RESUMO
The hydrophobic nature of an extractant is particularly critical in the treatment of wastewater. Considering that dicationic ionic liquids (DILs) are likely to be more hydrophobic, a comparative study of the separation of phenol from waters using [NTf2]- based monocationic ionic liquids (MILs) and DILs is carried out both from experimental and theoretical analysis perspectives. Experimental results revealed that DILs exhibited superior extraction ability compared to MILs, with extraction efficiencies of 93.7% and 97.4% using [BMIM][NTf2] and [C6(MIM)2][NTf2]2 as extractants, respectively. The microscopic examination through theoretical calculations elucidated the higher hydrophobicity and extraction efficiency of DILs over MILs. The results indicated that the DIL showed stronger hydrophobicity than the MIL because the hydrogen bond strength between the DIL and water was lower than that of the MIL. Although the hydrogen bond strength between the DIL and phenol was lower than that of the MIL, the stronger van der Waals forces existed between DIL and phenol, so DIL was more efficient in extracting phenol. In addition, the experimental parameters were optimized to provide basic data for application, such as mass ratio of ILs to water, extraction time and temperature, pH, and initial phenol content. Finally, the DILs were recovered using rotary evaporation apparatus, and the results demonstrated that DILs had good recovery and reuse performance. In brief, this work could provide an effective method for the treatment of phenol-containing wastewater. And the revelation of molecular mechanism is expected to positively impact the design of high-performance task-specific ILs.
Assuntos
Líquidos Iônicos , Líquidos Iônicos/química , Fenol , Águas Residuárias , Fenóis , Água/química , Interações Hidrofóbicas e HidrofílicasRESUMO
Ajaniaflavida, a new species from western Sichuan and eastern Xizang, China, is described and illustrated. It is readily assigned to A.sect.Ajania owing to its straw-colored, glossy involucres and marginally whitish scarious phyllaries. Within the section, it is distinct in being a shrub of 1-2 m in height, and in having creamy yellow florets. It is superficially similar to A.ramosa in A.sect.Phaeoscyphus, but can easily be distinguished by, among other characters, the plant height, color of the florets and margins of the phyllaries. In addition, we provide a distribution map of the new species.
RESUMO
Ligularialushuiensis, a new species from northwestern Yunnan, China, is described and illustrated. It was tentatively placed in L.sect.Ligulariaser.Ligularia on the basis of the pinnate-palmate leaf venation, racemose synflorescence and pappus which is as long as tubular corolla. Within the series, it appeared somewhat close to both L.lamarum and L.pseudolamarum. However, L.lushuiensis can be easily distinguished from the latter two species by, among other characters, the leaf margin, bract size, involucre shape and size, and number and width of ray florets. Morphologically, L.lushuiensis is also superficially similar to L.secunda but differs readily by having distally shortly yellowish and brownish puberulent stems, palmately-pinnately veined leaves regularly dentate at margin, scarious, brown and larger bracts, and larger ray laminae. In addition, a distribution map and a diagnostic key to Chinese species of L.ser.Ligularia are also provided.