Removal of Hg2+ From Desulfurization Wastewater By Tannin-Immobilized Graphene Oxide

A novel adsorbent by immobilizing tannic acid (TA) on graphene oxide (GO) was proposed and used to remove Hg2+ from desulfurization wastewater. The morphology and physic-chemical property of tannin-immobilized graphene oxide (TAIGO) was characterized by Scanning electron microscopy (SEM), Atomic Force Microscope (AFM), and Fourier transform infrared spectroscopy (FTIR). The characterization results showed that the TA was immobilized on the GO successfully, and new functional groups were introduced on TAIGO. The effect of contact time, adsorbent dose, pH, and ion components on removal efficiency were evaluated. It was found that the adsorption process would complete within 15 min, and a higher removal efficiency could be obtained on the increased adsorbent dosage. The pH value would affect the protonation process of TAIGO and the form of Hg2+ in the wastewater. The high-concertation Cl- and SO32- would hinder the absorption performance, while SO42- and cations had a negligible impact. Besides, an excellent economic benefit of TAIGO was achieved in the regeneration performance evaluation experiment, and removal efficiency of was 88% remained after three recycles. Most importantly, the TAIGO exhibited a better adsorption performance and economic benefit than GO and TA. The adsorption process was fitted with the pseudo-second-order kinetic model(R=0.9995), and the adsorption of TAIGO for Hg2+ was mainly relies on the functional groups on GO and the chelation reaction between TA and Hg2+. These facts indicated that the TAIGO was a low-cost and high removal of Hg2+ efficiency adsorbent, which could be further used in the practical desulfurization wastewater.

Nickel-Catcher-Doped Zwitterionic Hydrogel Coating on Nickel–Titanium Alloy Toward Capture and Detection of Nickel Ions

Nickel–titanium (NiTi) alloys show broad applicability in biomedical fields. However, the unexpected aggregation of bacteria and the corrosion of body fluid on NiTi-based medical devices often lead to the leakage of nickel ions, resulting in inevitable allergic and cytotoxic activities. Therefore, the capture and detection of nickel ions are important to avoid serious adverse reactions caused by NiTi-based medical devices. Herein, we presented a nickel ion capture strategy by the combination of zwitterionic hydrogels as anti-bacteria layers and carbon disulfide (CS2) components as nickel-catchers (Ni-catchers). On the one hand, the hydration layer of zwitterionic hydrogel can efficiently inhibit bacteria adhesion and reduce nickel ions leakage from NiTi corrosion. On the other hand, Ni-catchers can capture leaked nickel ions from NiTi alloy actively by chelation reaction. Therefore, this strategy shows great capabilities in resisting bacteria adhesion and capturing nickel ions, providing the potential possibility for the detection of nickel ion leakage for implantable biomedical materials and devices.

New Polyporphyrin Arrays with Controlled Fluorescence Obtained by Diaxial Sn(IV)-Porphyrin Phenolates Chelation with Cu2+ Cation

New coordination oligomers and polymers of Sn(IV)-tetra(4-sulfonatophenyl)porphyrin have been constructed by the chelation reaction of its diaxialphenolates with Cu2+. The structure and properties of the synthesized polyporphyrin arrays were investigated by 1H Nuclear Magnetic Resonance (1H NMR), Infra Red (IR), Ultra Violet - Visible (UV-Vis) and fluorescence spectroscopy, mass spectrometry, Powder X-Rays Diffraction (PXRD), Electron Paramagnetic Resonance (EPR), thermal gravimetric, elemental analysis, and quantum chemical calculations. The results show that the diaxial coordination of bidentate organic ligands (L-tyrazine and diaminohydroquinone) leads to the quenching of the tetrapyrrole chromophore fluorescence, while the chelation of the porphyrinate diaxial complexes with Cu2+ is accompanied by an increase in the fluorescence in the organo-inorganic hybrid polymers formed. The obtained results are of particular interest to those involved in creating new ‘chemo-responsive’ (i.e., selectively interacting with other chemical species as receptors, sensors, or photocatalysts) materials, the optoelectronic properties of which can be controlled by varying the number and connection type of monomeric fragments in the polyporphyrin arrays.

