Green synthesis of diatom-allophane bio-nanocomposites for highly efficient oxytetracycline adsorption.

The extensive use of the antibiotic oxytetracycline (OTC) has led to considerable environmental contamination and other negative impacts, prompting an urgent need for a green, effective, and innovative OTC adsorption material. In this study, diatom-allophane bio-nanocomposites were synthesized using a simple and eco-friendly method, yielding a homogeneous coating of allophane nanoparticles on diatom surfaces. The resultant bio-nanocomposites were found to have hierarchically porous structures and abundant active sites derived from successful allophane loading and dispersion on diatom surfaces. The OTC adsorption capacity of this novel adsorbent is remarkable (219.112 mg·g-1), surpassing the capacities of raw allophane and diatoms by >5 and 10 times, respectively. Mechanistically, OTC adsorption by the bio-nanocomposites was found to be driven primarily by chemisorption through a process involving complexation between the amide and amino groups on OTC and the aluminum hydroxyl and carboxyl groups on the adsorbent surface. Electrostatic interactions and hydrogen bonding also contribute significantly to OTC capture. Furthermore, the diatom-allophane bio-nanocomposites exhibit excellent performance over a wide pH range (4-7), in the presence of various cations (Na+, K+, Ca2+, Mg2+) and anions (Cl-, NO3-, SO42-), and in real water bodies. These findings demonstrate the potential of the diatom-allophane bio-nanocomposite as a green, efficient, and promising biological-mineral adsorbent for environmental remediation, leveraging the combined utilization of biological and mineral resources.

Construction of an allophane-based molecularly imprinted polymer for the efficient removal of antibiotic from aqueous solution.

The widespread presence of ciprofloxacin (CIP) antibiotic in the water and soil poses substantial potential risks to the environment, threatening both human and animal health. In this study, we used nanoclay mineral allophane (Allo), ß-cyclodextrin (ß-CD) as a bifunctional monomer, and sodium alginate as a cross-linking agent, to prepare 3D porous Allo-ß-CD molecularly imprinted polymers (MIPs) for the efficient removal of CIP from aqueous solution. The prepared Allo-ß-CD MIP was characterized by scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and zeta potential measurements. The effects of initial concentration, time, pH level, and ion concentration on CIP removal dynamics were systematically studied. The adsorption kinetics and equilibrium data of CIP were well-fitted by the pseudo-second-order kinetic model and Langmuir isotherm models, respectively. The Allo-ß-CD MIP can efficiently remove CIP from an aqueous solution, with a maximal adsorption capacity of 635 mg/g. It also has impressive recyclability, and enhanced selectivity, and is widely adaptable to various environmental conditions. The adsorption mechanisms of the as-prepared adsorbent include H bonds, hydrophobic interactions, surface complexation, and n-π EDA interactions. Given the experimental evidence, as-prepared adsorbent is therefore a promising candidate for the effective removal of CIP from the aquatic environment.

Intensive adsorption of tetracycline by cobalt oxide quantum dots-loaded mineral carbon.

Spent bleaching earth (SBE), a waste by-product produced from the bleaching step of edible oil by montmorillonite clays (bleaching earth), causes serious public health and environmental problems. Accordingly, in this study, SBE was pyrolyzed to yield mineral carbon materials (SBE@C) and cobalt oxide (Co3O4) was loaded to improve the active site of those materials. Due to the carrier function of SBE@C, ultra-fine Co3O4 quantum dots (QDs) (2-6 nm) were homogeneously and robustly immobilized onto SBE@C. The obtained adsorbent exhibited high regeneration performance and an outstanding adsorption capacity (253.36 mg/g). It can be attributed to the surface complexation of cobalt with TC being the dominant process contributing to adsorption behavior. Further, Co3O4 QDs-SBE@C still maintained adequate sorption capacity at a broad range of pH values and in the presence of co-occurring ions. These results suggested the significant application potential of SBE and demonstrated the efficiency of using Co3O4 QDs-SBE@C for wastewater remediation.

Highly Efficient Ruthenium-Catalyzed Semi-hydrogenation of Urea Derivatives to Formamides.

The utilization of CO2 as a non-toxic and cheap feedstock for C1 is a desirable route to achieve high value-added chemicals. In this context, we report a highly efficient ruthenium-catalyzed semi-hydrogenation reaction of CO2 -derived ureas. Various alkyl and aryl urea derivatives were successfully hydrogenated to obtain the corresponding recyclable amines and formamides (up to 97 % yield), highlighting the good substrate applicability of this method, which makes this method a sustainable alternative for the hydrogenation of CO2 to formamides in the presence of amines. In the meantime, we have discovered a new pathway that enables rapid hydrogenation of urea derivatives even at lower H2 pressure (<5 bar). This methodology might provide a new insight into the reduction functionalization of CO2 under mild pressure to form new C-N bond. Based on the control experiments and the observed intermediate products, we clarify the mechanism for selective semi-hydrogenation of ureas.

[Study on the relationship between iodine status and growth in infants at the key period of brain development].

OBJECTIVE: To investigate the relationship between iodine nutrition and growth/development in infants at the key period of brain development. METHODS: All women from pregnancy to the end of lactation and the weaning infants within 3 years in the Linxia Hui Autonomous Prefecture (Linxia Prefecture) were added iodized oil in 2006 - 2010. In 2006, 2010 one town was randomly selected from each of the five directions (east, south, west, north, central) of each county in Linxia Prefecture. One village was chosen from every town and 20 infants, 20 pregnant women and 20 lactating women were randomly selected in each town. Urinary iodine (UI) of the infants, pregnant and lactating women were determined. DQ value, height and weight of part of infants were measured. According to the above sampling plan, UI of pregnant women, lactating women and infants had been monitored every year after intervention. 0-3 infants were choosing to be control before intervention. RESULTS: UI of 1056 and 2989 0-3 infants were investigated before and after the iodine oil intervention. After the 'iodine oil' intervention, the median UI of infants increased from 107.3 µg/L to 139.6 - 190.7 µg/L, the percentage of UI level that lower than 50 µg/L, decreased from 23.9% to 6.7% - 12.9%. DQ value increased from 92.8 to 104.3, the percentage of normal height and above increased from 65.0% to 82.1% and the percentage of the normal weight and above, increased from 59.3% to 81.4%. The outcomes of DQ value, height and weight showed statistically significant differences, compared to the pre-intervention outcomes (P < 0.05). The median UI of pregnant and lactating women increased from 89.3 µg/L to 118.2 - 187.8 µg/L and from 84.9 µg/L to 135.2 - 187.5 µg/L respectively. CONCLUSION: Infant's growth and development were retarded when iodine deficiency existed at the key period of brain development. Intake of oral iodine oil at key period of brain development could provide adequate nutrition thus improve growth and development on infants.