123 > P84 > L64 > P105 > F127, which increased with the EO ratio of the Pluronic copolymers. Moreover, the shape parameter and the degree of anisotropy increase with increasing molecular weight and mole ratio of PO of the Pluronic copolymers. Depending on the conformation of different Pluronic copolymers, the morphology transition of three regimes on hydrophobic surfaces is present: mushroom or hemisphere, progressively semiellipsoid, and rectangle brush regimes induced by decreasing molecular weight and mole ratio of EO of Pluronic copolymers

Insight into synergistic effect of adsorption-photocatalysis for the removal of organic dye pollutants by Cr doped ZnO

The adsorption of dye molecules is an important process for the photodegradation removal of dye pollutants. In this work, a semiconductor photocatalyst of Cr doped ZnO nanorods (Cr-ZnO NRs) was synthesized, and its adsorption-photocatalysis synergy (APS) effect was investigated for anionic azo methyl orange (MO-) and cationic azo methylene blue (MB+). The detailed thermodynamic information (including adsorption maximum capacity qmax, adsorption equilibrium constant Kads and adsorption efficiency AE%) and dynamic information (including adsorption rate constant ka, degradation rate constant kd and degradation efficiency DE%) were obtained to evaluate the different reaction performances for MO- and MB+. With qmax(MB+)= 40.59 mg g-1 > qmax(MO-)= 15.95 mg g-1, ka (MB+) = 20.61 min-1> ka (MO-)= 4.62 min-1 and AE(MB+)=40% > AE(MO-)=9%, Cr-ZnO NRs showed much superior adsorption performance for MB+ than MO-. With kd (MB+) = 0.0430 min-1> kd (MO-)= 0.0014 min-1 and DE(MB+)=98% > AE(MO-)=20%, Cr-ZnO NRs also showed much superior photodegradation performance for MB+ than MO-. The APS mechanism of Cr-ZnO NRs is revealed to be multiple π-π interactions and stronger electrostatic attractions dominant for enhanced adsorption of MB+, and higher adsorption efficiency and more photocatalytic active species dominant for enhanced photodegradation of MB+. The APS was furthermore characterized and verified by zeta potential analysis, FTIR investigation and fluorescence imaging. The results indicate that Cr-ZnO NRs is a promising adsorbent and photocatalyst candidate favorable for positive MB+ than negative MO-. Such a APS investigation can effectively help to improve the photodegradation treatment performance of photocatalyst for dye pollutants removal

Investigation on the adsorption-interaction mechanism of Pb(II) at surface of silk fibroin protein-derived hybrid nanoflower adsorbent

For further the understanding of the adsorption mechanism of heavy metal ions on the surface of protein-inorganic hybrid nanoflowers, a novel protein-derived hybrid nanoflower was prepared to investigate the adsorption behavior and reveal the function of organic and inorganic parts on the surface of nanoflowers in the adsorption process in this study. Silk fibroin (SF)-derived and copper-based protein-inorganic hybrid nanoflowers of SF@Cu-NFs were prepared through self-assembly. The product was characterized and applied to adsorption of heavy metal ion of Pb(II). With Chinese peony flower-like morphology, the prepared SF@Cu-NFs showed ordered three-dimensional structure and exhibited excellent efficiency for Pb(II) removal. On one hand, the adsorption performance of SF@Cu-HNFs for Pb(II) removal was evaluated through systematical thermodynamic and adsorption kinetics investigation. The good fittings of Langmuir and pseudo-second-order models indicated the monolayer adsorption and high capacity of about 2000 mg g of Pb(II) on SF@Cu-NFs. Meanwhile, the negative values of Δ r G m ( T ) θ and Δ r H m θ proved the spontaneous and exothermic process of Pb(II) adsorption. On the other hand, the adsorption mechanism of SF@Cu-HNFs for Pb(II) removal was revealed with respect to its individual organic and inorganic component. Organic SF protein was designated as responsible 'stamen' adsorption site for fast adsorption of Pb(II), which was originated from multiple coordinative interaction by numerous amide groups; inorganic Cu(PO) crystal was designated as responsible 'petal' adsorption site for slow adsorption of Pb(II), which was restricted from weak coordinative interaction by strong ion bond of Cu(II). With only about 10% weight content, SF protein was proven to play a key factor for SF@Cu-HNFs formation and have a significant effect on Pb(II) treatment. By fabricating SF@Cu-HNFs hybrid nanoflowers derived from SF protein, this work not only successfully provides insights on its adsorption performance and interaction mechanism for Pb(II) removal, but also provides a new idea for the preparation of adsorption materials for heavy metal ions in environmental sewage in the future

