Traces of antibiotics within domestic and industrial effluents have toxic impact on human health as well as surrounding flora and fauna. Potential increase in antibiotic resistance of microorganisms is likely to rise due to the incomplete removal of antibiotics by traditional wastewater processing, methods such as membrane filtration and biological treatment. In this study, we investigated a novel class of material termed Polymer of Intrinsic Microporosity (PIM) that is based on amorphous microporous organic materials for the application of antibiotic removal form aqueous environments. The adsorption of four commonly used antibiotics (doxycycline, ciprofloxacin, penicillin G, and amoxicillin) was evaluated and found that at least 80% of the initial concentrations was eliminated under the optimized conditions. Langmuir and Freundlich models were then employed to correlate the equilibria data; the Freundlich model fit well the data in all cases. For kinetic data, pseudo-first and second order models were examined. Pseudo-second order model fit well the kinetic data and allowed the calculation of the adsorption rate constants. Thermodynamic parameters were obtained by conducting the adsorption studies at varied reaction temperatures. Surface potential, adsorption at various solution pHs, thermogravimetric analysis (TGA), Infrared spectroscopy (IR), and surface area experiments were conducted to draw possible adsorption mechanisms. The removal of antibiotics from water by PIM-1 is likely to be governed by both surface and pore-filling adsorption and could be facilitated by electrostatic interactions between the aromatic rings and charged functional groups as well as hydrogen bond formation between the adsorbent and adsorbate. Our work shows that the application of such novel microporous material could contribute to the removal of such challenging and persistent contaminants from wastewater with further optimizations of large-scale adsorption processes.

Bacterial antibiotic resistance has been deemed one of the largest modern threats to human health. One of the root causes of antibiotic resistance is the inability of traditional wastewater management techniques, such as filtration and disinfection, to completely eliminate residual antibiotics from domestic and industrial effluents. In this study, we examine the ability of UiO-66; a metal-organic framework (MOF); in removing the antibiotic Doxycycline from aqueous environments. This study’s findings suggest that UiO-66 was able to remove nearly 90% of the initial Doxycycline concentration. To correlate the isothermal data, Langmuir and Freundlich models were used. It was determined that the Langmuir model was best suited. Pseudo-first and -second order models were examined for kinetic data, where the pseudo-second order model was best suited—consistent with the maximum theoretical adsorption capacity found by the Langumir model. Thermodynamic analysis was also examined by studying UiO-66 adsorption under different temperatures. Mechanisms of adsorption were also analyzed through measuring adsorption at varying pH levels, thermogravimetric analysis (TGA), Infrared spectroscopy (IR) and Brunauer–Emmet–Teller (BET). This study also explores the possibility of recycling MOFs through exposure to gamma radiation, heat, and heating under low pressure, in order for UiO-66 to be used in multiple, consecutive cycles of Doxycycline removal.

New cationic enamine-β-diimine cobalt complex [LCoBr·THF][BArF] (I) and its neutral analogue [LCoBr₂] (II) where L = [(2,4,6-Me₃-C₆H₂)NHCMeC{CMe(N-2,4,6-Me₃(C₆H₂))}₂] and BArF⁻ = [{3,5-(CF₃)₂C₆H₃}₄B]⁻, were synthesised and then characterized by single-crystal X-ray diffraction, MALDI-MS, IR and elemental analysis. These complexes, the first examples reported where putatively tridentate β-triketimines prefer a bidentate coordination mode, were examined as catalysts for the polymerization of isoprene, activated by diethylaluminium chloride (DEAC) or ethylaluminium sesquichloride (EASC). The weakly coordinating BArF anion in I strongly improved activity in comparison to II. Both I and II produced polyisoprene of ca. 80% cis-1,4 and 20% 3,4 enchainment, with trace levels of trans-1,4 and no 1, 2 polymer. A kinetic study for both I and II demonstrated that the polymerization was first-order in monomer and that approximately 46% and 50% of cobalt formed active centres for I and II respectively. EASC was the most active of a range of organoaluminium compounds screened for both I and II. The resulting activities of up to 6 × 10⁵ mol isoprene per mol Co per h are the highest yet recorded for catalysts selective for cis-1,4 enchained polyisoprene.

Cobalt II ions ligated by fac -κ ³ -β-triketimine ligands form bromide-bridged square-based pyramidal dimers which upon activation with MAO and fed with a constant supply of butadiene produce high- cis -1,4-polybutadiene with activities and molecular weights surpassing all previously seen for this metal.

Four new β-triketimine cobalt complexes [(LCo-μ-Br)₂][BArF]₂ where L = N,N′,N′′-triaryl-β-diketimine were synthesised and then characterized by single-crystal X-ray diffraction, MALDI-MS and elemental analysis. In combination with three previously reported, they provided a series of seven subtly different complexes which were screened for activity in the catalysis of isoprene polymerization: the structure of the ligand (L) had strong effects on activity and stereoselectivity. The produced polyisoprene contained a mixture of cis-1,4, trans-1,4 and 3,4-enchained monomers; 4,1-errors followed 3,4 errors. The highest percentage of cis-1,4 content (80%) was obtained with complex 5 where two electron-withdrawing fluorine substituents occupied the 2- and 6-positions of two of the imino-aryl rings. This polymer was obtained in 98.5% conversion. Both cis-1,4 content and activity decreased when electron donor substituents were present on the aryl rings, so that complex 1, with three methyl substituents in positions 2, 4 and 6 gave the lowest cis-1,4 content (73.6%), with a conversion of only 58.5%, under identical conditions. The temperature of the polymerization, the type of aluminium co-catalyst used, and the Al/Co ratio strongly affected the activity and microstructure of the polyisoprene produced. Ethylaluminiumsesquichloride was the most active of a range of organoaluminiums screened. A kinetic study using complex 6 as catalyst demonstrated that the polymerization was first-order in monomer, and that approximately 12% of cobalt formed active centers. The combination of high molecular weight (>10⁵) with moderately high activity at conveniently accessible temperatures to give predominantly cis-1,4-polyisoprene but with 3,4 units to promote efficient crosslinking is potentially attractive, and has not previously been attained with 3d elements.

Two cobalt complexes, the α-diimine complex 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene-cobalt(II) dibromide (A) and the β-diimine complex 2,4-bis[(2,6-diisopropylphenyl)imino]pentane-cobalt(II) dibromide (B) were synthesized and fully characterized by elemental analysis, electrospray MS and single crystal X-ray diffraction. These complexes were then assessed as pre-catalysts of the polymerization of isoprene in chlorobenzene using diethylaluminiumchloride (DEAC) as co-catalyst at 35 °C. While the aryl substituents were identical in each case, the β-diimine complex B was over 100-fold more active (R_p = 1.17 × 10⁻³ M s⁻¹) than α-diimine complex A (R_p = 1.07 × 10⁻⁵ M s⁻¹). A produced polyisoprene with molecular weight (M_n = 2.1 × 10⁵ g mol⁻¹) double that achieved with B. The polymers produced by both A and B were predominantly cis-1,4 enchained (80%) with 3,4 regioerrors (20%). For B, this 1,4 : 3,4 selectivity ratio was not influenced by aluminium alkyl reagent (ethylaluminiumsesquichloride (EASC), or DEAC) whereas for A, where EASC co-catalyst was used, a 1,4-trans-rich (61%) polyisoprene was obtained. Moreover, increasing Al mole ratio decreased the activity for B but increased it for A.