Selenium-chelating corn oligopeptide as a potential antioxidant supplement: investigation of the protein conformational changes and identification of the antioxidant fragment composition

A selenium-chelating corn oligopeptide (Se-COP) with high protein and low molecular weight was prepared as a selenium supplement. We utilized infrared (IR), ultraviolet (UV), and circular dichroism (CD) spectroscopy, 1-anilinonaphthalene-8-sulfonate (ANS)-binding fluorescence spectra, and isothermal titration calorimetry (ITC) to analyze and describe Se-COP and its reactions. It was concluded that the chelation reaction was a spontaneous process driven by enthalpy and entropy, with ΔH=3.79 × 104 ± 4075 cal/mol, ΔS = 146 cal/mol, ΔG = –23356.30 ± 126.94 cal/mol, binding constant Ka = 1.18 × 104 ± 855 M–1, and binding site number n = 0.13 ± 0.0126, and described as coordination bonds forming and hydrophobic interaction, as well as protein conformational changes including secondary and tertiary hydrophobic structure. Se-COP had strong antioxidant capacity, and mass spectrometry (MS) was used to identify the antioxidant peptide fragment, which was characterized as LLPPY and quantified at 428.95 ng/mg. This study indicated that Se-COP prepared by chelation may be a Se supplement with antioxidant capacity that can be applied in functional foods or ingredients.

Temperature-responsive iron nanozymes based on poly(N-vinylcaprolactam) with multi-enzyme activity

Fe(ii)-based nanozymes (FeCPNGs) have been successfully prepared by a chelation reaction and presented peroxidase and SOD activity.

A new voltammetric immunosensing platform for prostate-specific antigen based on the Cu(ii)-pyrophosphate ion chelation reaction

An electrochemical immunoassay was designed to detect prostate-specific antigen via pyrophosphatase-hydrolysed Cu(ii)-coordinated pyrophosphate ion with the capture of the releasing Cu(ii) ion.

Magnesium Phosphate Cement as Mineral Bone Adhesive

Mineral bone cements were actually not developed for their application as bone-bonding agents, but as bone void fillers. In particular, calcium phosphate cements (CPC) are considered to be unsuitable for that application, particularly under moist conditions. Here, we showed the ex vivo ability of different magnesium phosphate cements (MPC) to adhere on bovine cortical bone substrates. The cements were obtained from a mixture of farringtonite (Mg3(PO4)2) with different amounts of phytic acid (C6H18O24P6, inositol hexaphosphate, IP6), whereas cement setting occurred by a chelation reaction between Mg2+ ions and IP6. We were able to show that cements with 25% IP6 and a powder-to-liquid ratio (PLR) of 2.0 g/mL resulted in shear strengths of 0.81 ± 0.12 MPa on bone even after 7 d storage in aqueous conditions. The samples showed a mixed adhesive–cohesive failure with cement residues on the bone surface as indicated by scanning electron microscopy and energy-dispersive X-ray analysis. The presented material demonstrated appropriate bonding characteristics, which could enable a broadening of the mineral bone cements’ application field to bone adhesives.

The Effects of Different Oxytetracycline and Copper Treatments on the Performance of Anaerobic Digesters and the Dynamics of Bacterial Communities

Oxytetracycline and copper are the common residues in animal manures. Meanwhile, anaerobic digestion is considered as a clean biotechnology for the disposal of animal manures. In this paper, the performance of anaerobic digesters and the dynamics of bacterial communities under the different treatments of oxytetracycline and copper were discussed. The parameters of methane production and pH values were studied to reflect the performance of anaerobic digester. Results showed that the changes of methane production and pH values were not obvious compared with the control. This means that the treatments of oxytetracycline and copper almost have no effects on the performance of anaerobic digesters. This phenomenon might be due to the chelation reaction between oxytetracycline and copper. This chelation reaction might reduce the toxicity of oxytetracycline. The study on the dynamics of bacterial communities was based on the polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) method. Results indicated that the bacterial communities had significant differences under the different treatments of oxytetracycline and copper. UnculturedBacteroidetesbacterium (CU922272.1) and unculturedBacteroidetesbacterium (AB780945.1) showed adaptability to the different treatments of oxytetracycline and copper and were the dominant bacterial communities.