Mesoscopic Simulations of Adsorption and Association of PEO-PPO-PEO Triblock Copolymers on a Hydrophobic Surface: From Mushroom Hemisphere to Rectangle Brush

The dissipative particle dynamics (DPD) method is used to investigate the adsorption behavior of PEO-PPO-PEO triblock copolymers at the liquid/solid interface. The effect of molecular architecture on the self-assembled monolayer adsorption of PEO-PPO-PEO triblock copolymers on hydrophobic surfaces is elucidated by the adsorption process, film properties, and adsorption morphologies. The adsorption thicknesses on hydrophobic surfaces and the diffusion coefficient as well as the aggregation number of Pluronic copolymers in aqueous solution observed in our simulations agree well with previous experimental and numerical observations. The radial distribution function revealed that the ability of self-assembly on hydrophobic surfaces is P123 > P84 > L64 > P105 > F127, which increased with the EO ratio of the Pluronic copolymers. Moreover, the shape parameter and the degree of anisotropy increase with increasing molecular weight and mole ratio of PO of the Pluronic copolymers. Depending on the conformation of different Pluronic copolymers, the morphology transition of three regimes on hydrophobic surfaces is present: mushroom or hemisphere, progressively semiellipsoid, and rectangle brush regimes induced by decreasing molecular weight and mole ratio of EO of Pluronic copolymers

Insight into adsorption-interaction mechanism of Cr(VI) at silica adsorbent surface by evanescent wave measurement

The investigation of adsorption performance at adsorbent surface can help to reveal the treatment mechanism and improve the treatment efficiency of adsorption technology for heavy metal ions (HMIs). This work developed a methodology to investigate the adsorption behavior of HMI Cr(VI) at silica surface by confined near field evanescent wave (CNFEW) measurement. Silica optical fiber (SOF) was used as adsorption substrate and light waveguide element to integrate both Cr(VI) adsorption and CNFEW production on its surface. According to thesensitive CNFEW response, the adsorption behavior of Cr(VI) was in situ monitored and real time evaluated. The thermodynamic information of adsorption equilibrium constant (Kads) and adsorption free energy (ΔG)), and dynamic information of apparent adsorption rate (vads) and adsorption time (tads)), were obtained through Langmuir isotherm and kinetic fitting, respectively. Different reaction performances between Cr(VI) and adsorption sites were successfully differentiated, evaluated and characterized. A site-decided-mechanism was therefore presented to describe the surface interaction process for Cr(VI), which including fast adsorption on type I Si-O- site through electrostatic attraction with 〖∆G〗_(SiO^--Cr(VI))^I=-45.71 kJ mol^(-1) and slow adsorption on type II Si-OH site through coordinative interaction with 〖∆G〗_(SiOH-Cr(VI))^II=-26.18 kJ mol^(-1). The adsorption mechanism of Cr(VI) at SOF silica surface was furthermore verified by zeta potential analysis, FTIR investigation and fluorescence imaging. Unlike conventional ex situ or in bulk detection, the present CNFEW-based approach targets the 'localized' adsorption of Cr(VI) adsorbed to the solid adsorbent surface. Consequently, our work favorably constructs an surface platform and provides new insights on understanding the adsorption mechanism for HMIs