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An On-Off-On type fluorescent sensor (HL) has been developed, which exhibited high selectivity and sensitivity for Cu2+ over other common ions in 100% aqueous solution. Once HL combined with Cu2+, blue fluorescence was almost completely quenched and the L-Cu ensemble was formed. Moreover, the ensemble showed high specificity for S2- based on the displacement approach, and no interferences were observed in the presence of other anions. Such fluorescence modulation behavior simulates the performance of an IMPLICATION logic gate. In addition, the fluorescent sensor was successfully applied to fluorescent cellular imaging implying potential applications in physiological and environmental systems. [ABSTRACT FROM AUTHOR]

The pre-designable porous structures found in covalent organic frameworks (COFs) render them attractive as a molecular platform for addressing environmental issues such as removal of toxic heavy metal ions from water. However, a rational structural design of COFs in this aspect has not been explored. Here we report the rational design of stable COFs for Hg(II) removal through elaborate structural design and control over skeleton, pore size, and pore walls. The resulting framework is stable under strong acid and base conditions, possesses high surface area, has large mesopores, and contains dense sulfide functional termini on the pore walls. These structural features work together in removing Hg(II) from water and achieve a benchmark system that combines capacity, efficiency, effectivity, applicability, selectivity, and reusability. These results suggest that COFs offer a powerful platform for tailor-made structural design to cope with various types of pollution. [ABSTRACT FROM AUTHOR]

A novel porous membrane adsorbent (Tan-ESM) was prepared by grafting of amino groups onto the eggshell membrane surface and then immobilized with tannins. The prepared Tan-ESM adsorbent combined the advantage of the high metal affinity of tannins with high specific surface, high density of surface functional groups as well as water-insoluble of the eggshell membrane. Adsorption property of Tan-ESM was investigated by removing Cu(II) ions from aqueous solution. The physico-chemical properties of Tan-ESM were characterized using infrared spectrometer and scanning electronic microscope. Adsorption experiments were carried out to investigate the effects of several important parameters including solution pH, adsorbent dosage, temperature, contact time and ionic strength of solution on the adsorption behavior. Adsorption capacity of Tan-ESM for Cu(II) ions was five times as much as untreated eggshell membrane. The equilibrium adsorption could be obtained within 30 min. Kinetics experiments indicated that the pseudo-first-order model displayed the best correlation with adsorption kinetics data. Besides, the Crank model showed that the intraparticle solute diffusion is the rate-controlling step. Finally, adsorption data could be better described by the Langmuir isotherm model. Continuous adsorption tests indicated that exhaustion time decreased with increasing initial Cu(II) ions concentration. The high adsorption capacity, effective adsorption–desorption results indicate the prepared Tan-ESM can be an effective adsorbent for removing Cu(II) ions from an aqueous solution. [ABSTRACT FROM AUTHOR]

Graphene oxide nanosheets (GO) were dispersed and crosslinked with a water soluble polymer, namely poly(allylamine hydrochloride) (PAH) with high amine density, to prepared a novel PAH-GO composite, which was used for removing Cu(II) ions from aqueous solutions. The physico-chemical properties of PAH-GO composites were investigated by transmission electron microscopy, thermogravimetric analysis, etc. Adsorption experiments indicated that adsorption process was strongly dependent on pH and temperature, however weakly dependent on ionic strength. The maximum adsorption capacity was about 349.03 mg/g higher than that of currently reported. Competitive adsorption studies for the ternary system suggested that the adsorption of PAH-GO composite for Cu(II) ions was much preferable to Cd(II) and Ni(II) ions. Thermodynamic parameters suggested that adsorptions were endothermic and spontaneous processes. The Langmuir adsorption isotherm was applicable fit adsorption process, and adsorption kinetic process could be described by the pseudo-second-order model. Adsorption–desorption results showed that the reusability of PAH-GO composite was encouraging. Based on the results obtained, we conclude that PAH-GO composite can be an effective and potential adsorbent for removing Cu(II) ions from an aqueous solution. [ABSTRACT FROM AUTHOR]

Three propionic acid ionic liquids(PrAILs), 1-alkyl-3-methylimidazoliumpropionate ([Cnmim][Pro] (n= 4, 5, 6)), were prepared by the neutralization method and characterizedby 1H NMR spectroscopy. The values of the densities andsurface tensions of aqueous [C4mim][Pro], [C5mim][Pro], and [C6mim][Pro] with various molalities weredetermined at 298 K, and the values of the parachor for these solutionswere calculated. The values of the apparent molar volumes and partialmolar volumes at infinite dilution for the ILs were estimated in termsof Pitzer’s theory. With the use of Li’s model of surfacetension and the empirical equation of the parachor, the values ofthe surface tensions of these aqueous solutions for three PrAILs wereestimated and the estimated values were in good agreement with experimentalones. [ABSTRACT FROM AUTHOR]